package tuya

import (
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"hash/crc32"
	"strings"
	"time"

	"github.com/AlexxIT/go2rtc/pkg/core"
	mqtt "github.com/eclipse/paho.mqtt.golang"
)

type TuyaMqttClient struct {
	client           mqtt.Client
	waiter           core.Waiter
	wakeupWaiter     core.Waiter
	speakerWaiter    core.Waiter
	publishTopic     string
	subscribeTopic   string
	auth             string
	iceServers       []ICEServer
	uid              string
	motoId           string
	deviceId         string
	sessionId        string
	closed           bool
	webrtcVersion    int
	handleAnswer     func(answer AnswerFrame)
	handleCandidate  func(candidate CandidateFrame)
	handleDisconnect func()
	handleError      func(err error)
}

type MqttFrameHeader struct {
	Type          string `json:"type"`
	From          string `json:"from"`
	To            string `json:"to"`
	SubDevID      string `json:"sub_dev_id"`
	SessionID     string `json:"sessionid"`
	MotoID        string `json:"moto_id"`
	TransactionID string `json:"tid"`
}

type MqttFrame struct {
	Header  MqttFrameHeader `json:"header"`
	Message json.RawMessage `json:"msg"`
}

type OfferFrame struct {
	Mode              string      `json:"mode"`
	Sdp               string      `json:"sdp"`
	StreamType        int         `json:"stream_type"` // 0: mainStream(HD), 1: substream(SD)
	Auth              string      `json:"auth"`
	DatachannelEnable bool        `json:"datachannel_enable"` // true for HEVC, false for H264
	Token             []ICEServer `json:"token"`
}

type AnswerFrame struct {
	Mode string `json:"mode"`
	Sdp  string `json:"sdp"`
}

type CandidateFrame struct {
	Mode      string `json:"mode"`
	Candidate string `json:"candidate"`
}

type ResolutionFrame struct {
	Mode  string `json:"mode"`
	Value int    `json:"cmdValue"` // 0: HD, 1: SD
}

type SpeakerFrame struct {
	Mode  string `json:"mode"`
	Value int    `json:"cmdValue"` // 0: off, 1: on
}

type DisconnectFrame struct {
	Mode string `json:"mode"`
}

type MqttLowPowerMessage struct {
	Protocol int    `json:"protocol"`
	T        int    `json:"t"`
	S        int    `json:"s,omitempty"`
	Type     string `json:"type,omitempty"`
	Data     struct {
		DevID                string                 `json:"devId,omitempty"`
		Online               bool                   `json:"online,omitempty"`
		LastOnlineChangeTime int64                  `json:"lastOnlineChangeTime,omitempty"`
		GwID                 string                 `json:"gwId,omitempty"`
		Cmd                  string                 `json:"cmd,omitempty"`
		Dps                  map[string]interface{} `json:"dps,omitempty"`
	} `json:"data"`
}

type MqttMessage struct {
	Protocol int       `json:"protocol"`
	Pv       string    `json:"pv"`
	T        int64     `json:"t"`
	Data     MqttFrame `json:"data"`
}

func NewTuyaMqttClient(deviceId string) *TuyaMqttClient {
	return &TuyaMqttClient{
		deviceId:     deviceId,
		sessionId:    core.RandString(6, 62),
		waiter:       core.Waiter{},
		wakeupWaiter: core.Waiter{},
	}
}

func (c *TuyaMqttClient) Start(hubConfig *MQTTConfig, webrtcConfig *WebRTCConfig, webrtcVersion int) error {
	c.webrtcVersion = webrtcVersion
	c.motoId = webrtcConfig.MotoID
	c.auth = webrtcConfig.Auth
	c.iceServers = webrtcConfig.P2PConfig.Ices

	c.publishTopic = hubConfig.PublishTopic
	c.subscribeTopic = hubConfig.SubscribeTopic

	c.publishTopic = strings.Replace(c.publishTopic, "moto_id", c.motoId, 1)
	c.publishTopic = strings.Replace(c.publishTopic, "{device_id}", c.deviceId, 1)

	parts := strings.Split(c.subscribeTopic, "/")
	c.uid = parts[3]

	opts := mqtt.NewClientOptions().AddBroker(hubConfig.Url).
		SetClientID(hubConfig.ClientID).
		SetUsername(hubConfig.Username).
		SetPassword(hubConfig.Password).
		SetOnConnectHandler(c.onConnect).
		SetAutoReconnect(true).
		SetMaxReconnectInterval(30 * time.Second).
		SetConnectTimeout(30 * time.Second).
		SetKeepAlive(60 * time.Second).
		SetPingTimeout(20 * time.Second)

	c.client = mqtt.NewClient(opts)

	if token := c.client.Connect(); token.Wait() && token.Error() != nil {
		return token.Error()
	}

