package uncanny

/*
// Include our message format definitions
#cgo CPPFLAGS: -I${SRCDIR}/..
#include <stdint.h>
#include <messages.h>

// Since we can't use C macros in Go directly, let's add some wrappers.
// WARNING: CGo type translation can be very wonky, so make sure to always
// cast to the expected type!

const uint16_t can_msg_feedback_status = CAN_MSG_FEEDBACK_STATUS;
const size_t can_msg_feedback_status_field_reset_sw = CAN_MSG_FEEDBACK_STATUS_FIELD_RESET_SW;
const uint8_t can_msg_feedback_status_bit_reset_sw = CAN_MSG_FEEDBACK_STATUS_BIT_RESET_SW;
const size_t can_msg_feedback_status_field_empty_h = CAN_MSG_FEEDBACK_STATUS_FIELD_EMPTY_H;
const uint8_t can_msg_feedback_status_bit_empty_h = CAN_MSG_FEEDBACK_STATUS_BIT_EMPTY_H;
const size_t can_msg_feedback_status_field_empty_g = CAN_MSG_FEEDBACK_STATUS_FIELD_EMPTY_G;
const uint8_t can_msg_feedback_status_bit_empty_g = CAN_MSG_FEEDBACK_STATUS_BIT_EMPTY_G;
const size_t can_msg_feedback_status_field_empty_f = CAN_MSG_FEEDBACK_STATUS_FIELD_EMPTY_F;
const uint8_t can_msg_feedback_status_bit_empty_f = CAN_MSG_FEEDBACK_STATUS_BIT_EMPTY_F;
const size_t can_msg_feedback_status_field_empty_e = CAN_MSG_FEEDBACK_STATUS_FIELD_EMPTY_E;
const uint8_t can_msg_feedback_status_bit_empty_e = CAN_MSG_FEEDBACK_STATUS_BIT_EMPTY_E;
const size_t can_msg_feedback_status_field_empty_d = CAN_MSG_FEEDBACK_STATUS_FIELD_EMPTY_D;
const uint8_t can_msg_feedback_status_bit_empty_d = CAN_MSG_FEEDBACK_STATUS_BIT_EMPTY_D;
const size_t can_msg_feedback_status_field_end_h = CAN_MSG_FEEDBACK_STATUS_FIELD_END_H;
const uint8_t can_msg_feedback_status_bit_end_h = CAN_MSG_FEEDBACK_STATUS_BIT_END_H;
const size_t can_msg_feedback_status_field_end_g = CAN_MSG_FEEDBACK_STATUS_FIELD_END_G;
const uint8_t can_msg_feedback_status_bit_end_g = CAN_MSG_FEEDBACK_STATUS_BIT_END_G;
const size_t can_msg_feedback_status_field_end_f = CAN_MSG_FEEDBACK_STATUS_FIELD_END_F;
const uint8_t can_msg_feedback_status_bit_end_f = CAN_MSG_FEEDBACK_STATUS_BIT_END_F;
const size_t can_msg_feedback_status_field_end_e = CAN_MSG_FEEDBACK_STATUS_FIELD_END_E;
const uint8_t can_msg_feedback_status_bit_end_e = CAN_MSG_FEEDBACK_STATUS_BIT_END_E;
const size_t can_msg_feedback_status_field_end_d = CAN_MSG_FEEDBACK_STATUS_FIELD_END_D;
const uint8_t can_msg_feedback_status_bit_end_d = CAN_MSG_FEEDBACK_STATUS_BIT_END_D;

const uint16_t can_msg_power_status = CAN_MSG_POWER_STATUS;

const uint16_t can_msg_power_dispense = CAN_MSG_POWER_DISPENSE;
const uint8_t can_msg_power_dispense_off = CAN_MSG_POWER_DISPENSE_OFF;
const uint8_t can_msg_power_dispense_slot1 = CAN_MSG_POWER_DISPENSE_SLOT1;
const uint8_t can_msg_power_dispense_slot2 = CAN_MSG_POWER_DISPENSE_SLOT2;
const uint8_t can_msg_power_dispense_slot3 = CAN_MSG_POWER_DISPENSE_SLOT3;
const uint8_t can_msg_power_dispense_slot4 = CAN_MSG_POWER_DISPENSE_SLOT4;
const uint8_t can_msg_power_dispense_slot5 = CAN_MSG_POWER_DISPENSE_SLOT5;

