Polylang UI Improvements

PolylangUI.php

<?php

/*
 * Copyright (c) Rasso Hilber
 * https://rassohilber.com
 */

namespace Hirasso\WP;

/**
 * Improvements of the Polylang admin UI, that helps my customers to better understand
 * what they are doing. Can be required from a theme or plugin and then instanciated via
 * new \Hirasso\WP\PolylangUI()
 */
final class PolylangUI
{
    protected ?\WP_Post $post = null;
    protected ?\PLL_Language $postLanguage = null;

    public function __construct()
    {
        add_action('admin_head', [$this, 'on_admin_head']);
        add_action('admin_bar_menu', [$this, 'add_post_language_switcher'], 999);
        add_filter('acf/prepare_field', [$this, 'acf_prepare_field'], PHP_INT_MAX - 100);
    }

    /**
     * Detect if we are currently on the post edit screen for a translatable post type
     */
    public function on_admin_head()
    {
        if (get_current_screen()?->base !== 'post') {
            return;
        }

        if (!$post = get_post()) {
            return;
        }

        if (!pll_is_translated_post_type(get_post_type($post))) {
            return;
        }

        if (!$postLanguage = pll_get_post_language($post->ID, \OBJECT)) {
            return;
        }

        $this->post = $post;
        $this->postLanguage = $postLanguage;

        add_filter('pll_admin_languages_filter', fn () => []);
    }

    /**
     * Add a post specific language switcher on admin post edit pages, instead of the default
     * global Polylang language switcher
     */
    public function add_post_language_switcher(\WP_Admin_Bar $wpAdminBar): void
    {
        $post = $this->post;
        $postLanguage = $this->postLanguage;

        if (!$post || !$postLanguage) {
            return;
        }

        $parentNodeID = 'languages';

        // Main node (parent item)
        $wpAdminBar->add_node([
            'id' => $parentNodeID,
            'title' => sprintf(
                '%s %s: %s',
                $postLanguage->flag,
                __('Post Language'),
                $postLanguage->name
            ),
            'meta' => ['class' => 'pll-filtered-languages']
        ]);

        $translations = pll_get_post_translations($post->ID) ?: [];

        if (count($translations) < 2) {
            return;
        }

        foreach ($translations as $lang => $translatedPostID) {
            if ($translatedPostID === $post->ID) {
                continue;
            }

            $editLink = get_edit_post_link($translatedPostID);
            $langObject = PLL()->model->get_language($lang);

            $wpAdminBar->add_node([
                'id' => 'post-language-' . $lang,
                'title' => $langObject->flag . ' ' . $langObject->name,
                'href' => $editLink,
                'parent' => $parentNodeID,
            ]);
        }
    }

    /**
     * Move the polylang translation status in the admin area from a field's instructions
     * to an icon in the field's label, with a (ACF-native) tooltip that
     * displays the field's translation status.
     *
     * Currently depending on preg_replace until
     * WP_Syntex\Polylang_Pro\Integrations\ACF\Translation_Instructions::get_field_instruction()
     * becomes `public`.
     */
    public function acf_prepare_field(?array $field): ?array
    {
        if (empty($field)) {
            return null;
        }

        $pllIcon = '<span style="font-size: 1.2em; vertical-align: middle;" class="dashicons dashicons-translation"></span>';

        if (!preg_match(
            "#{$pllIcon}\s(?<translationStatus>.*)#",
            $field['instructions'] ?? '',
            $matches
        )) {
            return $field;
        }

        /** remove the instructions from the $field */
        $field['instructions'] = str_replace($matches[0], '', $field['instructions']);

        $translationStatus = preg_replace('/This field is (.*)\./', '$1', $matches['translationStatus']);
        $field['label'] = $field['label'] . " <span title='$translationStatus' style='font-size: 1.2em; vertical-align: middle; opacity: 0.7;' class='dashicons dashicons-translation acf-js-tooltip '></span>";

        return $field;
    }
}