<?php

declare(strict_types=1);

namespace LIT\MCP\Integrations\Divi\Design;

use LIT\MCP\Abilities\Ability;
use LIT\MCP\Abilities\Annotations;
use LIT\MCP\Abilities\Errors;
use LIT\MCP\Integrations\Divi\Release\FeatureSets;
use LIT\MCP\Integrations\Divi\Release\RequiresDiviFeatures;
use WP_Error;

defined('ABSPATH') || exit;

/**
 * lit/divi-design-restore (spec §5, G6, ruling V10): writes a snapshot back through the change pipeline – dry run with
 * the diff to the current state, confirm with design_rev, and first a snapshot of the current state, so a restore can
 * be undone as well. The area comes from the snapshot ID; its RestorePlanner brings the rights, the Divi features and
 * the plan. A snapshot of an area without a planner is refused as unsupported, never treated as a no-op.
 */
final class DiviDesignRestoreAbility implements Ability, RequiresDiviFeatures
{
    private const ID = '/^(colors|variables|presets|theme_options|custom_css)-\d{8}T\d{6}Z-[0-9a-f]{6}$/D';

    /** @var array<string, RestorePlanner> area => planner */
    private array $planners = [];

    public function __construct(
        private DesignChange $change,
        private SnapshotStore $snapshots,
        RestorePlanner ...$planners
    ) {
        foreach ($planners as $planner) {
            $this->planners[$planner->area()] = $planner;
        }
    }

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

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

    public function description(): string
    {
        return 'Stellt einen Snapshot des Designsystems wieder her (snapshot_id aus lit/divi-design-snapshots oder '
            . 'einer Änderungsantwort). Zuerst Probelauf (Unterschied zum aktuellen Stand, design_rev), nach Rückfrage '
            . 'beim Nutzer confirm: true; vorher wird der aktuelle Stand selbst gesichert. Bereiche: presets, colors '
            . '(Farben, die es im Snapshot nicht gibt, entfallen), variables (Variablen, die erst nach dem Snapshot '
            . 'entstanden, bleiben archiviert erhalten) und theme_options (Theme-Optionen, die im Snapshot nicht '
            . 'gesetzt sind, kehren zum Divi-Standard zurück) und custom_css (das ganze eigene CSS, nur für dasselbe '
            . 'Theme).';
    }

    public function inputSchema(): array
    {
        return [
            'type' => 'object',
            'properties' => ['snapshot_id' => ['type' => 'string']] + DesignChange::inputProperties(),
            'required' => ['snapshot_id'],
            'additionalProperties' => false,
        ];
    }

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

    public function annotations(): array
    {
        return Annotations::destructive(false);
    }

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

    /** The features of the snapshot's area; without a restorable area those of every area (fail closed). */
    public function diviFeatures(array $input): array
    {
        return FeatureSets::merge(...array_map(
            static fn (RestorePlanner $planner): array => $planner->features(),
            $this->plannersFor($input)
        ));
    }

    public function permission(array $input): bool|WP_Error
    {
        return $this->rights($input) ?? true;
    }

    public function execute(array $input): mixed
    {
        $refusal = $this->rights($input);
        if ($refusal !== null) {
            return $refusal;
        }
        $id = is_string($input['snapshot_id'] ?? null) ? $input['snapshot_id'] : '';
        $area = self::areaOf($input);
        if ($area === null) {
            return Errors::invalidInput(
                'Ungültige Snapshot-ID.',
                ['snapshot_id' => 'z. B. presets-20261016T101500Z-a1b2c3']
            );
        }
        $planner = $this->planners[$area] ?? null;
        if ($planner === null) {
            return Errors::unsupported(
                'Snapshots dieses Bereichs lassen sich hier nicht wiederherstellen.',
                'Den Stand des Snapshots im Divi-Builder bzw. -Customizer von Hand herstellen.'
            );
        }
        $snapshot = $this->snapshots->get($area, $id);
        if ($snapshot === null) {
            return Errors::notFound(
                sprintf('Snapshot %s gibt es nicht (mehr).', $id),
                'Vorhandene Snapshots mit lit/divi-design-snapshots auflisten; je Bereich bleiben die letzten 20.'
            );
        }

        return $this->change->run(
            $this->name(),
            $planner->designArea(),
            $input,
            static fn (array $raw): DesignPlan|WP_Error => $planner->plan($raw, $snapshot['data'], $id)
        );
    }

    /**
     * Spec §10: the rights of the snapshot's area; without a restorable area those of every area (fail closed).
     *
     * @param array<string, mixed> $input
     */
    private function rights(array $input): ?WP_Error
    {
        foreach ($this->plannersFor($input) as $planner) {
            $refusal = $planner->rights();
            if ($refusal !== null) {
                return $refusal;
            }
        }

        return null;
    }

    /**
     * @param array<string, mixed> $input
     * @return list<RestorePlanner> The planner of the snapshot's area, or every planner.
     */
    private function plannersFor(array $input): array
    {
        $planner = $this->planners[self::areaOf($input) ?? ''] ?? null;

        return $planner !== null ? [$planner] : array_values($this->planners);
    }

    /** @param array<string, mixed> $input */
    private static function areaOf(array $input): ?string
    {
        $id = $input['snapshot_id'] ?? null;

        return is_string($id) && preg_match(self::ID, $id, $match) === 1 ? $match[1] : null;
    }
}