<?php
/**
 * Compression engine.
 *
 * @package AceloraSiteAccelerator
 */

namespace Acelora\SiteAccelerator\Modules;

use Acelora\SiteAccelerator\Includes\Settings;

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

/**
 * Detects GZIP and Brotli support and adds compatibility headers.
 */
class Compression_Engine {

	/**
	 * Settings.
	 *
	 * @var Settings
	 */
	private $settings;

	/**
	 * Constructor.
	 *
	 * @param Settings $settings Settings.
	 */
	public function __construct( Settings $settings ) {
		$this->settings = $settings;
	}

	/**
	 * Register hooks.
	 *
	 * @return void
	 */
	public function register() {
		add_action( 'send_headers', array( $this, 'send_headers' ), 20 );
	}

	/**
	 * Add vary header for compression compatibility.
	 *
	 * @return void
	 */
	public function send_headers() {
		if ( $this->settings->get( 'compression.enabled', 1 ) && ! headers_sent() ) {
			header( 'Vary: Accept-Encoding', false );
		}
	}

	/**
	 * Compression status.
	 *
	 * @return array
	 */
	public function status() {
		$accept = isset( $_SERVER['HTTP_ACCEPT_ENCODING'] ) ? sanitize_text_field( wp_unslash( $_SERVER['HTTP_ACCEPT_ENCODING'] ) ) : '';

		return array(
			'gzip_php'       => extension_loaded( 'zlib' ),
			'gzip_requested' => false !== stripos( $accept, 'gzip' ),
			'brotli_loaded'  => extension_loaded( 'brotli' ),
			'brotli_requested' => false !== stripos( $accept, 'br' ),
			'server'         => isset( $_SERVER['SERVER_SOFTWARE'] ) ? sanitize_text_field( wp_unslash( $_SERVER['SERVER_SOFTWARE'] ) ) : '',
		);
	}
}