<?php
namespace Zadex\Library;

defined('ABSPATH') || exit;

use WP_Error;
use WP_REST_Request;
use WP_REST_Response;
use Zadex\Documents\Document;
use Zadex\Documents\Sanitizer;
use Zadex\Frontend\Templates;
use Zadex\Widgets\WidgetRegistry;

/**
 * REST routes of the template library (namespace zadex/v1, cookie auth + nonce, `edit_posts`):
 *
 *  GET    /library?type=section|page      saved templates (summaries)
 *  POST   /library                         { title, type, elements, css?, pageSettings?, tags? } -> { id, item }
 *  GET    /library/{id}                    one saved template with its elements
 *  DELETE /library/{id}                    delete a saved template (delete_post)
 *  GET    /library/remote                  starter kit index (remote URL or bundled library/kits.json)
 *  GET    /library/remote/{slug}           one starter kit with its (sanitized) elements
 *  POST   /library/import                  { version, elements, pageSettings?, css? } -> sanitized copy (page JSON import)
 *  GET    /documents/{id}/export           { version, elements, pageSettings, css, template, title } (edit_post)
 */
final class LibraryController
{
    public const NS = 'zadex/v1';
    public const EXPORT_VERSION = 1;

    private WidgetRegistry $widgets;
    private Store $store;
    private Kits $kits;

    public function __construct(WidgetRegistry $widgets, Store $store, Kits $kits)
    {
        $this->widgets = $widgets;
        $this->store = $store;
        $this->kits = $kits;
    }

    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) $v > 0]];
        register_rest_route(self::NS, '/library', [
            [
                'methods'             => 'GET',
                'callback'            => [$this, 'list_items'],
                'permission_callback' => [$this, 'can_use'],
            ],
            [
                'methods'             => 'POST',
                'callback'            => [$this, 'create_item'],
                'permission_callback' => [$this, 'can_use'],
            ],
        ]);
        register_rest_route(self::NS, '/library/(?P<id>\d+)', [
            [
                'methods'             => 'GET',
                'callback'            => [$this, 'get_item'],
                'permission_callback' => [$this, 'can_use'],
                'args'                => $id_args,
            ],
            [
                'methods'             => 'DELETE',
                'callback'            => [$this, 'delete_item'],
                'permission_callback' => [$this, 'can_delete'],
                'args'                => $id_args,
            ],
        ]);
        register_rest_route(self::NS, '/library/remote', [
            'methods'             => 'GET',
            'callback'            => [$this, 'remote_index'],
            'permission_callback' => [$this, 'can_use'],
        ]);
        register_rest_route(self::NS, '/library/remote/(?P<slug>[a-z0-9\-]+)', [
            'methods'             => 'GET',
            'callback'            => [$this, 'remote_item'],
            'permission_callback' => [$this, 'can_use'],
        ]);
        register_rest_route(self::NS, '/library/import', [
            'methods'             => 'POST',
            'callback'            => [$this, 'import_page'],
            'permission_callback' => [$this, 'can_use'],
        ]);
        register_rest_route(self::NS, '/documents/(?P<id>\d+)/export', [
            'methods'             => 'GET',
            'callback'            => [$this, 'export_document'],
            'permission_callback' => [$this, 'can_edit_post'],
            'args'                => $id_args,
        ]);
    }

    public function can_use(): bool
    {
        return current_user_can('edit_posts');
    }

    public function can_delete(WP_REST_Request $request): bool
    {
        $id = (int) $request['id'];
        if (!current_user_can('edit_posts')) {
            return false;
        }
        // Unknown ids fall through to the handler's 404; real templates need delete_post.
        return !$this->store->exists($id) || current_user_can('delete_post', $id);
    }

    public function can_edit_post(WP_REST_Request $request): bool
    {
        return current_user_can('edit_post', (int) $request['id']);
    }

    public function list_items(WP_REST_Request $request): WP_REST_Response
    {
        $type = is_string($request['type'] ?? null) ? (string) $request['type'] : '';
        return new WP_REST_Response(['items' => $this->store->all(in_array($type, Store::TYPES, true) ? $type : '')]);
    }

