<?php
namespace W3TC;

/**
 * class BrowserCache_Environment
 */
class BrowserCache_Environment {
	/**
	 * Fixes environment in each wp-admin request
	 *
	 * @param Config  $config
	 * @param bool    $force_all_checks
	 * @throws Util_Environment_Exceptions
	 */
	public function fix_on_wpadmin_request( $config, $force_all_checks ) {
		$exs = new Util_Environment_Exceptions();

		if ( $config->get_boolean( 'config.check' ) || $force_all_checks ) {
			if ( $config->get_boolean( 'browsercache.enabled' ) ) {
				$this->rules_cache_add( $config, $exs );
			} else {
				$this->rules_cache_remove( $exs );
			}

			if ( $config->get_boolean( 'browsercache.enabled' ) &&
				$config->get_boolean( 'browsercache.no404wp' ) ) {
				$this->rules_no404wp_add( $config, $exs );
			} else {
				$this->rules_no404wp_remove( $exs );
			}
		}

		if ( count( $exs->exceptions() ) > 0 )
			throw $exs;
	}

	/**
	 * Fixes environment once event occurs
	 *
	 * @throws Util_Environment_Exceptions
	 */
	public function fix_on_event( $config, $event, $old_config = null ) {
	}

	/**
	 * Fixes environment after plugin deactivation
	 *
	 * @throws Util_Environment_Exceptions
	 */
	public function fix_after_deactivation() {
		$exs = new Util_Environment_Exceptions();

		$this->rules_cache_remove( $exs );
		$this->rules_no404wp_remove( $exs );

		if ( count( $exs->exceptions() ) > 0 )
			throw $exs;
	}

	/**
	 * Returns required rules for module
	 *
	 * @param Config  $config
	 * @return array
	 */
	public function get_required_rules( $config ) {
		if ( !$config->get_boolean( 'browsercache.enabled' ) )
			return null;

		$rewrite_rules = array();
		if ( Dispatcher::should_browsercache_generate_rules_for_cdn( $config ) ) {
			$domain = Dispatcher::get_cdn_domain();
			$cdn_rules_path = sprintf( 'ftp://%s/%s', $domain,
				Util_Rule::get_cdn_rules_path() );
			$rewrite_rules[] = array(
				'filename' => $cdn_rules_path,
				'content' => $this->rules_cache_generate( $config, true )
			);
		}

		$browsercache_rules_cache_path = Util_Rule::get_browsercache_rules_cache_path();
		$rewrite_rules[] = array(
			'filename' => $browsercache_rules_cache_path,
			'content' => $this->rules_cache_generate( $config )
		);

		if ( $config->get_boolean( 'browsercache.no404wp' ) ) {
			$browsercache_rules_no404wp_path =
				Util_Rule::get_browsercache_rules_no404wp_path();
			$rewrite_rules[] = array(
				'filename' => $browsercache_rules_no404wp_path,
				'content' => $this->rules_no404wp_generate( $config )
			);
		}
		return $rewrite_rules;
	}

	/**
	 * Returns mime types
	 *
	 * @return array
	 */
	public function get_mime_types() {
		$a = array(
			'cssjs' => include W3TC_INC_DIR . '/mime/cssjs.php',
			'html' => include W3TC_INC_DIR . '/mime/html.php',
			'other' => include W3TC_INC_DIR . '/mime/other.php'
		);

		$other_compression = $a['other'];
		unset( $other_compression['asf|asx|wax|wmv|wmx'] );
		unset( $other_compression['avi'] );
		unset( $other_compression['divx'] );
		unset( $other_compression['gif'] );
		unset( $other_compression['gz|gzip'] );
		unset( $other_compression['jpg|jpeg|jpe'] );
		unset( $other_compression['mid|midi'] );
		unset( $other_compression['mov|qt'] );
		unset( $other_compression['mp3|m4a'] );
		unset( $other_compression['mp4|m4v'] );
		unset( $other_compression['mpeg|mpg|mpe'] );
		unset( $other_compression['png'] );
		unset( $other_compression['ra|ram'] );
		unset( $other_compression['tar'] );
		unset( $other_compression['wma'] );
		unset( $other_compression['zip'] );

