Migration from "old" mailforms to "new" form extension

ext_localconf.php

<?php
// Location: EXT:yourextension/ext_localconf.php
defined('TYPO3_MODE') or die ('Access denied.');

$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['ext/install']['update']['serfhos_deprecated_mailform'] = \Serfhos\OldMailMigration\Install\Updates\MailFormDataUpdate::class;

MailFormDataUpdate.php

<?php
// Location: EXT:yourextension/Classes/Install/Updates/MailFormDataUpdate.php

namespace Serfhos\OldMailMigration\Install\Updates;

use TYPO3\CMS\Core\Utility\GeneralUtility;
use TYPO3\CMS\Core\Utility\MailUtility;

/**
 * Migrate "mailform" data to new 7.6 ext:form
 */
class MailFormDataUpdate extends \TYPO3\CMS\Install\Updates\AbstractUpdate
{

    /**
     * @var array
     */
    protected $currentRow = [];

    /**
     * @var string
     */
    protected $title = 'Migrate "mailform" data to new 7.6 ext:form';

    /**
     * Checks if an update is needed
     *
     * @param string &$description The description for the update
     * @return bool Whether an update is needed (TRUE) or not (FALSE)
     */
    public function checkForUpdate(&$description)
    {
        $query = $this->getMigrateFormElementsQuery();
        $oldDataSets = $this->getDatabaseConnection()->exec_SELECTcountRows('tt_content.uid', $query['FROM'], $query['WHERE']);
        if ($this->isWizardDone() || $oldDataSets === 0) {
            return false;
        }

        $description = 'As the old mailform is moved to compatibility6 (since 7), this migration is to move the data to the new mailform functionality.';

        return true;
    }

    /**
     * Performs the database migrations if requested
     *
     * @param array &$databaseQueries Queries done in this update
     * @param mixed &$customMessages Custom messages
     * @return boolean
     */
    public function performUpdate(array &$databaseQueries, &$customMessages)
    {
        $res = $this->getDatabaseConnection()->exec_SELECT_queryArray($this->getMigrateFormElementsQuery());
        while ($row = $this->getDatabaseConnection()->sql_fetch_assoc($res)) {
            $this->currentRow = $row;

            $updateFields = [
                'tstamp' => time(),
                'subheader' => '',
                'pages' => '',
                'bodytext' => $this->getNewFormSetup($row),
            ];

            $this->getDatabaseConnection()->exec_UPDATEquery('tt_content', 'uid = ' . $row['uid'], $updateFields);
            $databaseQueries[] = $this->getDatabaseConnection()->debug_lastBuiltQuery;
        }

        $this->markWizardAsDone();
        return true;
    }

    /**
     * Get all old configuration for crmpost
     *
     * @param array $row
     * @return string
     */
    protected function getNewFormSetup($row)
    {
        $formSetup = [
            'prefix' => 'tx_form',
            'confirmation' => 1,
            'postProcessor.' => [
                '1' => 'mail',
                '1.' => [
                    'recipientEmail' => $row['subheader'],
                    'senderEmail' => MailUtility::getSystemFromAddress(),
                    'subject' => '',
                ],
                '2' => 'redirect',
                '2.' => [
                    'destination' => $row['pages'],
                ],
            ],
        ];

        $formFields = GeneralUtility::trimExplode(LF, $row['bodytext'], true);
        foreach ($formFields as $i => $field) {
            $this->addFieldSetup($i + 1, $field, $formSetup);
        }

        return $this->typoscriptArrayToString($formSetup);
    }

    /**
     * Calculate field setup based on setup line
     *
     * @param integer $index
     * @param string $setupLine
     * @param array $formSetup
     * @throws \Exception
     */
    protected function addFieldSetup($index, $setupLine, &$formSetup)
    {
        $configs = explode('|', $setupLine);
        $label = trim(array_shift($configs));
        list($name, $typeSetup) = explode('=', array_shift($configs));
        $name = trim($name);
        $required = false;
        if (strpos($name, '*') === 0) {
            $name = substr($name, 1);
            $required = true;
        }
        $typeSetup = explode(',', $typeSetup);
        $type = trim($typeSetup[0]);

        $options = trim(implode('|', $configs));
        unset($configs);

        switch ($type) {
            case 'input':
                $formSetup[$index . '0'] = 'TEXTLINE';
                $formSetup[$index . '0.'] = [
                    'type' => 'text',
                    'name' => $name,
                    'label.' => [
                        'value' => $label
                    ]
                ];

                if ($required) {
                    $formSetup[$index . '0.']['required'] = 'required';
                }

                break;
            case 'textarea':
                $formSetup[$index . '0'] = 'TEXTAREA';
                $formSetup[$index . '0.'] = [
                    'name' => $name,
                    'cols' => ($typeSetup[1] ?: 40),
                    'rows' => ($typeSetup[2] ?: 5),
                    'label.' => [
                        'value' => $label
                    ]
                ];

                if ($required) {
                    $formSetup[$index . '0.']['required'] = 'required';
                }

                break;

            case 'select':
                $values = explode(',', $options);

