package mqtt

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"
	"sync"
	"time"

	"iot-base-station/internal/device"
	"iot-base-station/internal/analytics"
	"iot-base-station/pkg/mqtt"

	MQTT "github.com/eclipse/paho.mqtt.golang"
	"go.uber.org/zap"
)

// Adapter MQTT协议适配器
type Adapter struct {
	client     mqtt.Client
	config     Config
	logger     *zap.Logger
	dataChan   chan *device.DeviceData
	eventChan  chan *device.DeviceEvent
	mu         sync.RWMutex
	devices    map[string]bool // 在线设备
}

// Config MQTT配置
type Config struct {
	Broker     string `yaml:"broker"`
	ClientID   string `yaml:"client_id"`
	Username   string `yaml:"username"`
	Password   string `yaml:"password"`
	KeepAlive  int    `yaml:"keep_alive"`
	QoS        int    `yaml:"qos"`
	Topics     Topics `yaml:"topics"`
}

// Topics MQTT主题配置
type Topics struct {
	Data      string `yaml:"data"`
	Event     string `yaml:"event"`
	Config    string `yaml:"config"`
	Firmware  string `yaml:"firmware"`
	Response  string `yaml:"response"`
	Status    string `yaml:"status"`
}

// Message MQTT消息
type Message struct {
	Topic   string                 `json:"topic"`
	Payload map[string]interface{} `json:"payload"`
	QoS     byte                   `json:"qos"`
	Retained bool                   `json:"retained"`
}

// NewAdapter 创建MQTT适配器
func NewAdapter(config Config, logger *zap.Logger) *Adapter {
	return &Adapter{
		config:    config,
		logger:    logger,
		dataChan:  make(chan *device.DeviceData, 1000),
		eventChan: make(chan *device.DeviceEvent, 100),
		devices:   make(map[string]bool),
	}
}

// Start 启动MQTT适配器
func (a *Adapter) Start(ctx context.Context) error {
	// 创建MQTT客户端
	opts := MQTT.NewClientOptions()
	opts.AddBroker(a.config.Broker)
	opts.SetClientID(a.config.ClientID)
	opts.SetUsername(a.config.Username)
	opts.SetPassword(a.config.Password)
	opts.SetKeepAlive(time.Duration(a.config.KeepAlive) * time.Second)
	opts.SetDefaultPublishHandler(a.messageHandler)
	opts.SetOnConnectHandler(a.connectHandler)
	opts.SetConnectionLostHandler(a.connectLostHandler)

	// 连接MQTT代理
	client := MQTT.NewClient(opts)
	if token := client.Connect(); token.Wait() && token.Error() != nil {
		return fmt.Errorf("failed to connect to MQTT broker: %w", token.Error())
	}

	a.client = mqtt.NewClient(client)

	// 订阅主题
	if err := a.subscribeTopics(); err != nil {
		return fmt.Errorf("failed to subscribe topics: %w", err)
	}

	a.logger.Info("MQTT adapter started", zap.String("broker", a.config.Broker))

	// 启动消息处理
	go a.processMessages(ctx)

	return nil
}

// Stop 停止MQTT适配器
func (a *Adapter) Stop() error {
	if a.client != nil {
		a.client.Disconnect(250)
	}
	close(a.dataChan)
	close(a.eventChan)
	a.logger.Info("MQTT adapter stopped")
	return nil
}

// Name 返回适配器名称
func (a *Adapter) Name() string {
	return "mqtt"
}

// GetDataChannel 获取数据通道
func (a *Adapter) GetDataChannel() <-chan *device.DeviceData {
	return a.dataChan
}

// GetEventChannel 获取事件通道
func (a *Adapter) GetEventChannel() <-chan *device.DeviceEvent {
	return a.eventChan
}

// SendCommand 发送命令到设备
func (a *Adapter) SendCommand(deviceID, command string, payload map[string]interface{}) error {
	topic := fmt.Sprintf("%s/%s/%s", a.config.Topics.Config, deviceID, command)
	
	message, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("failed to marshal command: %w", err)
	}

	return a.client.Publish(topic, byte(a.config.QoS), false, message)
}

// SendFirmwareUpdate 发送固件更新命令
func (a *Adapter) SendFirmwareUpdate(deviceID, version, url string) error {
	topic := fmt.Sprintf("%s/%s", a.config.Topics.Firmware, deviceID)
	
	payload := map[string]interface{}{
		"version": version,
		"url":     url,
		"command": "update",
	}

	message, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("failed to marshal firmware update: %w", err)
	}

	return a.client.Publish(topic, byte(a.config.QoS), false, message)
}

// subscribeTopics 订阅MQTT主题
func (a *Adapter) subscribeTopics() error {
	topics := []string{
		a.config.Topics.Data + "/+/+",
		a.config.Topics.Event + "/+",
		a.config.Topics.Status + "/+",
	}

	for _, topic := range topics {
		if token := a.client.Subscribe(topic, byte(a.config.QoS), nil); token.Wait() && token.Error() != nil {
			return fmt.Errorf("failed to subscribe to topic %s: %w", topic, token.Error())
		}
	}

	return nil
}

// messageHandler 消息处理器
func (a *Adapter) messageHandler(client MQTT.Client, msg MQTT.Message) {
	topic := msg.Topic()
	payload := msg.Payload()

	a.logger.Debug("Received MQTT message", 
		zap.String("topic", topic),
		zap.ByteString("payload", payload))

