package auth

import (
	"fmt"
	"net/http"
	"strings"

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

func Middleware(jwtSecret string) gin.HandlerFunc {
	return func(ctx *gin.Context) {
		header := strings.TrimSpace(ctx.GetHeader("Authorization"))
		if header == "" {
			ctx.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "missing authorization header"})
			return
		}

		parts := strings.SplitN(header, " ", 2)
		if len(parts) != 2 || !strings.EqualFold(parts[0], "Bearer") {
			ctx.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "invalid authorization header"})
			return
		}

		claims := &JWTClaims{}
		token, err := jwt.ParseWithClaims(parts[1], 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(jwtSecret), nil
		})
		if err != nil || !token.Valid {
			ctx.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "invalid token"})
			return
		}

		ctx.Set("userID", claims.UserID)
		ctx.Next()
	}
}