<?php
/**
 * CDN integration.
 *
 * @package AceloraSiteAccelerator
 */

namespace Acelora\SiteAccelerator\Modules;

use Acelora\SiteAccelerator\Includes\Settings;

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

/**
 * Rewrites local asset URLs to a custom CDN host.
 */
class CDN {

	/**
	 * 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_filter( 'script_loader_src', array( $this, 'rewrite_url' ), 20 );
		add_filter( 'style_loader_src', array( $this, 'rewrite_url' ), 20 );
		add_filter( 'wp_get_attachment_url', array( $this, 'rewrite_url' ), 20 );
		add_filter( 'the_content', array( $this, 'rewrite_content' ), 99 );
		add_filter( 'acelora_site_accelerator_optimize_html', array( $this, 'rewrite_content' ), 90 );
	}

	/**
	 * Rewrite URLs in content.
	 *
	 * @param string $html HTML.
	 * @return string
	 */
	public function rewrite_content( $html ) {
		if ( ! $this->enabled() ) {
			return $html;
		}

		$base = preg_quote( content_url(), '#' );

		return preg_replace_callback(
			'#(["\'])(' . $base . '[^"\']+\.(?:css|js|jpe?g|png|gif|webp|svg|woff2?|ttf|eot))(["\'])#i',
			function ( $matches ) {
				return $matches[1] . esc_url( $this->rewrite_url( $matches[2] ) ) . $matches[3];
			},
			$html
		);
	}

	/**
	 * Rewrite a URL.
	 *
	 * @param string $url URL.
	 * @return string
	 */
	public function rewrite_url( $url ) {
		if ( ! $this->enabled() || $this->is_excluded( $url ) ) {
			return $url;
		}

		$cdn       = untrailingslashit( $this->settings->get( 'cdn.url', '' ) );
		$content   = untrailingslashit( content_url() );
		$site      = untrailingslashit( site_url() );
		$home_host = wp_parse_url( home_url(), PHP_URL_HOST );
		$url_host  = wp_parse_url( $url, PHP_URL_HOST );

		if ( $url_host && strtolower( $url_host ) !== strtolower( $home_host ) ) {
			return $url;
		}

		if ( 0 === strpos( $url, $content ) ) {
			return $cdn . substr( $url, strlen( $content ) );
		}

		if ( 0 === strpos( $url, $site . '/wp-includes' ) ) {
			return $cdn . substr( $url, strlen( $site ) );
		}

		return $url;
	}

	/**
	 * Validate current CDN configuration.
	 *
	 * @return array
	 */
	public function verification() {
		$url = $this->settings->get( 'cdn.url', '' );

		return array(
			'enabled' => $this->enabled(),
			'url'     => $url,
			'valid'   => (bool) filter_var( $url, FILTER_VALIDATE_URL ),
			'host'    => $url ? wp_parse_url( $url, PHP_URL_HOST ) : '',
		);
	}

	/**
	 * Whether CDN rewriting is enabled.
	 *
	 * @return bool
	 */
	private function enabled() {
		return (bool) $this->settings->get( 'cdn.enabled', 0 ) && '' !== $this->settings->get( 'cdn.url', '' );
	}

	/**
	 * Exclusion check.
	 *
	 * @param string $url URL.
	 * @return bool
	 */
	private function is_excluded( $url ) {
		foreach ( $this->settings->list_value( $this->settings->get( 'cdn.exclusions', '' ) ) as $pattern ) {
			if ( '' !== $pattern && false !== stripos( $url, $pattern ) ) {
				return true;
			}
		}

		return false;
	}
}