	// 解析主题
	parts := strings.Split(topic, "/")
	if len(parts) < 3 {
		a.logger.Warn("Invalid topic format", zap.String("topic", topic))
		return
	}

	rootTopic := parts[0]
	deviceID := parts[1]

	// 根据主题类型处理消息
	switch rootTopic {
	case a.config.Topics.Data:
		a.handleDataMessage(deviceID, parts[2], payload)
	case a.config.Topics.Event:
		a.handleEventMessage(deviceID, payload)
	case a.config.Topics.Status:
		a.handleStatusMessage(deviceID, payload)
	default:
		a.logger.Warn("Unknown topic", zap.String("topic", topic))
	}
}

// handleDataMessage 处理数据消息
func (a *Adapter) handleDataMessage(deviceID, dataType string, payload []byte) {
	var data map[string]interface{}
	if err := json.Unmarshal(payload, &data); err != nil {
		a.logger.Error("Failed to unmarshal data message", zap.Error(err))
		return
	}

	// 更新设备在线状态
	a.updateDeviceStatus(deviceID, true)

	// 创建设备数据对象
	deviceData := &device.DeviceData{
		DeviceID:  deviceID,
		Timestamp: time.Now(),
		Metrics:   data,
		Quality: device.DataQuality{
			Good:    true,
			Source:  "mqtt",
		},
	}

	// 发送到数据通道
	select {
	case a.dataChan <- deviceData:
	default:
		a.logger.Warn("Data channel full, dropping message", zap.String("device_id", deviceID))
	}
}

// handleEventMessage 处理事件消息
func (a *Adapter) handleEventMessage(deviceID string, payload []byte) {
	var eventData map[string]interface{}
	if err := json.Unmarshal(payload, &eventData); err != nil {
		a.logger.Error("Failed to unmarshal event message", zap.Error(err))
		return
	}

	// 解析事件类型和严重程度
	eventType, _ := eventData["type"].(string)
	severity, _ := eventData["severity"].(string)
	message, _ := eventData["message"].(string)

	// 创建设备事件对象
	deviceEvent := &device.DeviceEvent{
		ID:        generateEventID(),
		DeviceID:  deviceID,
		Type:      device.EventType(eventType),
		Severity:  device.EventSeverity(severity),
		Message:   message,
		Data:      eventData,
		Timestamp: time.Now(),
	}

	// 发送到事件通道
	select {
	case a.eventChan <- deviceEvent:
	default:
		a.logger.Warn("Event channel full, dropping message", zap.String("device_id", deviceID))
	}
}

// handleStatusMessage 处理状态消息
func (a *Adapter) handleStatusMessage(deviceID string, payload []byte) {
	var statusData map[string]interface{}
	if err := json.Unmarshal(payload, &statusData); err != nil {
		a.logger.Error("Failed to unmarshal status message", zap.Error(err))
		return
	}

	// 解析状态
	status, _ := statusData["status"].(string)
	isOnline := status == "online"

	// 更新设备状态
	a.updateDeviceStatus(deviceID, isOnline)

	// 创建状态事件
	deviceEvent := &device.DeviceEvent{
		ID:        generateEventID(),
		DeviceID:  deviceID,
		Type:      device.EventConnect,
		Severity:  device.SeverityInfo,
		Message:   fmt.Sprintf("设备状态: %s", status),
		Data:      statusData,
		Timestamp: time.Now(),
	}

	// 发送到事件通道
	select {
	case a.eventChan <- deviceEvent:
	default:
		a.logger.Warn("Event channel full, dropping message", zap.String("device_id", deviceID))
	}
}

// updateDeviceStatus 更新设备状态
func (a *Adapter) updateDeviceStatus(deviceID string, isOnline bool) {
	a.mu.Lock()
	defer a.mu.Unlock()

	a.devices[deviceID] = isOnline
}

// processMessages 处理消息
func (a *Adapter) processMessages(ctx context.Context) {
	for {
		select {
		case <-ctx.Done():
			return
		default:
			// 这里可以添加消息批处理逻辑
			time.Sleep(100 * time.Millisecond)
		}
	}
}

// connectHandler 连接处理器
func (a *Adapter) connectHandler(client MQTT.Client) {
	a.logger.Info("Connected to MQTT broker")
}

// connectLostHandler 连接丢失处理器
func (a *Adapter) connectLostHandler(client MQTT.Client, err error) {
	a.logger.Error("Connection to MQTT broker lost", zap.Error(err))
}

// generateEventID 生成事件ID
func generateEventID() string {
	return fmt.Sprintf("mqtt_event_%d", time.Now().UnixNano())
}