package web

import (
	"crypto/hmac"
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"net/http"
	"strconv"
	"time"

	"xiaji-go/models"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
)

type WebServer struct {
	db        *gorm.DB
	port      int
	username  string
	password  string
	secretKey string
}

func NewWebServer(db *gorm.DB, port int, username, password string) *WebServer {
	return &WebServer{
		db:        db,
		port:      port,
		username:  username,
		password:  password,
		secretKey: "xiaji-go-session-" + password, // 简单派生
	}
}

// generateToken 生成登录 token
func (s *WebServer) generateToken(username string) string {
	mac := hmac.New(sha256.New, []byte(s.secretKey))
	mac.Write([]byte(username))
	return hex.EncodeToString(mac.Sum(nil))
}

// validateToken 验证 token
func (s *WebServer) validateToken(username, token string) bool {
	expected := s.generateToken(username)
	return hmac.Equal([]byte(expected), []byte(token))
}

// authRequired 登录认证中间件
func (s *WebServer) authRequired() gin.HandlerFunc {
	return func(c *gin.Context) {
		username, _ := c.Cookie("xiaji_user")
		token, _ := c.Cookie("xiaji_token")

		if username == "" || token == "" || !s.validateToken(username, token) {
			// 判断是 API 请求还是页面请求
			path := c.Request.URL.Path
			if len(path) >= 4 && path[:4] == "/api" || c.Request.Method == "POST" {
				c.JSON(http.StatusUnauthorized, gin.H{"error": "未登录"})
			} else {
				c.Redirect(http.StatusFound, "/login")
			}
			c.Abort()
			return
		}
		c.Next()
	}
}

func (s *WebServer) Start() {
	gin.SetMode(gin.ReleaseMode)
	r := gin.Default()
	r.LoadHTMLGlob("templates/*")

	// 公开路由（无需登录）
	r.GET("/login", s.handleLoginPage)
	r.POST("/login", s.handleLogin)
	r.GET("/logout", s.handleLogout)

	// 健康检查（公开）
	r.GET("/health", func(c *gin.Context) {
		c.JSON(http.StatusOK, gin.H{"status": "ok"})
	})

	// 需要登录的路由
	auth := r.Group("/")
	auth.Use(s.authRequired())
	{
		auth.GET("/", s.handleIndex)
		auth.GET("/api/records", s.handleRecords)
		auth.POST("/delete/:id", s.handleDelete)
		auth.GET("/export", s.handleExport)
	}

	logAddr := fmt.Sprintf(":%d", s.port)
	fmt.Printf("🌐 Web后台运行在 http://127.0.0.1%s\n", logAddr)
	if err := r.Run(logAddr); err != nil {
		fmt.Printf("❌ Web服务启动失败: %v\n", err)
	}
}

func (s *WebServer) handleLoginPage(c *gin.Context) {
	// 已登录则跳转首页
	username, _ := c.Cookie("xiaji_user")
	token, _ := c.Cookie("xiaji_token")
	if username != "" && token != "" && s.validateToken(username, token) {
		c.Redirect(http.StatusFound, "/")
		return
	}
	c.HTML(http.StatusOK, "login.html", gin.H{"error": ""})
}

func (s *WebServer) handleLogin(c *gin.Context) {
	username := c.PostForm("username")
	password := c.PostForm("password")

	if username == s.username && password == s.password {
		token := s.generateToken(username)
		maxAge := 7 * 24 * 3600 // 7天

		c.SetCookie("xiaji_user", username, maxAge, "/", "", false, true)
		c.SetCookie("xiaji_token", token, maxAge, "/", "", false, true)
		c.Redirect(http.StatusFound, "/")
		return
	}

	c.HTML(http.StatusOK, "login.html", gin.H{"error": "用户名或密码错误"})
}

func (s *WebServer) handleLogout(c *gin.Context) {
	c.SetCookie("xiaji_user", "", -1, "/", "", false, true)
	c.SetCookie("xiaji_token", "", -1, "/", "", false, true)
	c.Redirect(http.StatusFound, "/login")
}

func (s *WebServer) handleIndex(c *gin.Context) {
	username, _ := c.Cookie("xiaji_user")
	c.HTML(http.StatusOK, "index.html", gin.H{"username": username})
}

func (s *WebServer) handleRecords(c *gin.Context) {
	var items []models.Transaction
	s.db.Where("is_deleted = ?", false).Order("id desc").Limit(50).Find(&items)

	type txResponse struct {
		ID       uint    `json:"id"`
		UserID   int64   `json:"user_id"`
		Amount   float64 `json:"amount"`
		Category string  `json:"category"`
		Note     string  `json:"note"`
		Date     string  `json:"date"`
	}

	resp := make([]txResponse, len(items))
	for i, item := range items {
		resp[i] = txResponse{
			ID:       item.ID,
			UserID:   item.UserID,
			Amount:   item.AmountYuan(),
			Category: item.Category,
			Note:     item.Note,
			Date:     item.Date,
		}
	}

	c.JSON(http.StatusOK, resp)
}

func (s *WebServer) handleDelete(c *gin.Context) {
	idStr := c.Param("id")
	id, err := strconv.ParseUint(idStr, 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的ID"})
		return
	}

	result := s.db.Model(&models.Transaction{}).Where("id = ? AND is_deleted = ?", id, false).Update("is_deleted", true)
	if result.Error != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "删除失败"})
		return
	}
	if result.RowsAffected == 0 {
		c.JSON(http.StatusNotFound, gin.H{"error": "记录不存在或已删除"})
		return
	}

	c.JSON(http.StatusOK, gin.H{"status": "success"})
}

func (s *WebServer) handleExport(c *gin.Context) {
	var items []models.Transaction
	s.db.Where("is_deleted = ?", false).Order("date asc, id asc").Find(&items)

	now := time.Now().Format("20060102")
	filename := fmt.Sprintf("xiaji_%s.csv", now)

	c.Header("Content-Type", "text/csv; charset=utf-8")
	c.Header("Content-Disposition", fmt.Sprintf("attachment; filename=%s", filename))

	// BOM for Excel
	c.Writer.Write([]byte{0xEF, 0xBB, 0xBF})
	c.Writer.WriteString("ID,日期,分类,金额(元),备注\n")

	for _, item := range items {
		line := fmt.Sprintf("%d,%s,%s,%.2f,\"%s\"\n", item.ID, item.Date, item.Category, item.AmountYuan(), item.Note)
		c.Writer.WriteString(line)
	}
}