Merge branch 'staging-unstable' into 'master'

Basic, but fully functional implementation

See merge request s3lph/matemat!23

.gitlab-ci.yml

@@ -29,7 +29,7 @@ build:
   - docker push "registry.gitlab.com/s3lph/matemat:$(git rev-parse HEAD)"
   - docker push registry.gitlab.com/s3lph/matemat:latest-staging
   only:
-  - /^staging-.*$/
+  - staging
 
 staging:
   stage: staging
@@ -41,4 +41,4 @@ staging:
     name: staging
     url: https://matemat.kernelpanic.lol/
   only:
-  - /^staging-.*$/
+  - staging

doc

@@ -1 +1 @@
-Subproject commit 92e168a288b396a7a97d200b80affdf8690bd03d
+Subproject commit ece840af5b19d2c78b2dbfa14adac145fab79f4f

matemat/db/facade.py

@@ -4,7 +4,7 @@ from typing import List, Optional, Any, Type
 import crypt
 from hmac import compare_digest
 
-from matemat.primitives import User, Product
+from matemat.db.primitives import User, Product
 from matemat.exceptions import AuthenticationError, DatabaseConsistencyError
 from matemat.db import DatabaseWrapper
 from matemat.db.wrapper import Transaction
@@ -232,7 +232,7 @@ class MatematDatabase(object):
                 'tkhash': tkhash
             })
 
-    def change_user(self, user: User, **kwargs)\
+    def change_user(self, user: User, agent: Optional[User], **kwargs)\
             -> None:
         """
         Commit changes to the user in the database.  If writing the requested changes succeeded, the values are updated
@@ -240,6 +240,7 @@ class MatematDatabase(object):
         the ID field in the provided user object.
 
         :param user: The user object to update and to identify the requested user by.
+        :param agent: The user that is performing the change.  Must be present if the balance is changed.
         :param kwargs: The properties to change.
         :raises DatabaseConsistencyError: If the user represented by the object does not exist.
         """
@@ -250,6 +251,27 @@ class MatematDatabase(object):
         is_admin: bool = kwargs['is_admin'] if 'is_admin' in kwargs else user.is_admin
         is_member: bool = kwargs['is_member'] if 'is_member' in kwargs else user.is_member
         with self.db.transaction() as c:
+            c.execute('SELECT balance FROM users WHERE user_id = :user_id', {'user_id': user.id})
+            row = c.fetchone()
+            if row is None:
+                raise DatabaseConsistencyError(f'User with ID {user.id} does not exist')
+            oldbalance: int = row[0]
+            if balance != oldbalance:
+                if agent is None:
+                    raise ValueError('agent must not be None for a balance change')
+                c.execute('''
+                INSERT INTO transactions (user_id, value, old_balance)
+                  VALUES (:user_id, :value, :old_balance)
+                ''', {
+                    'user_id': user.id,
+                    'value': balance - oldbalance,
+                    'old_balance': oldbalance
+                })
+                # TODO: Implement reason field
+                c.execute('''
+                INSERT INTO modifications (ta_id, agent_id, reason)
+                  VALUES (last_insert_rowid(), :agent_id, NULL)
+                ''', {'agent_id': agent.id})
             c.execute('''
             UPDATE users SET
               username = :username,
@@ -411,60 +433,38 @@ class MatematDatabase(object):
                 raise DatabaseConsistencyError(
                     f'delete_product should affect 1 products row, but affected {affected}')
 
-    def increment_consumption(self, user: User, product: Product, count: int = 1) -> None:
+    def increment_consumption(self, user: User, product: Product) -> None:
         """
         Decrement the user's balance by the price of the product, decrement the products stock, and create an entry in
         the statistics table.
+
         :param user: The user buying a product.
         :param product: The product the user is buying.
-        :param count: How many units of the product the user is buying, defaults to 1.
         :raises DatabaseConsistencyError: If the user or the product does not exist in the database.
         """
+        price: int = product.price_member if user.is_member else product.price_non_member
         with self.db.transaction() as c:
-            # Retrieve the consumption entry for the (user, product) pair, if any.
             c.execute('''
-            SELECT count
+            INSERT INTO transactions (user_id, value, old_balance)
-            FROM consumption
+              VALUES (:user_id, :value, :old_balance)
-            WHERE user_id = :user_id
-              AND product_id = :product_id
             ''', {
                 'user_id': user.id,
+                'value': -price,
+                'old_balance': user.balance
+            })
+            c.execute('''
+            INSERT INTO consumptions (ta_id, product_id)
+              VALUES (last_insert_rowid(), :product_id)
+            ''', {
                 'product_id': product.id
             })
-            row = c.fetchone()
+            # Subtract the price from the user's account balance.
-            if row is None:
-                # If the entry does not exist, create a new one.
-                c.execute('''
-                INSERT INTO consumption (user_id, product_id, count)
-                VALUES (:user_id, :product_id, :count)
-                ''', {
-                    'user_id': user.id,
-                    'product_id': product.id,
-                    'count': count
-                })
-            else:
-                # If the entry exists, update the consumption count.
-                c.execute('''
-                UPDATE consumption
-                SET count = count + :count
-                WHERE user_id = :user_id AND product_id = :product_id
-                ''', {
-                    'user_id': user.id,
-                    'product_id': product.id,
-                    'count': count
-                })
-            # Make sure exactly one consumption row was updated/inserted.
-            affected = c.execute('SELECT changes()').fetchone()[0]
-            if affected != 1:
-                raise DatabaseConsistencyError(
-                    f'increment_consumption should affect 1 consumption row, but affected {affected}')
-            # Compute the cost of the transaction and subtract it from the user's account balance.
             c.execute('''
             UPDATE users
             SET balance = balance - :cost
             WHERE user_id = :user_id''', {
                 'user_id': user.id,
-                'cost': count * product.price_member if user.is_member else count * product.price_non_member
+                'cost': price
             })
             # Make sure exactly one user row was updated.
             affected = c.execute('SELECT changes()').fetchone()[0]
@@ -474,11 +474,10 @@ class MatematDatabase(object):
             # Subtract the number of purchased units from the product's stock.
             c.execute('''
             UPDATE products
-            SET stock = stock - :count
+            SET stock = stock - 1
             WHERE product_id = :product_id
             ''', {
                 'product_id': product.id,
-                'count': count
             })
             # Make sure exactly one product row was updated.
             affected = c.execute('SELECT changes()').fetchone()[0]
@@ -509,6 +508,7 @@ class MatematDatabase(object):
     def deposit(self, user: User, amount: int) -> None:
         """
         Update the account balance of a user.
+
         :param user: The user to update the account balance for.
         :param amount: The amount to add to the account balance.
         :raises DatabaseConsistencyError: If the user represented by the object does not exist.
@@ -516,6 +516,18 @@ class MatematDatabase(object):
         if amount < 0:
             raise ValueError('Cannot deposit a negative value')
         with self.db.transaction() as c:
+            c.execute('''
+            INSERT INTO transactions (user_id, value, old_balance)
+              VALUES (:user_id, :value, :old_balance)
+            ''', {
+                'user_id': user.id,
+                'value': amount,
+                'old_balance': user.balance
+            })
+            c.execute('''
+            INSERT INTO deposits (ta_id)
+              VALUES (last_insert_rowid())
+            ''')
             c.execute('''
             UPDATE users
             SET balance = balance + :amount

matemat/db/migrations.py

@@ -0,0 +1,115 @@
+
+from typing import Dict
+
+import sqlite3
+
+
+def migrate_schema_1_to_2(c: sqlite3.Cursor):
+    # Create missing tables
+    c.execute('''
+        CREATE TABLE transactions (
+          ta_id INTEGER PRIMARY KEY,
+          user_id INTEGER NOT NULL,
+          value INTEGER(8) NOT NULL,
+          old_balance INTEGER(8) NOT NULL,
+          date INTEGER(8) DEFAULT (STRFTIME('%s', 'now')),
+          FOREIGN KEY (user_id) REFERENCES users(user_id)
+            ON DELETE CASCADE ON UPDATE CASCADE
+        );
+    ''')
+    c.execute('''
+        CREATE TABLE consumptions (
+          ta_id INTEGER PRIMARY KEY,
+          product_id INTEGER DEFAULT NULL,
+          FOREIGN KEY (ta_id) REFERENCES transactions(ta_id)
+            ON DELETE CASCADE ON UPDATE CASCADE,
+          FOREIGN KEY (product_id) REFERENCES products(product_id)
+            ON DELETE SET NULL ON UPDATE CASCADE
+        );
+    ''')
+    c.execute('''
+        CREATE TABLE deposits (
+          ta_id INTEGER PRIMARY KEY,
+          FOREIGN KEY (ta_id) REFERENCES transactions(ta_id)
+            ON DELETE CASCADE ON UPDATE CASCADE
+        );
+    ''')
+    c.execute('''
+        CREATE TABLE modifications (
+          ta_id INTEGER NOT NULL,
+          agent_id INTEGER NOT NULL,
+          reason TEXT DEFAULT NULL,
+          PRIMARY KEY (ta_id),
+          FOREIGN KEY (ta_id) REFERENCES transactions(ta_id)
+            ON DELETE CASCADE ON UPDATE CASCADE,
+          FOREIGN KEY (agent_id) REFERENCES users(user_id)
+            ON DELETE SET NULL ON UPDATE CASCADE
+        );
+    ''')
+
+    #
+    # Convert entries from the old consumption table into entries for the new consumptions table
+    #
+
+    # Fetch current users, their balance and membership status
+    c.execute('SELECT user_id, balance, is_member FROM users')
+    balances: Dict[int, int] = dict()
+    memberships: Dict[int, bool] = dict()
+    for user_id, balance, member in c:
+        balances[user_id] = balance
+        memberships[user_id] = bool(member)
+
+    # Fetch current products and their prices
+    c.execute('SELECT product_id, price_member, price_non_member FROM products')
+    prices_member: Dict[int, int] = dict()
+    prices_non_member: Dict[int, int] = dict()
+    for product_id, price_member, price_non_member in c:
+        prices_member[product_id] = price_member
+        prices_non_member[product_id] = price_non_member
+
+    # As the following migration does reverse insertions, compute the max. primary key that can occur, and
+    # further down count downward from there
+    c.execute('SELECT SUM(count) FROM consumption')
+    ta_id: int = c.fetchone()[0]
+
+    # Iterate (users x products)
+    for user_id in balances.keys():
+        member: bool = memberships[user_id]
+        for product_id in prices_member:
+            price: int = prices_member[product_id] if member else prices_non_member[product_id]
+
+            # Select the number of items the user has bought from this product
+            c.execute('''
+                SELECT consumption.count FROM consumption
+                  WHERE user_id = :user_id AND product_id = :product_id
+                ''', {
+                'user_id': user_id,
+                'product_id': product_id
+            })
+            row = c.fetchone()
+            if row is not None:
+                count: int = row[0]
+                # Insert one row per bought item, setting the date to NULL, as it is not known
+                for _ in range(count):
+                    # This migration "goes back in time", so after processing a purchase entry, "locally
+                    # refund" the payment to reconstruct the "older" entries
+                    balances[user_id] += price
+                    # Insert into base table
+                    c.execute('''
+                        INSERT INTO transactions (ta_id, user_id, value, old_balance, date)
+                          VALUES (:ta_id, :user_id, :value, :old_balance, NULL)
+                        ''', {
+                        'ta_id': ta_id,
+                        'user_id': user_id,
+                        'value': -price,
+                        'old_balance': balances[user_id]
+                    })
+                    # Insert into specialization table
+                    c.execute('INSERT INTO consumptions (ta_id, product_id) VALUES (:ta_id, :product_id)', {
+                        'ta_id': ta_id,
+                        'product_id': product_id
+                    })
+                    # Decrement the transaction table insertion primary key
+                    ta_id -= 1
+    # Drop the old consumption table
+    c.execute('DROP TABLE consumption')