		$a['other_compression'] = $other_compression;

		return $a;
	}

	/**
	 * Generate rules for FTP upload
	 *
	 * @param Config  $config
	 * @return string
	 */
	public function rules_cache_generate_for_ftp( $config ) {
		return $this->rules_cache_generate( $config, true );
	}



	/*
	 * rules cache
	 */

	/**
	 * Writes cache rules
	 *
	 * @throws Util_WpFile_FilesystemOperationException with S/FTP form if it can't get the required filesystem credentials
	 */
	private function rules_cache_add( $config, $exs ) {
		Util_Rule::add_rules( $exs,
			Util_Rule::get_browsercache_rules_cache_path(),
			$this->rules_cache_generate( $config ),
			W3TC_MARKER_BEGIN_BROWSERCACHE_CACHE,
			W3TC_MARKER_END_BROWSERCACHE_CACHE,
			array(
				W3TC_MARKER_BEGIN_MINIFY_CORE => 0,
				W3TC_MARKER_BEGIN_PGCACHE_CORE => 0,
				W3TC_MARKER_BEGIN_BROWSERCACHE_NO404WP => 0,
				W3TC_MARKER_BEGIN_WORDPRESS => 0,
				W3TC_MARKER_END_PGCACHE_CACHE => strlen( W3TC_MARKER_END_PGCACHE_CACHE ) + 1,
				W3TC_MARKER_END_MINIFY_CACHE => strlen( W3TC_MARKER_END_MINIFY_CACHE ) + 1
			)
		);
	}

	/**
	 * Removes cache directives
	 *
	 * @throws Util_WpFile_FilesystemOperationException with S/FTP form if it can't get the required filesystem credentials
	 */
	private function rules_cache_remove( $exs ) {
		Util_Rule::remove_rules( $exs,
			Util_Rule::get_browsercache_rules_cache_path(),
			W3TC_MARKER_BEGIN_BROWSERCACHE_CACHE,
			W3TC_MARKER_END_BROWSERCACHE_CACHE );
	}

	/**
	 * Returns cache rules
	 *
	 * @param Config  $config
	 * @param bool    $cdnftp
	 * @return string
	 */
	public function rules_cache_generate( $config, $cdnftp = false ) {
		switch ( true ) {
		case Util_Environment::is_apache():
		case Util_Environment::is_litespeed():
			return $this->rules_cache_generate_apache( $config );

		case Util_Environment::is_nginx():
			return $this->rules_cache_generate_nginx( $config, $cdnftp );
		}
		return '';
	}

	/**
	 * Returns cache rules
	 *
	 * @param Config  $config
	 * @return string
	 */
	private function rules_cache_generate_apache( $config ) {
		$mime_types2 = $this->get_mime_types();
		$cssjs_types = $mime_types2['cssjs'];
		$cssjs_types = array_unique( $cssjs_types );
		$html_types = $mime_types2['html'];
		$other_types = $mime_types2['other'];
		$other_compression_types = $mime_types2['other_compression'];

		$cssjs_expires = $config->get_boolean( 'browsercache.cssjs.expires' );
		$html_expires = $config->get_boolean( 'browsercache.html.expires' );
		$other_expires = $config->get_boolean( 'browsercache.other.expires' );

		$cssjs_lifetime = $config->get_integer( 'browsercache.cssjs.lifetime' );
		$html_lifetime = $config->get_integer( 'browsercache.html.lifetime' );
		$other_lifetime = $config->get_integer( 'browsercache.other.lifetime' );
		$compatibility = $config->get_boolean( 'pgcache.compatibility' );

		$mime_types = array();

		if ( $cssjs_expires && $cssjs_lifetime ) {
			$mime_types = array_merge( $mime_types, $cssjs_types );
		}

		if ( $html_expires && $html_lifetime ) {
			$mime_types = array_merge( $mime_types, $html_types );
		}

		if ( $other_expires && $other_lifetime ) {
			$mime_types = array_merge( $mime_types, $other_types );
		}