const uint8_t can_msg_display_status = CAN_MSG_DISPLAY_STATUS;
const uint8_t can_msg_display_cmd = CAN_MSG_DISPLAY_CMD;

const uint16_t can_msg_auto_status = CAN_MSG_AUTO_STATUS;
const uint8_t can_msg_auto_status_disable = CAN_MSG_AUTO_STATUS_DISABLE;
const uint8_t can_msg_auto_status_enable = CAN_MSG_AUTO_STATUS_ENABLE;
*/
import "C"

import (
	"errors"
	"github.com/brutella/can"
)

var (
	InvalidMessageID = errors.New("Invalid message ID, cannot decode")
	InvalidMessageLength = errors.New("Invalid message length, cannot decode")
	UnsupportedMessageType = errors.New("Unsupported message type, cannot decode")
)

type MessageType int
const (
	MessageTypeInvalid MessageType = iota
	MessageTypeFeedbackStatus
	MessageTypeFeedbackRequest
	MessageTypePowerStatus
	MessageTypePowerRequest
	MessageTypeDispenseCommand
	MessageTypeDisplayStatus
	MessageTypeDisplayRequest
	MessageTypeDisplayCommand
	MessageTypeAutoCommand
)

// DecodeMessage decodes a CAN frame and returns an appropriate message
// object and the message type.
//
// For request messages, only the type is returned (object and error are nil)
//
// When the message cannot be decoded, a nil object and MessageTypeInvalid is
// returned, plus an appropriate error. If the message ID is unknown, error
// will be UnsupportedMessageType.
func DecodeMessage(frame can.Frame) (MessageType, interface{}, error) {
	switch frame.ID {
	case uint32(C.can_msg_feedback_status):
		msg, err := DecodeFeedbackStatus(frame)
		return MessageTypeFeedbackStatus, msg, err
	case uint32(C.can_msg_feedback_status) | can.MaskRtr:
		return MessageTypeFeedbackRequest, nil, nil
	case uint32(C.can_msg_power_status):
		msg, err := DecodePowerStatus(frame)
		return MessageTypePowerStatus, msg, err
	case uint32(C.can_msg_power_status) | can.MaskRtr:
		return MessageTypePowerRequest, nil, nil
	case uint32(C.can_msg_power_dispense):
		msg, err := DecodeDispenseCommand(frame)
		return MessageTypeDispenseCommand, msg, err
	case uint32(C.can_msg_display_status):
		msg, err := DecodeDisplayStatus(frame)
		return MessageTypeDisplayStatus, msg, err
	case uint32(C.can_msg_display_status) | can.MaskRtr:
		return MessageTypeDisplayRequest, nil, nil
	case uint32(C.can_msg_display_cmd):
		msg, err := DecodeDisplayCommand(frame)
		return MessageTypeDisplayCommand, msg, err
	case uint32(C.can_msg_auto_status):
		msg, err := DecodeAutoCommand(frame)
		return MessageTypeAutoCommand, msg, err
	}
	return MessageTypeInvalid, nil, UnsupportedMessageType
}

type FeedbackStatus struct {
	EndD bool
	EndE bool
	EndF bool
	EndG bool
	EndH bool
	EmptyD bool
	EmptyE bool
	EmptyF bool
	EmptyG bool
	EmptyH bool
	ResetSw bool
}

func EncodeFeedbackRequest() can.Frame {
	return can.Frame{
		ID: uint32(C.can_msg_feedback_status) | can.MaskRtr,
	}
}