    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 template elements.', 'zadex'), ['status' => 400]);
        }
        $id = $this->store->create(
            is_string($body['title'] ?? null) ? $body['title'] : '',
            Store::sanitize_type($body['type'] ?? 'section'),
            $body['elements'],
            is_string($body['css'] ?? null) ? $body['css'] : '',
            is_array($body['pageSettings'] ?? null) ? $body['pageSettings'] : null,
            Store::sanitize_tags($body['tags'] ?? [])
        );
        if (is_wp_error($id)) {
            return $id;
        }
        return new WP_REST_Response(['id' => $id, 'item' => $this->store->summary(get_post($id))], 201);
    }

    public function get_item(WP_REST_Request $request)
    {
        $item = $this->store->get((int) $request['id']);
        if ($item === null) {
            return new WP_Error('zadex_not_found', __('Template not found.', 'zadex'), ['status' => 404]);
        }
        return new WP_REST_Response($item);
    }

    public function delete_item(WP_REST_Request $request)
    {
        $id = (int) $request['id'];
        if (!$this->store->exists($id)) {
            return new WP_Error('zadex_not_found', __('Template not found.', 'zadex'), ['status' => 404]);
        }
        return new WP_REST_Response(['deleted' => $this->store->delete($id), 'id' => $id]);
    }

    public function remote_index(): WP_REST_Response
    {
        return new WP_REST_Response(['kits' => $this->kits->index()]);
    }

    public function remote_item(WP_REST_Request $request)
    {
        $kit = $this->kits->get((string) $request['slug']);
        if ($kit === null) {
            return new WP_Error('zadex_not_found', __('Kit not found.', 'zadex'), ['status' => 404]);
        }
        return new WP_REST_Response($kit);
    }

    /** Sanitizes an uploaded page export (the editor inserts or replaces with the result). */
    public function import_page(WP_REST_Request $request)
    {
        $body = $request->get_json_params();
        $clean = is_array($body) ? $this->sanitize_export($body) : null;
        if ($clean === null) {
            return new WP_Error('zadex_bad_import', __('This file is not a Zadex page export.', 'zadex'), ['status' => 400]);
        }
        return new WP_REST_Response($clean);
    }

    /** @return array{version:int, title:string, elements:array, pageSettings:array|object, css:string}|null */
    public function sanitize_export(array $body): ?array
    {
        // Accept a page export ({version, elements}) or a bare document ({elements}) or the editor's `data` envelope.
        $elements = $body['elements'] ?? ($body['data']['elements'] ?? null);
        if (!is_array($elements)) {
            return null;
        }
        $sanitizer = new Sanitizer($this->widgets);
        $clean = $sanitizer->sanitize_elements($elements);
        if (!$clean && $elements) {
            return null;
        }
        $page = is_array($body['pageSettings'] ?? null) ? $body['pageSettings'] : [];
        // Page settings may be the stored envelope {settings, css}.
        if (isset($page['settings']) && is_array($page['settings'])) {
            $page = $page['settings'];
        }
        $page = $sanitizer->sanitize_settings_generic($page);
        if (isset($body['template']) && is_string($body['template']) && !isset($page['page_template'])) {
            $page['page_template'] = Templates::sanitize($body['template']);
        }
        return [
            'version'      => self::EXPORT_VERSION,
            'title'        => is_string($body['title'] ?? null) ? sanitize_text_field($body['title']) : '',
            'elements'     => $clean,
            'pageSettings' => $page ? $page : (object) [],
            'css'          => Document::sanitize_css(is_string($body['css'] ?? null) ? $body['css'] : ''),
        ];
    }

    public function export_document(WP_REST_Request $request)
    {
        $id = (int) $request['id'];
        $post = get_post($id);
        if (!$post) {
            return new WP_Error('zadex_not_found', __('Post not found.', 'zadex'), ['status' => 404]);
        }
        return new WP_REST_Response(self::export_payload($id, (string) $post->post_title));
    }

    /** The page JSON format shared by the REST export, the editor's "Export page" button and the site kit. */
    public static function export_payload(int $id, string $title = ''): array
    {
        $data = Document::get_data($id);
        $page = Document::get_page_settings($id);
        $settings = isset($page['settings']) && is_array($page['settings']) ? $page['settings'] : $page;
        $template = Templates::get($id);
        if ($template !== '') {
            $settings['page_template'] = $template;
        }
        return [
            'version'      => self::EXPORT_VERSION,
            'generator'    => 'zadex',
            'title'        => $title,
            'elements'     => $data['elements'],
            'pageSettings' => $settings ? $settings : (object) [],
            'css'          => Document::get_css($id),
            'template'     => $template,
        ];
    }
}