		$rules = '';
		$rules .= W3TC_MARKER_BEGIN_BROWSERCACHE_CACHE . "\n";

		if ( count( $mime_types ) ) {
			$rules .= "<IfModule mod_mime.c>\n";

			foreach ( $mime_types as $ext => $mime_type ) {
				$extensions = explode( '|', $ext );

				if ( !is_array( $mime_type ) )
					$mime_type = (array)$mime_type;
				foreach ( $mime_type as $mime_type2 ) {
					$rules .= "    AddType " . $mime_type2;
					foreach ( $extensions as $extension ) {
						$rules .= " ." . $extension;
					}
					$rules .= "\n";
				}
			}

			$rules .= "</IfModule>\n";


			$rules .= "<IfModule mod_expires.c>\n";
			$rules .= "    ExpiresActive On\n";

			if ( $cssjs_expires && $cssjs_lifetime ) {
				foreach ( $cssjs_types as $mime_type ) {
					$rules .= "    ExpiresByType " . $mime_type . " A" . $cssjs_lifetime . "\n";
				}
			}

			if ( $html_expires && $html_lifetime ) {
				foreach ( $html_types as $mime_type ) {
					$rules .= "    ExpiresByType " . $mime_type . " A" . $html_lifetime . "\n";
				}
			}

			if ( $other_expires && $other_lifetime ) {
				foreach ( $other_types as $mime_type ) {
					if ( is_array( $mime_type ) )
						foreach ( $mime_type as $mime_type2 )
							$rules .= "    ExpiresByType " . $mime_type2 . " A" . $other_lifetime . "\n";
						else
							$rules .= "    ExpiresByType " . $mime_type . " A" . $other_lifetime . "\n";
				}
			}

			$rules .= "</IfModule>\n";
		}

		$cssjs_compression = $config->get_boolean( 'browsercache.cssjs.compression' );
		$html_compression = $config->get_boolean( 'browsercache.html.compression' );
		$other_compression = $config->get_boolean( 'browsercache.other.compression' );

		if ( $cssjs_compression || $html_compression || $other_compression ) {
			$compression_types = array();

			if ( $cssjs_compression ) {
				$compression_types = array_merge( $compression_types, $cssjs_types );
			}

			if ( $html_compression ) {
				$compression_types = array_merge( $compression_types, $html_types );
			}

			if ( $other_compression ) {
				$compression_types = array_merge( $compression_types,
					$other_compression_types );
			}

			$rules .= "<IfModule mod_deflate.c>\n";
			if ( $compatibility ) {
				$rules .= "    <IfModule mod_setenvif.c>\n";
				$rules .= "        BrowserMatch ^Mozilla/4 gzip-only-text/html\n";
				$rules .= "        BrowserMatch ^Mozilla/4\\.0[678] no-gzip\n";
				$rules .= "        BrowserMatch \\bMSIE !no-gzip !gzip-only-text/html\n";
				$rules .= "        BrowserMatch \\bMSI[E] !no-gzip !gzip-only-text/html\n";
				$rules .= "    </IfModule>\n";
			}
			if ( version_compare( Util_Environment::get_server_version(), '2.3.7', '>=' ) ) {
				$rules .= "    <IfModule mod_filter.c>\n";
			}
			$rules .= "        AddOutputFilterByType DEFLATE " . implode( ' ', $compression_types ) . "\n";
			$rules .= "    <IfModule mod_mime.c>\n";
			$rules .= "        # DEFLATE by extension\n";
			$rules .= "        AddOutputFilter DEFLATE js css htm html xml\n";
			$rules .= "    </IfModule>\n";

			if ( version_compare( Util_Environment::get_server_version(), '2.3.7', '>=' ) ) {
				$rules .= "    </IfModule>\n";
			}
			$rules .= "</IfModule>\n";
		}