func DecodeFeedbackStatus(frame can.Frame) (FeedbackStatus, error) {
	var ret FeedbackStatus
	if frame.ID != uint32(C.can_msg_feedback_status) {
		return ret, InvalidMessageID
	}
	if frame.Length != 2 {
		return ret, InvalidMessageLength
	}
	ret.EndD = frame.Data[int(C.can_msg_feedback_status_field_end_d)] & uint8(C.can_msg_feedback_status_bit_end_d) != 0
	ret.EndE = frame.Data[int(C.can_msg_feedback_status_field_end_e)] & uint8(C.can_msg_feedback_status_bit_end_e) != 0
	ret.EndF = frame.Data[int(C.can_msg_feedback_status_field_end_f)] & uint8(C.can_msg_feedback_status_bit_end_f) != 0
	ret.EndG = frame.Data[int(C.can_msg_feedback_status_field_end_g)] & uint8(C.can_msg_feedback_status_bit_end_g) != 0
	ret.EndH = frame.Data[int(C.can_msg_feedback_status_field_end_h)] & uint8(C.can_msg_feedback_status_bit_end_h) != 0
	ret.EmptyD = frame.Data[int(C.can_msg_feedback_status_field_empty_d)] & uint8(C.can_msg_feedback_status_bit_empty_d) != 0
	ret.EmptyE = frame.Data[int(C.can_msg_feedback_status_field_empty_e)] & uint8(C.can_msg_feedback_status_bit_empty_e) != 0
	ret.EmptyF = frame.Data[int(C.can_msg_feedback_status_field_empty_f)] & uint8(C.can_msg_feedback_status_bit_empty_f) != 0
	ret.EmptyG = frame.Data[int(C.can_msg_feedback_status_field_empty_g)] & uint8(C.can_msg_feedback_status_bit_empty_g) != 0
	ret.EmptyH = frame.Data[int(C.can_msg_feedback_status_field_empty_h)] & uint8(C.can_msg_feedback_status_bit_empty_h) != 0
	ret.ResetSw = frame.Data[int(C.can_msg_feedback_status_field_reset_sw)] & uint8(C.can_msg_feedback_status_bit_reset_sw) != 0
	return ret, nil
}

func (f FeedbackStatus) Encode() can.Frame {
	var data [8]uint8
	if f.EndD {
		data[int(C.can_msg_feedback_status_field_end_d)] |= uint8(C.can_msg_feedback_status_bit_end_d)
	}
	if f.EndE {
		data[int(C.can_msg_feedback_status_field_end_e)] |= uint8(C.can_msg_feedback_status_bit_end_e)
	}
	if f.EndF {
		data[int(C.can_msg_feedback_status_field_end_f)] |= uint8(C.can_msg_feedback_status_bit_end_f)
	}
	if f.EndG {
		data[int(C.can_msg_feedback_status_field_end_g)] |= uint8(C.can_msg_feedback_status_bit_end_g)
	}
	if f.EndH {
		data[int(C.can_msg_feedback_status_field_end_h)] |= uint8(C.can_msg_feedback_status_bit_end_h)
	}
	if f.EmptyD {
		data[int(C.can_msg_feedback_status_field_empty_d)] |= uint8(C.can_msg_feedback_status_bit_empty_d)
	}
	if f.EmptyE {
		data[int(C.can_msg_feedback_status_field_empty_e)] |= uint8(C.can_msg_feedback_status_bit_empty_e)
	}
	if f.EmptyF {
		data[int(C.can_msg_feedback_status_field_empty_f)] |= uint8(C.can_msg_feedback_status_bit_empty_f)
	}
	if f.EmptyG {
		data[int(C.can_msg_feedback_status_field_empty_g)] |= uint8(C.can_msg_feedback_status_bit_empty_g)
	}
	if f.EmptyH {
		data[int(C.can_msg_feedback_status_field_empty_h)] |= uint8(C.can_msg_feedback_status_bit_empty_h)
	}
	if f.ResetSw {
		data[int(C.can_msg_feedback_status_field_reset_sw)] |= uint8(C.can_msg_feedback_status_bit_reset_sw)
	}
	return can.Frame{
		ID: uint32(C.can_msg_feedback_status),
		Length: 2,
		Data: data,
	}
}

type PowerStatus struct {
	Bits int
}

func EncodePowerRequest() can.Frame {
	return can.Frame{
		ID: uint32(C.can_msg_power_status) | can.MaskRtr,
	}
}

func DecodePowerStatus(frame can.Frame) (PowerStatus, error) {
	var ret PowerStatus
	if frame.ID != uint32(C.can_msg_power_status) {
		return ret, InvalidMessageID
	}
	if frame.Length != 2 {
		return ret, InvalidMessageLength
	}
	ret.Bits = (int(frame.Data[0]) << 8) | int(frame.Data[1])
	return ret, nil
}

func (f PowerStatus) Encode() can.Frame {
	var data [8]uint8
	data[0] = uint8(f.Bits >> 8)
	data[1] = uint8(f.Bits)
	return can.Frame{
		ID: uint32(C.can_msg_power_status),
		Length: 2,
		Data: data,
	}
}

