<?php
namespace Agentsia_Agents;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * IndexNow key hosting (#17 — GEO Bing/IndexNow).
 *
 * The Agentsia backend generates an IndexNow key and pushes it here via
 * POST /wp-json/agentsia/v1/indexnow-key (authenticated with an Application
 * Password). The plugin then serves that key as raw text/plain on
 * https://<host>/<key>.txt — the exact contract IndexNow (Bing/Yandex/Seznam,
 * NOT Google) requires to verify site ownership before accepting submissions.
 *
 * No file is written to disk: the key is served dynamically on template_redirect
 * (which fires on every front-end request, including would-be 404s), so there is
 * no rewrite rule and no flush to manage.
 *
 * The key is NOT a secret — the IndexNow protocol requires it to be publicly
 * served — so storing it in a plain option and echoing it verbatim is by design.
 */
final class IndexNow {

	const REST_NAMESPACE = 'agentsia/v1';
	const REST_ROUTE     = '/indexnow-key';
	const OPTION_KEY     = 'agentsia_indexnow_key';

	private static ?self $instance = null;

	public static function instance(): self {
		if ( self::$instance === null ) {
			self::$instance = new self();
		}
		return self::$instance;
	}

	public function register(): void {
		add_action( 'rest_api_init', [ $this, 'register_routes' ] );
		// Priority 0 : intercept BEFORE WordPress resolves the (non-existent) /<key>.txt to a 404 template.
		add_action( 'template_redirect', [ $this, 'maybe_serve_key' ], 0 );
	}

	public function register_routes(): void {
		register_rest_route(
			self::REST_NAMESPACE,
			self::REST_ROUTE,
			[
				'methods'             => 'POST',
				'callback'            => [ $this, 'handle_set_key' ],
				// Hosting a site-level ownership file is an administrator action. If the connected
				// Application Password user is NOT an admin, the backend receives a 403 and falls
				// back to manual hosting instructions — never a silent failure.
				// The dedicated « Agentsia » user (connection button) holds `agentsia_seo` instead of `manage_options`.
				'permission_callback' => static function () {
					return current_user_can( 'manage_options' ) || current_user_can( 'agentsia_seo' );
				},
			]
		);
	}

	/**
	 * Store the IndexNow key pushed by the backend.
	 *
	 * @return \WP_REST_Response|\WP_Error
	 */
	public function handle_set_key( \WP_REST_Request $request ) {
		$key = strtolower( trim( (string) $request->get_param( 'key' ) ) );
		if ( ! preg_match( '/^[a-f0-9]{8,128}$/', $key ) ) {
			return new \WP_Error(
				'agentsia_indexnow_bad_key',
				__( 'Clé IndexNow invalide (8 à 128 caractères hexadécimaux attendus).', 'agentsia-agents' ),
				[ 'status' => 400 ]
			);
		}
		// autoload = false : lue seulement au moment de servir /<key>.txt, pas sur chaque page.
		update_option( self::OPTION_KEY, $key, false );

		return new \WP_REST_Response(
			[
				'stored'      => true,
				'keyLocation' => home_url( '/' . $key . '.txt' ),
			],
			200
		);
	}

	/**
	 * Serve the stored key as raw text/plain when the request path is exactly /<key>.txt.
	 * No-op otherwise (lets WordPress handle the request normally).
	 */
	public function maybe_serve_key(): void {
		$key = (string) get_option( self::OPTION_KEY, '' );
		if ( $key === '' ) {
			return;
		}

		$request_uri = isset( $_SERVER['REQUEST_URI'] ) ? wp_unslash( $_SERVER['REQUEST_URI'] ) : '';
		$path        = (string) wp_parse_url( (string) $request_uri, PHP_URL_PATH );
		$path        = ltrim( rawurldecode( $path ), '/' );

		// Only the exact "<key>.txt" filename at the site root matches. Constant-time compare.
		if ( ! hash_equals( $key . '.txt', $path ) ) {
			return;
		}

		nocache_headers();
		status_header( 200 );
		header( 'Content-Type: text/plain; charset=UTF-8' );
		// The key matches /^[a-f0-9]{8,128}$/ (validated on store) → safe to echo verbatim; the IndexNow
		// protocol requires the raw key as the entire body, with nothing else.
		echo $key; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
		exit;
	}
}