		foreach ( $mime_types2 as $type => $extensions )
			$rules .= $this->_rules_cache_generate_apache_for_type( $config,
				$extensions, $type );

		if ( $config->get_boolean( 'browsercache.hsts' ) ) {
			$lifetime = $config->get_integer( 'browsercache.other.lifetime' );
			$rules .= "<IfModule mod_headers.c>\n";
			$rules .= "    Header set strict-transport-security \"max-age=$lifetime\"\n";
			$rules .= "</IfModule>\n";
		}

		if ( $config->get_boolean( 'browsercache.rewrite' ) ) {
			$core = Dispatcher::component( 'BrowserCache_Core' );
			$extensions = $core->get_replace_extensions( $config );

			$rules .= "<IfModule mod_rewrite.c>\n";
			$rules .= "    RewriteCond %{REQUEST_FILENAME} !-f\n";
			$rules .= '    RewriteRule ^(.+)\.(x[0-9]{5})\.(' .
				implode( '|', $extensions ) . ')$ $1.$3 [L]' . "\n";
			$rules .= "</IfModule>\n";
		}

		$rules .= W3TC_MARKER_END_BROWSERCACHE_CACHE . "\n";

		return $rules;
	}

	/**
	 * Writes cache rules
	 *
	 * @param Config  $config
	 * @param array   $mime_types
	 * @param string  $section
	 * @return string
	 */
	private function _rules_cache_generate_apache_for_type( $config, $mime_types,
		$section ) {
		$is_disc_enhanced = $config->get_boolean( 'pgcache.enabled' ) &&
			$config->get_string( 'pgcache.engine' ) == 'file_generic';
		$cache_control = $config->get_boolean( 'browsercache.' . $section . '.cache.control' );
		$etag = $config->get_boolean( 'browsercache.' . $section . '.etag' );
		$w3tc = $config->get_boolean( 'browsercache.' . $section . '.w3tc' );
		$unset_setcookie = $config->get_boolean( 'browsercache.' . $section . '.nocookies' );
		$set_last_modified = $config->get_boolean( 'browsercache.' . $section . '.last_modified' );
		$compatibility = $config->get_boolean( 'pgcache.compatibility' );

		$extensions = array_keys( $mime_types );

		// Remove ext from filesmatch if its the same as permalink extension
		$pext = strtolower( pathinfo( get_option( 'permalink_structure' ), PATHINFO_EXTENSION ) );
		if ( $pext ) {
			$extensions = $this->_remove_extension_from_list( $extensions, $pext );
		}

		$extensions_lowercase = array_map( 'strtolower', $extensions );
		$extensions_uppercase = array_map( 'strtoupper', $extensions );

		$rules = '';
		$headers_rules = '';

		if ( $section == 'html' ) {
			$headers_rules .= "        Header append Vary User-Agent env=!dont-vary\n";
		}

		if ( $cache_control ) {
			$cache_policy = $config->get_string( 'browsercache.' . $section . '.cache.policy' );

			switch ( $cache_policy ) {
			case 'cache':
				$headers_rules .= "        Header set Pragma \"public\"\n";
				$headers_rules .= "        Header set Cache-Control \"public\"\n";
				break;

			case 'cache_public_maxage':
				$expires = $config->get_boolean( 'browsercache.' . $section . '.expires' );
				$lifetime = $config->get_integer( 'browsercache.' . $section . '.lifetime' );

				$headers_rules .= "        Header set Pragma \"public\"\n";

				if ( $expires )
					$headers_rules .= "        Header append Cache-Control \"public\"\n";
				else
					$headers_rules .= "        Header set Cache-Control \"max-age=" . $lifetime . ", public\"\n";

				break;

			case 'cache_validation':
				$headers_rules .= "        Header set Pragma \"public\"\n";
				$headers_rules .= "        Header set Cache-Control \"public, must-revalidate, proxy-revalidate\"\n";
				break;

			case 'cache_noproxy':
				$headers_rules .= "        Header set Pragma \"public\"\n";
				$headers_rules .= "        Header set Cache-Control \"private, must-revalidate\"\n";
				break;

			case 'cache_maxage':
				$expires = $config->get_boolean( 'browsercache.' . $section . '.expires' );
				$lifetime = $config->get_integer( 'browsercache.' . $section . '.lifetime' );