matemat/db/schemas.py

@@ -0,0 +1,103 @@
+from typing import Dict, List
+
+SCHEMAS: Dict[int, List[str]] = dict()
+
+SCHEMAS[1] = [
+    '''
+    CREATE TABLE users (
+      user_id INTEGER PRIMARY KEY,
+      username TEXT UNIQUE NOT NULL,
+      email TEXT DEFAULT NULL,
+      password TEXT NOT NULL,
+      touchkey TEXT DEFAULT NULL,
+      is_admin INTEGER(1) NOT NULL DEFAULT 0,
+      is_member INTEGER(1) NOT NULL DEFAULT 1,
+      balance INTEGER(8) NOT NULL DEFAULT 0,
+      lastchange INTEGER(8) NOT NULL DEFAULT 0
+    );
+    ''',
+    '''
+    CREATE TABLE products (
+      product_id INTEGER PRIMARY KEY,
+      name TEXT UNIQUE NOT NULL,
+      stock INTEGER(8) NOT NULL DEFAULT 0,
+      price_member INTEGER(8) NOT NULL,
+      price_non_member INTEGER(8) NOT NULL
+    );
+    ''',
+    '''
+    CREATE TABLE consumption (
+      user_id INTEGER NOT NULL,
+      product_id INTEGER NOT NULL,
+      count INTEGER(8) NOT NULL DEFAULT 0,
+      PRIMARY KEY (user_id, product_id),
+      FOREIGN KEY (user_id) REFERENCES users(user_id)
+        ON DELETE CASCADE ON UPDATE CASCADE,
+      FOREIGN KEY (product_id) REFERENCES products(product_id)
+        ON DELETE CASCADE ON UPDATE CASCADE
+    );
+    ''']
+
+SCHEMAS[2] = [
+    '''
+    CREATE TABLE users (
+      user_id INTEGER PRIMARY KEY,
+      username TEXT UNIQUE NOT NULL,
+      email TEXT DEFAULT NULL,
+      password TEXT NOT NULL,
+      touchkey TEXT DEFAULT NULL,
+      is_admin INTEGER(1) NOT NULL DEFAULT 0,
+      is_member INTEGER(1) NOT NULL DEFAULT 1,
+      balance INTEGER(8) NOT NULL DEFAULT 0,
+      lastchange INTEGER(8) NOT NULL DEFAULT 0
+    );
+    ''',
+    '''
+    CREATE TABLE products (
+      product_id INTEGER PRIMARY KEY,
+      name TEXT UNIQUE NOT NULL,
+      stock INTEGER(8) NOT NULL DEFAULT 0,
+      price_member INTEGER(8) NOT NULL,
+      price_non_member INTEGER(8) NOT NULL
+    );
+    ''',
+    '''
+    CREATE TABLE transactions (  -- "superclass" of the following 3 tables
+      ta_id INTEGER PRIMARY KEY,
+      user_id INTEGER NOT NULL,
+      value INTEGER(8) NOT NULL,
+      old_balance INTEGER(8) NOT NULL,
+      date INTEGER(8) DEFAULT (STRFTIME('%s', 'now')),
+      FOREIGN KEY (user_id) REFERENCES users(user_id)
+        ON DELETE CASCADE ON UPDATE CASCADE
+    );
+    ''',
+    '''
+    CREATE TABLE consumptions (  -- transactions involving buying a product
+      ta_id INTEGER PRIMARY KEY,
+      product_id INTEGER DEFAULT NULL,
+      FOREIGN KEY (ta_id) REFERENCES transactions(ta_id)
+        ON DELETE CASCADE ON UPDATE CASCADE,
+      FOREIGN KEY (product_id) REFERENCES products(product_id)
+        ON DELETE SET NULL ON UPDATE CASCADE
+    );
+    ''',
+    '''
+    CREATE TABLE deposits (  -- transactions involving depositing cash
+      ta_id INTEGER PRIMARY KEY,
+      FOREIGN KEY (ta_id) REFERENCES transactions(ta_id)
+        ON DELETE CASCADE ON UPDATE CASCADE
+    );
+    ''',
+    '''
+    CREATE TABLE modifications (  -- transactions involving balance modification by an admin
+      ta_id INTEGER NOT NULL,
+      agent_id INTEGER NOT NULL,
+      reason TEXT DEFAULT NULL,
+      PRIMARY KEY (ta_id),
+      FOREIGN KEY (ta_id) REFERENCES transactions(ta_id)
+        ON DELETE CASCADE ON UPDATE CASCADE,
+      FOREIGN KEY (agent_id) REFERENCES users(user_id)
+        ON DELETE CASCADE ON UPDATE CASCADE
+    );
+    ''']

matemat/db/test/test_facade.py

@@ -143,18 +143,23 @@ class DatabaseTest(unittest.TestCase):
 
     def test_change_user(self) -> None:
         with self.db as db:
+            agent = db.create_user('admin', 'supersecurepassword', 'admin@example.com', True, True)
             user = db.create_user('testuser', 'supersecurepassword', 'testuser@example.com', True, True)
-            user.email = 'newaddress@example.com'
+            db.change_user(user, agent, email='newaddress@example.com', is_admin=False, is_member=False, balance=4200)
-            user.is_admin = False
+            # Changes must be reflected in the passed user object
-            user.is_member = False
+            self.assertEqual('newaddress@example.com', user.email)
-            db.change_user(user)
+            self.assertFalse(user.is_admin)
-            checkuser = db.login('testuser', 'supersecurepassword')
+            self.assertFalse(user.is_member)
-            self.assertEqual('newaddress@example.com', checkuser.email)
+            self.assertEqual(4200, user.balance)
+            # Changes must be reflected in the database
+            checkuser = db.get_user(user.id)
+            self.assertEqual('newaddress@example.com', user.email)
             self.assertFalse(checkuser.is_admin)
             self.assertFalse(checkuser.is_member)
+            self.assertEqual(4200, checkuser.balance)
             user._user_id = -1
             with self.assertRaises(DatabaseConsistencyError):
-                db.change_user(user)
+                db.change_user(user, agent, is_member='True')
 
     def test_delete_user(self) -> None:
         with self.db as db:
@@ -221,14 +226,18 @@ class DatabaseTest(unittest.TestCase):
     def test_change_product(self) -> None:
         with self.db as db:
             product = db.create_product('Club Mate', 200, 200)
-            product.name = 'Flora Power Mate'
+            db.change_product(product, name='Flora Power Mate', price_member=150, price_non_member=250, stock=42)
-            product.price_member = 150
+            # Changes must be reflected in the passed object
-            product.price_non_member = 250
+            self.assertEqual('Flora Power Mate', product.name)
-            db.change_product(product)
+            self.assertEqual(150, product.price_member)
-            checkproduct = db.list_products()[0]
+            self.assertEqual(250, product.price_non_member)
+            self.assertEqual(42, product.stock)
+            # Changes must be reflected in the database
+            checkproduct = db.get_product(product.id)
             self.assertEqual('Flora Power Mate', checkproduct.name)
             self.assertEqual(150, checkproduct.price_member)
             self.assertEqual(250, checkproduct.price_non_member)
+            self.assertEqual(42, checkproduct.stock)
             product._product_id = -1
             with self.assertRaises(DatabaseConsistencyError):
                 db.change_product(product)
@@ -313,14 +322,14 @@ class DatabaseTest(unittest.TestCase):
             db.restock(fritzmate, 10)
 
             # user1 is somewhat addicted to caffeine
-            db.increment_consumption(user1, clubmate, 1)
+            for _ in range(3):
-            db.increment_consumption(user1, clubmate, 2)
+                db.increment_consumption(user1, clubmate)
-            db.increment_consumption(user1, florapowermate, 3)
+                db.increment_consumption(user1, florapowermate)
 
             # user2 is reeeally addicted
-            db.increment_consumption(user2, clubmate, 7)
+            for _ in range(7):
-            db.increment_consumption(user2, florapowermate, 3)
+                db.increment_consumption(user2, clubmate)
-            db.increment_consumption(user2, florapowermate, 4)
+                db.increment_consumption(user2, florapowermate)
 
             with db.transaction(exclusive=False) as c:
                 c.execute('''SELECT balance FROM users WHERE user_id = ?''', [user1.id])

matemat/db/test/test_migrations.py

@@ -0,0 +1,124 @@
+
+import unittest
+
+import sqlite3
+
+from matemat.db import DatabaseWrapper
+from matemat.db.schemas import SCHEMAS
+
+
+class TestMigrations(unittest.TestCase):
+
+    def setUp(self):
+        # Create an in-memory database for testing
+        self.db = DatabaseWrapper(':memory:')
+
+    def _initialize_db(self, schema_version: int):
+        self.db._sqlite_db = sqlite3.connect(':memory:')
+        cursor: sqlite3.Cursor = self.db._sqlite_db.cursor()
+        cursor.execute('BEGIN EXCLUSIVE')
+        for cmd in SCHEMAS[schema_version]:
+            cursor.execute(cmd)
+        cursor.execute('COMMIT')
+
+    def test_downgrade_fail(self):
+        # Test that downgrades are forbidden
+        self.db.SCHEMA_VERSION = 1
+        self.db._sqlite_db = sqlite3.connect(':memory:')
+        self.db._sqlite_db.execute('PRAGMA user_version = 2')
+        with self.assertRaises(RuntimeError):
+            with self.db:
+                pass
+
+    def test_upgrade_1_to_2(self):
+        # Setup test db with example entries covering - hopefully - all cases
+        self._initialize_db(1)
+        cursor: sqlite3.Cursor = self.db._sqlite_db.cursor()
+        cursor.execute('''
+            INSERT INTO users VALUES
+              (1, 'testadmin', 'a@b.c', '$2a$10$herebehashes', NULL, 1, 1, 1337, 0),
+              (2, 'testuser', NULL, '$2a$10$herebehashes', '$2a$10$herebehashes', 0, 1, 4242, 0),
+              (3, 'alien', NULL, '$2a$10$herebehashes', '$2a$10$herebehashes', 0, 0, 1234, 0)
+            ''')
+        cursor.execute('''
+            INSERT INTO products VALUES
+              (1, 'Club Mate', 42, 200, 250),
+              (2, 'Flora Power Mate (1/4l)', 10, 100, 150)
+            ''')
+        cursor.execute('''
+            INSERT INTO consumption VALUES
+              (1, 1, 5), (1, 2, 3), (2, 2, 10), (3, 1, 3), (3, 2, 4)
+            ''')
+        cursor.execute('PRAGMA user_version = 1')
+
+        # Kick off the migration
+        self.db._setup()
+
+        # Test whether the new tables were created
+        cursor.execute('PRAGMA table_info(transactions)')
+        self.assertNotEqual(0, len(cursor.fetchall()))
+        cursor.execute('PRAGMA table_info(consumptions)')
+        self.assertNotEqual(0, len(cursor.fetchall()))
+        cursor.execute('PRAGMA table_info(deposits)')
+        self.assertNotEqual(0, len(cursor.fetchall()))
+        cursor.execute('PRAGMA table_info(modifications)')
+        self.assertNotEqual(0, len(cursor.fetchall()))
+        # Test whether the old consumption table was dropped
+        cursor.execute('PRAGMA table_info(consumption)')
+        self.assertEqual(0, len(cursor.fetchall()))
+
+        # Test number of entries in the new tables
+        cursor.execute('SELECT COUNT(ta_id) FROM transactions')
+        self.assertEqual(25, cursor.fetchone()[0])
+        cursor.execute('SELECT COUNT(ta_id) FROM consumptions')
+        self.assertEqual(25, cursor.fetchone()[0])
+        cursor.execute('SELECT COUNT(ta_id) FROM deposits')
+        self.assertEqual(0, cursor.fetchone()[0])
+        cursor.execute('SELECT COUNT(ta_id) FROM modifications')
+        self.assertEqual(0, cursor.fetchone()[0])
+
+        # The (user_id=2 x product_id=1) combination should never appear
+        cursor.execute('''
+            SELECT COUNT(t.ta_id)
+              FROM transactions AS t
+              LEFT JOIN consumptions AS c
+                ON t.ta_id = c.ta_id
+              WHERE t.user_id = 2 AND c.product_id = 1''')
+        self.assertEqual(0, cursor.fetchone()[0])
+
+        # Test that one entry per consumption was created, and their values match the negative price
+        cursor.execute('''
+            SELECT COUNT(t.ta_id)
+              FROM transactions AS t
+              LEFT JOIN consumptions AS c
+                ON t.ta_id = c.ta_id
+              WHERE t.user_id = 1 AND c.product_id = 1 AND t.value = -200''')
+        self.assertEqual(5, cursor.fetchone()[0])
+        cursor.execute('''
+            SELECT COUNT(t.ta_id)
+              FROM transactions AS t
+              LEFT JOIN consumptions AS c
+                ON t.ta_id = c.ta_id
+              WHERE t.user_id = 1 AND c.product_id = 2 AND t.value = -100''')
+        self.assertEqual(3, cursor.fetchone()[0])
+        cursor.execute('''
+            SELECT COUNT(t.ta_id)
+              FROM transactions AS t
+              LEFT JOIN consumptions AS c
+                ON t.ta_id = c.ta_id
+              WHERE t.user_id = 2 AND c.product_id = 2 AND t.value = -100''')
+        self.assertEqual(10, cursor.fetchone()[0])
+        cursor.execute('''
+            SELECT COUNT(t.ta_id)
+              FROM transactions AS t
+              LEFT JOIN consumptions AS c
+                ON t.ta_id = c.ta_id
+              WHERE t.user_id = 3 AND c.product_id = 1 AND t.value = -250''')
+        self.assertEqual(3, cursor.fetchone()[0])
+        cursor.execute('''
+            SELECT COUNT(t.ta_id)
+              FROM transactions AS t
+              LEFT JOIN consumptions AS c
+                ON t.ta_id = c.ta_id
+              WHERE t.user_id = 3 AND c.product_id = 2 AND t.value = -150''')
+        self.assertEqual(4, cursor.fetchone()[0])

matemat/db/test/test_wrapper.py

@@ -1,6 +1,8 @@
 
 import unittest
 
+import sqlite3
+
 from matemat.db import DatabaseWrapper
 
 

matemat/db/wrapper.py

@@ -4,6 +4,8 @@ from typing import Any, Optional
 import sqlite3
 
 from matemat.exceptions import DatabaseConsistencyError
+from matemat.db.schemas import SCHEMAS
+from matemat.db.migrations import migrate_schema_1_to_2
 