                $formSetup[$index . '0'] = 'SELECT';
                $formSetup[$index . '0.'] = [
                    'name' => $name,
                    'label.' => [
                        'value' => $label
                    ],
                ];

                if ($required) {
                    $formSetup[$index . '0.']['required'] = 'required';
                }

                foreach ($values as $i => $option) {
                    $formSetup[$index . '0.'][$i + 1 . '0'] = 'OPTION';
                    $formSetup[$index . '0.'][$i + 1 . '0.'] = [
                        'text' => trim($option),
                        'value' => trim($option),
                    ];
                    // Make sure first is selected
                    if ($i === 0) {
                        $formSetup[$index . '0.'][$i + 1 . '0.']['selected'] = 'selected';
                    }
                }

                if ($required) {
                    $formSetup[$index . '0.']['required'] = 'required';
                }

                break;

            case 'hidden':
                if ($name === 'subject') {
                    $formSetup['postProcessor.']['1.']['subject'] = $options;
                } elseif ($name === 'html_enabled') {
                    // Deprecated..
                } else {
                    $formSetup[$index . '0'] = 'HIDDEN';
                    $formSetup[$index . '0.'] = [
                        'type' => 'hidden',
                        'name' => $name,
                        'value' => $options,
                    ];
                }

                break;

            case 'submit':
                $formSetup[$index . '0'] = 'SUBMIT';
                $formSetup[$index . '0.'] = [
                    'type' => 'submit',
                    'name' => $name,
                    'value' => $options,
                ];

                break;

            case '':
                // No form setup in this line, maybe a comment?
                break;

            default:
                throw new \Exception('Unknown type: ' . $type . ' - Page: ' . $this->currentRow['pid']);
        }
    }

    /**
     * Get query parts for generic workflow
     *
     * @return array
     */
    protected function getMigrateFormElementsQuery()
    {
        return [
            'SELECT' => 'tt_content.*',
            'FROM' => 'tt_content, pages',
            'WHERE' => 'tt_content.pid= pages.uid'
                . ' AND tt_content.CType = "mailform"'
                . ' AND tt_content.subheader <> ""'
                . ' AND tt_content.bodytext LIKE "%formtype_mail=submit%"'
                . ' AND tt_content.hidden = 0 AND tt_content.deleted = 0'
                . ' AND pages.hidden = 0 AND pages.deleted = 0'
        ];
    }

    /**
     * Converts a TypoScript array to a formatted string
     * Takes care of indentation, curly brackets and parentheses
     *
     * @param array $typoscriptArray The TypoScript array
     * @param string $addKey Key which has underlying configuration
     * @param int $tabCount The amount of tabs for indentation
     * @return string The formatted TypoScript string
     * @see \TYPO3\CMS\Form\Domain\Factory\JsonToTypoScript::typoscriptArrayToString()
     */
    protected function typoscriptArrayToString(array $typoscriptArray, $addKey = '', $tabCount = -1)
    {
        $typoscript = '';
        if ($addKey != '') {
            $typoscript .= str_repeat(TAB, $tabCount) . str_replace('.', '', $addKey) . ' {' . LF;
        }
        $tabCount++;
        foreach ($typoscriptArray as $key => $value) {
            if (!is_array($value)) {
                if (strstr($value, LF)) {
                    $typoscript .= str_repeat(TAB, $tabCount) . $key . ' (' . LF;
                    if ($key !== 'text') {
                        $value = str_replace(LF, LF . str_repeat(TAB, ($tabCount + 1)), $value);
                        $typoscript .= str_repeat(TAB, ($tabCount + 1)) . $value . LF;
                    } else {
                        $typoscript .= $value . LF;
                    }
                    $typoscript .= str_repeat(TAB, $tabCount) . ')' . LF;
                } else {
                    $typoscript .= str_repeat(TAB, $tabCount) . $key . ' = ' . $value . LF;
                }
            } else {
                $typoscript .= $this->typoscriptArrayToString($value, $key, $tabCount);
            }
        }
        if ($addKey != '') {
            $tabCount--;
            $typoscript .= str_repeat(TAB, $tabCount) . '}' . LF;
        }
        return $typoscript;
    }
}