package auth

import (
	"cls/pkg/logger"
	"context"
	"errors"
	"fmt"
	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt/v4"
	"github.com/redis/go-redis/v9"
	"net/http"
	"time"
)

const (
	JWTClaimsKey = "JWT_CLAIMS"
)

// Claims JWT声明
type Claims struct {
	Username string `json:"username"` // 加密后的手机号，空表示游客
	GuestId  string `json:"guest_id"` // 游客ID，用于标识未登录用户
	Openid   string `json:"openid"`
	jwt.RegisteredClaims
}

// AuthMiddleware 认证中间件
type AuthMiddleware struct {
	config    *Config
	secretKey []byte
	log       logger.Logger
	redis     redis.Cmdable
}

// NewAuthMiddleware 创建认证中间件
func NewAuthMiddleware(secretKey string, config *Config, redis redis.Cmdable, log logger.New) *AuthMiddleware {
	if config == nil {
		config = DefaultConfig()
	}
	return &AuthMiddleware{
		config:    config,
		secretKey: []byte(secretKey),
		log:       log("cls:infrastructure:middleware"),
		redis:     redis,
	}
}

func (m *AuthMiddleware) HandleCallback(openid string) string {
	t, _, err := m.generateGuestToken(openid)
	if err != nil {
		m.log.Error(err)
		return ""
	}
	return t
}

// Handle 处理认证逻辑
func (m *AuthMiddleware) Handle() gin.HandlerFunc {
	return func(c *gin.Context) {
		path := c.Request.URL.Path

		// 获取token
		token := m.ExtractToken(c)
		// 如果没有token，创建临时游客token
		if token == "" {
			if !m.shouldSkip(path) {
				c.Next()
				return
			} else {
				c.AbortWithStatus(http.StatusUnauthorized)
				return
			}
		}

		// 验证已有token
		claims, err := m.validateToken(token)
		if err != nil {
			if !m.shouldSkip(path) {
				c.Next()
				return
			} else {
				c.AbortWithStatus(http.StatusUnauthorized)
				return
			}
		}

		// token有效，根据phone判断是否为游客
		isGuest := claims.Username == ""

		// 设置 claims 到上下文
		mapClaims := map[string]interface{}{}
		if isGuest {
			mapClaims["guest_id"] = claims.GuestId
			c.Set("guest_id", claims.GuestId)
		} else {
			mapClaims["username"] = claims.Username
			c.Set("username", claims.Username)
		}
		mapClaims["openid"] = claims.Openid
		c.Set("openid", claims.Openid)

		c.Set(JWTClaimsKey, mapClaims)
		c.Set("is_guest", isGuest)

		// 如果是跳过认证的路径，直接继续
		if m.shouldSkip(path) {
			c.Next()
			return
		}

		c.Next()
	}
}

// generateGuestToken 生成游客token，返回token字符串和游客ID
func (m *AuthMiddleware) generateGuestToken(openid ...string) (string, string, error) {
	guestId := generateGuestId()
	o := ""
	fmt.Println("have openid ?,", openid)
	if len(openid) != 0 {
		o = openid[0]
	}
	claims := &Claims{
		Username: "",
		GuestId:  guestId,
		Openid:   o,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(24 * time.Hour)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
			NotBefore: jwt.NewNumericDate(time.Now()),
			Issuer:    "cls-system",
			Subject:   "guest-access",
			Audience:  []string{"cls-api"},
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	tokenString, err := token.SignedString(m.secretKey)
	if err != nil {
		return "", "", err
	}
	return tokenString, guestId, nil
}