 
 class Transaction(object):
@@ -39,38 +41,8 @@ class Transaction(object):
 
 
 class DatabaseWrapper(object):
-    SCHEMA_VERSION = 1
 
-    SCHEMA = '''
+    SCHEMA_VERSION = 2
-    CREATE TABLE users (
-      user_id INTEGER PRIMARY KEY,
-      username TEXT UNIQUE NOT NULL,
-      email TEXT DEFAULT NULL,
-      password TEXT NOT NULL,
-      touchkey TEXT DEFAULT NULL,
-      is_admin INTEGER(1) NOT NULL DEFAULT 0,
-      is_member INTEGER(1) NOT NULL DEFAULT 1,
-      balance INTEGER(8) NOT NULL DEFAULT 0,
-      lastchange INTEGER(8) NOT NULL DEFAULT 0
-    );
-    CREATE TABLE products (
-      product_id INTEGER PRIMARY KEY,
-      name TEXT UNIQUE NOT NULL,
-      stock INTEGER(8) NOT NULL DEFAULT 0,
-      price_member INTEGER(8) NOT NULL,
-      price_non_member INTEGER(8) NOT NULL
-    );
-    CREATE TABLE consumption (
-      user_id INTEGER NOT NULL,
-      product_id INTEGER NOT NULL,
-      count INTEGER(8) NOT NULL DEFAULT 0,
-      PRIMARY KEY (user_id, product_id),
-      FOREIGN KEY (user_id) REFERENCES users(user_id)
-        ON DELETE CASCADE ON UPDATE CASCADE,
-      FOREIGN KEY (product_id) REFERENCES products(product_id)
-        ON DELETE CASCADE ON UPDATE CASCADE
-    );
-    '''
 
     def __init__(self, filename: str) -> None:
         self._filename: str = filename
@@ -92,13 +64,20 @@ class DatabaseWrapper(object):
         with self.transaction() as c:
             version: int = self._user_version
             if version < 1:
-                c.executescript(self.SCHEMA)
+                # Don't use executescript, as it issues a COMMIT first
+                for command in SCHEMAS[self.SCHEMA_VERSION]:
+                    c.execute(command)
             elif version < self.SCHEMA_VERSION:
-                self._upgrade(old=version, new=self.SCHEMA_VERSION)
+                self._upgrade(from_version=version, to_version=self.SCHEMA_VERSION)
+            elif version > self.SCHEMA_VERSION:
+                raise RuntimeError('Database schema is newer than supported by this version of Matemat.')
             self._user_version = self.SCHEMA_VERSION
 
-    def _upgrade(self, old: int, new: int) -> None:
+    def _upgrade(self, from_version: int, to_version: int) -> None:
-        pass
+        with self.transaction() as c:
+            # Note to future s3lph: If there are further migrations, also consider upgrades like 1 -> 3
+            if from_version == 1 and to_version == 2:
+                migrate_schema_1_to_2(c)
 
     def connect(self) -> None:
         if self.is_connected():

matemat/util/currency_format.py

@@ -0,0 +1,56 @@
+
+
+def format_chf(value: int, with_currencysign: bool = True) -> str:
+    """
+    Formats a centime value into a commonly understood representation ("CHF -13.37").
+
+    :param value: The value to format, in centimes.
+    :param with_currencysign: Whether to include the currency prefix ("CHF ") in the output.
+    :return: A human-readable string representation.
+    """
+    sign: str = ''
+    if value < 0:
+        # As // and % round towards -Inf, convert into a positive value and prepend the negative sign
+        sign = '-'
+        value = -value
+    # Split into full francs and fractions (centimes)
+    full: int = value // 100
+    frac: int = value % 100
+    csign: str = 'CHF ' if with_currencysign else ''
+    # Put it all together; centimes are always padded with 2 zeros
+    return f'{csign}{sign}{full}.{frac:02}'
+
+
+def parse_chf(value: str) -> int:
+    """
+    Parse a currency value into machine-readable format (integer centimes).  The prefix "CHF", the decimal point, and
+    digits after the decimal point are optional.
+
+    :param value: The value to parse.
+    :return: An integer representation of the value.
+    :raises: Value error: If more than two digits after the decimal point are present.
+    """
+    # Remove optional leading "CHF" and strip whitespace
+    value = value.strip()
+    if value.startswith('CHF'):
+        value = value[3:]
+    value = value.strip()
+    if '.' not in value:
+        # already is an integer; parse and turn into centimes
+        return int(value, 10) * 100
+    # Split at the decimal point
+    full, frac = value.split('.', 1)
+    if len(frac) > 2:
+        raise ValueError('Needs max. 2 digits after decimal point')
+    elif len(frac) < 2:
+        # Right-pad fraction with zeros ("x." -> "x.00", "x.x" -> "x.x0")
+        frac = frac + '0' * (2 - len(frac))
+    # Parse both parts
+    ifrac: int = int(frac, 10)
+    ifull: int = int(full, 10)
+    if ifrac < 0:
+        raise ValueError('Fraction part must not be negative.')
+    if full.startswith('-'):
+        ifrac = -ifrac
+    # Combine into centime integer
+    return ifull * 100 + ifrac

matemat/util/test/test_currency_format.py

@@ -0,0 +1,133 @@
+
+import unittest
+
+from matemat.util.currency_format import format_chf, parse_chf
+
+
+class TestCurrencyFormat(unittest.TestCase):
+
+    def test_format_zero(self):
+        self.assertEqual('CHF 0.00', format_chf(0))
+        self.assertEqual('0.00', format_chf(0, False))
+
+    def test_format_positive_full(self):
+        self.assertEqual('CHF 42.00', format_chf(4200))
+        self.assertEqual('42.00', format_chf(4200, False))
+
+    def test_format_negative_full(self):
+        self.assertEqual('CHF -42.00', format_chf(-4200))
+        self.assertEqual('-42.00', format_chf(-4200, False))
+
+    def test_format_positive_frac(self):
+        self.assertEqual('CHF 13.37', format_chf(1337))
+        self.assertEqual('13.37', format_chf(1337, False))
+
+    def test_format_negative_frac(self):
+        self.assertEqual('CHF -13.37', format_chf(-1337))
+        self.assertEqual('-13.37', format_chf(-1337, False))
+
+    def test_format_pad_left_positive(self):
+        self.assertEqual('CHF 0.01', format_chf(1))
+        self.assertEqual('0.01', format_chf(1, False))
+
+    def test_format_pad_left_negative(self):
+        self.assertEqual('CHF -0.01', format_chf(-1))
+        self.assertEqual('-0.01', format_chf(-1, False))
+
+    def test_format_pad_right_positive(self):
+        self.assertEqual('CHF 4.20', format_chf(420))
+        self.assertEqual('4.20', format_chf(420, False))
+
+    def test_format_pad_right_negative(self):
+        self.assertEqual('CHF -4.20', format_chf(-420))
+        self.assertEqual('-4.20', format_chf(-420, False))
+
+    def test_parse_empty(self):
+        with self.assertRaises(ValueError):
+            parse_chf('')
+        with self.assertRaises(ValueError):
+            parse_chf('CHF')
+        with self.assertRaises(ValueError):
+            parse_chf('CHF ')
+
+    def test_parse_zero(self):
+        self.assertEqual(0, parse_chf('CHF0'))
+        self.assertEqual(0, parse_chf('CHF 0'))
+        self.assertEqual(0, parse_chf('CHF -0'))
+        self.assertEqual(0, parse_chf('CHF 0.'))
+        self.assertEqual(0, parse_chf('CHF 0.0'))
+        self.assertEqual(0, parse_chf('CHF 0.00'))
+        self.assertEqual(0, parse_chf('CHF -0.'))
+        self.assertEqual(0, parse_chf('CHF -0.0'))
+        self.assertEqual(0, parse_chf('CHF -0.00'))
+        self.assertEqual(0, parse_chf('0'))
+        self.assertEqual(0, parse_chf('0'))
+        self.assertEqual(0, parse_chf('-0'))
+        self.assertEqual(0, parse_chf('0.'))
+        self.assertEqual(0, parse_chf('0.0'))
+        self.assertEqual(0, parse_chf('0.00'))
+        self.assertEqual(0, parse_chf('-0.'))
+        self.assertEqual(0, parse_chf('-0.0'))
+        self.assertEqual(0, parse_chf('-0.00'))
+
+    def test_parse_positive_full(self):
+        self.assertEqual(4200, parse_chf('CHF 42.00'))
+        self.assertEqual(4200, parse_chf('42.00'))
+        self.assertEqual(4200, parse_chf('CHF 42'))
+        self.assertEqual(4200, parse_chf('42'))
+        self.assertEqual(4200, parse_chf('CHF 42.'))
+        self.assertEqual(4200, parse_chf('42.'))
+        self.assertEqual(4200, parse_chf('CHF 42.0'))
+        self.assertEqual(4200, parse_chf('42.0'))
+
+    def test_parse_negative_full(self):
+        self.assertEqual(-4200, parse_chf('CHF -42.00'))
+        self.assertEqual(-4200, parse_chf('-42.00'))
+        self.assertEqual(-4200, parse_chf('CHF -42'))
+        self.assertEqual(-4200, parse_chf('-42'))
+        self.assertEqual(-4200, parse_chf('CHF -42.'))
+        self.assertEqual(-4200, parse_chf('-42.'))
+        self.assertEqual(-4200, parse_chf('CHF -42.0'))
+        self.assertEqual(-4200, parse_chf('-42.0'))
+
+    def test_parse_positive_frac(self):
+        self.assertEqual(1337, parse_chf('CHF 13.37'))
+        self.assertEqual(1337, parse_chf('13.37'))
+
+    def test_parse_negative_frac(self):
+        self.assertEqual(-1337, parse_chf('CHF -13.37'))
+        self.assertEqual(-1337, parse_chf('-13.37'))
+
+    def test_parse_pad_left_positive(self):
+        self.assertEqual(1, parse_chf('CHF 0.01'))
+        self.assertEqual(1, parse_chf('0.01'))
+
+    def test_parse_pad_left_negative(self):
+        self.assertEqual(-1, parse_chf('CHF -0.01'))
+        self.assertEqual(-1, parse_chf('-0.01'))
+
+    def test_parse_pad_right_positive(self):
+        self.assertEqual(420, parse_chf('CHF 4.20'))
+        self.assertEqual(420, parse_chf('4.20'))
+        self.assertEqual(420, parse_chf('CHF 4.2'))
+        self.assertEqual(420, parse_chf('4.2'))
+
+    def test_parse_pad_right_negative(self):
+        self.assertEqual(-420, parse_chf('CHF -4.20'))
+        self.assertEqual(-420, parse_chf('-4.20'))
+        self.assertEqual(-420, parse_chf('CHF -4.2'))
+        self.assertEqual(-420, parse_chf('-4.2'))
+
+    def test_parse_too_many_decimals(self):
+        with self.assertRaises(ValueError):
+            parse_chf('123.456')
+        with self.assertRaises(ValueError):
+            parse_chf('CHF 0.456')
+        with self.assertRaises(ValueError):
+            parse_chf('CHF 0.450')
+
+    def test_parse_wrong_separator(self):
+        with self.assertRaises(ValueError):
+            parse_chf('13,37')
+        with self.assertRaises(ValueError):
+            parse_chf('CHF 13,37')

matemat/webserver/httpd.py

@@ -18,6 +18,7 @@ from matemat import __version__ as matemat_version
 from matemat.exceptions import HttpException
 from matemat.webserver import RequestArguments, PageletResponse, RedirectResponse, TemplateResponse
 from matemat.webserver.util import parse_args
+from matemat.util.currency_format import format_chf
 
