invoiceninja/app/Utils/Traits/InvoiceEmailBuilder.php

<?php
/**
 * Invoice Ninja (https://invoiceninja.com)
 *
 * @link https://github.com/invoiceninja/invoiceninja source repository
 *
 * @copyright Copyright (c) 2019. Invoice Ninja LLC (https://invoiceninja.com)
 *
 * @license https://opensource.org/licenses/AAL
 */

namespace App\Utils\Traits;

use App\Models\Invoice;
use Illuminate\Support\Carbon;
use Parsedown;

/**
 * Class InvoiceEmailBuilder
 * @package App\Utils\Traits
 */
trait InvoiceEmailBuilder
{


    /**
     * Builds the correct template to send
     * @param  string $reminder_template The template name ie reminder1
     * @return array                   
     */
    public function getEmailData($reminder_template = null) :array
    {
        //client
        //$client = $this->client;

        if(!$reminder_template)
            $reminder_template = $this->calculateTemplate();

        //Need to determine which email template we are producing
        return $this->generateTemplateData($reminder_template);

    }

    private function generateTemplateData(string $reminder_template) :array
    {
        $data = [];

        $client = $this->client;

        $body_template = $client->getSetting('email_template_'.$reminder_template);
        $subject_template = $client->getSetting('email_subject_'.$reminder_template);

        $data['body'] = $this->parseTemplate($body_template, false);
        $data['subject'] = $this->parseTemplate($subject_template, true);

        return $data;
    }

    private function parseTemplate(string $template_data, bool $is_markdown = true) :string
    {
        $invoice_variables = $this->makeValues();

        //process variables
        $data = str_replace(array_keys($invoice_variables), array_values($invoice_variables), $template_data);

        //process markdown
        if($is_markdown)
            $data = Parsedown::instance()->line($data);

        return $data;
    }

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

        //if the invoice 
        if($this->status_id == Invoice::STATUS_DRAFT || Carbon::parse($this->due_date) > now()) 
        {
            return 'invoice';
        }
        else if($client->getSetting('enable_reminder1') !== false && $this->inReminderWindow($client->getSetting('schedule_reminder1'), $client->getSetting('num_days_reminder1')))
        {
            return 'template1';
        }
        else if($client->getSetting('enable_reminder2') !== false && $this->inReminderWindow($client->getSetting('schedule_reminder2'), $client->getSetting('num_days_reminder2')))
        {
            return 'template2';
        }
        else if($client->getSetting('enable_reminder3') !== false && $this->inReminderWindow($client->getSetting('schedule_reminder3'), $client->getSetting('num_days_reminder3')))
        {
            return 'template3';
        }
        //also implement endless reminders here
        //
           
    }

    private 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:
                # code...
                break;
        }
    }

}