package middleware

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

	"tyapi-server/internal/config"

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

// JWTAuthMiddleware JWT认证中间件
type JWTAuthMiddleware struct {
	config *config.Config
	logger *zap.Logger
}

// NewJWTAuthMiddleware 创建JWT认证中间件
func NewJWTAuthMiddleware(cfg *config.Config, logger *zap.Logger) *JWTAuthMiddleware {
	return &JWTAuthMiddleware{
		config: cfg,
		logger: logger,
	}
}

// GetName 返回中间件名称
func (m *JWTAuthMiddleware) GetName() string {
	return "jwt_auth"
}

// GetPriority 返回中间件优先级
func (m *JWTAuthMiddleware) GetPriority() int {
	return 60 // 中等优先级，在日志之后，业务处理之前
}

// Handle 返回中间件处理函数
func (m *JWTAuthMiddleware) Handle() gin.HandlerFunc {
	return func(c *gin.Context) {
		// 获取Authorization头部
		authHeader := c.GetHeader("Authorization")
		if authHeader == "" {
			m.respondUnauthorized(c, "缺少认证头部")
			return
		}

		// 检查Bearer前缀
		const bearerPrefix = "Bearer "
		if !strings.HasPrefix(authHeader, bearerPrefix) {
			m.respondUnauthorized(c, "认证头部格式无效")
			return
		}

		// 提取token
		tokenString := authHeader[len(bearerPrefix):]
		if tokenString == "" {
			m.respondUnauthorized(c, "缺少认证令牌")
			return
		}

		// 验证token
		claims, err := m.validateToken(tokenString)
		if err != nil {
			m.logger.Warn("无效的认证令牌",
				zap.Error(err),
				zap.String("request_id", c.GetString("request_id")))
			m.respondUnauthorized(c, "认证令牌无效")
			return
		}

		// 将用户信息添加到上下文
		c.Set("user_id", claims.UserID)
		c.Set("username", claims.Username)
		c.Set("email", claims.Email)
		c.Set("token_claims", claims)

		c.Next()
	}
}

// IsGlobal 是否为全局中间件
func (m *JWTAuthMiddleware) IsGlobal() bool {
	return false // 不是全局中间件，需要手动应用到需要认证的路由
}

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

// validateToken 验证JWT token
func (m *JWTAuthMiddleware) validateToken(tokenString string) (*JWTClaims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &JWTClaims{}, func(token *jwt.Token) (interface{}, error) {
		// 验证签名方法
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, jwt.ErrSignatureInvalid
		}
		return []byte(m.config.JWT.Secret), nil
	})

	if err != nil {
		return nil, err
	}

	claims, ok := token.Claims.(*JWTClaims)
	if !ok || !token.Valid {
		return nil, jwt.ErrSignatureInvalid
	}

	return claims, nil
}

// respondUnauthorized 返回未授权响应
func (m *JWTAuthMiddleware) respondUnauthorized(c *gin.Context, message string) {
	c.JSON(http.StatusUnauthorized, gin.H{
		"success":    false,
		"message":    "认证失败",
		"error":      message,
		"request_id": c.GetString("request_id"),
		"timestamp":  time.Now().Unix(),
	})
	c.Abort()
}

// GenerateToken 生成JWT token
func (m *JWTAuthMiddleware) GenerateToken(userID, username, email string) (string, error) {
	now := time.Now()

	claims := &JWTClaims{
		UserID:   userID,
		Username: username,
		Email:    email,
		RegisteredClaims: jwt.RegisteredClaims{
			Issuer:    "tyapi-server",
			Subject:   userID,
			Audience:  []string{"tyapi-client"},
			ExpiresAt: jwt.NewNumericDate(now.Add(m.config.JWT.ExpiresIn)),
			NotBefore: jwt.NewNumericDate(now),
			IssuedAt:  jwt.NewNumericDate(now),
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString([]byte(m.config.JWT.Secret))
}

// GenerateRefreshToken 生成刷新token
func (m *JWTAuthMiddleware) GenerateRefreshToken(userID string) (string, error) {
	now := time.Now()

	claims := &jwt.RegisteredClaims{
		Issuer:    "tyapi-server",
		Subject:   userID,
		Audience:  []string{"tyapi-refresh"},
		ExpiresAt: jwt.NewNumericDate(now.Add(m.config.JWT.RefreshExpiresIn)),
		NotBefore: jwt.NewNumericDate(now),
		IssuedAt:  jwt.NewNumericDate(now),
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString([]byte(m.config.JWT.Secret))
}

// ValidateRefreshToken 验证刷新token
func (m *JWTAuthMiddleware) ValidateRefreshToken(tokenString string) (string, error) {
	token, err := jwt.ParseWithClaims(tokenString, &jwt.RegisteredClaims{}, func(token *jwt.Token) (interface{}, error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, jwt.ErrSignatureInvalid
		}
		return []byte(m.config.JWT.Secret), nil
	})

	if err != nil {
		return "", err
	}

	claims, ok := token.Claims.(*jwt.RegisteredClaims)
	if !ok || !token.Valid {
		return "", jwt.ErrSignatureInvalid
	}

	// 检查是否为刷新token
	if len(claims.Audience) == 0 || claims.Audience[0] != "tyapi-refresh" {
		return "", jwt.ErrSignatureInvalid
	}

	return claims.Subject, nil
}

// OptionalAuthMiddleware 可选认证中间件（用户可能登录也可能未登录）
type OptionalAuthMiddleware struct {
	jwtAuth *JWTAuthMiddleware
}

// NewOptionalAuthMiddleware 创建可选认证中间件
func NewOptionalAuthMiddleware(jwtAuth *JWTAuthMiddleware) *OptionalAuthMiddleware {
	return &OptionalAuthMiddleware{
		jwtAuth: jwtAuth,
	}
}

// GetName 返回中间件名称
func (m *OptionalAuthMiddleware) GetName() string {
	return "optional_auth"
}

// GetPriority 返回中间件优先级
func (m *OptionalAuthMiddleware) GetPriority() int {
	return 60 // 与JWT认证中间件相同
}

// Handle 返回中间件处理函数
func (m *OptionalAuthMiddleware) Handle() gin.HandlerFunc {
	return func(c *gin.Context) {
		// 获取Authorization头部
		authHeader := c.GetHeader("Authorization")
		if authHeader == "" {
			// 没有认证头部，设置匿名用户标识
			c.Set("is_authenticated", false)
			c.Next()
			return
		}

		// 检查Bearer前缀
		const bearerPrefix = "Bearer "
		if !strings.HasPrefix(authHeader, bearerPrefix) {
			c.Set("is_authenticated", false)
			c.Next()
			return
		}

		// 提取并验证token
		tokenString := authHeader[len(bearerPrefix):]
		claims, err := m.jwtAuth.validateToken(tokenString)
		if err != nil {
			// token无效，但不返回错误，设置为未认证
			c.Set("is_authenticated", false)
			c.Next()
			return
		}

		// token有效，设置用户信息
		c.Set("is_authenticated", true)
		c.Set("user_id", claims.UserID)
		c.Set("username", claims.Username)
		c.Set("email", claims.Email)
		c.Set("token_claims", claims)

		c.Next()
	}
}

// IsGlobal 是否为全局中间件
func (m *OptionalAuthMiddleware) IsGlobal() bool {
	return false
}