 #
 # Python internal class hacks
@@ -116,8 +117,10 @@ class MatematHTTPServer(HTTPServer):
         self.pagelet_variables = pagelet_variables
         # Set up the Jinja2 environment
         self.jinja_env: jinja2.Environment = jinja2.Environment(
-            loader=jinja2.FileSystemLoader(os.path.abspath(templateroot))
+            loader=jinja2.FileSystemLoader(os.path.abspath(templateroot)),
+            autoescape=jinja2.select_autoescape(default=True),
         )
+        self.jinja_env.filters['chf'] = format_chf
         # Set up logger
         self.logger: logging.Logger = logging.getLogger('matemat.webserver')
         self.logger.setLevel(log_level)

matemat/webserver/pagelets/__init__.py

@@ -8,3 +8,8 @@ from .main import main_page
 from .login import login_page
 from .logout import logout
 from .touchkey import touchkey_page
+from .buy import buy
+from .deposit import deposit
+from .admin import admin
+from .moduser import moduser
+from .modproduct import modproduct

matemat/webserver/pagelets/admin.py

@@ -0,0 +1,211 @@
+from typing import Any, Dict, Union
+
+import os
+import magic
+
+from matemat.webserver import pagelet, RequestArguments, PageletResponse, RedirectResponse, TemplateResponse
+from matemat.db import MatematDatabase
+from matemat.db.primitives import User
+from matemat.exceptions import DatabaseConsistencyError, HttpException
+
+
+@pagelet('/admin')
+def admin(method: str,
+          path: str,
+          args: RequestArguments,
+          session_vars: Dict[str, Any],
+          headers: Dict[str, str],
+          config: Dict[str, str]) \
+        -> Union[str, bytes, PageletResponse]:
+    """
+    The admin panel, shows a user's own settings.  Additionally, for administrators, settings to modify other users and
+    products are shown.
+    """
+    # If no user is logged in, redirect to the login page
+    if 'authentication_level' not in session_vars or 'authenticated_user' not in session_vars:
+        return RedirectResponse('/login')
+    authlevel: int = session_vars['authentication_level']
+    uid: int = session_vars['authenticated_user']
+    # Show a 403 Forbidden error page if no user is logged in (0) or a user logged in via touchkey (1)
+    if authlevel < 2:
+        raise HttpException(403)
+
+    # Connect to the database
+    with MatematDatabase(config['DatabaseFile']) as db:
+        # Fetch the authenticated user
+        user = db.get_user(uid)
+        # If the POST request contains a "change" parameter, delegate the change handling to the function below
+        if method == 'POST' and 'change' in args:
+            handle_change(args, user, db, config)
+        # If the POST request contains an "adminchange" parameter, delegate the change handling to the function below
+        elif method == 'POST' and 'adminchange' in args and user.is_admin:
+            handle_admin_change(args, db, config)
+
+        # Fetch all existing users and products from the database
+        users = db.list_users()
+        products = db.list_products()
+        # Render the "Admin/Settings" page
+        return TemplateResponse('admin.html',
+                                authuser=user, authlevel=authlevel, users=users, products=products,
+                                setupname=config['InstanceName'])
+
+
+def handle_change(args: RequestArguments, user: User, db: MatematDatabase, config: Dict[str, str]) -> None:
+    """
+    Write the changes requested by a user for its own account to the database.
+
+    :param args: The RequestArguments object passed to the pagelet.
+    :param user: The user to edit.
+    :param db: The database facade where changes are written to.
+    :param config: The dictionary of config file entries from the [Pagelets] section.
+    """
+    try:
+        # Read the type of change requested by the user, then switch over it
+        change = str(args.change)
+
+        # The user requested a modification of its general account information (username, email)
+        if change == 'account':
+            # Username and email must be set in the request arguments
+            if 'username' not in args or 'email' not in args:
+                return
+            username = str(args.username)
+            email = str(args.email)
+            # An empty e-mail field should be interpreted as NULL
+            if len(email) == 0:
+                email = None
+            # Attempt to update username and e-mail
+            try:
+                db.change_user(user, agent=None, name=username, email=email)
+            except DatabaseConsistencyError:
+                return
+
+        # The user requested a password change
+        elif change == 'password':
+            # The old password and 2x the new password must be present
+            if 'oldpass' not in args or 'newpass' not in args or 'newpass2' not in args:
+                return
+            # Read the passwords from the request arguments
+            oldpass = str(args.oldpass)
+            newpass = str(args.newpass)
+            newpass2 = str(args.newpass2)
+            # The two instances of the new password must match
+            if newpass != newpass2:
+                raise ValueError('New passwords don\'t match')
+            # Write the new password to the database
+            db.change_password(user, oldpass, newpass)
+
+        # The user requested a touchkey change
+        elif change == 'touchkey':
+            # The touchkey must be present
+            if 'touchkey' not in args:
+                return
+            # Read the touchkey from the request arguments
+            touchkey = str(args.touchkey)
+            # An empty touchkey field should set the touchkey to NULL (disable touchkey login)
+            if len(touchkey) == 0:
+                touchkey = None
+            # Write the new touchkey to the database
+            db.change_touchkey(user, '', touchkey, verify_password=False)
+
+        # The user requested an avatar change
+        elif change == 'avatar':
+            # The new avatar field must be present
+            if 'avatar' not in args:
+                return
+            # Read the raw image data from the request
+            avatar = bytes(args.avatar)
+            # Only process the image, if its size is more than zero.  Zero size means no new image was uploaded
+            if len(avatar) == 0:
+                return
+            # Detect the MIME type
+            filemagic: magic.FileMagic = magic.detect_from_content(avatar)
+            # Currently, only image/png is supported, don't process any other formats
+            if filemagic.mime_type != 'image/png':
+                # TODO: Optionally convert to png
+                return
+            # Create the absolute path of the upload directory
+            abspath: str = os.path.join(os.path.abspath(config['UploadDir']), 'thumbnails/users/')
+            os.makedirs(abspath, exist_ok=True)
+            # Write the image to the file
+            with open(os.path.join(abspath, f'{user.id}.png'), 'wb') as f:
+                f.write(avatar)
+
+    except UnicodeDecodeError:
+        raise ValueError('an argument not a string')
+
+
+def handle_admin_change(args: RequestArguments, db: MatematDatabase, config: Dict[str, str]):
+    """
+    Write the changes requested by an admin for users of products.
+
+    :param args: The RequestArguments object passed to the pagelet.
+    :param db: The database facade where changes are written to.
+    :param config: The dictionary of config file entries from the [Pagelets] section.
+    """
+    try:
+        # Read the type of change requested by the admin, then switch over it
+        change = str(args.adminchange)
+
+        # The user requested to create a new user
+        if change == 'newuser':
+            # Only create a new user if all required properties of the user are present in the request arguments
+            if 'username' not in args or 'email' not in args or 'password' not in args:
+                return
+            # Read the properties from the request arguments
+            username = str(args.username)
+            email = str(args.email)
+            # An empty e-mail field should be interpreted as NULL
+            if len(email) == 0:
+                email = None
+            password = str(args.password)
+            is_member = 'ismember' in args
+            is_admin = 'isadmin' in args
+            # Create the user in the database
+            db.create_user(username, password, email, member=is_member, admin=is_admin)
+
+        # The user requested to create a new product
+        elif change == 'newproduct':
+            # Only create a new product if all required properties of the product are present in the request arguments
+            if 'name' not in args or 'pricemember' not in args or 'pricenonmember' not in args:
+                return
+            # Read the properties from the request arguments
+            name = str(args.name)
+            price_member = int(str(args.pricemember))
+            price_non_member = int(str(args.pricenonmember))
+            # Create the user in the database
+            newproduct = db.create_product(name, price_member, price_non_member)
+            # If a new product image was uploaded, process it
+            if 'image' in args:
+                # Read the raw image data from the request
+                image = bytes(args.image)
+                # Only process the image, if its size is more than zero.  Zero size means no new image was uploaded
+                if len(image) == 0:
+                    return
+                # Detect the MIME type
+                filemagic: magic.FileMagic = magic.detect_from_content(image)
+                # Currently, only image/png is supported, don't process any other formats
+                if filemagic.mime_type != 'image/png':
+                    # TODO: Optionally convert to png
+                    return
+                # Create the absolute path of the upload directory
+                abspath: str = os.path.join(os.path.abspath(config['UploadDir']), 'thumbnails/products/')
+                os.makedirs(abspath, exist_ok=True)
+                # Write the image to the file
+                with open(os.path.join(abspath, f'{newproduct.id}.png'), 'wb') as f:
+                    f.write(image)
+
+        # The user requested to restock a product
+        elif change == 'restock':
+            # Only restock a product if all required properties are present in the request arguments
+            if 'productid' not in args or 'amount' not in args:
+                return
+            # Read the properties from the request arguments
+            productid = int(str(args.productid))
+            amount = int(str(args.amount))
+            # Fetch the product to restock from the database
+            product = db.get_product(productid)
+            # Write the new stock count to the database
+            db.restock(product, amount)
+
+    except UnicodeDecodeError:
+        raise ValueError('an argument not a string')

matemat/webserver/pagelets/buy.py

@@ -0,0 +1,33 @@
+from typing import Any, Dict, Union
+
+from matemat.webserver import pagelet, RequestArguments, PageletResponse, RedirectResponse
+from matemat.db import MatematDatabase
+
+
+@pagelet('/buy')
+def buy(method: str,
+        path: str,
+        args: RequestArguments,
+        session_vars: Dict[str, Any],
+        headers: Dict[str, str],
+        config: Dict[str, str]) \
+        -> Union[str, bytes, PageletResponse]:
+    """
+    The purchasing mechanism.  Called by the user clicking an item on the product list.
+    """
+    # If no user is logged in, redirect to the main page, as a purchase must always be bound to a user
+    if 'authenticated_user' not in session_vars:
+        return RedirectResponse('/')
+    # Connect to the database
+    with MatematDatabase(config['DatabaseFile']) as db:
+        # Fetch the authenticated user from the database
+        uid: int = session_vars['authenticated_user']
+        user = db.get_user(uid)
+        # Read the product from the database, identified by the product ID passed as request argument
+        if 'pid' in args:
+            pid = int(str(args.pid))
+            product = db.get_product(pid)
+            # Create a consumption entry for the (user, product) combination
+            db.increment_consumption(user, product)
+    # Redirect to the main page (where this request should have come from)
+    return RedirectResponse('/')

matemat/webserver/pagelets/deposit.py

@@ -0,0 +1,32 @@
+from typing import Any, Dict, Union
+
+from matemat.webserver import pagelet, RequestArguments, PageletResponse, RedirectResponse
+from matemat.db import MatematDatabase
+
+
+@pagelet('/deposit')
+def deposit(method: str,
+            path: str,
+            args: RequestArguments,
+            session_vars: Dict[str, Any],
+            headers: Dict[str, str],
+            config: Dict[str, str]) \
+        -> Union[str, bytes, PageletResponse]:
+    """
+    The cash depositing mechanism.  Called by the user submitting a deposit from the product list.
+    """
+    # If no user is logged in, redirect to the main page, as a deposit must always be bound to a user
+    if 'authenticated_user' not in session_vars:
+        return RedirectResponse('/')
+    # Connect to the database
+    with MatematDatabase(config['DatabaseFile']) as db:
+        # Fetch the authenticated user from the database
+        uid: int = session_vars['authenticated_user']
+        user = db.get_user(uid)
+        if 'n' in args:
+            # Read the amount of cash to deposit from the request arguments
+            n = int(str(args.n))
+            # Write the deposit to the database
+            db.deposit(user, n)
+    # Redirect to the main page (where this request should have come from)
+    return RedirectResponse('/')

matemat/webserver/pagelets/login.py

@@ -1,9 +1,8 @@
-
 from typing import Any, Dict, Union
 
 from matemat.exceptions import AuthenticationError, HttpException
 from matemat.webserver import pagelet, RequestArguments, PageletResponse, RedirectResponse, TemplateResponse
-from matemat.primitives import User
+from matemat.db.primitives import User
 from matemat.db import MatematDatabase
 
 
@@ -13,18 +12,34 @@ def login_page(method: str,
                args: RequestArguments,
                session_vars: Dict[str, Any],
                headers: Dict[str, str],
-               config: Dict[str, str])\
+               config: Dict[str, str]) \
         -> Union[bytes, str, PageletResponse]:
-    if 'user' in session_vars:
+    """
+    The password login mechanism.  If called via GET, render the UI template; if called via POST, attempt to log in with
+    the provided credentials (username and passsword).
+    """
+    # If a user is already logged in, simply redirect to the main page, showing the product list
+    if 'authenticated_user' in session_vars:
         return RedirectResponse('/')
+    # If requested via HTTP GET, render the login page showing the login UI
     if method == 'GET':
-        return TemplateResponse('login.html', setupname=config['InstanceName'])
+        return TemplateResponse('login.html',
+                                setupname=config['InstanceName'])
+    # If requested via HTTP POST, read the request arguments and attempt to log in with the provided credentials
     elif method == 'POST':
+        # Connect to the database
         with MatematDatabase(config['DatabaseFile']) as db:
             try:
+                # Read the request arguments and attempt to log in with them
                 user: User = db.login(str(args.username), str(args.password))
             except AuthenticationError:
+                # Reload the touchkey login page on failure
                 return RedirectResponse('/login')
-            session_vars['user'] = user
+        # Set the user ID session variable
+        session_vars['authenticated_user'] = user.id
+        # Set the authlevel session variable (0 = none, 1 = touchkey, 2 = password login)
+        session_vars['authentication_level'] = 2
+        # Redirect to the main page, showing the product list
         return RedirectResponse('/')
+    # If neither GET nor POST was used, show a 405 Method Not Allowed error page
     raise HttpException(405)

matemat/webserver/pagelets/logout.py

@@ -1,4 +1,3 @@
-
 from typing import Any, Dict, Union
 
 from matemat.webserver import pagelet, RequestArguments, PageletResponse, RedirectResponse
@@ -10,8 +9,15 @@ def logout(method: str,
            args: RequestArguments,
            session_vars: Dict[str, Any],
            headers: Dict[str, str],
-           config: Dict[str, str])\
+           config: Dict[str, str]) \
         -> Union[bytes, str, PageletResponse]:
-    if 'user' in session_vars:
+    """
-        del session_vars['user']
+    The logout mechanism, clearing the authentication values in the session storage.
+    """
+    # Remove the authenticated user ID from the session storage, if any
+    if 'authenticated_user' in session_vars:
+        del session_vars['authenticated_user']
+    # Reset the authlevel session variable (0 = none, 1 = touchkey, 2 = password login)
+    session_vars['authentication_level'] = 0
+    # Redirect to the main page, showing the user list
     return RedirectResponse('/')

matemat/webserver/pagelets/main.py

@@ -1,8 +1,6 @@
-
 from typing import Any, Dict, Union
 
 from matemat.webserver import pagelet, RequestArguments, PageletResponse, TemplateResponse
-from matemat.primitives import User
 from matemat.db import MatematDatabase
 
