invoiceninja/app/Utils/Traits/MakesReminders.php

<?php
/**
 * Invoice Ninja (https://invoiceninja.com).
 *
 * @link https://github.com/invoiceninja/invoiceninja source repository
 *
 * @copyright Copyright (c) 2021. Invoice Ninja LLC (https://invoiceninja.com)
 *
 * @license https://opensource.org/licenses/AAL
 */

namespace App\Utils\Traits;

use App\Models\RecurringInvoice;
use Illuminate\Support\Carbon;

/**
 * Class MakesReminders.
 */
trait MakesReminders
{
    
    public function inReminderWindow($schedule_reminder, $num_days_reminder)
    {
        switch ($schedule_reminder) {
            case 'after_invoice_date':
                return Carbon::parse($this->date)->addDays($num_days_reminder)->startOfDay()->eq(Carbon::now()->startOfDay());
                break;
            case 'before_due_date':
                return Carbon::parse($this->due_date)->subDays($num_days_reminder)->startOfDay()->eq(Carbon::now()->startOfDay());
                break;
            case 'after_due_date':
                return Carbon::parse($this->due_date)->addDays($num_days_reminder)->startOfDay()->eq(Carbon::now()->startOfDay());
                break;
            default:
                return null;
                break;
        }
    }

    public function calculateTemplate(string $entity_string): string
    {
        //if invoice is currently a draft, or being marked as sent, this will be the initial email
        $client = $this->client;

        if ($entity_string != 'invoice') {
            return $entity_string;
        }

        //if the invoice
        if ($this->inReminderWindow(
            $client->getSetting('schedule_reminder1'),
            $client->getSetting('num_days_reminder1')
        )) {
            return 'reminder1';
        } elseif ($this->inReminderWindow(
            $client->getSetting('schedule_reminder2'),
            $client->getSetting('num_days_reminder2')
        )) {
            return 'reminder2';
        } elseif ($this->inReminderWindow(
            $client->getSetting('schedule_reminder3'),
            $client->getSetting('num_days_reminder3')
        )) {
            return 'reminder3';
        } elseif ($this->checkEndlessReminder(
            $this->last_sent_date,
            $client->getSetting('endless_reminder_frequency_id')
        )) {
            return 'endless_reminder';
        } else {
            return $entity_string;
        }

        //also implement endless reminders here
    }

    private function checkEndlessReminder($last_sent_date, $endless_reminder_frequency_id) :bool
    {
        if (Carbon::now()->startOfDay()->eq($this->addTimeInterval($last_sent_date, $endless_reminder_frequency_id))) {
            return true;
        }

        return false;
    }

    private function addTimeInterval($date, $endless_reminder_frequency_id) :?Carbon
    {
        if (!$date) 
            return null;
        
        switch ($endless_reminder_frequency_id) {
            case RecurringInvoice::FREQUENCY_WEEKLY:
                return Carbon::parse($date)->addWeek()->startOfDay();
            case RecurringInvoice::FREQUENCY_TWO_WEEKS:
                return Carbon::parse($date)->addWeeks(2)->startOfDay();
            case RecurringInvoice::FREQUENCY_FOUR_WEEKS:
                return Carbon::parse($date)->addWeeks(4)->startOfDay();
            case RecurringInvoice::FREQUENCY_MONTHLY:
                return Carbon::parse($date)->addMonthNoOverflow()->startOfDay();
            case RecurringInvoice::FREQUENCY_TWO_MONTHS:
                return Carbon::parse($date)->addMonthsNoOverflow(2)->startOfDay();
            case RecurringInvoice::FREQUENCY_THREE_MONTHS:
                return Carbon::parse($date)->addMonthsNoOverflow(3)->startOfDay();
            case RecurringInvoice::FREQUENCY_FOUR_MONTHS:
                return Carbon::parse($date)->addMonthsNoOverflow(4)->startOfDay();
            case RecurringInvoice::FREQUENCY_SIX_MONTHS:
                return Carbon::parse($date)->addMonthsNoOverflow(6)->startOfDay();
            case RecurringInvoice::FREQUENCY_ANNUALLY:
                return Carbon::parse($date)->addYear()->startOfDay();
            case RecurringInvoice::FREQUENCY_TWO_YEARS:
                return Carbon::parse($date)->addYears(2)->startOfDay();
            case RecurringInvoice::FREQUENCY_THREE_YEARS:
                return Carbon::parse($date)->addYears(3)->startOfDay();
            default:
                return null;
        }
    }
}