<?php

namespace AOP\App\Frontend;

use AOP\App\Enqueue;
use AOP\App\Plugin;

/**
 * The Block Bindings source `aop/option`: a block attribute (the text of a paragraph or heading, the text and link of
 * a button, the image of an image block, ...) shows the value of a public field. Markup:
 *
 *     <!-- wp:paragraph {"metadata":{"bindings":{"content":{"source":"aop/option","args":{"name":"phone"}}}}} -->
 *
 * The name of the source and of its argument are part of the data contract with Pro (they are in the content of
 * posts and templates): Pro registers the same source.
 *
 * @since 1.0.0
 */
final class BlockBindings
{
    public const SOURCE = 'aop/option';

    /**
     * The attributes the editor gets a preview value for (see editorData()).
     */
    private const PREVIEW_ATTRIBUTES = ['content', 'text', 'caption', 'url', 'alt', 'title', 'id', 'datetime', 'linkTarget', 'rel'];

    /**
     * Register on init. Not when Pro has taken over (it registers the source itself), not on a WordPress without
     * Block Bindings, and not again.
     */
    public static function register(): void
    {
        if (Plugin::isDisabled() || !function_exists('register_block_bindings_source')) {
            return;
        }

        // Registered twice is a "doing it wrong" of WordPress (init that runs again, or another plugin first).
        if (get_block_bindings_source(self::SOURCE) !== null) {
            return;
        }

        register_block_bindings_source(self::SOURCE, [
            'label' => self::label(),
            'get_value_callback' => [self::class, 'value'],
        ]);
    }

    public static function label(): string
    {
        return __('Admin Options Pages', 'admin-options-pages');
    }

    /**
     * The value WordPress puts in the block, or null to keep what the block has.
     *
     * @param array     $args      The `args` of the binding: `name` is the option name of the field.
     * @param \WP_Block $block     The block (not used).
     * @param string    $attribute The bound attribute.
     */
    public static function value(array $args, $block, string $attribute): ?string
    {
        $name = isset($args['name']) && is_string($args['name']) ? $args['name'] : '';

        return $name === '' ? null : Output::binding($name, $attribute);
    }

    /**
     * The script that registers the source in the block editor and the site editor (field list and preview).
     */
    public static function enqueueEditor(): void
    {
        if (Plugin::isDisabled() || !current_user_can('edit_posts')) {
            return;
        }

        $handle = Plugin::PREFIX . 'bindings-js';

        Enqueue::buildScript($handle, 'bindings');
        Enqueue::scriptTranslations($handle);
        wp_add_inline_script($handle, 'window.aopBindings = ' . wp_json_encode(self::editorData()) . ';', 'before');
    }

    /**
     * What the editor needs: the public fields, with a label and the values the website would show, so a bound block
     * looks in the editor as it will on the website. Only public fields: their values are on the website anyway.
     *
     * @return array{source: string, label: string, fields: array<int, array{name: string, label: string, values: array<string, string>}>}
     */
    public static function editorData(): array
    {
        $fields = [];

        // Built from the stored pages, not from the kept list: in the editor a field that is gone (a page deleted
        // with SQL, by a script or another plugin) must not be offered. One query, in the admin only.
        foreach (PublicFields::rebuild() as $name => $field) {
            if (PublicFields::get($name) === null) {
                continue;
            }

            $values = [];

            foreach (self::PREVIEW_ATTRIBUTES as $attribute) {
                $value = Output::binding($name, $attribute);

                if ($value !== null) {
                    $values[$attribute] = $value;
                }
            }

            $label = isset($field['field_label']) ? trim(stripslashes((string) $field['field_label'])) : '';

            $fields[] = [
                'name' => (string) $name,
                'label' => $label !== '' ? sprintf('%s (%s)', $label, $name) : (string) $name,
                'values' => $values,
            ];
        }

        return ['source' => self::SOURCE, 'label' => self::label(), 'fields' => $fields];
    }
}