 
@@ -12,13 +10,27 @@ def main_page(method: str,
               args: RequestArguments,
               session_vars: Dict[str, Any],
               headers: Dict[str, str],
-              config: Dict[str, str])\
+              config: Dict[str, str]) \
         -> Union[bytes, str, PageletResponse]:
+    """
+    The main page, showing either the user list (if no user is logged in) or the product list (if a user is logged in).
+    """
     with MatematDatabase(config['DatabaseFile']) as db:
-        if 'user' in session_vars:
+        # Check whether a user is logged in
-            user: User = session_vars['user']
+        if 'authenticated_user' in session_vars:
+            # Fetch the user id and authentication level (touchkey vs password) from the session storage
+            uid: int = session_vars['authenticated_user']
+            authlevel: int = session_vars['authentication_level']
+            # Fetch the user object from the database (for name display, price calculation and admin check)
+            user = db.get_user(uid)
+            # Fetch the list of products to display
             products = db.list_products()
-            return TemplateResponse('main.html', user=user, list=products, setupname=config['InstanceName'])
+            # Prepare a response with a jinja2 template
+            return TemplateResponse('productlist.html',
+                                    authuser=user, products=products, authlevel=authlevel,
+                                    setupname=config['InstanceName'])
         else:
+            # If no user is logged in, fetch the list of users and render the userlist template
             users = db.list_users()
-            return TemplateResponse('main.html', list=users, setupname=config['InstanceName'])
+            return TemplateResponse('userlist.html',
+                                    users=users, setupname=config['InstanceName'])

matemat/webserver/pagelets/modproduct.py

@@ -0,0 +1,119 @@
+from typing import Any, Dict, Union
+
+import os
+import magic
+
+from matemat.webserver import pagelet, RequestArguments, PageletResponse, RedirectResponse, TemplateResponse
+from matemat.db import MatematDatabase
+from matemat.db.primitives import Product
+from matemat.exceptions import DatabaseConsistencyError, HttpException
+from matemat.util.currency_format import parse_chf
+
+
+@pagelet('/modproduct')
+def modproduct(method: str,
+               path: str,
+               args: RequestArguments,
+               session_vars: Dict[str, Any],
+               headers: Dict[str, str],
+               config: Dict[str, str]) \
+        -> Union[str, bytes, PageletResponse]:
+    """
+    The product modification page available from the admin panel.
+    """
+    # If no user is logged in, redirect to the login page
+    if 'authentication_level' not in session_vars or 'authenticated_user' not in session_vars:
+        return RedirectResponse('/login')
+    authlevel: int = session_vars['authentication_level']
+    auth_uid: int = session_vars['authenticated_user']
+    # Show a 403 Forbidden error page if no user is logged in (0) or a user logged in via touchkey (1)
+    if authlevel < 2:
+        raise HttpException(403)
+
+    # Connect to the database
+    with MatematDatabase(config['DatabaseFile']) as db:
+        # Fetch the authenticated user
+        authuser = db.get_user(auth_uid)
+        if not authuser.is_admin:
+            # Show a 403 Forbidden error page if the user is not an admin
+            raise HttpException(403)
+        if 'productid' not in args:
+            # Show a 400 Bad Request error page if no product to edit was specified
+            # (should never happen during normal operation)
+            raise HttpException(400, '"productid" argument missing')
+
+        # Fetch the product to modify from the database
+        modproduct_id = int(str(args.productid))
+        product = db.get_product(modproduct_id)
+
+        # If the request contains a "change" parameter, delegate the change handling to the function below
+        if 'change' in args:
+            handle_change(args, product, db, config)
+            # If the product was deleted, redirect back to the admin page, as there is nothing to edit any more
+            if str(args.change) == 'del':
+                return RedirectResponse('/admin')
+
+        # Render the "Modify Product" page
+        return TemplateResponse('modproduct.html',
+                                authuser=authuser, product=product, authlevel=authlevel,
+                                setupname=config['InstanceName'])
+
+
+def handle_change(args: RequestArguments, product: Product, db: MatematDatabase, config: Dict[str, str]) -> None:
+    """
+    Write the changes requested by an admin to the database.
+
+    :param args: The RequestArguments object passed to the pagelet.
+    :param product: The product to edit.
+    :param db: The database facade where changes are written to.
+    :param config: The dictionary of config file entries from the [Pagelets] section.
+    """
+    # Read the type of change requested by the admin, then switch over it
+    change = str(args.change)
+
+    # Admin requested deletion of the product
+    if change == 'del':
+        # Delete the product from the database
+        db.delete_product(product)
+        # Delete the product image, if it exists
+        try:
+            abspath: str = os.path.join(os.path.abspath(config['UploadDir']), 'thumbnails/products/')
+            os.remove(os.path.join(abspath, f'{product.id}.png'))
+        except FileNotFoundError:
+            pass
+
+    # Admin requested update of the product details
+    elif change == 'update':
+        # Only write a change if all properties of the product are present in the request arguments
+        if 'name' not in args or 'pricemember' not in args or 'pricenonmember' not in args or 'stock' not in args:
+            return
+        # Read the properties from the request arguments
+        name = str(args.name)
+        price_member = parse_chf(str(args.pricemember))
+        price_non_member = parse_chf(str(args.pricenonmember))
+        stock = int(str(args.stock))
+        # Attempt to write the changes to the database
+        try:
+            db.change_product(product,
+                              name=name, price_member=price_member, price_non_member=price_non_member, stock=stock)
+        except DatabaseConsistencyError:
+            return
+        # If a new product image was uploaded, process it
+        if 'image' in args:
+            # Read the raw image data from the request
+            image = bytes(args.image)
+            # Only process the image, if its size is more than zero.  Zero size means no new image was uploaded
+            if len(image) == 0:
+                return
+            # Detect the MIME type
+            filemagic: magic.FileMagic = magic.detect_from_content(image)
+            # Currently, only image/png is supported, don't process any other formats
+            if filemagic.mime_type != 'image/png':
+                # TODO: Optionally convert to png
+                return
+            # Create the absolute path of the upload directory
+            abspath: str = os.path.join(os.path.abspath(config['UploadDir']), 'thumbnails/products/')
+            os.makedirs(abspath, exist_ok=True)
+            # Write the image to the file
+            with open(os.path.join(abspath, f'{product.id}.png'), 'wb') as f:
+                f.write(image)

matemat/webserver/pagelets/moduser.py

@@ -0,0 +1,130 @@
+from typing import Any, Dict, Union
+
+import os
+import magic
+
+from matemat.webserver import pagelet, RequestArguments, PageletResponse, RedirectResponse, TemplateResponse
+from matemat.db import MatematDatabase
+from matemat.db.primitives import User
+from matemat.exceptions import DatabaseConsistencyError, HttpException
+from matemat.util.currency_format import parse_chf
+
+
+@pagelet('/moduser')
+def moduser(method: str,
+            path: str,
+            args: RequestArguments,
+            session_vars: Dict[str, Any],
+            headers: Dict[str, str],
+            config: Dict[str, str]) \
+        -> Union[str, bytes, PageletResponse]:
+    """
+    The user modification page available from the admin panel.
+    """
+    # If no user is logged in, redirect to the login page
+    if 'authentication_level' not in session_vars or 'authenticated_user' not in session_vars:
+        return RedirectResponse('/login')
+    authlevel: int = session_vars['authentication_level']
+    auth_uid: int = session_vars['authenticated_user']
+    # Show a 403 Forbidden error page if no user is logged in (0) or a user logged in via touchkey (1)
+    if authlevel < 2:
+        raise HttpException(403)
+
+    # Connect to the database
+    with MatematDatabase(config['DatabaseFile']) as db:
+        # Fetch the authenticated user
+        authuser = db.get_user(auth_uid)
+        if not authuser.is_admin:
+            # Show a 403 Forbidden error page if the user is not an admin
+            raise HttpException(403)
+        if 'userid' not in args:
+            # Show a 400 Bad Request error page if no users to edit was specified
+            # (should never happen during normal operation)
+            raise HttpException(400, '"userid" argument missing')
+
+        # Fetch the user to modify from the database
+        moduser_id = int(str(args.userid))
+        user = db.get_user(moduser_id)
+
+        # If the request contains a "change" parameter, delegate the change handling to the function below
+        if 'change' in args:
+            handle_change(args, user, authuser, db, config)
+            # If the user was deleted, redirect back to the admin page, as there is nothing to edit any more
+            if str(args.change) == 'del':
+                return RedirectResponse('/admin')
+
+        # Render the "Modify User" page
+        return TemplateResponse('moduser.html',
+                                authuser=authuser, user=user, authlevel=authlevel,
+                                setupname=config['InstanceName'])
+
+
+def handle_change(args: RequestArguments, user: User, authuser: User, db: MatematDatabase, config: Dict[str, str]) \
+        -> None:
+    """
+    Write the changes requested by an admin to the database.
+
+    :param args: The RequestArguments object passed to the pagelet.
+    :param user: The user to edit.
+    :param authuser: The user performing the modification.
+    :param db: The database facade where changes are written to.
+    :param config: The dictionary of config file entries from the [Pagelets] section.
+    """
+    # Read the type of change requested by the admin, then switch over it
+    change = str(args.change)
+
+    # Admin requested deletion of the user
+    if change == 'del':
+        # Delete the user from the database
+        db.delete_user(user)
+        # Delete the user's avatar, if it exists
+        try:
+            abspath: str = os.path.join(os.path.abspath(config['UploadDir']), 'thumbnails/users/')
+            os.remove(os.path.join(abspath, f'{user.id}.png'))
+        except FileNotFoundError:
+            pass
+
+    # Admin requested update of the user's details
+    elif change == 'update':
+        # Only write a change if all properties of the user are present in the request arguments
+        if 'username' not in args or 'email' not in args or 'password' not in args or 'balance' not in args:
+            return
+        # Read the properties from the request arguments
+        username = str(args.username)
+        email = str(args.email)
+        password = str(args.password)
+        balance = parse_chf(str(args.balance))
+        is_member = 'ismember' in args
+        is_admin = 'isadmin' in args
+        # An empty e-mail field should be interpreted as NULL
+        if len(email) == 0:
+            email = None
+        # Attempt to write the changes to the database
+        try:
+            # If a password was entered, replace the password in the database
+            if len(password) > 0:
+                db.change_password(user, '', password, verify_password=False)
+            # Write the user detail changes
+            db.change_user(user, agent=authuser, name=username, email=email, is_member=is_member, is_admin=is_admin,
+                           balance=balance)
+        except DatabaseConsistencyError:
+            return
+        # If a new avatar was uploaded, process it
+        if 'avatar' in args:
+            # Read the raw image data from the request
+            avatar = bytes(args.avatar)
+            # Only process the image, if its size is more than zero.  Zero size means no new image was uploaded
+            if len(avatar) == 0:
+                return
+            # Detect the MIME type
+            filemagic: magic.FileMagic = magic.detect_from_content(avatar)
+            # Currently, only image/png is supported, don't process any other formats
+            if filemagic.mime_type != 'image/png':
+                # TODO: Optionally convert to png
+                return
+            # Create the absolute path of the upload directory
+            abspath: str = os.path.join(os.path.abspath(config['UploadDir']), 'thumbnails/users/')
+            os.makedirs(abspath, exist_ok=True)
+            # Write the image to the file
+            with open(os.path.join(abspath, f'{user.id}.png'), 'wb') as f:
+                f.write(avatar)

matemat/webserver/pagelets/touchkey.py

@@ -1,11 +1,8 @@
-
+from typing import Any, Dict, Union
-from typing import Any, Dict, Tuple, Union
-
-import urllib.parse
 
 from matemat.exceptions import AuthenticationError, HttpException
 from matemat.webserver import pagelet, RequestArguments, PageletResponse, RedirectResponse, TemplateResponse
-from matemat.primitives import User
+from matemat.db.primitives import User
 from matemat.db import MatematDatabase
 
