package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"

	"auth"
	"config"

	"github.com/gorilla/mux"
)

// Server represents the API server
type Server struct {
	config *config.Config
	router *mux.Router
}

type WechatLoginResponse struct {
	OpenID     string `json:"openid"`
	SessionKey string `json:"session_key"`
	UnionID    string `json:"unionid,omitempty"`
	ErrCode    int    `json:"errcode,omitempty"`
	ErrMsg     string `json:"errmsg,omitempty"`
}

// NewServer creates a new instance of Server
func NewServer(cfg *config.Config) *Server {
	s := &Server{
		config: cfg,
		router: mux.NewRouter(),
	}
	s.setupRoutes()
	return s
}

// setupRoutes configures all the routes for the server
func (s *Server) setupRoutes() {
	// 公开路由
	s.router.HandleFunc("/auth/login", s.WechatLoginHandler)

	// 受保护路由(需要JWT)
	authRouter := s.router.PathPrefix("").Subrouter()
	authRouter.Use(auth.NewAuthMiddleware(s.config.Security.JWTSigningKey))
	authRouter.HandleFunc("/otp/save", SaveHandler).Methods("POST")
	authRouter.HandleFunc("/otp/recover", RecoverHandler).Methods("POST")

	// 添加CORS中间件
	s.router.Use(s.corsMiddleware)
}

// corsMiddleware handles CORS
func (s *Server) corsMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		origin := r.Header.Get("Origin")

		// Check if the origin is allowed
		allowed := false
		for _, allowedOrigin := range s.config.CORS.AllowedOrigins {
			if origin == allowedOrigin {
				allowed = true
				break
			}
		}

		if allowed {
			w.Header().Set("Access-Control-Allow-Origin", origin)
			w.Header().Set("Access-Control-Allow-Methods",
				joinStrings(s.config.CORS.AllowedMethods))
			w.Header().Set("Access-Control-Allow-Headers",
				joinStrings(s.config.CORS.AllowedHeaders))
		}

		if r.Method == "OPTIONS" {
			w.WriteHeader(http.StatusOK)
			return
		}

		next.ServeHTTP(w, r)
	})
}

// joinStrings joins string slice with commas
func joinStrings(slice []string) string {
	result := ""
	for i, s := range slice {
		if i > 0 {
			result += ", "
		}
		result += s
	}
	return result
}

func (s *Server) WechatLoginHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	// 读取请求体
	body, err := ioutil.ReadAll(r.Body)
	if err != nil {
		http.Error(w, "Bad request", http.StatusBadRequest)
		return
	}

	var req struct {
		Code string `json:"code"`
	}
	if err := json.Unmarshal(body, &req); err != nil {
		http.Error(w, "Invalid request", http.StatusBadRequest)
		return
	}

	// 向微信服务器请求session_key
	url := fmt.Sprintf("https://api.weixin.qq.com/sns/jscode2session?appid=%s&secret=%s&js_code=%s&grant_type=authorization_code",
		s.config.Wechat.AppID, s.config.Wechat.AppSecret, req.Code)

	resp, err := http.Get(url)
	if err != nil {
		http.Error(w, "Wechat service unavailable", http.StatusServiceUnavailable)
		return
	}
	defer resp.Body.Close()

	body, err = ioutil.ReadAll(resp.Body)
	if err != nil {
		http.Error(w, "Wechat service error", http.StatusInternalServerError)
		return
	}

	var wechatResp WechatLoginResponse
	if err := json.Unmarshal(body, &wechatResp); err != nil {
		http.Error(w, "Wechat response parse error", http.StatusInternalServerError)
		return
	}

	if wechatResp.ErrCode != 0 {
		http.Error(w, wechatResp.ErrMsg, http.StatusUnauthorized)
		return
	}

	// 生成JWT token
	token, err := s.generateSessionToken(wechatResp.OpenID)
	if err != nil {
		http.Error(w, "Failed to generate token", http.StatusInternalServerError)
		return
	}

	// 返回响应
	response := map[string]interface{}{
		"token":  token,
		"openid": wechatResp.OpenID,
	}
	if err := json.NewEncoder(w).Encode(response); err != nil {
		http.Error(w, "Failed to encode response", http.StatusInternalServerError)
	}
}

func (s *Server) generateSessionToken(openid string) (string, error) {
	return auth.GenerateToken(openid, s.config.Security.JWTSigningKey, s.config.Security.TokenExpiry)
}

// Start starts the HTTP server
func (s *Server) Start() error {
	addr := fmt.Sprintf(":%d", s.config.Server.Port)
	log.Printf("Starting server on %s", addr)

	srv := &http.Server{
		Handler:      s.router,
		Addr:         addr,
		WriteTimeout: s.config.Server.Timeout,
		ReadTimeout:  s.config.Server.Timeout,
	}

	return srv.ListenAndServe()
}

func main() {
	// 加载配置
	cfg, err := config.LoadConfig("config")
	if err != nil {
		log.Fatalf("Failed to load config: %v", err)
	}

	// 初始化数据库连接
	log.Println("Initializing database connection...")
	if err := InitDB(cfg.Database); err != nil {
		log.Fatalf("Failed to initialize database: %v", err)
	}
	log.Println("Database connection established successfully")

	// 创建并启动服务器
	server := NewServer(cfg)
	if err := server.Start(); err != nil {
		log.Fatalf("Server failed to start: %v", err)
	}
}