<?php
namespace QWSpeedCache\Optimization;

defined( 'ABSPATH' ) || exit;

/**
 * CSS Minify & Combine – original implementation.
 */
class Css {

	private $settings;
	private $cache_dir;

	public function __construct() {
 		if ( ! \QWSpeedCache\Plugin::should_optimize() ) { return; }
		$this->settings  = \QWSpeedCache\Plugin::instance()->get_all_settings();
		$this->cache_dir = QWSC_CACHE_DIR . 'css/';

		if ( empty( $this->settings['minify_css'] ) && empty( $this->settings['combine_css'] ) ) {
			return;
		}

		if ( ! is_dir( $this->cache_dir ) ) {
			wp_mkdir_p( $this->cache_dir );
		}

		add_action( 'wp_print_styles', array( $this, 'process' ), 999 );
	}

	public function process() {
		if ( ! \QWSpeedCache\Plugin::should_optimize() || is_admin() || is_customize_preview() ) {
			return;
		}
		// Per-post "Disable minify/combine" is evaluated here, after the main query.
		if ( \QWSpeedCache\Admin\PostMetabox::flag( 'no_minify' ) ) {
			return;
		}

		global $wp_styles;
		if ( empty( $wp_styles->queue ) ) {
			return;
		}

		$to_process = array();
		$excludes   = $this->get_excludes();

		foreach ( $wp_styles->queue as $handle ) {
			if ( empty( $wp_styles->registered[ $handle ] ) ) {
				continue;
			}
			$obj = $wp_styles->registered[ $handle ];
			$src = isset( $obj->src ) ? (string) $obj->src : '';
			if ( '' === $src ) {
				continue;
			}
			if ( \QWSpeedCache\Optimization\JsExclusions::is_excluded( $handle, $src, $excludes ) ) {
				continue;
			}
			if ( false !== strpos( $src, 'wp-includes' ) || false !== strpos( $src, 'wp-admin' ) ) {
				continue;
			}
			$to_process[ $handle ] = $obj;
		}

		if ( empty( $to_process ) ) {
			return;
		}

		if ( \QWSpeedCache\Optimization\CombineSafety::allow( $this->settings, 'css' ) ) {
			$to_combine = \QWSpeedCache\Optimization\CombineSafety::filter_items( $to_process, $this->settings, array( $this, 'get_local_path_public' ), 'css' );
			if ( count( $to_combine ) >= 2 ) {
				$this->combine( $to_combine );
			}
		} elseif ( ! empty( $this->settings['minify_css'] ) ) {
			$this->minify_individual( $to_process );
		}
	}

	private function get_excludes() {
		return \QWSpeedCache\Optimization\JsExclusions::parse_list( $this->settings['exclude_css'] ?? '' );
	}

	/**
	 * Generate an asset safely: never replace a registered original if this
	 * file is absent, empty or could not be written to the cache directory.
	 *
	 * @param string $path Cache file path.
	 * @param string $data Generated asset bytes.
	 * @return bool Whether the generated file is ready for use.
	 */
	private static function ensure_cache_asset( $path, $data ) {
		if ( ! is_string( $data ) || '' === $data ) {
			return false;
		}
		$expected = strlen( $data );
		clearstatcache( true, $path );
		if ( is_file( $path ) && is_readable( $path ) && filesize( $path ) === $expected ) {
			return true;
		}
		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents -- Generated local cache under wp-content/cache; verify the complete write.
		$written = @file_put_contents( $path, $data, LOCK_EX );
		clearstatcache( true, $path );
		return $written === $expected && is_file( $path ) && is_readable( $path ) && filesize( $path ) === $expected;
	}

	private function minify_individual( $items ) {
		global $wp_styles;
		foreach ( $items as $handle => $obj ) {
			$src = $this->get_local_path( $obj->src );
			if ( ! $src || ! file_exists( $src ) ) {
				continue;
			}
			// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- Reading a validated local enqueued CSS asset, never fetching a remote URL.
			$content = file_get_contents( $src );
			if ( false === $content ) {
				continue;
			}
			$content = $this->rewrite_relative_urls( $content, $obj->src );
			$min     = $this->minify( $content );
			$hash    = substr( md5( $min ), 0, 12 );
			// A registered asset handle is extension-controlled; never use it directly as a filesystem component.
			$safe_handle = sanitize_file_name( (string) $handle );
			if ( '' === $safe_handle ) {
				$safe_handle = 'asset';
			}
			$out     = $this->cache_dir . $safe_handle . '-' . $hash . '.css';
			if ( self::ensure_cache_asset( $out, $min ) ) {
				$wp_styles->registered[ $handle ]->src = $this->url_from_path( $out );
			}
		}
	}