// GenerateUserToken 生成用户token
func (m *AuthMiddleware) GenerateUserToken(encryptedPhone string, openid string) (string, error) {
	claims := &Claims{
		Username: encryptedPhone,
		GuestId:  "", // 登录用户不需要游客ID
		Openid:   openid,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(30 * 24 * time.Hour)), // 30天过期
			IssuedAt:  jwt.NewNumericDate(time.Now()),
			NotBefore: jwt.NewNumericDate(time.Now()),
			Issuer:    "cls-system",
			Subject:   "user-access",
			Audience:  []string{"cls-api"},
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)

	tokenStr, err := token.SignedString(m.secretKey)
	if err != nil {
		return "", err
	}
	err = m.redis.Set(context.Background(), encryptedPhone, tokenStr, time.Now().Add(30*24*time.Hour).Sub(time.Now())).Err()
	if err != nil {
		return "", err
	}
	return tokenStr, nil
}

// validateToken 验证token
func (m *AuthMiddleware) validateToken(tokenString string) (*Claims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (interface{}, error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
		}
		return m.secretKey, nil
	})

	if err != nil {
		return nil, fmt.Errorf("解析token失败: %v", err)
	}

	claims, ok := token.Claims.(*Claims)

	if ok && token.Valid {
		if claims.Username != "" {
			result, _ := m.redis.Get(context.Background(), claims.Username).Result()
			if result != tokenString {
				return nil, errors.New("用户token失效")
			}
		}
		return claims, nil
	}
	return nil, fmt.Errorf("无效的token")
}

// extractToken 从请求头中提取token
func (m *AuthMiddleware) ExtractToken(c *gin.Context) string {
	auth := c.GetHeader(m.config.TokenKey)

	if auth == "" {
		return ""
	}

	const prefix = "Bearer "
	if len(auth) <= len(prefix) || auth[:len(prefix)] != prefix {
		return ""
	}

	return auth[len(prefix):]
}

// shouldSkip 检查是否需要跳过认证
func (m *AuthMiddleware) shouldSkip(path string) bool {
	for _, skipPath := range m.config.SkipPaths {
		if path == skipPath {
			return true
		}
	}
	return false
}

// generateGuestId 生成游客ID
func generateGuestId() string {
	return "G" + time.Now().Format("060102150405") + randomString(6)
}

// randomString 生成随机字符串
func randomString(n int) string {
	const letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
	b := make([]byte, n)
	for i := range b {
		b[i] = letters[time.Now().UnixNano()%int64(len(letters))]
	}
	return string(b)
}

// DecodeToken 从 gin.Context 中解析 token 并返回原始的加密手机号
func (m *AuthMiddleware) DecodeToken(c *gin.Context) (string, error) {
	// 从请求头中提取 token
	tokenString := m.ExtractToken(c)
	if tokenString == "" {
		return "", fmt.Errorf("未找到有效的 token")
	}

	// 解析 token
	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (interface{}, error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
		}
		return m.secretKey, nil
	})

	if err != nil {
		return "", fmt.Errorf("解析 token 失败: %v", err)
	}

	// 验证 token 并获取 claims
	if claims, ok := token.Claims.(*Claims); ok && token.Valid {
		// 返回原始的加密手机号
		return claims.Username, nil
	}

	return "", fmt.Errorf("无效的 token")
}

// GetSecretKey 获取密钥
func (m *AuthMiddleware) GetSecretKey() []byte {
	return m.secretKey
}

// DecodeTokenStatic 静态方法，不需要 AuthMiddleware 实例，直接解析 token 字符串
func DecodeTokenStatic(tokenString string, secretKey []byte) (string, error) {
	// 移除 Bearer 前缀（如果有）
	if len(tokenString) > 7 && tokenString[:7] == "Bearer " {
		tokenString = tokenString[7:]
	}

	// 解析 token
	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (interface{}, error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
		}
		return secretKey, nil
	})

	if err != nil {
		return "", fmt.Errorf("解析 token 失败: %v", err)
	}

	// 验证 token 并获取 claims
	if claims, ok := token.Claims.(*Claims); ok && token.Valid {
		// 返回原始的加密手机号
		return claims.Username, nil
	}

	return "", fmt.Errorf("无效的 token")
}