package ws

import (
	"context"
	"encoding/json"
	"net/http"
	"sync"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/gorilla/websocket"

	"github.com/hhs/camtalk/internal/errors"
	"github.com/hhs/camtalk/internal/logger"
	"github.com/hhs/camtalk/internal/models"
	"github.com/hhs/camtalk/internal/orchestrator"
	"github.com/hhs/camtalk/internal/session"
)

var upgrader = websocket.Upgrader{
	CheckOrigin: func(r *http.Request) bool { return true }, // 开发阶段允许所有来源
}

// Client 代表一个 WebSocket 客户端连接。
type Client struct {
	conn          *websocket.Conn
	sessionID     string
	sessionMgr    session.Manager
	orchestrator  orchestrator.Orchestrator
	cancelFuncs   map[string]context.CancelFunc // requestID → cancel func
	mu            sync.Mutex
}

// SendJSON 向客户端发送 JSON 消息（公开以便 errors 包调用）。
func (c *Client) SendJSON(v any) error {
	c.mu.Lock()
	defer c.mu.Unlock()
	return c.conn.WriteJSON(v)
}

// WSClient 实现 orchestrator.Sender 接口，将消息推送到 WebSocket 连接。
type WSClient struct {
	client    *Client
	requestID string
}

// SendSTTResult 发送语音识别结果。
func (w *WSClient) SendSTTResult(result models.WsSTTResult) error {
	result.RequestID = w.requestID
	return w.client.SendJSON(result)
}

// SendLLMChunk 发送 LLM 流式文本增量。
func (w *WSClient) SendLLMChunk(chunk models.WsLLMChunk) error {
	chunk.RequestID = w.requestID
	return w.client.SendJSON(chunk)
}

// SendLLMDone 发送 LLM 流结束信号。
func (w *WSClient) SendLLMDone(done models.WsLLMDone) error {
	done.RequestID = w.requestID
	return w.client.SendJSON(done)
}

// SendTTSAudio 发送 TTS 音频数据。
func (w *WSClient) SendTTSAudio(audio models.WsTTSAudio) error {
	audio.RequestID = w.requestID
	return w.client.SendJSON(audio)
}

// SendError 发送错误消息。
func (w *WSClient) SendError(err models.WsError) error {
	err.RequestID = w.requestID
	return w.client.SendJSON(err)
}

// ServeWS 处理 WebSocket 升级请求。
func ServeWS(sessionMgr session.Manager, orch orchestrator.Orchestrator) gin.HandlerFunc {
	return func(c *gin.Context) {
		serveWS(c, sessionMgr, orch)
	}
}

func serveWS(c *gin.Context, sessionMgr session.Manager, orch orchestrator.Orchestrator) {
	conn, err := upgrader.Upgrade(c.Writer, c.Request, nil)
	if err != nil {
		logger.Log.Errorw("websocket upgrade failed", "error", err)
		return
	}
	defer conn.Close()

	// 创建会话
	sessionID, err := sessionMgr.Create(context.Background(), models.DefaultConfig())
	if err != nil {
		logger.Log.Errorw("create session failed", "error", err)
		return
	}

	client := &Client{
		conn:         conn,
		sessionID:    sessionID,
		sessionMgr:   sessionMgr,
		orchestrator: orch,
		cancelFuncs:  make(map[string]context.CancelFunc),
	}

	// 发送 connected 消息
	_ = client.SendJSON(models.WsConnected{
		Type:          "connected",
		SessionID:     sessionID,
		ServerVersion: "0.1.0",
	})
	logger.Log.Infow("client connected", "session", sessionID)

	// 心跳检测
	lastPong := time.Now()
	conn.SetPongHandler(func(string) error {
		lastPong = time.Now()
		return nil
	})

	// 启动心跳检查 goroutine
	done := make(chan struct{})
	go func() {
		ticker := time.NewTicker(30 * time.Second)
		defer ticker.Stop()
		for {
			select {
			case <-ticker.C:
				if time.Since(lastPong) > 60*time.Second {
					logger.Log.Warnw("heartbeat timeout", "session", sessionID)
					conn.Close()
					return
				}
			case <-done:
				return
			}
		}
	}()