 
@@ -15,21 +12,35 @@ def touchkey_page(method: str,
                   args: RequestArguments,
                   session_vars: Dict[str, Any],
                   headers: Dict[str, str],
-                  config: Dict[str, str])\
+                  config: Dict[str, str]) \
         -> Union[bytes, str, PageletResponse]:
-    if 'user' in session_vars:
+    """
+    The touchkey login mechanism.  If called via GET, render the UI template; if called via POST, attempt to log in with
+    the provided credentials (username and touchkey).
+    """
+    # If a user is already logged in, simply redirect to the main page, showing the product list
+    if 'authenticated_user' in session_vars:
         return RedirectResponse('/')
+    # If requested via HTTP GET, render the login page showing the touchkey UI
     if method == 'GET':
         return TemplateResponse('touchkey.html',
-                                username=str(args.username) if 'username' in args else None,
+                                username=str(args.username), uid=int(str(args.uid)),
                                 setupname=config['InstanceName'])
+    # If requested via HTTP POST, read the request arguments and attempt to log in with the provided credentials
     elif method == 'POST':
+        # Connect to the database
         with MatematDatabase(config['DatabaseFile']) as db:
             try:
+                # Read the request arguments and attempt to log in with them
                 user: User = db.login(str(args.username), touchkey=str(args.touchkey))
             except AuthenticationError:
-                quoted = urllib.parse.quote_plus(bytes(args.username))
+                # Reload the touchkey login page on failure
-                return RedirectResponse(f'/touchkey?username={quoted}')
+                return RedirectResponse(f'/touchkey?uid={str(args.uid)}&username={str(args.username)}')
-            session_vars['user'] = user
+        # Set the user ID session variable
+        session_vars['authenticated_user'] = user.id
+        # Set the authlevel session variable (0 = none, 1 = touchkey, 2 = password login)
+        session_vars['authentication_level'] = 1
+        # Redirect to the main page, showing the product list
         return RedirectResponse('/')
+    # If neither GET nor POST was used, show a 405 Method Not Allowed error page
     raise HttpException(405)

matemat/webserver/test/abstract_httpd_test.py

@@ -119,10 +119,12 @@ class MockServer:
         # Set up logger
         self.logger: logging.Logger = logging.getLogger('matemat unit test')
         self.logger.setLevel(logging.DEBUG)
+        # Disable logging
+        self.logger.addHandler(logging.NullHandler())
         # Initalize a log handler to stderr and set the log format
-        sh: logging.StreamHandler = logging.StreamHandler()
+        # sh: logging.StreamHandler = logging.StreamHandler()
-        sh.setFormatter(logging.Formatter('%(asctime)s %(name)s [%(levelname)s]: %(message)s'))
+        # sh.setFormatter(logging.Formatter('%(asctime)s %(name)s [%(levelname)s]: %(message)s'))
-        self.logger.addHandler(sh)
+        # self.logger.addHandler(sh)
 
 
 class MockSocket(bytes):

static/css/matemat.css

@@ -0,0 +1,31 @@
+.thumblist-item {
+    display: inline-block;
+    margin: 10px;
+    padding: 10px;
+    background: #f0f0f0;
+    text-decoration: none;
+}
+
+.thumblist-item a {
+    text-decoration: none;
+}
+
+.thumblist-item .imgcontainer {
+    width: 150px;
+    height: 150px;
+    position: relative;
+}
+
+.thumblist-item .imgcontainer img {
+    max-width: 150px;
+    max-height: 150px;
+    position: absolute;
+    top: 50%;
+    left: 50%;
+    transform: translate(-50%, -50%);
+}
+
+.thumblist-title {
+    display: block;
+    font-weight: bolder;
+}

static/js/touchkey.js

@@ -0,0 +1,268 @@
+/**
+ * Initialize the touchkey setup.
+ *
+ * Requires an empty SVG container, and a HTML input tag (recommended: type="hidden") to write the string representation
+ * to.  Can additionally be provided with the ID of a HTML form which should be auto-submitted after touchkey entry.
+ *
+ * Example:
+ *
+ * <form id="touchkey-form" method="post" action="/login">
+ *     <svg id="touchkey-svg"></svg>
+ *     <input type="hidden" name="touchkey" id="touchkey-field" />
+ * </form>
+ * <script>
+ *     initTouchkey(false, "touchkey-svg", "touchkey-form", "touchkey-field");
+ * </script>
+ *
+ * @param {boolean} keepPattern: Whether to keep the pattern on screen, or to clear it after the end event.
+ * @param {string} svgid: HTML id of the SVG container the touchkey is drawn in.
+ * @param {string} formid: HTML id of the form that should be submitted after touchkey entry. null to disable
+ *                         auto-submit.
+ * @param {string} formfieldid: ID of the input object that should receive the entered touchkey as its value.
+ */
+initTouchkey = (keepPattern, svgid, formid, formfieldid) => {
+
+    // Define forEach (iteration) and slice (abused for shallow copying) on HTMLCollections (reuse the Array methods)
+    HTMLCollection.prototype.forEach = Array.prototype.forEach;
+    HTMLCollection.prototype.slice = Array.prototype.slice;
+
+    // Max. distance to a nodes center, before the path snaps to the node.
+    // Expressed as inverse ratio of the container width
+    const SNAPPING_SENSITIVITY = 12;
+
+    // Get the DOM objects for the SVG, the form and the input field
+    let svg = document.getElementById(svgid);
+    let form;
+    if (formid !== null) {
+        form = document.getElementById(formid);
+    }
+    let formfield = document.getElementById(formfieldid);
+
+    // Reference to the SVG line object that's currently being drawn by the user, or null, if none
+    let currentStroke = null;
+    // ID generator for the SVG line objects drawn by the user
+    let strokeId = 0;
+    // Set of touchkey pattern nodes that have already been visited by a users pattern, and may not be reused again
+    let doneMap = {};
+    // The string representation of the touchkey entered by the user.
+    let enteredKey = '';
+
+    /**
+     * Helper function to create a new stroke after the user completed one stroke by connecting two pattern nodes.
+     *
+     * @param {number} fromX: X coordinate of the starting point of this line.
+     * @param {number} fromY: Y coordinate of the starting point of this line.
+     * @param {number} toX: X coordinate of the ending point of this line.
+     * @param {number} toY: Y coordinate of the ending point of this line.
+     * @returns {string} The ID of the generated line object.
+     */
+    let drawLine = (fromX, fromY, toX, toY) => {
+        // Create a new SVG line object
+        let line = document.createElementNS('http://www.w3.org/2000/svg', 'line');
+        // Generate and set an unique ID for the line object
+        let id = 'touchkey-svg-stroke-' + (strokeId++);
+        line.setAttribute('id', id);
+        // Create and set the HTML class attribute
+        line.setAttribute('class', 'touchkey-svg-stroke');
+        // Create and set the coordinate attributes
+        line.setAttribute('x1', fromX.toString());
+        line.setAttribute('y1', fromY.toString());
+        line.setAttribute('x2', toX.toString());
+        line.setAttribute('y2', toY.toString());
+        // Create and set the style attribute (grey, circular ends, 5% width)
+        line.setAttribute('style', 'stroke: grey; stroke-width: 5%; stroke-linecap: round');
+        // Add the line to the SVG
+        svg.appendChild(line);
+        // Return the previously generated ID to identify the line object by
+        return id;
+    };
+
+    /**
+     * Helper function used to remove the "trailing stroke" (i.e. after the user let go, there is a dangling stroke from
+     * the node that was hit last to the mouse pointer/finger).
+     */
+    let endPath = () => {
+        // Remove the current stroke ...
+        svg.removeChild(svg.getElementById(currentStroke));
+        // ... and set its reference to null
+        currentStroke = null;
+    };
+
+    /**
+     * Helper function used to clear the touchkey pattern drawn by the user.
+     */
+    let clearTouchkey = () => {
+        // Reset the set of visited pattern nodes
+        doneMap = {};
+        // Reset the touchkey string representation
+        enteredKey = '';
+        // Remove all line objects. Create a shallow copy of the list first to retain deletion order.
+        svg.getElementsByClassName('touchkey-svg-stroke').slice().forEach((line) => {
+            svg.removeChild(line);
+        });
+    };
+
+    /**
+     * Helper function to read and convert the event coordinates of a MouseEvent or TouchEvent to coordinates relative
+     * to the SVG's origin.
+     *
+     * @param {(MouseEvent|TouchEvent)} ev: The event to get the X and Y coordinates from.
+     * @param {(ClientRect|DOMRect)} svgrect: Bounds rectangle of the SVG container.
+     * @returns {Array} The X and Y coordinates relative to the SVG's origin.
+     */
+    let getEventCoordinates = (ev, svgrect) => {
+        // Check for existence of the "touches" property to distinguish between touch and mouse events
+        // For a touch event, take the page coordinates of the first touch
+        // For a mouse event, take the event coordinates
+        // Then subtract the SVG's origin from the page-relative coordinates to obtain the translated coordinates
+        const trX = (typeof ev.touches !== 'undefined' ? ev.touches[0].pageX : ev.x) - svgrect.left;
+        const trY = (typeof ev.touches !== 'undefined' ? ev.touches[0].pageY : ev.y) - svgrect.top;
+        return [trX, trY]
+    };
+
+    /**
+     * Find the pattern node closest to a coordinate.
+     *
+     * @param {number} evX: X coordinate of the point to search the closest node for.
+     * @param {number} evY: Y coordinate of the point to search the closest node for.
+     * @param {(ClientRect|DOMRect)} svgrect: Bounds rectangle of the SVG container.
+     * @returns {Array} The node's ID, the distance, the X and Y coordinate of the node's center.
+     */
+    let getNearestPatternNode = (evX, evY, svgrect) => {
+        // Initialize nearest neighbors search variables
+        let minId = '';
+        let minDist2 = Infinity;  // Squared distance
+        let minX = 0;
+        let minY = 0;
+        // Iterate the pattern nodes for nearest neighbors search
+        document.getElementsByClassName('touchkey-svg-node').forEach((node) => {
+            // Get the position of a node's center, converted from ratio into absolute pixel count
+            let x = parseFloat(node.getAttribute('cx')) / 100.0 * svgrect.width;
+            let y = parseFloat(node.getAttribute('cy')) / 100.0 * svgrect.height;
+            // Compute the squared distance from the event coordinate to the node's center
+            let dist2 = Math.pow(evX - x, 2) + Math.pow(evY - y, 2);
+            // Keep the properties of the closest node
+            if (dist2 < minDist2) {
+                minDist2 = dist2;
+                minId = node.dataset.stringRepresentation;
+                minX = x;
+                minY = y;
+            }
+        });
+
+        return [minId, Math.sqrt(minDist2), minX, minY];
+    };
+
+    /**
+     * Event handler for "mouse down" / "touch down" events.
+     *
+     * Selects an "anchor node", i.e. the node where the pattern path started, and draws a line from there to the event
+     * coordinates.
+     */
+    svg.ontouchstart = svg.onmousedown = (ev) => {
+        // Remove any previous strokes that may still be there if "keepPattern" was set to true in the init call
+        clearTouchkey();
+        // Get the SVG container's rectangle
+        const svgrect = svg.getBoundingClientRect();
+        // Get the event coordinates relative to the SVG container's origin
+        const [trX, trY] = getEventCoordinates(ev, svgrect);
+        // Get the closest pattern node
+        const [minId, _, minX, minY] = getNearestPatternNode(trX, trY, svgrect);
+        // Create the line from the anchor node to the event position
+        currentStroke = drawLine(minX, minY, trX, trY);
+        // Mark the anchor node as visited
+        doneMap[minId] = 1;
+        // Add the anchor node's string representation to the touchkey string representation
+        enteredKey += minId;
+    };
+
+    /**
+     * Event handler for "mouse move" / "touch move" events.
+     */
+    svg.ontouchmove = svg.onmousemove = (ev) => {
+        // Only act if the user started is drawing a pattern (only relevant for mouse input)
+        if (currentStroke != null) {
+            // Get the SVG container's rectangle
+            const svgrect = svg.getBoundingClientRect();
+            // Get the event coordinates relative to the SVG container's origin
+            const [trX, trY] = getEventCoordinates(ev, svgrect);
+            // Get the closest pattern node
+            const [minId, minDist, minX, minY] = getNearestPatternNode(trX, trY, svgrect);
+            // If the closest node is not visited yet, and the event coordinate is less than  from the node's
+            // center, snap the current stroke to the node, and create a new stroke starting from this node
+            if (minDist < (svgrect.width / SNAPPING_SENSITIVITY) && !(minId in doneMap)) {
+                // Snap the current stroke to the node
+                let line = svg.getElementById(currentStroke);
+                line.setAttribute('x2', minX.toString());
+                line.setAttribute('y2', minY.toString());
+                // Create a new line object from the closest node to the event position
+                currentStroke = drawLine(minX, minY, trX, trY);
+                // Mark the closest node as visited
+                doneMap[minId] = 1;
+                // Append its string representation to the touchkey string representation
+                enteredKey += minId;
+            } else {
+                // If the stroke was not snapped to the closest node, update its end position
+                let line = svg.getElementById(currentStroke);
+                line.setAttribute('x2', trX);
+                line.setAttribute('y2', trY);
+            }
+        }
+    };
+
+    /**
+     * Event handler for "mouse up" / "touch end" events.
+     *
+     * Sets the input object value, and optionally clears the SVG path and submits the form.
+     */
+    svg.ontouchend = svg.onmouseup = () => {
+        // Remove the trailing, unfinished stroke
+        endPath();
+        // Write the touchkey string representation to the input field
+        formfield.value = enteredKey;
+        // Erase the touchkey pattern, if requested in the init call
+        if (keepPattern !== true) {
+            clearTouchkey();
+        }
+        // Submit the HTML form, if requested in the init call
+        if (formid !== null) {
+            form.submit();
+        }
+    };
+
+    /*
+     * Create the SVG touchkey nodes
+     */
+
+    // Node ID provider
+    let touchkey_node_counter = 0;
+    // Percentages for centers of quarters of the container's width and height
+    ['12.5%', '37.5%', '62.5%', '87.5%'].forEach((y) => {
+        ['12.5%', '37.5%', '62.5%', '87.5%'].forEach((x) => {
+            // Create a new pattern node
+            let node = document.createElementNS('http://www.w3.org/2000/svg', 'circle');
+
+            // Generate a new ID (and the touchkey string representation from it)
+            let id = touchkey_node_counter++;
+            node.dataset.stringRepresentation = id.toString(16).toLowerCase();
+
+            // Class
+            node.setAttribute('class', 'touchkey-svg-node');
+            // Center
+            node.setAttribute('cx', x);
+            node.setAttribute('cy', y);
+            // Radius
+            node.setAttribute('r', '10%');
+            // Center color
+            node.setAttribute('fill', 'white');
+            // Circle color
+            node.setAttribute('stroke', 'grey');
+            // Circle width
+            node.setAttribute('stroke-width', '2%');
+
+            // Add the node to the SVG container
+            svg.appendChild(node);
+        });
+    });
+
+};