				$headers_rules .= "        Header set Pragma \"public\"\n";

				if ( $expires )
					$headers_rules .= "        Header append Cache-Control \"public, must-revalidate, proxy-revalidate\"\n";
				else
					$headers_rules .= "        Header set Cache-Control \"max-age=" . $lifetime . ", public, must-revalidate, proxy-revalidate\"\n";

				break;

			case 'no_cache':
				$headers_rules .= "        Header set Pragma \"no-cache\"\n";
				$headers_rules .= "        Header set Cache-Control \"max-age=0, private, no-store, no-cache, must-revalidate\"\n";
				break;
			}
		}

		if ( $etag ) {
			$rules .= "    FileETag MTime Size\n";
		} else {
			if ( $compatibility ) {
				$rules .= "    FileETag None\n";
				$headers_rules .= "         Header unset ETag\n";
			}
		}

		if ( $unset_setcookie )
			$headers_rules .= "         Header unset Set-Cookie\n";

		if ( !$set_last_modified )
			$headers_rules .= "         Header unset Last-Modified\n";

		if ( $w3tc )
			$headers_rules .= "         Header set X-Powered-By \"" .
				Util_Environment::w3tc_header() . "\"\n";

		if ( strlen( $headers_rules ) > 0 ) {
			$rules .= "    <IfModule mod_headers.c>\n";
			$rules .= $headers_rules;
			$rules .= "    </IfModule>\n";
		}

		if ( strlen( $rules ) > 0 ) {
			$rules = "<FilesMatch \"\\.(" . implode( '|',
				array_merge( $extensions_lowercase, $extensions_uppercase ) ) .
				")$\">\n" . $rules;
			$rules .= "</FilesMatch>\n";
		}

		return $rules;
	}

	/**
	 * Returns cache rules
	 *
	 * @param Config  $config
	 * @param bool    $cdnftp
	 * @return string
	 */
	private function rules_cache_generate_nginx( $config, $cdnftp = false ) {
		$mime_types = $this->get_mime_types();
		$cssjs_types = $mime_types['cssjs'];
		$cssjs_types = array_unique( $cssjs_types );
		$html_types = $mime_types['html'];
		$other_types = $mime_types['other'];
		$other_compression_types = $mime_types['other_compression'];

		$rules = '';
		$rules .= W3TC_MARKER_BEGIN_BROWSERCACHE_CACHE . "\n";

		if ( $config->get_boolean( 'browsercache.rewrite' ) ) {
			$core = Dispatcher::component( 'BrowserCache_Core' );
			$extensions = $core->get_replace_extensions( $config );

			$rules .= 'location ~ "^(?<w3tcbc_base>.+)\.(x[0-9]{5})' .
				'(?<w3tcbc_ext>\.(' . implode( '|', $extensions ) . '))$" {' . "\n";
			$rules .= '    if (-f $document_root$w3tcbc_base$w3tcbc_ext) {' . "\n";
			$rules .= '        rewrite .* $w3tcbc_base$w3tcbc_ext;' . "\n";
			$rules .= "    }\n";
			$rules .= "}\n";

		}

		$cssjs_compression = $config->get_boolean( 'browsercache.cssjs.compression' );
		$html_compression = $config->get_boolean( 'browsercache.html.compression' );
		$other_compression = $config->get_boolean( 'browsercache.other.compression' );

		if ( $cssjs_compression || $html_compression || $other_compression ) {
			$compression_types = array();

			if ( $cssjs_compression ) {
				$compression_types = array_merge( $compression_types, $cssjs_types );
			}

			if ( $html_compression ) {
				$compression_types = array_merge( $compression_types, $html_types );
			}

			if ( $other_compression ) {
				$compression_types = array_merge( $compression_types,
					$other_compression_types );
			}

			unset( $compression_types['html|htm'] );