	if err := c.waiter.Wait(); err != nil {
		return err
	}

	return nil
}

func (c *TuyaMqttClient) Stop() {
	c.waiter.Done(errors.New("mqtt: stopped"))
	c.wakeupWaiter.Done(errors.New("mqtt: stopped"))
	c.speakerWaiter.Done(errors.New("mqtt: stopped"))

	if c.client != nil {
		_ = c.SendDisconnect()
		c.client.Disconnect(100)
	}

	c.closed = true
}

// WakeUp sends a wake-up signal to battery-powered cameras (LowPower mode).
// The camera wakes up and starts responding immediately - we don't wait for dps[149].
// Note: LowPower cameras sleep after ~3 minutes of inactivity.
func (c *TuyaMqttClient) WakeUp(localKey string) error {
	// Calculate CRC32 of localKey as wake-up payload
	crc := crc32.ChecksumIEEE([]byte(localKey))

	// Convert to hex string
	hexStr := fmt.Sprintf("%08x", crc)

	// Convert hex string to byte array (2 chars at a time)
	payload := make([]byte, len(hexStr)/2)
	for i := 0; i < len(hexStr); i += 2 {
		b, err := hex.DecodeString(hexStr[i : i+2])
		if err != nil {
			return fmt.Errorf("failed to decode hex: %w", err)
		}
		payload[i/2] = b[0]
	}

	// Publish to wake-up topic: m/w/{deviceId}
	wakeUpTopic := fmt.Sprintf("m/w/%s", c.deviceId)
	token := c.client.Publish(wakeUpTopic, 1, false, payload)
	if token.Wait() && token.Error() != nil {
		return fmt.Errorf("failed to publish wake-up message: %w", token.Error())
	}

	// Subscribe to lowPower topic to receive dps[149] status updates
	// (we don't wait for this signal - camera responds immediately)
	lowPowerTopic := fmt.Sprintf("smart/decrypt/in/%s", c.deviceId)
	if token := c.client.Subscribe(lowPowerTopic, 1, c.onLowPowerMessage); token.Wait() && token.Error() != nil {
		return fmt.Errorf("failed to subscribe to lowPower topic: %w", token.Error())
	}

	return nil
}

func (c *TuyaMqttClient) SendOffer(sdp string, streamResolution string, streamType int, isHEVC bool) error {
	// Map Skill StreamType to MQTT stream_type values
	// streamType comes from GetStreamType() and uses Skill StreamType values:
	// - mainStream = 2 (HD)
	// - substream = 4 (SD)
	//
	// But MQTT expects mapped stream_type values:
	// - mainStream (2) → stream_type: 0
	// - substream (4) → stream_type: 1

	mqttStreamType := streamType
	switch streamType {
	case 2:
		mqttStreamType = 0 // mainStream (HD)
	case 4:
		mqttStreamType = 1 // substream (SD)
	}

	return c.sendMqttMessage("offer", 302, "", OfferFrame{
		Mode:              "webrtc",
		Sdp:               sdp,
		StreamType:        mqttStreamType,
		Auth:              c.auth,
		DatachannelEnable: isHEVC, // must be true for HEVC
		Token:             c.iceServers,
	})
}

func (c *TuyaMqttClient) SendCandidate(candidate string) error {
	return c.sendMqttMessage("candidate", 302, "", CandidateFrame{
		Mode:      "webrtc",
		Candidate: candidate,
	})
}

func (c *TuyaMqttClient) SendResolution(resolution int) error {
	// Check if camera supports clarity switching
	isClaritySupported := (c.webrtcVersion & (1 << 5)) != 0
	if !isClaritySupported {
		return nil
	}

	return c.sendMqttMessage("resolution", 312, "", ResolutionFrame{
		Mode:  "webrtc",
		Value: resolution, // 0: HD, 1: SD
	})
}

func (c *TuyaMqttClient) SendSpeaker(speaker int) error {
	if err := c.sendMqttMessage("speaker", 312, "", SpeakerFrame{
		Mode:  "webrtc",
		Value: speaker, // 0: off, 1: on
	}); err != nil {
		return err
	}

	// Wait for camera response
	if err := c.speakerWaiter.Wait(); err != nil {
		return fmt.Errorf("speaker wait failed: %w", err)
	}

	return nil
}

func (c *TuyaMqttClient) SendDisconnect() error {
	return c.sendMqttMessage("disconnect", 302, "", DisconnectFrame{
		Mode: "webrtc",
	})
}

func (c *TuyaMqttClient) onConnect(client mqtt.Client) {
	if token := client.Subscribe(c.subscribeTopic, 1, c.onMessage); token.Wait() && token.Error() != nil {
		c.waiter.Done(token.Error())
		return
	}

	c.waiter.Done(nil)
}

func (c *TuyaMqttClient) onMessage(client mqtt.Client, msg mqtt.Message) {
	var rmqtt MqttMessage
	if err := json.Unmarshal(msg.Payload(), &rmqtt); err != nil {
		c.onError(err)
		return
	}

