package middlewares

import (
	"net/http"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt/v5"
	"go.uber.org/zap"
)

var (
	jwtSecret   []byte
	jwtIssuer   string
	expireHours int
)

// JWTClaims JWT声明结构
type JWTClaims struct {
	UserID   int    `json:"user_id"`
	Username string `json:"username"`
	jwt.RegisteredClaims
}

// InitJWT 初始化JWT配置
func InitJWT(secret string, expire int, issuer string) {
	jwtSecret = []byte(secret)
	expireHours = expire
	jwtIssuer = issuer
}

// GenerateToken 生成JWT token
func GenerateToken(userID int, username string) (string, error) {
	claims := JWTClaims{
		UserID:   userID,
		Username: username,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Duration(expireHours) * time.Hour)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
			NotBefore: jwt.NewNumericDate(time.Now()),
			Issuer:    jwtIssuer,
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString(jwtSecret)
}

// ParseToken 解析JWT token
func ParseToken(tokenString string) (*JWTClaims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &JWTClaims{}, func(token *jwt.Token) (interface{}, error) {
		return jwtSecret, nil
	})

	if err != nil {
		return nil, err
	}

	if claims, ok := token.Claims.(*JWTClaims); ok && token.Valid {
		return claims, nil
	}

	return nil, jwt.ErrTokenInvalidClaims
}

// JWTAuth JWT认证中间件
func JWTAuth() gin.HandlerFunc {
	return func(c *gin.Context) {
		// 从Header获取token
		authHeader := c.GetHeader("Authorization")
		if authHeader == "" {
			Logger.Warn("JWT认证失败：缺少Authorization头部",
				zap.String("path", c.Request.URL.Path),
				zap.String("client_ip", c.ClientIP()),
			)
			c.JSON(http.StatusOK, gin.H{
				"code":    401,
				"message": "缺少认证token",
			})
			c.Abort()
			return
		}

		// Bearer token格式检查
		if !strings.HasPrefix(authHeader, "Bearer ") {
			Logger.Warn("JWT认证失败：token格式错误",
				zap.String("auth_header", authHeader),
				zap.String("path", c.Request.URL.Path),
				zap.String("client_ip", c.ClientIP()),
			)
			c.JSON(http.StatusOK, gin.H{
				"code":    401,
				"message": "token格式错误",
			})
			c.Abort()
			return
		}

		tokenString := strings.TrimPrefix(authHeader, "Bearer ")

		// 解析token
		claims, err := ParseToken(tokenString)
		if err != nil {
			Logger.Warn("JWT认证失败：token解析错误",
				zap.Error(err),
				zap.String("path", c.Request.URL.Path),
				zap.String("client_ip", c.ClientIP()),
			)
			c.JSON(http.StatusOK, gin.H{
				"code":    401,
				"message": "token无效或已过期",
			})
			c.Abort()
			return
		}

		// 将用户信息存储到上下文
		c.Set("user_id", claims.UserID)
		c.Set("username", claims.Username)

		Logger.Debug("JWT认证成功",
			zap.Int("user_id", claims.UserID),
			zap.String("username", claims.Username),
			zap.String("path", c.Request.URL.Path),
		)

		c.Next()
	}
}

// GetCurrentUser 从上下文获取当前用户信息
func GetCurrentUser(c *gin.Context) (int, string, bool) {
	userID, userExists := c.Get("user_id")
	username, nameExists := c.Get("username")

	if !userExists || !nameExists {
		return 0, "", false
	}

	return userID.(int), username.(string), true
}