// Copyright 2024 Patial Tech. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package user

import (
	"errors"
	"time"

	"gitserver.in/patialtech/rano/util/uid"
)

var (
	ErrExpiredToken = errors.New("expired token")
	ErrInvalidToken = errors.New("invalid token")
)

// newTokenToVerifyEmail for a user for given duration
func newTokenToVerifyEmail(userID int64, d time.Duration) (string, error) {
	expiresAt := time.Now().Add(d).UTC().UnixMilli()
	return uid.Encode([]uint64{
		uint64(userID),
		1, // identifies that its token to verify email
		uint64(expiresAt),
	})
}

// tokenToVerifyEmail will check for valid email token that is yet not expired
//
// returns userID on success
func tokenToVerifyEmail(token string) (int64, error) {
	ids, err := uid.Decode(token)
	if err != nil {
		return 0, nil
	}

	// slice must have 3 entries
	if len(ids) != 3 {
		return 0, ErrInvalidToken
	}

	// must be an email verify token
	if ids[1] != 1 {
		return 0, ErrInvalidToken
	}

	// check expiry
	if int64(ids[2]) < time.Now().UTC().UnixMilli() {
		return 0, ErrExpiredToken
	}

	return int64(ids[0]), nil
}