			// some nginx cant handle values longer than 47 chars
			unset( $compression_types['odp'] );

			$rules .= "gzip on;\n";
			$rules .= "gzip_types " .
				implode( ' ', array_unique( $compression_types ) ) . ";\n";
		}

		if ( $config->get_boolean( 'browsercache.no404wp' ) ) {
			$exceptions = $config->get_array( 'browsercache.no404wp.exceptions' );

			$impoloded = implode( '|', $exceptions );
			if ( !empty( $impoloded ) ) {
				$wp_uri = network_home_url( '', 'relative' );
				$wp_uri = rtrim( $wp_uri, '/' );

				$rules .= "location ~ (" . $impoloded . ") {\n";
				$rules .= '    try_files $uri $uri/ $uri.html ' . $wp_uri .
					'/index.php?$args;' . "\n";
				$rules .= "}\n";
			}
		}

		foreach ( $mime_types as $type => $extensions )
			$this->_rules_cache_generate_nginx_for_type( $config, $rules,
				$extensions, $type );

		if ( $config->get_boolean( 'browsercache.hsts' ) ) {
			$lifetime = $config->get_integer( 'browsercache.other.lifetime' );
			$rules .= "add_header strict-transport-security \"max-age=$lifetime\";\n";
		}

		$rules .= W3TC_MARKER_END_BROWSERCACHE_CACHE . "\n";

		return $rules;
	}

	/**
	 * Adds cache rules for type to &$rules
	 *
	 * @param Config  $config
	 * @param string  $rules
	 * @param array   $mime_types
	 * @param string  $section
	 * @return void
	 */
	private function _rules_cache_generate_nginx_for_type( $config, &$rules,
		$mime_types, $section ) {

		$expires = $config->get_boolean( 'browsercache.' . $section . '.expires' );
		$etag = $config->get_boolean( 'browsercache.' . $section . '.etag' );
		$cache_control = $config->get_boolean( 'browsercache.' . $section . '.cache.control' );
		$w3tc = $config->get_boolean( 'browsercache.' . $section . '.w3tc' );
		$last_modified = $config->get_boolean( 'browsercache.' . $section . '.last_modified' );

		if ( $etag || $expires || $cache_control || $w3tc || !$last_modified ) {
			$lifetime = $config->get_integer( 'browsercache.' . $section . '.lifetime' );

			$extensions = array_keys( $mime_types );

			// Remove ext from filesmatch if its the same as permalink extension
			$pext = strtolower( pathinfo( get_option( 'permalink_structure' ), PATHINFO_EXTENSION ) );
			if ( $pext ) {
				$extensions = $this->_remove_extension_from_list( $extensions, $pext );
			}

			$rules .= "location ~ \\.(" . implode( '|', $extensions ) . ")$ {\n";

			if ( $expires ) {
				$rules .= "    expires " . $lifetime . "s;\n";
			}
			if ( version_compare( Util_Environment::get_server_version(), '1.3.3', '>=' ) ) {
				if ( $etag ) {
					$rules .= "    etag on;\n";
				} else {
					$rules .= "    etag off;\n";
				}
			}
			if ( $last_modified ) {
				$rules .= "    if_modified_since exact;\n";
			} else {
				$rules .= "    if_modified_since off;\n";
			}