const DispenseSlotOff int = -1

type DispenseCommand struct {
	Slot int
}

func DecodeDispenseCommand(frame can.Frame) (DispenseCommand, error) {
	var ret DispenseCommand
	if frame.ID != uint32(C.can_msg_power_dispense) {
		return ret, InvalidMessageID
	}
	if frame.Length != 1 {
		return ret, InvalidMessageLength
	}
	switch frame.Data[0] {
	case uint8(C.can_msg_power_dispense_off):
		ret.Slot = DispenseSlotOff
	case uint8(C.can_msg_power_dispense_slot1):
		ret.Slot = 0
	case uint8(C.can_msg_power_dispense_slot2):
		ret.Slot = 1
	case uint8(C.can_msg_power_dispense_slot3):
		ret.Slot = 2
	case uint8(C.can_msg_power_dispense_slot4):
		ret.Slot = 3
	case uint8(C.can_msg_power_dispense_slot5):
		ret.Slot = 4
	}
	return ret, nil
}

func (f DispenseCommand) Encode() can.Frame {
	var data [8]uint8
	switch f.Slot {
	case DispenseSlotOff:
		data[0] = uint8(C.can_msg_power_dispense_off)
	case 0:
		data[0] = uint8(C.can_msg_power_dispense_slot1)
	case 1:
		data[0] = uint8(C.can_msg_power_dispense_slot2)
	case 2:
		data[0] = uint8(C.can_msg_power_dispense_slot3)
	case 3:
		data[0] = uint8(C.can_msg_power_dispense_slot4)
	case 4:
		data[0] = uint8(C.can_msg_power_dispense_slot5)
	}
	return can.Frame{
		ID: uint32(C.can_msg_power_dispense),
		Length: 1,
		Data: data,
	}
}

type DisplayStatus struct {
	Buttons []bool
}

func EncodeDisplayRequest() can.Frame {
	return can.Frame{
		ID: uint32(C.can_msg_display_status) | can.MaskRtr,
	}
}

func DecodeDisplayStatus(frame can.Frame) (DisplayStatus, error) {
	var ret DisplayStatus
	if frame.ID != uint32(C.can_msg_display_status) {
		return ret, InvalidMessageID
	}
	if frame.Length != 1 {
		return ret, InvalidMessageLength
	}
	ret.Buttons = make([]bool, 8)
	for i := uint(0); i < 8; i++ {
		ret.Buttons[i] = frame.Data[0] & (1 << i) != 0;
	}
	return ret, nil
}

func (f DisplayStatus) Encode() can.Frame {
	var data [8]uint8
	for i := uint(0); i < 8; i++ {
		if f.Buttons[i] {
			data[0] |= (1 << i)
		}
	}
	return can.Frame{
		ID: uint32(C.can_msg_display_status),
		Length: 1,
		Data: data,
	}
}

type DisplayCommand struct {
	Command int
	Data []byte
}

func DecodeDisplayCommand(frame can.Frame) (DisplayCommand, error) {
	var ret DisplayCommand
	if frame.ID != uint32(C.can_msg_display_cmd) {
		return ret, InvalidMessageID
	}
	if frame.Length < 1 {
		return ret, InvalidMessageLength
	}
	ret.Command = int(frame.Data[0])
	ret.Data = make([]byte, frame.Length - 1)
	copy(ret.Data, frame.Data[1:frame.Length-1])
	return ret, nil
}

func (f DisplayCommand) Encode() can.Frame {
	data := [8]uint8{}
	data[0] = uint8(f.Command)
	length := len(f.Data)
	if length > 7 {
		length = 7
	}
	copy(data[1:], f.Data[:length])
	return can.Frame{
		ID: uint32(C.can_msg_display_cmd),
		Length: uint8(length + 1),
		Data: data,
	}
}

type AutoCommand struct {
	AutoUpdate bool
}

func DecodeAutoCommand(frame can.Frame) (AutoCommand, error) {
	var ret AutoCommand
	if frame.ID != uint32(C.can_msg_auto_status) {
		return ret, InvalidMessageID
	}
	if frame.Length != 1 {
		return ret, InvalidMessageLength
	}
	// we accept all non-null values as "enable"
	if frame.Data[0] != uint8(C.can_msg_auto_status_disable) {
		ret.AutoUpdate = true
	}
	return ret, nil
}

func (f AutoCommand) Encode() can.Frame {
	data := [8]uint8{}
	if f.AutoUpdate {
		data[0] = uint8(C.can_msg_auto_status_enable)
	} else {
		data[0] = uint8(C.can_msg_auto_status_disable)
	}
	return can.Frame{
		ID: uint32(C.can_msg_auto_status),
		Length: 1,
		Data: data,
	}
}