<?php

declare(strict_types=1);

namespace LIT\MCP\Integrations\Divi\Pages;

use LIT\MCP\Abilities\Ability;
use LIT\MCP\Abilities\ToolResult;
use WP_Error;

defined('ABSPATH') || exit;

/**
 * The frame of the Divi write tools (spec §5.6): permission and execute both load the page
 * through DiviWriter::page() (rights, Divi layout, tree_rev lock – execute never trusts state
 * from permission), the tool changes the tree in change() – only when its whole input
 * validated, all or nothing (ruling S39) – and DiviWriter::commit() stores it (library entries:
 * GlobalEdits) and builds the result. The composition is bound to the page (DiviWriter::composition(), ruling S22).
 */
abstract class DiviWriteAbility implements Ability
{
    public function __construct(protected DiviWriter $writer)
    {
    }

    /**
     * Changes the tree of $page, or returns why nothing is written. Client values enter the
     * tree only through $composition (Composer / TreeEditor).
     *
     * @param array<string, mixed> $input
     */
    abstract protected function change(DiviPage $page, array $input, DiviComposition $composition): DiviChange|WP_Error;

    public function outputSchema(): ?array
    {
        return ToolResult::schema([
            'tree_rev' => ['type' => 'string'],
            // Global library entries (answer F2): the pages that show the entry, and the backup
            // made when revisions are off (also for live Theme Builder layouts, ruling Q2).
            'affected' => ['type' => 'array', 'items' => ['type' => 'object']],
            'affected_count' => ['type' => 'integer'],
            'hidden_count' => ['type' => 'integer'],
            'backup_id' => ['type' => 'integer'],
            // Theme Builder layouts: the enabled templates that show the layout.
            'templates' => ['type' => 'array', 'items' => ['type' => 'object']],
        ], ['tree_rev']);
    }

    public function isDirect(): bool
    {
        return true;
    }

    final public function permission(array $input): bool|WP_Error
    {
        $refusal = $this->precheck($input);
        if ($refusal !== null) {
            return $refusal;
        }

        $page = $this->writer->page($input);

        return $page instanceof WP_Error ? $page : true;
    }

    final public function execute(array $input): mixed
    {
        $refusal = $this->precheck($input);
        if ($refusal !== null) {
            return $refusal;
        }

        $page = $this->writer->page($input);
        if ($page instanceof WP_Error) {
            return $page;
        }

        $change = $this->change($page, $input, $this->writer->composition($page));
        if ($change instanceof WP_Error) {
            return $this->writer->notice($page, $change);
        }

        return $this->writer->commit($this->name(), $page, $change, $input);
    }

    /**
     * Checks of a tool beyond the page (rights and Tools-tab gates of another group) – run in
     * permission() and again in execute(). Null = none.
     *
     * @param array<string, mixed> $input
     */
    protected function precheck(array $input): ?WP_Error
    {
        return null;
    }
}