package auth

import (
	"fmt"
	"time"

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

type Claims struct {
	UserID   int    `json:"user_id"`
	Username string `json:"username"`
	Email    string `json:"email,omitempty"`
	jwt.RegisteredClaims
}

func GenerateJWT(userID int, username, email string, cfg *Config) (string, int64, error) {
	expiresAt := time.Now().Add(time.Duration(cfg.JWTExpiry) * time.Second)

	claims := &Claims{
		UserID:   userID,
		Username: username,
		Email:    email,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(expiresAt),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
			Issuer:    "opal-task",
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	signedToken, err := token.SignedString(cfg.JWTSecret)
	if err != nil {
		return "", 0, err
	}

	return signedToken, expiresAt.Unix(), nil
}

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

	if err != nil {
		return nil, err
	}

	if claims, ok := token.Claims.(*Claims); ok && token.Valid {
		return claims, nil
	}

	return nil, fmt.Errorf("invalid token")
}