templates/admin.html

@@ -0,0 +1,25 @@
+{% extends "base.html" %}
+
+{% block header %}
+    {# If the logged in user is an administrator, call the title "Administration", otherwise "Settings" #}
+    {% if authuser.is_admin %}
+        <h1>Administration</h1>
+    {% else %}
+        <h1>Settings</h1>
+    {% endif %}
+    {{ super() }}
+{% endblock %}
+
+{% block main %}
+
+    {# Always show the settings a user can edit for itself #}
+    {% include "admin_all.html" %}
+
+    {# Only show the "restricted" section if the user is an admin #}
+    {% if authuser.is_admin %}
+        {% include "admin_restricted.html" %}
+    {% endif %}
+
+    {{ super() }}
+
+{% endblock %}

templates/admin_all.html

@@ -0,0 +1,68 @@
+<section id="admin-myaccount">
+    <h2>My Account</h2>
+
+    <form id="admin-myaccount-form" method="post" action="/admin?change=account" accept-charset="UTF-8">
+        <label for="admin-myaccount-username">Username: </label>
+        <input id="admin-myaccount-username" type="text" name="username" value="{{ authuser.name }}" /><br/>
+
+        <label for="admin-myaccount-email">E-Mail: </label>
+        <input id="admin-myaccount-email" type="text" name="email" value="{% if authuser.email is not none %}{{ authuser.email }}{% endif %}" /><br/>
+
+        <label for="admin-myaccount-ismember">Member: </label>
+        <input id="admin-myaccount-ismember" type="checkbox" disabled="disabled" {% if authuser.is_member %} checked="checked" {% endif %}/><br/>
+
+        <label for="admin-myaccount-isadmin">Admin: </label>
+        <input id="admin-myaccount-isadmin" type="checkbox" disabled="disabled" {% if authuser.is_admin %} checked="checked" {% endif %}/><br/>
+
+        <input type="submit" value="Save changes" />
+    </form>
+</section>
+
+<section id="admin-avatar">
+    <h2>Avatar</h2>
+
+    <form id="admin-avatar-form" method="post" action="/admin?change=avatar" enctype="multipart/form-data" accept-charset="UTF-8">
+        <img src="/upload/thumbnails/users/{{ authuser.id }}.png" alt="Avatar of {{ authuser.name }}" /><br/>
+
+        <label for="admin-avatar-avatar">Upload new file: </label>
+        <input id="admin-avatar-avatar" type="file" name="avatar" accept="image/png" /><br/>
+
+        <input type="submit" value="Save changes" />
+    </form>
+</section>
+
+<section id="admin-password">
+    <h2>Password</h2>
+
+    <form id="admin-password-form" method="post" action="/admin?change=password" accept-charset="UTF-8">
+        <label for="admin-password-oldpass">Current password: </label>
+        <input id="admin-password-oldpass" type="password" name="oldpass" /><br/>
+
+        <label for="admin-password-newpass">New password: </label>
+        <input id="admin-password-newpass" type="password" name="newpass" /><br/>
+
+        <label for="admin-password-newpass2">Repeat password: </label>
+        <input id="admin-password-newpass2" type="password" name="newpass2" /><br/>
+
+        <input type="submit" value="Save changes" />
+    </form>
+</section>
+
+<section id="admin-touchkey">
+    <h2>Touchkey</h2>
+
+    <form id="admin-touchkey-form" method="post" action="/admin?change=touchkey" accept-charset="UTF-8">
+        Draw a new touchkey (leave empty to disable):
+        <br/>
+        <svg id="touchkey-svg" width="400" height="400"></svg>
+        <br/>
+        <input id="admin-touchkey-touchkey" type="hidden" name="touchkey" value="" />
+
+        <input type="submit" value="Save changes" />
+    </form>
+
+    <script src="/js/touchkey.js" ></script>
+    <script>
+        initTouchkey(true, 'touchkey-svg', null, 'admin-touchkey-touchkey');
+    </script>
+</section>

templates/admin_restricted.html

@@ -0,0 +1,90 @@
+<section id="admin-restricted-newuser">
+    <h2>Create New User</h2>
+
+    <form id="admin-newuser-form" method="post" action="/admin?adminchange=newuser" accept-charset="UTF-8">
+        <label for="admin-newuser-username">Username: </label>
+        <input id="admin-newuser-username" type="text" name="username" /><br/>
+
+        <label for="admin-newuser-email">E-Mail (optional): </label>
+        <input id="admin-newuser-email" type="text" name="email" /><br/>
+
+        <label for="admin-newuser-password">Password: </label>
+        <input id="admin-newuser-password" type="password" name="password" /><br/>
+
+        <label for="admin-newuser-ismember">Member: </label>
+        <input id="admin-newuser-ismember" type="checkbox" name="ismember" /><br/>
+
+        <label for="admin-newuser-isadmin">Admin: </label>
+        <input id="admin-newuser-isadmin" type="checkbox" name="isadmin" /><br/>
+
+        <input type="submit" value="Create User" />
+    </form>
+</section>
+
+<section id="admin-restricted-moduser">
+    <h2>Modify User</h2>
+
+    <form id="admin-moduser-form" method="get" action="/moduser" accept-charset="UTF-8">
+        <label for="admin-moduser-userid">Username: </label>
+        <select id="admin-moduser-userid" name="userid">
+            {% for user in users %}
+            <option value="{{ user.id }}">{{ user.name }}</option>
+            {% endfor %}
+        </select><br/>
+
+        <input type="submit" value="Go" />
+    </form>
+</section>
+
+<section id="admin-restricted-newproduct">
+    <h2>Create New Product</h2>
+
+    <form id="admin-newproduct-form" method="post" action="/admin?adminchange=newproduct" enctype="multipart/form-data" accept-charset="UTF-8">
+        <label for="admin-newproduct-name">Name: </label>
+        <input id="admin-newproduct-name" type="text" name="name" /><br/>
+
+        <label for="admin-newproduct-price-member">Member price: </label>
+        <input id="admin-newproduct-price-member" type="number" min="0" name="pricemember" /><br/>
+
+        <label for="admin-newproduct-price-non-member">Non-member price: </label>
+        <input id="admin-newproduct-price-non-member" type="number" min="0" name="pricenonmember" /><br/>
+
+        <label for="admin-newproduct-image">Image: </label>
+        <input id="admin-newproduct-image" type="file" accept="image/png" /><br/>
+
+        <input type="submit" value="Create Product" />
+    </form>
+</section>
+
+<section id="admin-restricted-restock">
+    <h2>Restock Product</h2>
+
+    <form id="admin-restock-form" method="post" action="/admin?adminchange=restock" accept-charset="UTF-8">
+        <label for="admin-restock-productid">Product: </label>
+        <select id="admin-restock-productid" name="productid">
+            {% for product in products %}
+            <option value="{{ product.id }}">{{ product.name }} ({{ product.stock }})</option>
+            {% endfor %}
+        </select><br/>
+
+        <label for="admin-restock-amount">Amount: </label>
+        <input id="admin-restock-amount" type="number" min="0" name="amount" /><br/>
+
+        <input type="submit" value="Restock" />
+    </form>
+</section>
+
+<section id="admin-restricted-modproduct">
+    <h2>Modify Product</h2>
+
+    <form id="admin-modproduct-form" method="get" action="/modproduct" accept-charset="UTF-8">
+        <label for="admin-modproduct-productid">Product: </label>
+        <select id="admin-modproduct-productid" name="productid">
+            {% for product in products %}
+            <option value="{{ product.id }}">{{ product.name }}</option>
+            {% endfor %}
+        </select><br/>
+
+        <input type="submit" value="Go">
+    </form>
+</section>

templates/base.html

@@ -1,17 +1,55 @@
 <!DOCTYPE html>
 <html>
-    <head>
+
-        <title>{{ setupname }}</title>
+<head>
-        <style>
+    {% block head %}
-            body {
+        {# Show the setup name, as set in the config file, as tab title. Don't escape HTML entities. #}
-                color: #f0f0f0;
+        <title>{{ setupname|safe }}</title>
-                background: #000000;
+        <link rel="stylesheet" href="/css/matemat.css"/>
-            }
+    {% endblock %}
-        </style>
+</head>
-    </head>
+
-    <body>
+<body>
-        <h1>{{ setupname }}</h1>
+
-        {% block main %}
+<header>
-        {% endblock %}
+    {% block header %}
-    </body>
+
+        {# Always show a link to the home page, either a list of users or of products. #}
+        <a href="/">Home</a>
+        {# Show a link to the settings, if a user logged in via password (authlevel 2). #}
+        {% if authlevel|default(0) > 1 %}
+            {% if authuser is defined %}
+                {# If a user is an admin, call the link "Administration".  Otherwise, call it "Settings". #}
+                {% if authuser.is_admin %}
+                    <a href="/admin">Administration</a>
+                {% else %}
+                    <a href="/admin">Settings</a>
+                {% endif %}
+            {% endif %}
+        {% endif %}
+    {% endblock %}
+</header>
+
+<main>
+    {% block main %}
+        {# Here be content. #}
+    {% endblock %}
+</main>
+
+<footer>
+    {% block footer %}
+        {# Show some information in the footer, e.g. the instance name, the version, and copyright info. #}
+        <ul>
+            <li> {{ setupname|safe }}
+            <li> Matemat {{ __version__ }}
+            <li> &copy; 2018 s3lph
+            <li> MIT License
+                {# This used to be a link to the GitLab repo.  However, users of the testing environment always clicked
+                that link and couldn't come back, because the UI was running in touch-only kiosk mode. #}
+            <li> gitlab.com/s3lph/matemat
+        </ul>
+    {% endblock %}
+</footer>
+
+</body>
 </html>

templates/login.html

@@ -1,9 +1,23 @@
 {% extends "base.html" %}
 
+{% block header %}
+    <h1>Welcome</h1>
+    {{ super() }}
+{% endblock %}
+
 {% block main %}
-        <form action="/login" method="post">
+
-            Username: <input type="text" name="username"/><br/>
+    {# Show a username/password login form #}
-            Password: <input type="password" name="password" /><br/>
+    <form method="post" action="/login" id="loginform" accept-charset="UTF-8">
-            <input type="submit" value="Login"/>
+        <label for="login-username">Username: </label>
-        </form>
+        <input id="login-username" type="text" name="username"/><br/>
-{% endblock%}
+
+        <label for="login-password">Password: </label>
+        <input id="login-password" type="password" name="password"/><br/>
+
+        <input type="submit" value="Login">
+    </form>
+
+    {{ super() }}
+
+{% endblock %}

templates/main.html

@@ -1,22 +0,0 @@
-{% extends "base.html" %}
-
-{% block main %}
-        {{ user|default("") }}
-        <ul>
-        {% if user is defined %}
-            {% for l in list %}
-                <li/> <b>{{ l.name }}</b>
-                {% if user.is_member %}
-                    {{ l.price_member }}
-                {% else %}
-                    {{ l.price_non_member }}
-                {% endif %}
-            {% endfor %}
-        {% else %}
-            {% for l in list %}
-            <li/> <b><a href="/touchkey?username={{ l.name }}">{{ l.name }}</a></b>
-            {% endfor %}
-            <li/> <a href="/login">Password login</a>
-        {% endif %}
-        </ul>
-{% endblock %}