	private function combine( $items ) {
		global $wp_styles;
		$combined = '';
		$handles  = array();
		foreach ( $items as $handle => $obj ) {
			$src = $this->get_local_path( $obj->src );
			if ( ! $src || ! file_exists( $src ) ) {
				continue;
			}
			// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- Reading a validated local enqueued CSS asset, never fetching a remote URL.
			$content = file_get_contents( $src );
			if ( false === $content ) {
				continue;
			}
			$content = $this->rewrite_relative_urls( $content, $obj->src );
			if ( ! empty( $this->settings['minify_css'] ) ) {
				$content = $this->minify( $content );
			}
			$combined .= "/* {$handle} */\n" . $content . "\n";
			$handles[] = $handle;
		}
		if ( empty( $combined ) ) {
			return;
		}
		$hash = substr( md5( $combined ), 0, 12 );
		$out  = $this->cache_dir . 'combined-' . $hash . '.css';
		$was_ready = is_file( $out ) && is_readable( $out ) && filesize( $out ) === strlen( $combined );
		if ( ! self::ensure_cache_asset( $out, $combined ) ) {
			return; // Originals are still queued and will load normally.
		}
		if ( ! $was_ready ) {
			do_action( 'qwsc_combined_css_written', $out );
		}
		foreach ( $handles as $handle ) {
			wp_dequeue_style( $handle );
		}
		wp_enqueue_style( 'qwsc-combined-css', $this->url_from_path( $out ), array(), QWSC_VERSION );
	}


	/**
	 * Keep relative CSS assets pointing to their original stylesheet location.
	 * WordPress core, theme, custom uploads and relocated content paths can
	 * have different filesystem and URL roots; use the registered source URL.
	 *
	 * @param string $css       Original CSS.
	 * @param string $source_url Registered stylesheet URL.
	 * @return string
	 */
	private function rewrite_relative_urls( $css, $source_url ) {
		if ( ! is_string( $css ) || '' === $css || ! is_string( $source_url ) || '' === $source_url ) {
			return $css;
		}
		$source_url = trim( $source_url );
		if ( 0 === strpos( $source_url, '//' ) ) {
			$source_url = ( is_ssl() ? 'https:' : 'http:' ) . $source_url;
		} elseif ( ! preg_match( '#^https?://#i', $source_url ) ) {
			if ( '/' === $source_url[0] ) {
				$site = wp_parse_url( home_url( '/' ) );
				if ( ! is_array( $site ) || empty( $site['scheme'] ) || empty( $site['host'] ) ) {
					return $css;
				}
				$source_url = $site['scheme'] . '://' . $site['host'] . ( isset( $site['port'] ) ? ':' . $site['port'] : '' ) . $source_url;
			} else {
				global $wp_styles;
				$asset_base = ( isset( $wp_styles->base_url ) && is_string( $wp_styles->base_url ) ) ? $wp_styles->base_url : site_url( '/' );
				$source_url = trailingslashit( $asset_base ) . ltrim( $source_url, '/' );
			}
		}
		$parts = wp_parse_url( $source_url );
		if ( ! is_array( $parts ) || empty( $parts['host'] ) || empty( $parts['scheme'] ) || ! in_array( strtolower( $parts['scheme'] ), array( 'http', 'https' ), true ) ) {
			return $css;
		}
		$origin = $parts['scheme'] . '://' . $parts['host'] . ( isset( $parts['port'] ) ? ':' . $parts['port'] : '' );
		$path   = isset( $parts['path'] ) ? $parts['path'] : '/';
		$base   = $origin . trailingslashit( dirname( $path ) );
		$resolve = static function ( $url ) use ( $origin, $base ) {
			$url = trim( $url );
			if ( '' === $url || preg_match( '#^(?:[a-z][a-z0-9+.-]*:|//|\#|/|var\()#i', $url ) ) {
				return $url;
			}
			return $base . $url;
		};
		// Preserve existing quotes, and do not alter absolute, data or fragment URLs.
		$css = preg_replace_callback( '/url\(\s*([\"\']?)([^)\"\']+)\1\s*\)/i', static function ( $m ) use ( $resolve ) {
			$url = trim( $m[2] );
			$new = $resolve( $url );
			return $new === $url ? $m[0] : 'url(' . $m[1] . $new . $m[1] . ')';
		}, $css );
		// CSS also permits @import "subdir/theme.css" without url().
		return preg_replace_callback( '/@import\s+([\"\'])([^\"\']+)\1/i', static function ( $m ) use ( $resolve ) {
			return '@import ' . $m[1] . $resolve( $m[2] ) . $m[1];
		}, $css );
	}

	private function minify( $css ) {
		return \QWSpeedCache\Optimization\Minify\Engine::css( $css );
	}

	public function get_local_path_public( $src ) {
		return $this->get_local_path( $src );
	}

	private function get_local_path( $src ) {
		return LocalAssetPath::resolve( $src );
	}

	private function url_from_path( $path ) {
		return content_url( 'cache/qw-speed-cache/css/' . basename( $path ) );
	}
}