package middleware

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

	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt/v5"
)

// UserClaims represents the JWT claims structure
type UserClaims struct {
	UserID string `json:"user_id"`
	Email  string `json:"email"`
	Role   string `json:"role"`
	jwt.RegisteredClaims
}

// CORS middleware
func CORS() gin.HandlerFunc {
	return func(c *gin.Context) {
		origin := c.Request.Header.Get("Origin")
		if origin == "" {
			origin = "*"
		}

		c.Writer.Header().Set("Access-Control-Allow-Origin", origin)
		c.Writer.Header().Set("Access-Control-Allow-Credentials", "true")
		c.Writer.Header().Set("Access-Control-Allow-Headers", "Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization, accept, origin, Cache-Control, X-Requested-With")
		c.Writer.Header().Set("Access-Control-Allow-Methods", "POST, OPTIONS, GET, PUT, DELETE, PATCH")

		if c.Request.Method == "OPTIONS" {
			c.AbortWithStatus(204)
			return
		}

		c.Next()
	}
}

// RequestLogger logs HTTP requests
func RequestLogger() gin.HandlerFunc {
	return func(c *gin.Context) {
		start := time.Now()
		path := c.Request.URL.Path

		c.Next()

		latency := time.Since(start)
		status := c.Writer.Status()

		if status >= 400 {
			gin.DefaultWriter.Write([]byte(
				c.Request.Method + " " + path + " " +
				http.StatusText(status) + " " + latency.String() + "\n",
			))
		}
	}
}

// Rate limiter storage
var (
	rateLimitMu sync.Mutex
	rateLimits  = make(map[string][]time.Time)
)

// RateLimiter implements per-IP rate limiting
func RateLimiter() gin.HandlerFunc {
	return func(c *gin.Context) {
		ip := c.ClientIP()

		// Skip rate limiting for internal Docker IPs
		if strings.HasPrefix(ip, "172.") || strings.HasPrefix(ip, "10.") || ip == "127.0.0.1" {
			c.Next()
			return
		}

		rateLimitMu.Lock()
		defer rateLimitMu.Unlock()

		now := time.Now()
		windowStart := now.Add(-time.Minute)

		// Clean old entries
		var recent []time.Time
		for _, t := range rateLimits[ip] {
			if t.After(windowStart) {
				recent = append(recent, t)
			}
		}

		// Check limit (500 requests per minute)
		if len(recent) >= 500 {
			c.AbortWithStatusJSON(http.StatusTooManyRequests, gin.H{
				"error": "Rate limit exceeded",
			})
			return
		}

		rateLimits[ip] = append(recent, now)
		c.Next()
	}
}

// AuthMiddleware validates JWT tokens
func AuthMiddleware(jwtSecret string) gin.HandlerFunc {
	return func(c *gin.Context) {
		authHeader := c.GetHeader("Authorization")
		if authHeader == "" {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{
				"error": "Authorization header required",
			})
			return
		}

		tokenString := strings.TrimPrefix(authHeader, "Bearer ")
		if tokenString == authHeader {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{
				"error": "Invalid authorization format",
			})
			return
		}

		token, err := jwt.ParseWithClaims(tokenString, &UserClaims{}, func(token *jwt.Token) (interface{}, error) {
			return []byte(jwtSecret), nil
		})

		if err != nil || !token.Valid {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{
				"error": "Invalid or expired token",
			})
			return
		}

		claims, ok := token.Claims.(*UserClaims)
		if !ok {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{
				"error": "Invalid token claims",
			})
			return
		}

		// Set user info in context
		c.Set("user_id", claims.UserID)
		c.Set("email", claims.Email)
		c.Set("role", claims.Role)

		c.Next()
	}
}

// AdminOnly restricts access to admin users
func AdminOnly() gin.HandlerFunc {
	return func(c *gin.Context) {
		role := c.GetString("role")
		if role != "admin" && role != "super_admin" {
			c.AbortWithStatusJSON(http.StatusForbidden, gin.H{
				"error": "Admin access required",
			})
			return
		}
		c.Next()
	}
}