package gpaste

import (
	"fmt"
	"time"

	"github.com/golang-jwt/jwt"
	"github.com/google/uuid"
)

type AuthService struct {
	users      UserStore
	hmacSecret []byte
}

func NewAuthService(store UserStore, signingSecret []byte) *AuthService {
	return &AuthService{users: store, hmacSecret: signingSecret}
}

func (as *AuthService) Login(username, password string) (string, error) {
	user, err := as.users.Get(username)
	if err != nil {
		return "", err
	}

	if err := user.ValidatePassword(password); err != nil {
		return "", err
	}

	// TODO: Set iss and aud
	claims := jwt.StandardClaims{
		Subject:   user.Username,
		ExpiresAt: time.Now().Add(7 * 24 * time.Hour).Unix(),
		NotBefore: time.Now().Unix(),
		IssuedAt:  time.Now().Unix(),
		Id:        uuid.NewString(),
	}

	token := jwt.NewWithClaims(jwt.GetSigningMethod("HS256"), claims)
	signed, err := token.SignedString(as.hmacSecret)
	if err != nil {
		return "", err
	}

	return signed, nil
}

func (as *AuthService) ValidateToken(rawToken string) error {
	claims := &jwt.StandardClaims{}
	token, err := jwt.ParseWithClaims(rawToken, claims, func(t *jwt.Token) (interface{}, error) {
		return as.hmacSecret, nil
	})
	if err != nil {
		return err
	}
	if !token.Valid {
		return fmt.Errorf("invalid token")
	}

	return nil
}