package uncanny

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

// since we can't use macros in Go directly, let's add some wrappers
// to avoid conflicts, we'll simply lowercase the symbol names

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 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
	MessageTypeFeedback
	MessageTypeFeedbackRequest
	MessageTypePower
	MessageTypePowerRequest
	MessageTypeDispense
	MessageTypeAuto
)

// 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 := DecodeFeedbackMessage(frame)
		return MessageTypeFeedback, msg, err
	case uint32(C.can_msg_feedback_status) | can.MaskRtr:
		return MessageTypeFeedbackRequest, nil, nil
	case uint32(C.can_msg_power_status):
		msg, err := DecodePowerMessage(frame)
		return MessageTypePower, msg, err
	case uint32(C.can_msg_power_status) | can.MaskRtr:
		return MessageTypePowerRequest, nil, nil
	case uint32(C.can_msg_power_dispense):
		msg, err := DecodeDispenseMessage(frame)
		return MessageTypeDispense, msg, err
	case uint32(C.can_msg_auto_status):
		msg, err := DecodeAutoMessage(frame)
		return MessageTypeAuto, msg, err
	}
	return MessageTypeInvalid, nil, UnsupportedMessageType
}

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

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

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

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

type PowerMessage struct {
	Bits int
}

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

func DecodePowerMessage(frame can.Frame) (PowerMessage, error) {
	var ret PowerMessage
	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 PowerMessage) Encode() can.Frame {
	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 DispenseMessage struct {
	Slot int
}

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

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

type AutoMessage struct {
	AutoUpdate bool
}

func DecodeAutoMessage(frame can.Frame) (AutoMessage, error) {
	var ret AutoMessage
	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] != C.can_msg_auto_status_disable {
		ret.AutoUpdate = true
	}
	return ret, nil
}

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