templates/modproduct.html

@@ -0,0 +1,45 @@
+{% extends "base.html" %}
+
+{% block header %}
+<h1>Administration</h1>
+{{ super() }}
+{% endblock %}
+
+{% block main %}
+
+<section id="modproduct">
+    <h2>Modify {{ product.name }}</h2>
+
+    <form id="modproduct-form" method="post" action="/modproduct?change=update" enctype="multipart/form-data" accept-charset="UTF-8">
+        <label for="modproduct-name">Name: </label>
+        <input id="modproduct-name" type="text" name="name" value="{{ product.name }}" /><br/>
+
+        <label for="modproduct-price-member">Member price: </label>
+        CHF <input id="modproduct-price-member" type="number" step="0.01" name="pricemember" value="{{ product.price_member|chf(False) }}" /><br/>
+
+        <label for="modproduct-price-non-member">Non-member price: </label>
+        CHF <input id="modproduct-price-non-member" type="number" step="0.01" name="pricenonmember" value="{{ product.price_non_member|chf(False) }}" /><br/>
+
+        <label for="modproduct-balance">Stock: </label>
+        <input id="modproduct-balance" name="stock" type="text" value="{{ product.stock }}" /><br/>
+
+        <label for="modproduct-image">
+            <img height="150" src="/upload/thumbnails/products/{{ product.id }}.png" alt="Image of {{ product.name }}" />
+        </label><br/>
+        <input id="modproduct-image" type="file" name="image" accept="image/png" /><br/>
+
+        <input id="modproduct-productid" type="hidden" name="productid" value="{{ product.id }}" /><br/>
+
+        <input type="submit" value="Save changes">
+    </form>
+
+    <form id="modproduct-delproduct-form" method="post" action="/modproduct?change=del" accept-charset="UTF-8">
+        <input id="modproduct-delproduct-productid" type="hidden" name="productid" value="{{ product.id }}" /><br/>
+        <input type="submit" value="Delete product" />
+    </form>
+
+</section>
+
+{{ super() }}
+
+{% endblock %}

templates/moduser.html

@@ -0,0 +1,51 @@
+{% extends "base.html" %}
+
+{% block header %}
+<h1>Administration</h1>
+{{ super() }}
+{% endblock %}
+
+{% block main %}
+
+<section id="moduser-account">
+    <h2>Modify {{ user.name }}</h2>
+
+    <form id="moduser-account-form" method="post" action="/moduser?change=update" enctype="multipart/form-data" accept-charset="UTF-8">
+        <label for="moduser-account-username">Username: </label>
+        <input id="moduser-account-username" type="text" name="username" value="{{ user.name }}" /><br/>
+
+        <label for="moduser-account-email">E-Mail: </label>
+        <input id="moduser-account-email" type="text" name="email" value="{% if user.email is not none %}{{ user.email }}{% endif %}" /><br/>
+
+        <label for="moduser-account-password">Password: </label>
+        <input id="moduser-account-password" type="password" name="password" /><br/>
+
+        <label for="moduser-account-ismember">Member: </label>
+        <input id="moduser-account-ismember" name="ismember" type="checkbox" {% if user.is_member %} checked="checked" {% endif %}/><br/>
+
+        <label for="moduser-account-isadmin">Admin: </label>
+        <input id="moduser-account-isadmin" name="isadmin" type="checkbox" {% if user.is_admin %} checked="checked" {% endif %}/><br/>
+
+        <label for="moduser-account-balance">Balance: </label>
+        CHF <input id="moduser-account-balance" name="balance" type="number" step="0.01" value="{{ user.balance|chf(False) }}" /><br/>
+
+        <label for="moduser-account-avatar">
+            <img height="150" src="/upload/thumbnails/users/{{ user.id }}.png" alt="Avatar of {{ user.name }}" />
+        </label><br/>
+        <input id="moduser-account-avatar" type="file" name="avatar" accept="image/png" /><br/>
+
+        <input id="moduser-account-userid" type="hidden" name="userid" value="{{ user.id }}" /><br/>
+
+        <input type="submit" value="Save changes">
+    </form>
+
+    <form id="moduser-deluser-form" method="post" action="/moduser?change=del" accept-charset="UTF-8">
+        <input id="moduser-deluser-userid" type="hidden" name="userid" value="{{ user.id }}" /><br/>
+        <input type="submit" value="Delete user" />
+    </form>
+
+</section>
+
+{{ super() }}
+
+{% endblock %}

templates/productlist.html

@@ -0,0 +1,42 @@
+{% extends "base.html" %}
+
+{% block header %}
+    {# Show the username. #}
+    <h1>Welcome, {{ authuser.name }}</h1>
+    {{ super() }}
+{% endblock %}
+
+{% block main %}
+
+    {# Show the users current balance #}
+    Your balance: {{ authuser.balance|chf }}
+    <br/>
+    {# Links to deposit two common amounts of cash.  TODO: Will be replaced by a nicer UI later (#20) #}
+    <a href="/deposit?n=100">Deposit CHF 1</a><br/>
+    <a href="/deposit?n=1000">Deposit CHF 10</a><br/>
+
+    {% for product in products %}
+        {# Show an item per product, consisting of the name, image, price and stock, triggering a purchase on click #}
+        <div class="thumblist-item">
+            <a href="/buy?pid={{ product.id }}">
+                <span class="thumblist-title">{{ product.name }}</span>
+                <span class="thumblist-detail">Price:
+                    {% if authuser.is_member %}
+                        {{ product.price_member|chf }}
+                    {% else %}
+                        {{ product.price_non_member|chf }}
+                    {% endif %}
+                    ; Stock: {{ product.stock }}</span><br/>
+                <div class="imgcontainer">
+                    <img src="/upload/thumbnails/products/{{ product.id }}.png" alt="Picture of {{ product.name }}"/>
+                </div>
+            </a>
+        </div>
+    {% endfor %}
+    <br/>
+    {# Logout link #}
+    <a href="/logout">Logout</a>
+
+    {{ super() }}
+
+{% endblock %}

templates/touchkey.html

@@ -1,9 +1,36 @@
 {% extends "base.html" %}
 
-{% block main %}
+{% block head %}
-        <form action="/touchkey" method="post">
+{{ super() }}
-            <input type="hidden" name="username" value="{{ username }}"/><br/>
+<style>
-            Touchkey: <input type="password" name="touchkey" /><br/>
+    svg {
-            <input type="submit" value="Login"/>
+        width: 600px;
-        </form>
+        height: auto;
+    }
+</style>
+{% endblock %}
+
+{% block header %}
+<h1>Welcome, {{ username }}</h1>
+{{ super() }}
+{% endblock %}
+
+{% block main %}
+
+<svg id="touchkey-svg" width="400" height="400"></svg>
+
+<form method="post" action="/touchkey" id="loginform" accept-charset="UTF-8">
+    <input type="hidden" name="uid" value="{{ uid }}" />
+    <input type="hidden" name="username" value="{{ username }}" />
+    <input type="hidden" name="touchkey" value="" id="loginform-touchkey-value" />
+</form>
+<a href="/">Cancel</a>
+
+<script src="/js/touchkey.js"></script>
+<script>
+    initTouchkey(false, 'touchkey-svg', 'loginform', 'loginform-touchkey-value');
+</script>
+
+{{ super() }}
+
 {% endblock %}

templates/userlist.html

@@ -0,0 +1,29 @@
+{% extends "base.html" %}
+
+{% block header %}
+    {# Show the setup name, as set in the config file, as page title. Don't escape HTML entities. #}
+    <h1>{{ setupname|safe }}</h1>
+    {{ super() }}
+{% endblock %}
+
+{% block main %}
+
+    {% for user in users %}
+        {# Show an item per user, consisting of the username, and the avatar, linking to the touchkey login #}
+        <div class="thumblist-item">
+            <a href="/touchkey?uid={{ user.id }}&username={{ user.name }}">
+                <span class="thumblist-title">{{ user.name }}</span><br/>
+                <div class="imgcontainer">
+                    <img src="/upload/thumbnails/users/{{ user.id }}.png" alt="Avatar of {{ user.name }}"/>
+                </div>
+            </a>
+        </div>
+    {% endfor %}
+
+    <br/>
+    {# Link to the password login #}
+    <a href="/login">Password login</a>
+
+    {{ super() }}
+
+{% endblock %}

touchkey.html

@@ -0,0 +1,147 @@
+<!DOCTYPE html>
+<html>
+    <head>
+        <style>
+         svg {
+             width: 600px;
+             height: auto;
+         }
+        </style>
+    </head>
+    <body>
+
+        <h1>Welcome, {{username}}</h1>
+
+        <svg id="svg" width="400" height="400">
+            <circle class="c" id="0" cx="12.5%" cy="12.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            <circle class="c" id="1" cx="37.5%" cy="12.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            <circle class="c" id="2" cx="62.5%" cy="12.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            <circle class="c" id="3" cx="87.5%" cy="12.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            
+            <circle class="c" id="4" cx="12.5%" cy="37.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            <circle class="c" id="5" cx="37.5%" cy="37.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            <circle class="c" id="6" cx="62.5%" cy="37.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            <circle class="c" id="7" cx="87.5%" cy="37.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            
+            <circle class="c" id="8" cx="12.5%" cy="62.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            <circle class="c" id="9" cx="37.5%" cy="62.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            <circle class="c" id="a" cx="62.5%" cy="62.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            <circle class="c" id="b" cx="87.5%" cy="62.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            
+            <circle class="c" id="c" cx="12.5%" cy="87.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            <circle class="c" id="d" cx="37.5%" cy="87.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            <circle class="c" id="e" cx="62.5%" cy="87.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+            <circle class="c" id="f" cx="87.5%" cy="87.5%" r="10%" stroke="grey" stroke-width="2%" fill="white" />
+        </svg>
+
+        <script>
+
+         HTMLCollection.prototype.forEach = Array.prototype.forEach;
+         HTMLCollection.prototype.slice = Array.prototype.slice;
+
+         mouseDown = false;
+         currentStroke = null;
+         strokeId = 0;
+         doneMap = {};
+         enteredKey = '';
+
+         svg = document.getElementById('svg');
+
+         drawLine = (fromX, fromY, toX, toY) => {
+             var line = document.createElementNS('http://www.w3.org/2000/svg', 'line');
+             var id = 'l-' + (strokeId++);
+             var idAttr = document.createAttribute('id');
+             var classAttr = document.createAttribute('class');
+             var x1attr = document.createAttribute('x1');
+             var y1attr = document.createAttribute('y1');
+             var x2attr = document.createAttribute('x2');
+             var y2attr = document.createAttribute('y2');
+             var styleAttr = document.createAttribute('style');
+             idAttr.value = id;
+             classAttr.value = 'l';
+             x1attr.value = fromX;
+             y1attr.value = fromY;
+             x2attr.value = toX;
+             y2attr.value = toY;
+             styleAttr.value = 'stroke: grey; stroke-width: 5%; stroke-linecap: round';
+             line.setAttributeNode(idAttr);
+             line.setAttributeNode(classAttr);
+             line.setAttributeNode(x1attr);
+             line.setAttributeNode(y1attr);
+             line.setAttributeNode(x2attr);
+             line.setAttributeNode(y2attr);
+             line.setAttributeNode(styleAttr);
+             svg.appendChild(line);
+             return id;
+         };
+
+         svg.onmousedown = (ev) => {
+             var svgrect = svg.getBoundingClientRect();
+             var minId = '';
+             var minDist = Infinity;
+             var minx = 0;
+             var miny = 0;
+             doneMap = {};
+             document.getElementsByClassName('c').forEach((circle) => {
+                 var x = parseFloat(circle.getAttribute('cx'))/100.0 * svgrect.width;
+                 var y = parseFloat(circle.getAttribute('cy'))/100.0 * svgrect.height;
+                 var dist = Math.pow(ev.offsetX - x, 2) + Math.pow(ev.offsetY - y, 2);
+                 if (dist < minDist) {
+                     minDist = dist;
+                     minId = circle.id;
+                     minx = x;
+                     miny = y;
+                 }
+             });
+             var minNode = svg.getElementById(minId);
+             currentStroke = drawLine(minx, miny, ev.offsetX, ev.offsetY);
+             doneMap[minId] = 1;
+             enteredKey += minId;
+         };
+
+         svg.onmouseup = (ev) => {
+             currentStroke = null;
+             doneMap = {};
+             console.log(enteredKey);
+             enteredKey = '';
+             svg.getElementsByClassName('l').slice().reverse().forEach((line) => {
+                 svg.removeChild(line);
+             });
+         };
+
+         svg.onmousemove = (ev) => {
+             if (currentStroke != null) {
+                 var svgrect = svg.getBoundingClientRect();
+                 var minId = '';
+                 var minDist = Infinity;
+                 var minx = 0;
+                 var miny = 0;
+                 document.getElementsByClassName('c').forEach((circle) => {
+                     var x = parseFloat(circle.getAttribute('cx'))/100.0 * svgrect.width;
+                     var y = parseFloat(circle.getAttribute('cy'))/100.0 * svgrect.height;
+                     var dist = Math.pow(ev.offsetX - x, 2) + Math.pow(ev.offsetY - y, 2);
+                     if (dist < minDist) {
+                         minDist = dist;
+                         minId = circle.id;
+                         minx = x;
+                         miny = y;
+                     }
+                 });
+                 if (minDist < 2000 && !(minId in doneMap)) {
+                     var line = svg.getElementById(currentStroke);
+                     line.setAttribute('x2', minx);
+                     line.setAttribute('y2', miny);
+                     currentStroke = drawLine(minx, miny, ev.offsetX, ev.offsetY);
+                     doneMap[minId] = 1;
+                     enteredKey += minId;
+                 }
+                 var line = svg.getElementById(currentStroke);
+                 line.setAttribute('x2', ev.offsetX);
+                 line.setAttribute('y2', ev.offsetY);
+             }
+         };
+
+        </script>
+
+    </body>
+</html>