package api

import (
	"context"
	"net/http"
	"os"
	"strings"

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

type contextKey string

const UserIDContextKey = contextKey("userID")

// AuthMiddleware проверяет JWT токен и добавляет user_id в контекст запроса.
func AuthMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		authHeader := r.Header.Get("Authorization")
		if authHeader == "" {
			http.Error(w, "Authorization header required", http.StatusUnauthorized)
			return
		}

		tokenString := strings.TrimPrefix(authHeader, "Bearer ")
		if tokenString == authHeader {
			http.Error(w, "Invalid token format", http.StatusUnauthorized)
			return
		}

		jwtSecret := []byte(os.Getenv("JWT_SECRET_KEY"))
		if len(jwtSecret) == 0 {
			http.Error(w, "JWT secret not configured", http.StatusInternalServerError)
			return
		}

		token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
			if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
				return nil, jwt.ErrSignatureInvalid
			}
			return jwtSecret, nil
		})

		if err != nil || !token.Valid {
			http.Error(w, "Invalid or expired token", http.StatusUnauthorized)
			return
		}

		claims, ok := token.Claims.(jwt.MapClaims)
		if !ok {
			http.Error(w, "Invalid token claims", http.StatusUnauthorized)
			return
		}

		userIDFloat, ok := claims["user_id"].(float64)
		if !ok {
			http.Error(w, "Invalid user_id in token", http.StatusUnauthorized)
			return
		}
		userID := int(userIDFloat)

		ctx := context.WithValue(r.Context(), UserIDContextKey, userID)
		next.ServeHTTP(w, r.WithContext(ctx))
	})
}