<?php

namespace AOP\App\Frontend;

use AOP\App\Database\PageRepository;
use AOP\App\Fields\FieldRegistry;
use AOP\App\Plugin;

/**
 * The fields whose value may be shown through the shortcode and the block bindings: fields of this plugin, of a
 * type that supports it, with "Use in shortcode and blocks" switched on. Everything else (options of WordPress or
 * other plugins, password fields, fields that are switched off or were stored before 1.0) is not public.
 *
 * The list is kept in the option `aop_public_fields` (option name => stored field, never values), rebuilt by
 * OptionNames::sync() after every write, so the website reads one option instead of the plugin table. Values
 * are always read with get_option().
 *
 * @since 1.0.0
 */
final class PublicFields
{
    /**
     * @var array<string, array>|null
     */
    private static $fields;

    public static function optionName(): string
    {
        return Plugin::PREFIX_ . 'public_fields';
    }

    /**
     * The stored field of a public option, or null.
     */
    public static function get(string $name): ?array
    {
        $field = self::all()[$name] ?? null;

        // The type is checked again: an add-on (or Pro) that provided it may be gone since the list was built.
        return $field !== null && self::isPublic($field) ? $field : null;
    }

    /**
     * @return array<string, array> Option name => stored field.
     */
    public static function all(): array
    {
        if (self::$fields === null) {
            $stored = get_option(self::optionName(), null);
            self::$fields = is_array($stored) ? $stored : self::rebuild();
        }

        return self::$fields;
    }

    /**
     * Build the list from the stored pages and keep it.
     *
     * @return array<string, array>
     */
    public static function rebuild(): array
    {
        self::$fields = self::fromPages();
        update_option(self::optionName(), self::$fields, false);

        return self::$fields;
    }

    /**
     * @return array<string, array>
     */
    public static function fromPages(): array
    {
        if (!PageRepository::tableExists()) {
            return [];
        }

        $fields = [];

        foreach (PageRepository::pageValueRows() as $row) {
            foreach (PageRepository::decode($row->page_value)['pages'] ?? [] as $page) {
                foreach ($page['fields'] ?? [] as $field) {
                    if (is_array($field) && !empty($field['field_name']) && self::isPublic($field)) {
                        $fields[(string) $field['field_name']] = $field;
                    }
                }
            }
        }

        return $fields;
    }

    /**
     * Forget the list of this request (tests, and after the option changed).
     */
    public static function reset(): void
    {
        self::$fields = null;
    }

    private static function isPublic(array $field): bool
    {
        if (($field['frontend'] ?? 'no') !== 'yes') {
            return false;
        }

        $type = FieldRegistry::instance()->get((string) ($field['type'] ?? ''));

        return $type !== null && $type->supportsFrontend();
    }
}