	// Filter by session ID to prevent processing messages from other sessions
	if rmqtt.Data.Header.SessionID != c.sessionId {
		return
	}

	switch rmqtt.Data.Header.Type {
	case "answer":
		c.onMqttAnswer(&rmqtt)
	case "candidate":
		c.onMqttCandidate(&rmqtt)
	case "disconnect":
		c.onMqttDisconnect()
	case "speaker":
		c.onMqttSpeaker(&rmqtt)
	}
}

func (c *TuyaMqttClient) onLowPowerMessage(client mqtt.Client, msg mqtt.Message) {
	var message MqttLowPowerMessage
	if err := json.Unmarshal(msg.Payload(), &message); err != nil {
		return
	}

	// Check if protocol is 4 and dps[149] is true
	// https://developer.tuya.com/en/docs/iot-device-dev/doorbell_solution?id=Kayamyivh15ox#title-2-Battery
	if message.Protocol == 4 {
		if val, ok := message.Data.Dps["149"]; ok {
			if ready, ok := val.(bool); ok && ready {
				// Camera is now ready after wake-up (dps[149]:true received).
				// However, we don't wait for this signal (like ismartlife.me doesn't either).
				// The camera starts responding immediately after WakeUp() is called,
				// so we proceed with the connection without blocking.
				// This waiter is kept for potential future use.
				c.wakeupWaiter.Done(nil)
			}
		}
	}
}

func (c *TuyaMqttClient) onMqttAnswer(msg *MqttMessage) {
	var answerFrame AnswerFrame
	if err := json.Unmarshal(msg.Data.Message, &answerFrame); err != nil {
		c.onError(err)
		return
	}

	c.onAnswer(answerFrame)
}

func (c *TuyaMqttClient) onMqttCandidate(msg *MqttMessage) {
	var candidateFrame CandidateFrame
	if err := json.Unmarshal(msg.Data.Message, &candidateFrame); err != nil {
		c.onError(err)
		return
	}

	// fix candidates
	candidateFrame.Candidate = strings.TrimPrefix(candidateFrame.Candidate, "a=")
	candidateFrame.Candidate = strings.TrimSuffix(candidateFrame.Candidate, "\r\n")

	c.onCandidate(candidateFrame)
}

func (c *TuyaMqttClient) onMqttDisconnect() {
	c.closed = true
	c.onDisconnect()
}

func (c *TuyaMqttClient) onMqttSpeaker(msg *MqttMessage) {
	var speakerResponse struct {
		ResCode int `json:"resCode"`
	}

	if err := json.Unmarshal(msg.Data.Message, &speakerResponse); err == nil {
		if speakerResponse.ResCode != 0 {
			c.speakerWaiter.Done(fmt.Errorf("speaker failed with resCode: %d", speakerResponse.ResCode))
			return
		}
	}

	c.speakerWaiter.Done(nil)
}

func (c *TuyaMqttClient) onAnswer(answer AnswerFrame) {
	if c.handleAnswer != nil {
		c.handleAnswer(answer)
	}
}

func (c *TuyaMqttClient) onCandidate(candidate CandidateFrame) {
	if c.handleCandidate != nil {
		c.handleCandidate(candidate)
	}
}

func (c *TuyaMqttClient) onDisconnect() {
	if c.handleDisconnect != nil {
		c.handleDisconnect()
	}
}

func (c *TuyaMqttClient) onError(err error) {
	if c.handleError != nil {
		c.handleError(err)
	}
}

func (c *TuyaMqttClient) sendMqttMessage(messageType string, protocol int, transactionID string, data interface{}) error {
	if c.closed {
		return fmt.Errorf("mqtt client is closed, send mqtt message fail")
	}

	jsonMessage, err := json.Marshal(data)
	if err != nil {
		return err
	}

	msg := &MqttMessage{
		Protocol: protocol,
		Pv:       "2.2",
		T:        time.Now().Unix(),
		Data: MqttFrame{
			Header: MqttFrameHeader{
				Type:          messageType,
				From:          c.uid,
				To:            c.deviceId,
				SessionID:     c.sessionId,
				MotoID:        c.motoId,
				TransactionID: transactionID,
			},
			Message: jsonMessage,
		},
	}

	payload, err := json.Marshal(msg)
	if err != nil {
		return err
	}

	token := c.client.Publish(c.publishTopic, 1, false, payload)
	if token.Wait() && token.Error() != nil {
		return token.Error()
	}

	return nil
}