package handler

import (
	"fmt"
	"net/http"
	"time"

	"github.com/gin-gonic/gin"

	"carrot_bbs/internal/pkg/response"
	"carrot_bbs/internal/pkg/ws"
	"carrot_bbs/internal/service"
)

// QRCodeHandler 二维码登录处理器
type QRCodeHandler struct {
	qrcodeService *service.QRCodeLoginService
}

// NewQRCodeHandler 创建二维码登录处理器
func NewQRCodeHandler(qrcodeService *service.QRCodeLoginService) *QRCodeHandler {
	return &QRCodeHandler{
		qrcodeService: qrcodeService,
	}
}

// GetQRCode 获取二维码
// GET /api/v1/auth/qrcode
func (h *QRCodeHandler) GetQRCode(c *gin.Context) {
	session, err := h.qrcodeService.CreateSession(c.Request.Context())
	if err != nil {
		response.InternalServerError(c, "failed to create qrcode session")
		return
	}

	// 生成二维码URL (deeplink格式)
	qrcodeURL := fmt.Sprintf("carrotbbs://qrcode/login?session_id=%s", session.SessionID)

	response.Success(c, gin.H{
		"session_id": session.SessionID,
		"qrcode_url": qrcodeURL,
		"expires_in": 300, // 5分钟
		"expires_at": session.ExpiresAt,
	})
}

// WSEvents WebSocket事件流
// GET /api/v1/auth/qrcode/events?session_id=xxx
func (h *QRCodeHandler) WSEvents(c *gin.Context) {
	sessionID := c.Query("session_id")
	if sessionID == "" {
		response.BadRequest(c, "session_id is required")
		return
	}

	ch, cancel, replay := h.qrcodeService.GetWSHub().Subscribe(sessionID, 0)
	defer cancel()

	w := c.Writer
	flusher, ok := w.(http.Flusher)
	if !ok {
		response.InternalServerError(c, "streaming unsupported")
		return
	}

	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("Cache-Control", "no-cache")
	w.Header().Set("Connection", "keep-alive")
	w.Header().Set("X-Accel-Buffering", "no")
	c.Status(http.StatusOK)
	flusher.Flush()

	writeEvent := func(ev ws.Event) bool {
		data, err := ws.EncodeData(ev)
		if err != nil {
			return false
		}
		if _, err := fmt.Fprintf(w, "id: %d\nevent: %s\ndata: %s\n\n", ev.ID, ev.Event, data); err != nil {
			return false
		}
		flusher.Flush()
		return true
	}

	// 发送历史事件
	for _, ev := range replay {
		if !writeEvent(ev) {
			return
		}
	}

	// 心跳
	heartbeat := time.NewTicker(25 * time.Second)
	defer heartbeat.Stop()

	for {
		select {
		case <-c.Request.Context().Done():
			return
		case ev, ok := <-ch:
			if !ok || !writeEvent(ev) {
				return
			}
		case <-heartbeat.C:
			if _, err := fmt.Fprint(w, "event: heartbeat\ndata: {}\n\n"); err != nil {
				return
			}
			flusher.Flush()
		}
	}
}

// Scan 扫描二维码
// POST /api/v1/auth/qrcode/scan
func (h *QRCodeHandler) Scan(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	type ScanRequest struct {
		SessionID string `json:"session_id" binding:"required"`
	}

	var req ScanRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	if err := h.qrcodeService.Scan(c.Request.Context(), req.SessionID, userID); err != nil {
		if err.Error() == "qrcode already scanned" {
			response.BadRequest(c, "qrcode already scanned by others")
			return
		}
		if err.Error() == "session not found or expired" {
			response.NotFound(c, "qrcode expired")
			return
		}
		response.InternalServerError(c, "failed to scan qrcode")
		return
	}

	// 获取用户信息返回
	user, err := h.qrcodeService.GetUserService().GetUserByID(c.Request.Context(), userID)
	if err != nil {
		response.InternalServerError(c, "failed to get user info")
		return
	}

	response.Success(c, gin.H{
		"user": gin.H{
			"id":       user.ID,
			"nickname": user.Nickname,
			"avatar":   user.Avatar,
		},
	})
}

// Confirm 确认登录
// POST /api/v1/auth/qrcode/confirm
func (h *QRCodeHandler) Confirm(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	type ConfirmRequest struct {
		SessionID string `json:"session_id" binding:"required"`
	}

	var req ConfirmRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	ip := c.ClientIP()
	userAgent := c.GetHeader("User-Agent")

	result, err := h.qrcodeService.Confirm(c.Request.Context(), req.SessionID, userID, ip, userAgent)
	if err != nil {
		if err.Error() == "unauthorized" {
			response.Unauthorized(c, "not authorized to confirm this login")
			return
		}
		if err.Error() == "session not found or expired" {
			response.NotFound(c, "qrcode expired")
			return
		}
		response.InternalServerError(c, "failed to confirm login")
		return
	}

	response.Success(c, gin.H{
		"success": true,
		"user": gin.H{
			"id":       result.User.ID,
			"username": result.User.Username,
			"nickname": result.User.Nickname,
			"avatar":   result.User.Avatar,
		},
	})
}

// Cancel 取消登录
// POST /api/v1/auth/qrcode/cancel
func (h *QRCodeHandler) Cancel(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	type CancelRequest struct {
		SessionID string `json:"session_id" binding:"required"`
	}

	var req CancelRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	if err := h.qrcodeService.Cancel(c.Request.Context(), req.SessionID, userID); err != nil {
		if err.Error() == "unauthorized" {
			response.Unauthorized(c, "not authorized to cancel this login")
			return
		}
		response.InternalServerError(c, "failed to cancel login")
		return
	}

	response.Success(c, gin.H{"success": true})
}