	// 消息读取循环
	for {
		_, message, err := conn.ReadMessage()
		if err != nil {
			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseNormalClosure) {
				logger.Log.Warnw("ws read error", "error", err)
			}
			break
		}

		// 解析消息类型
		var envelope struct {
			Type string `json:"type"`
		}
		if err := json.Unmarshal(message, &envelope); err != nil {
			errors.SendWSError(client, errors.CodeInvalidMessage, "", err)
			continue
		}

		switch envelope.Type {
		case "ping":
			_ = client.SendJSON(models.WsPong{Type: "pong"})

		case "query":
			var msg models.WsQuery
			if err := json.Unmarshal(message, &msg); err != nil {
				errors.SendWSError(client, errors.CodeInvalidMessage, msg.RequestID, err)
				continue
			}
			logger.Log.Infow("query received", "session", sessionID, "request", msg.RequestID)

			// 刷新会话 TTL
			if err := client.sessionMgr.Touch(context.Background(), sessionID); err != nil {
				logger.Log.Warnw("touch session failed", "session", sessionID, "error", err)
			}

			// 标记活跃请求
			if err := client.sessionMgr.SetActiveRequest(context.Background(), sessionID, msg.RequestID); err != nil {
				logger.Log.Warnw("set active request failed", "session", sessionID, "error", err)
			}

			// 获取对话历史
			history, _ := client.sessionMgr.GetHistory(context.Background(), sessionID, 20)

			// 创建可取消的 context
			ctx, cancel := context.WithCancel(context.Background())
			client.mu.Lock()
			client.cancelFuncs[msg.RequestID] = cancel
			client.mu.Unlock()

			// 创建 sender
			sender := &WSClient{client: client, requestID: msg.RequestID}

			// 启动 orchestrator 处理 goroutine
			go func() {
				defer func() {
					// 清理 cancel func
					client.mu.Lock()
					delete(client.cancelFuncs, msg.RequestID)
					client.mu.Unlock()
					cancel()
					// 清除活跃请求
					_ = client.sessionMgr.ClearActiveRequest(context.Background(), sessionID)
				}()

				if err := client.orchestrator.ProcessQuery(ctx, sessionID, msg, history, sender); err != nil {
					logger.Log.Errorw("process query failed", "session", sessionID, "request", msg.RequestID, "error", err)
				}
			}()

		case "config":
			var msg models.WsConfig
			if err := json.Unmarshal(message, &msg); err != nil {
				errors.SendWSError(client, errors.CodeInvalidMessage, "", err)
				continue
			}

			patch := models.SessionConfigPatch{
				TTSEnabled:  msg.Payload.TTSEnabled,
				DetailLevel: msg.Payload.DetailLevel,
				Language:    msg.Payload.Language,
			}
			if err := sessionMgr.UpdateConfig(context.Background(), sessionID, patch); err != nil {
				errors.SendWSError(client, errors.CodeInternalError, "", err)
				continue
			}
			logger.Log.Infow("config updated", "session", sessionID)

		case "interrupt":
			logger.Log.Infow("interrupt received", "session", sessionID)

			// 获取活跃请求 ID（实际 cancel 在 Phase 5 接入 orchestrator 后实现）
			reqID, _ := sessionMgr.GetActiveRequestID(context.Background(), sessionID)
			if reqID != "" {
				_ = sessionMgr.ClearActiveRequest(context.Background(), sessionID)
				// TODO: 取消对应 context cancel func
			}

		default:
			_ = client.SendJSON(models.WsError{
				Type:    "error",
				Code:    "INVALID_MESSAGE",
				Message: "unknown message type: " + envelope.Type,
			})
		}
	}

	close(done)

	// 断开连接时不销毁会话，让其自然过期（支持重连恢复）
	logger.Log.Infow("client disconnected", "session", sessionID)
}