<?php

declare(strict_types=1);

namespace LIT\MCP\Integrations\WordPress\Revisions;

use LIT\MCP\Abilities\Ability;
use LIT\MCP\Abilities\Errors;
use LIT\MCP\Abilities\Rev;
use LIT\MCP\Abilities\ToolResult;
use LIT\MCP\ChangeLog\ChangeLog;
use LIT\MCP\Integrations\WordPress\PostChangeResult;
use LIT\MCP\Integrations\WordPress\PostGuard;
use LIT\MCP\Integrations\WordPress\RevisionPoint;
use LIT\MCP\Integrations\WordPress\Schema\ContentSchema;
use WP_Error;
use WP_Post;

/**
 * lit/revision-restore: restores title, content and excerpt of an entry from one of
 * its own revisions; the status is not touched. Because this overwrites the current
 * content, rev of the current entry (from lit/content-get) is required (optimistic
 * lock, spec §2 principle 7) – the restore is itself a write. Before restoring, the
 * current state is saved as a revision (RevisionPoint::capture), so the restore is
 * undoable via another lit/revision-restore call. A revision id that does not belong
 * to a manageable entry (wrong post_type, or post_parent 0 – an orphaned revision) is
 * rejected as a validation error on revision_id, the only id field this tool takes.
 */
final class RevisionRestoreAbility implements Ability
{
    public function __construct(private ContentSchema $schema, private ChangeLog $log)
    {
    }

    public function name(): string
    {
        return 'lit/revision-restore';
    }

    public function label(): string
    {
        return 'Revision wiederherstellen';
    }

    public function description(): string
    {
        return 'Stellt Titel, Inhalt und Auszug eines Eintrags aus einer Revision wieder her (Status bleibt). '
            . 'Der aktuelle Stand wird vorher als Revision gesichert (revision_id im Ergebnis). rev des Eintrags '
            . 'aus lit-content-get ist Pflicht, damit parallele Änderungen nicht überschrieben werden. Erst nach '
            . 'Rückfrage mit confirm: true aufrufen.';
    }

    public function inputSchema(): array
    {
        return [
            'type' => 'object',
            'properties' => [
                'revision_id' => ['type' => 'integer', 'minimum' => 1],
                'rev' => [
                    'type' => 'string',
                    'description' => 'rev des Eintrags aus lit-content-get (optimistische Sperre).',
                ],
                'confirm' => ['type' => 'boolean', 'description' => 'true nach Bestätigung durch den Nutzer.'],
            ],
            'required' => ['revision_id', 'rev'],
            'additionalProperties' => false,
        ];
    }

    public function outputSchema(): ?array
    {
        return ToolResult::schema();
    }

    public function annotations(): array
    {
        return ['readonly' => false, 'destructive' => true, 'idempotent' => true];
    }

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

    public function permission(array $input): bool|WP_Error
    {
        $pair = $this->load($input);

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

    public function execute(array $input): mixed
    {
        $pair = $this->load($input);
        if ($pair instanceof WP_Error) {
            return $pair;
        }

        [$revision, $post] = $pair;
        $postId = (int) $post->ID;
        if (($input['confirm'] ?? false) !== true) {
            return Errors::confirmRequired(sprintf(
                '"%s" (ID %d) auf den Stand vom %s zurücksetzen?',
                $post->post_title,
                $postId,
                $revision->post_date
            ));
        }

        if (! Rev::matches($input, $post)) {
            return Errors::revMismatch();
        }

        // wp_restore_post_revision() saves via wp_update_post(), which would publish a missed schedule.
        $unstable = PostGuard::statusStable($post, 'revision_id');
        if ($unstable !== null) {
            return $unstable;
        }

        $backupId = RevisionPoint::capture($postId);
        $restored = wp_restore_post_revision((int) $revision->ID);
        if (! $restored) {
            return Errors::writeFailed(
                'WordPress konnte die Revision nicht wiederherstellen.',
                [],
                null,
                $backupId === null ? null : Errors::notSavedKeeping(sprintf('Revision %d', $backupId))
            );
        }

        // The restore is saved – failures from here on are logged and reported as warnings only.
        $change = (new PostChangeResult($this->name(), $this->log, $postId))->afterSave($input, 'Wiederherstellen');
        $updated = $change->reread($post) ?? $post;
        $summary = sprintf('"%s" auf Stand vom %s zurückgesetzt', $updated->post_title, $revision->post_date);
        $postType = (string) $post->post_type;
        $change->log($postType, $summary, $backupId);

        return $change->result($summary . sprintf(' (Status unverändert: %s).', $updated->post_status), $updated)
            ->changed((string) $postId, $postType, 'restored', (string) $updated->post_title)
            ->revisionId($backupId)
            ->urls((string) get_preview_post_link($updated), (string) get_edit_post_link($postId, 'raw'))
            ->toArray();
    }

    /**
     * @param array<string, mixed> $input
     * @return array{0: WP_Post, 1: WP_Post}|WP_Error
     */
    private function load(array $input): array|WP_Error
    {
        $revisionId = PostGuard::id($input['revision_id'] ?? null);
        $revision = $revisionId === null ? null : get_post($revisionId);
        if (! $revision instanceof WP_Post || $revision->post_type !== 'revision') {
            return Errors::notFound('Revision nicht gefunden.', 'Revisionen über lit/revisions-list abrufen.');
        }

        // field 'revision_id': post_parent 0 (an orphaned revision) is the only id this
        // input carries, so a validation error must name revision_id, not post_id.
        $post = PostGuard::editable((int) $revision->post_parent, $this->schema, 'revision_id');

        return $post instanceof WP_Error ? $post : [$revision, $post];
    }
}