<?php

namespace AOP\App;

use AOP\App\Admin\Input;
use AOP\App\Admin\AdminPages\SubpageCreate;
use AOP\App\Admin\AdminPages\SubpageEdit;
use AOP\App\Database\PageRepository;
use Illuminate\Support\Collection;

/**
 * Saves the page payload in Request::post(): validates, stores the page and keeps the options in step.
 * Works for the form post and for the REST endpoint; neither redirects nor prints anything here.
 */
class PageSaver
{
    /**
     * @var Input
     */
    private $input;

    public function __construct(?Input $input = null)
    {
        $this->input = $input ?? new Input();
    }

    /**
     * Create (Request::get()['page'] is the create screen) or update (the edit screen) the page.
     *
     * @return array{id: int, created: bool}
     *
     * @throws PageInvalid When the payload does not pass the rules.
     */
    public function save(Validation $validate): array
    {
        // The rules below compare with the pages as they are stored now, so read them before anything is written.
        Data::getAllFromPageValueColumn();

        $errors = Validator::collect($validate);

        if ($errors) {
            throw new PageInvalid($errors); // phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped -- a list of messages for the REST response, not output
        }

        $fields = isset(Request::post()['existing_menu'])
            ? $this->input->exitingMenuFields($validate)
            : $this->input->customMenuFields($validate);

        $this->deleteOptionsOfRemovedFields();

        if (Request::get()['page'] === SubpageCreate::SLUG) {
            return $this->create($fields);
        }

        return $this->update($fields);
    }

    /**
     * @return array{id: int, created: bool}
     */
    private function create(array $fields): array
    {
        $id = PageRepository::insert($fields['menu_slug'], $fields['stored_value']);

        OptionNames::sync();
        OptionNames::createFor(PageRepository::decode($fields['stored_value']));

        Flash::add(['pages_saved' => true]);

        return ['id' => $id, 'created' => true];
    }

    /**
     * @return array{id: int, created: bool}
     */
    private function update(array $fields): array
    {
        $id = (int) Data::IdEditPage();

        PageRepository::update($id, $fields['menu_slug'], $fields['stored_value']);

        OptionNames::sync();
        OptionNames::updateFor(PageRepository::decode($fields['stored_value']));

        return ['id' => $id, 'created' => false];
    }

    /**
     * Options of fields that were on the page before and are gone now.
     *
     * @return Collection
     */
    private function deleteOptionsOfRemovedFields()
    {
        return Collection::make(Data::getAllRegisteredFieldNames())
            ->diff(Data::getFieldsWithFieldNames())
            ->values()
            ->map(function ($name) {
                return delete_option($name);
            });
    }
}