<?php
namespace Zadex\Components;

defined('ABSPATH') || exit;

use WP_Error;
use WP_REST_Request;
use WP_REST_Response;
use Zadex\Documents\Document;
use Zadex\Documents\Sanitizer;
use Zadex\Widgets\WidgetRegistry;

/**
 * REST routes of components / global widgets (namespace zadex/v1, cookie auth + nonce):
 *
 *  GET    /components          edit_posts        { items: [{id, title, kind, usage, modified, status}] }
 *  POST   /components          edit_posts        { title, elements, css?, props? } -> full item (201)
 *  GET    /components/{id}     edit_posts        { id, title, kind, usage, modified, elements, css, props }
 *  PUT    /components/{id}     edit_post {id}    { title?, elements?, css?, props? } -> full item
 *  DELETE /components/{id}     delete_post {id}  { deleted, id, usage }
 *
 * Elements are sanitized like any document (Document::save, which also fires `zadex/document/saved`: usage index,
 * props sync). A component can never contain itself (400 `zadex_component_recursive`).
 */
final class ComponentsController
{
    public const NS = 'zadex/v1';

    private WidgetRegistry $widgets;

    public function __construct(WidgetRegistry $widgets)
    {
        $this->widgets = $widgets;
    }

    public function register(): void
    {
        add_action('rest_api_init', [$this, 'routes']);
    }

    public function routes(): void
    {
        $id_args = ['id' => ['validate_callback' => static fn($v): bool => is_numeric($v) && (int) $v > 0]];
        register_rest_route(self::NS, '/components', [
            ['methods' => 'GET', 'callback' => [$this, 'list_items'], 'permission_callback' => [$this, 'can_use']],
            ['methods' => 'POST', 'callback' => [$this, 'create_item'], 'permission_callback' => [$this, 'can_use']],
        ]);
        register_rest_route(self::NS, '/components/(?P<id>\d+)', [
            ['methods' => 'GET', 'callback' => [$this, 'get_item'], 'permission_callback' => [$this, 'can_use'], 'args' => $id_args],
            ['methods' => 'PUT', 'callback' => [$this, 'update_item'], 'permission_callback' => [$this, 'can_edit'], 'args' => $id_args],
            ['methods' => 'DELETE', 'callback' => [$this, 'delete_item'], 'permission_callback' => [$this, 'can_delete'], 'args' => $id_args],
        ]);
    }

    public function can_use(): bool
    {
        return current_user_can('edit_posts');
    }

    /** Unknown ids fall through to the handler's 404; real components need edit_post. */
    public function can_edit(WP_REST_Request $request): bool
    {
        $id = (int) $request['id'];
        if (!current_user_can('edit_posts')) {
            return false;
        }
        return !ComponentPost::exists($id) || current_user_can('edit_post', $id);
    }

    public function can_delete(WP_REST_Request $request): bool
    {
        $id = (int) $request['id'];
        if (!current_user_can('edit_posts')) {
            return false;
        }
        return !ComponentPost::exists($id) || current_user_can('delete_post', $id);
    }

    public function list_items(): WP_REST_Response
    {
        $items = [];
        foreach (ComponentPost::all() as $post) {
            $items[] = ComponentPost::summary($post);
        }
        return new WP_REST_Response(['items' => $items]);
    }

    public function get_item(WP_REST_Request $request)
    {
        $item = ComponentPost::full((int) $request['id']);
        if ($item === null) {
            return self::not_found();
        }
        return new WP_REST_Response($item);
    }

