package middleware

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

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

type Claims struct {
	UserID string `json:"user_id"`
	jwt.RegisteredClaims
}

var jwtSecret = []byte("gitm-default-secret")

func SetJWTSecret(secret string) {
	jwtSecret = []byte(secret)
}

func GenerateToken(userID string) (string, error) {
	claims := Claims{
		UserID: userID,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(24 * time.Hour)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
		},
	}
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString(jwtSecret)
}

func ValidateToken(tokenString string) (*Claims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (interface{}, error) {
		return jwtSecret, nil
	})
	if err != nil {
		return nil, err
	}
	if claims, ok := token.Claims.(*Claims); ok && token.Valid {
		return claims, nil
	}
	return nil, jwt.ErrSignatureInvalid
}

func AuthMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		authHeader := c.GetHeader("Authorization")
		if authHeader == "" {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "Authorization header required"})
			c.Abort()
			return
		}
		parts := strings.SplitN(authHeader, " ", 2)
		if len(parts) != 2 || parts[0] != "Bearer" {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "Invalid authorization format"})
			c.Abort()
			return
		}
		claims, err := ValidateToken(parts[1])
		if err != nil {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "Invalid token"})
			c.Abort()
			return
		}
		c.Set("user_id", claims.UserID)
		c.Next()
	}
}