package middleware

import (
	"easywish/config"
	"errors"
	"fmt"
	"net/http"

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

type Claims struct {
	Username string `json:"username"`
	jwt.RegisteredClaims
}

func JWTAuthMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		cfg := config.GetConfig()
		authHeader := c.GetHeader("Authorization")
		if authHeader == "" {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "Authorization header required"})
			return
		}

		tokenString := authHeader

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

		if err != nil {
			if errors.Is(err, jwt.ErrTokenExpired) {
				c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "Token expired"})
			} else {
				c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "Invalid token"})
			}
			return
		}

		if claims, ok := token.Claims.(*Claims); ok && token.Valid {
			c.Set("userID", claims.Username)
			c.Next()
		} else {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "Invalid claims"})
		}
	}
}