// Copyright (c) 2025 Nikolai Papin
//
// This file is part of Easywish
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
// the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package middleware

import (
	"easywish/config"
	"easywish/internal/utils/enums"
	"errors"
	"fmt"
	"net/http"

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

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

// TODO: validate token type
// TODO: validate session guid
func AuthMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		cfg := config.GetConfig()
		authHeader := c.GetHeader("Authorization")

		if authHeader == "" {
			c.Set("username", nil)
			c.Set("role", enums.GuestRole)
			c.Next()
			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("username", claims.Username)
			c.Set("role", claims.Role)
			c.Next()
		} else {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "Invalid claims"})
		}
	}
}