matemat/uncanny/server.go

package uncanny

import (
	"log"
	"fmt"
	"net/http"
	"path"
	"strconv"
)

const (
	// highest slot number (range: 0..maxSlot)
	maxSlot = 4
	// highest display line number (range: 0..maxLine)
	maxLine = 1
)

type Server struct {
	*http.ServeMux
	srv *http.Server
	can *Can
}

func NewServer(can *Can, addr string) *Server {
	ret := &Server{
		ServeMux: http.NewServeMux(),
		can:      can,
		srv:      &http.Server{
			Addr: addr,
		},
	}
	ret.registerHandlers()
	ret.srv.Handler = ret
	return ret
}

func (s *Server) registerHandlers() {
	s.HandleFunc("/", http.NotFound)
	s.HandleFunc("/dispense/", func(rw http.ResponseWriter, r *http.Request) {
		if matched, _ := path.Match("/dispense/[0-9]*", r.URL.Path); matched {
			slot, err := strconv.ParseUint(path.Base(r.URL.Path), 10, 32)
			if err != nil {
				log.Printf("Error decoding slot number: %v", err)
				http.Error(rw, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
			} else if slot < 0 || slot > maxSlot {
				log.Printf("Invalid slot number: %d", slot)
				http.Error(rw, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
			} else {
				s.can.Dispense(int(slot))
				rw.Header().Set("Content-Type", "text/plain")
				rw.WriteHeader(http.StatusOK)
				fmt.Fprintf(rw, "%d dispensing", slot)
			}
		} else {
			log.Printf("Mismatched path: %s", r.URL.Path)
			http.Error(rw, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
		}
	})
	s.HandleFunc("/stop", func(rw http.ResponseWriter, r *http.Request) {
		s.can.Cancel()
		rw.Header().Set("Content-Type", "text/plain")
		rw.WriteHeader(http.StatusOK)
		fmt.Fprintf(rw, "stopping")
	})
	s.HandleFunc("/level/", func(rw http.ResponseWriter, r *http.Request) {
		if matched, _ := path.Match("/level/[0-9]*", r.URL.Path); matched {
			slot, err := strconv.ParseUint(path.Base(r.URL.Path), 10, 32)
			if err != nil {
				log.Printf("Error decoding slot number: %v", err)
				http.Error(rw, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
			} else if slot < 0 || slot > maxSlot {
				log.Printf("Invalid slot number: %d", slot)
				http.Error(rw, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
			} else {
				rw.Header().Set("Content-Type", "text/plain")
				rw.WriteHeader(http.StatusOK)
				if s.can.IsEmpty(int(slot)) {
					fmt.Fprintf(rw, "%d empty", slot)
				} else {
					fmt.Fprintf(rw, "%d full", slot)
				}
			}
		} else {
			log.Printf("Mismatched path: %s", r.URL.Path)
			http.Error(rw, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
		}
	})
	s.HandleFunc("/active/", func(rw http.ResponseWriter, r *http.Request) {
		if matched, _ := path.Match("/active/[0-9]*", r.URL.Path); matched {
			slot, err := strconv.ParseUint(path.Base(r.URL.Path), 10, 32)
			if err != nil {
				log.Printf("Error decoding slot number: %v", err)
				http.Error(rw, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
			} else if slot < 0 || slot > maxSlot {
				log.Printf("Invalid slot number: %d", slot)
				http.Error(rw, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
			} else {
				rw.Header().Set("Content-Type", "text/plain")
				rw.WriteHeader(http.StatusOK)
				if s.can.IsDispensing(int(slot)) {
					fmt.Fprintf(rw, "%d dispensing", slot)
				} else {
					fmt.Fprintf(rw, "%d off", slot)
				}
			}
		} else {
			log.Printf("Mismatched path: %s", r.URL.Path)
			http.Error(rw, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
		}
	})
	s.HandleFunc("/display/", func(rw http.ResponseWriter, r *http.Request) {
		if matched, _ := path.Match("/display/[0-9]*", r.URL.Path); matched {
			line, err := strconv.ParseUint(path.Base(r.URL.Path), 10, 32)
			if err != nil {
				log.Printf("Error decoding line number: %v", err)
				http.Error(rw, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
			} else if line < 0 || line > maxLine {
				log.Printf("Invalid line number: %d", line)
				http.Error(rw, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
			} else {
				query := r.URL.Query()
				if _, ok := query["text"]; ok {
					text := query.Get("text")
					s.can.DisplayPrint(int(line), text)
					rw.Header().Set("Content-Type", "text/plain")
					rw.WriteHeader(http.StatusOK)
					fmt.Fprintf(rw, "Printed on line %d: '%s'", int(line), text)
				} else {
					log.Printf("Invalid query, missing text")
					http.Error(rw, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
				}
			}
		} else {
			log.Printf("Mismatched path: %s", r.URL.Path)
			http.Error(rw, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
		}
	})
}

func (s *Server) Start() error {
	log.Printf("Listening on %v", s.srv.Addr)
	return s.srv.ListenAndServe()
}

func (s *Server) Stop() error {
	return s.srv.Close()
}