<?php
/**
 * Document downloads: a signed, unexpired link within its download limit,
 * or a logged-in user who can edit the application. Every download is logged.
 *
 * @package mortgage_application
 */

namespace Mapp\Files;

use Mapp\Application\Repository;
use Mapp\Security\RateLimiter;

defined( 'ABSPATH' ) || exit;

class Endpoint {

	/**
	 * @param \WP_REST_Request $request Request.
	 * @return \WP_Error|void Streams the file and exits on success.
	 */
	public static function download( $request ) {
		$id      = (int) $request['id'];
		$file_id = (string) $request['file'];
		$denied  = new \WP_Error( 'mapp_file_denied', __( 'This link is invalid or has expired.', '1003-mortgage-application' ), array( 'status' => 403 ) );

		// Files hang off applications and standalone upload records.
		if ( ! Repository::exists( $id ) && Store::UPLOAD_POST_TYPE !== get_post_type( $id ) ) {
			return $denied;
		}
		$files = Store::files_for( $id );
		if ( ! isset( $files[ $file_id ] ) ) {
			return $denied;
		}

		$by_admin = is_user_logged_in() && current_user_can( 'edit_post', $id );
		if ( ! $by_admin ) {
			$exp     = (int) $request->get_param( 'exp' );
			$purpose = (string) $request->get_param( 'p' );
			$sig     = (string) $request->get_param( 'sig' );
			if ( $exp < time() || ! hash_equals( Store::signature( $id, $file_id, $exp, $purpose ), $sig ) ) {
				return $denied;
			}
			$limit = Store::download_limit();
			if ( $limit > 0 && (int) $files[ $file_id ]['downloads'] >= $limit ) {
				return new \WP_Error( 'mapp_file_limit', __( 'This file has reached its download limit. Ask for a new link.', '1003-mortgage-application' ), array( 'status' => 403 ) );
			}
			if ( ! RateLimiter::hit( 'download', RateLimiter::client_ip(), 60, HOUR_IN_SECONDS ) ) {
				return new \WP_Error( 'mapp_rate_limited', __( 'Too many downloads. Please try again later.', '1003-mortgage-application' ), array( 'status' => 429 ) );
			}
		}

		$bytes = Store::read( $id, $file_id );
		if ( null === $bytes ) {
			return new \WP_Error( 'mapp_file_gone', __( 'This file is no longer available.', '1003-mortgage-application' ), array( 'status' => 410 ) );
		}

		Store::mark( $id, $file_id, 'downloads', (int) $files[ $file_id ]['downloads'] + 1 );
		Access::log( $id, 'download', $file_id, $by_admin ? 'user:' . get_current_user_id() : 'link:' . sanitize_key( (string) $request->get_param( 'p' ) ) );

		$name = str_replace( array( '"', "\r", "\n" ), '', $files[ $file_id ]['name'] );
		if ( ! headers_sent() ) {
			nocache_headers();
			header( 'Content-Type: ' . $files[ $file_id ]['mime'] );
			header( 'Content-Disposition: attachment; filename="' . $name . '"' );
			header( 'Content-Length: ' . strlen( $bytes ) );
			header( 'X-Content-Type-Options: nosniff' );
			header( 'Referrer-Policy: no-referrer' );
		}
		echo $bytes; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- binary file.
		exit;
	}
}