    public function create_item(WP_REST_Request $request)
    {
        $body = $request->get_json_params();
        if (!is_array($body) || !isset($body['elements']) || !is_array($body['elements'])) {
            return new WP_Error('zadex_bad_request', __('Missing component elements.', 'zadex'), ['status' => 400]);
        }
        $title = is_string($body['title'] ?? null) ? trim(sanitize_text_field($body['title'])) : '';
        if ($title === '') {
            return new WP_Error('zadex_bad_request', __('A component needs a name.', 'zadex'), ['status' => 400]);
        }
        $elements = (new Sanitizer($this->widgets))->sanitize_elements($body['elements']);
        if (!$elements) {
            return new WP_Error('zadex_bad_request', __('The component has no valid elements.', 'zadex'), ['status' => 400]);
        }
        $id = wp_insert_post(wp_slash([
            'post_type'    => ComponentPost::POST_TYPE,
            'post_title'   => $title,
            'post_status'  => 'publish',
            'post_content' => '',
        ]), true);
        if (is_wp_error($id)) {
            return $id;
        }
        $id = (int) $id;
        $saved = $this->store($id, $elements, is_string($body['css'] ?? null) ? $body['css'] : '', $body['props'] ?? []);
        if (is_wp_error($saved)) {
            wp_delete_post($id, true);
            return $saved;
        }
        return new WP_REST_Response(ComponentPost::full($id), 201);
    }

    public function update_item(WP_REST_Request $request)
    {
        $id = (int) $request['id'];
        if (!ComponentPost::exists($id)) {
            return self::not_found();
        }
        $body = $request->get_json_params();
        if (!is_array($body)) {
            return new WP_Error('zadex_bad_request', __('Missing component data.', 'zadex'), ['status' => 400]);
        }
        if (isset($body['title']) && is_string($body['title'])) {
            $title = trim(sanitize_text_field($body['title']));
            if ($title !== '') {
                wp_update_post(wp_slash(['ID' => $id, 'post_title' => $title]));
            }
        }
        $elements = ComponentPost::tree($id);
        if (isset($body['elements']) && is_array($body['elements'])) {
            $elements = (new Sanitizer($this->widgets))->sanitize_elements($body['elements']);
            if (!$elements) {
                return new WP_Error('zadex_bad_request', __('The component has no valid elements.', 'zadex'), ['status' => 400]);
            }
        }
        $css = isset($body['css']) && is_string($body['css']) ? $body['css'] : Document::get_css($id);
        $props = array_key_exists('props', $body) ? $body['props'] : ComponentPost::props($id);
        $saved = $this->store($id, $elements, $css, $props);
        if (is_wp_error($saved)) {
            return $saved;
        }
        return new WP_REST_Response(ComponentPost::full($id));
    }

    public function delete_item(WP_REST_Request $request)
    {
        $id = (int) $request['id'];
        if (!ComponentPost::exists($id)) {
            return self::not_found();
        }
        $usage = Usage::count($id);
        $deleted = (bool) wp_delete_post($id, true);
        ComponentPost::reset_cache($id);
        return new WP_REST_Response(['deleted' => $deleted, 'id' => $id, 'usage' => $usage]);
    }

    /**
     * Stores tree + CSS + props through Document::save (sanitizer, revision, `zadex/document/saved`). Props travel in
     * the page settings (`component_props`), the same place the editor keeps them when the component is opened
     * as its own document; Components::document_saved copies them to `_zadex_component_props`.
     *
     * @return true|WP_Error
     */
    private function store(int $id, array $elements, string $css, $props)
    {
        if (Components::contains(Usage::component_ids($elements), $id)) {
            return new WP_Error('zadex_component_recursive', __('A component cannot contain itself.', 'zadex'), ['status' => 400]);
        }
        $props = ComponentPost::sanitize_props($props);
        $page = ['settings' => [ComponentPost::PAGE_KEY => $props], 'css' => ''];
        $result = Document::save($id, ['version' => Document::VERSION, 'elements' => $elements], $css, $page);
        if (is_wp_error($result)) {
            return $result;
        }
        // Also done by the `zadex/document/saved` hook; repeated here so the response never depends on hook order.
        Components::sync($id, Document::get_data($id)['elements'] ?? [], $props, $this->widgets);
        return true;
    }

    private static function not_found(): WP_Error
    {
        return new WP_Error('zadex_not_found', __('Component not found.', 'zadex'), ['status' => 404]);
    }
}