<?php
/**
 * REST API controller.
 *
 * @package Postlinkly
 * @since   1.0.0
 */

declare(strict_types=1);

namespace Postlinkly\Rest;

use Postlinkly\Hooks\ServiceProvider;
use Postlinkly\Post\PostModel;
use Postlinkly\Suggestion\SuggestionEngine;
use Postlinkly\Suggestion\SuggestionModel;

/**
 * REST API controller.
 *
 * Registers Postlinkly's REST routes under `postlinkly/v1`. All routes
 * require authentication via the `X-WP-Nonce` header (WordPress's
 * standard REST nonce mechanism). Every endpoint enforces a
 * `permission_callback` — unauthenticated requests receive a 401,
 * insufficient-capability requests receive a 403.
 *
 * v1.0 ships one endpoint:
 *
 *   GET /postlinkly/v1/suggestions?post_id=N
 *
 * @since 1.0.0
 */
final class RestController implements ServiceProvider {

	/**
	 * REST namespace.
	 */
	public const NAMESPACE = 'postlinkly/v1';

	/**
	 * @var SuggestionEngine
	 */
	private SuggestionEngine $engine;

	/**
	 * @since 1.0.0
	 *
	 * @param SuggestionEngine $engine The wired suggestion engine.
	 */
	public function __construct( SuggestionEngine $engine ) {
		$this->engine = $engine;
	}

	/**
	 * Registers Plugin service hooks.
	 *
	 * @since 1.0.0
	 *
	 * @return array<int, array<int, mixed>>
	 */
	public function get_hooks(): array {
		return array(
			array( 'rest_api_init', array( $this, 'register_routes' ) ),
		);
	}

	/**
	 * Registers all REST routes.
	 *
	 * @since 1.0.0
	 * @hook  rest_api_init
	 *
	 * @return void
	 */
	public function register_routes(): void {
		register_rest_route(
			self::NAMESPACE,
			'/suggestions',
			array(
				'methods'             => \WP_REST_Server::READABLE,
				'callback'            => array( $this, 'get_suggestions' ),
				'permission_callback' => array( $this, 'suggestions_permission' ),
				'args'                => array(
					'post_id' => array(
						'required'          => true,
						'type'              => 'integer',
						'minimum'           => 1,
						'sanitize_callback' => 'absint',
						'description'       => __( 'The post ID to get suggestions for.', 'postlinkly' ),
					),
					'limit'   => array(
						'required'          => false,
						'type'              => 'integer',
						'minimum'           => 1,
						'maximum'           => 100,
						'default'           => 10,
						'sanitize_callback' => 'absint',
						'description'       => __( 'Maximum number of suggestions to return.', 'postlinkly' ),
					),
				),
			)
		);
	}

	/**
	 * Permission callback for the suggestions endpoint.
	 *
	 * @since 1.0.0
	 *
	 * @param \WP_REST_Request $request The REST request.
	 *
	 * @return bool|\WP_Error True when authorised.
	 */
	public function suggestions_permission( \WP_REST_Request $request ): bool|\WP_Error {
		$post_id = (int) $request->get_param( 'post_id' );

		if ( ! is_user_logged_in() ) {
			return new \WP_Error(
				'rest_not_logged_in',
				__( 'You must be logged in to access suggestions.', 'postlinkly' ),
				array( 'status' => 401 )
			);
		}

		if ( ! current_user_can( 'edit_post', $post_id ) ) {
			return new \WP_Error(
				'rest_forbidden',
				__( 'You do not have permission to access suggestions for this post.', 'postlinkly' ),
				array( 'status' => 403 )
			);
		}

		return true;
	}

	/**
	 * Handles GET /postlinkly/v1/suggestions.
	 *
	 * @since 1.0.0
	 *
	 * @param \WP_REST_Request $request The REST request.
	 *
	 * @return \WP_REST_Response|\WP_Error
	 */
	public function get_suggestions( \WP_REST_Request $request ): \WP_REST_Response|\WP_Error {
		$post_id = (int) $request->get_param( 'post_id' );
		$limit   = (int) $request->get_param( 'limit' );

		$post = get_post( $post_id );
		if ( null === $post ) {
			return new \WP_Error(
				'rest_post_not_found',
				__( 'Post not found.', 'postlinkly' ),
				array( 'status' => 404 )
			);
		}

		$source  = new PostModel(
			(int) $post->ID,
			PostModel::TYPE_POST,
			(string) $post->post_title,
			(string) $post->post_status
		);
		$content = (string) $post->post_content;

		$suggestions = $this->engine->get_suggestions( $source, $content, $limit );

		return new \WP_REST_Response(
			array(
				'post_id'     => $post_id,
				'suggestions' => array_map( array( $this, 'serialise' ), $suggestions ),
			),
			200
		);
	}

	/**
	 * Serialises a SuggestionModel for the REST response.
	 *
	 * @since 1.0.0
	 *
	 * @param SuggestionModel $s Suggestion to serialise.
	 *
	 * @return array<string, mixed>
	 */
	private function serialise( SuggestionModel $s ): array {
		return array(
			'target_id'    => $s->target->id,
			'target_type'  => $s->target->type,
			'target_title' => $s->target->title,
			'anchor'       => $s->anchor,
			'sentence'     => $s->original_sentence,
			'total_score'  => round( $s->total_score, 4 ),
		);
	}
}