			$add_header_rules = '';

			if ( $cache_control ) {
				$cache_policy = $config->get_string( 'browsercache.' . $section . '.cache.policy' );

				switch ( $cache_policy ) {
				case 'cache':
					$add_header_rules .= "    add_header Pragma \"public\";\n";
					$add_header_rules .= "    add_header Cache-Control \"public\";\n";
					break;

				case 'cache_public_maxage':
					$add_header_rules .= "    add_header Pragma \"public\";\n";
					$add_header_rules .= "    add_header Cache-Control \"max-age=" . $lifetime . ", public\";\n";
					break;

				case 'cache_validation':
					$add_header_rules .= "    add_header Pragma \"public\";\n";
					$add_header_rules .= "    add_header Cache-Control \"public, must-revalidate, proxy-revalidate\";\n";
					break;

				case 'cache_noproxy':
					$add_header_rules .= "    add_header Pragma \"public\";\n";
					$add_header_rules .= "    add_header Cache-Control \"private, must-revalidate\";\n";
					break;

				case 'cache_maxage':
					$add_header_rules .= "    add_header Pragma \"public\";\n";
					$add_header_rules .= "    add_header Cache-Control \"max-age=" . $lifetime . ", public, must-revalidate, proxy-revalidate\";\n";
					break;

				case 'no_cache':
					$add_header_rules .= "    add_header Pragma \"no-cache\";\n";
					$add_header_rules .= "    add_header Cache-Control \"max-age=0, private, no-store, no-cache, must-revalidate\";\n";
					break;
				}
			}

			if ( $w3tc ) {
				$add_header_rules .= "    add_header X-Powered-By \"" .
					Util_Environment::w3tc_header() . "\";\n";
			}

			$rules .= $add_header_rules;
			$rules .= Dispatcher::on_browsercache_rules_generation_for_section(
				$config, false, $section, $add_header_rules );

			if ( !$config->get_boolean( 'browsercache.no404wp' ) ) {
				$wp_uri = network_home_url( '', 'relative' );
				$wp_uri = rtrim( $wp_uri, '/' );

				$rules .= '    try_files $uri $uri/ $uri.html ' . $wp_uri .
					'/index.php?$args;' . "\n";
			}
			$rules .= "}\n";
		}
	}



	/*
	 * rules_no404wp
	 */

	/**
	 * Writes no 404 by WP rules
	 *
	 * @param Config  $config
	 * @param Util_Environment_Exceptions $exs
	 * @throws Util_WpFile_FilesystemOperationException with S/FTP form
	 */
	private function rules_no404wp_add( $config, $exs ) {
		Util_Rule::add_rules( $exs, Util_Rule::get_browsercache_rules_no404wp_path(),
			$this->rules_no404wp_generate( $config ),
			W3TC_MARKER_BEGIN_BROWSERCACHE_NO404WP,
			W3TC_MARKER_END_BROWSERCACHE_NO404WP,
			array(
				W3TC_MARKER_BEGIN_WORDPRESS => 0,
				W3TC_MARKER_END_PGCACHE_CORE =>
				strlen( W3TC_MARKER_END_PGCACHE_CORE ) + 1,
				W3TC_MARKER_END_MINIFY_CORE =>
				strlen( W3TC_MARKER_END_MINIFY_CORE ) + 1,
				W3TC_MARKER_END_BROWSERCACHE_CACHE =>
				strlen( W3TC_MARKER_END_BROWSERCACHE_CACHE ) + 1,
				W3TC_MARKER_END_PGCACHE_CACHE =>
				strlen( W3TC_MARKER_END_PGCACHE_CACHE ) + 1,
				W3TC_MARKER_END_MINIFY_CACHE =>
				strlen( W3TC_MARKER_END_MINIFY_CACHE ) + 1
			)
		);
	}

	/**
	 * Removes 404 directives
	 *
	 * @throws Util_WpFile_FilesystemOperationException with S/FTP form
	 */
	private function rules_no404wp_remove( $exs ) {
		Util_Rule::remove_rules( $exs,
			Util_Rule::get_browsercache_rules_no404wp_path(),
			W3TC_MARKER_BEGIN_BROWSERCACHE_NO404WP,
			W3TC_MARKER_END_BROWSERCACHE_NO404WP
		);
	}

	/**
	 * Generate rules related to prevent for media 404 error by WP
	 *
	 * @param Config  $config
	 * @return string
	 */
	private function rules_no404wp_generate( $config ) {
		switch ( true ) {
		case Util_Environment::is_apache():
		case Util_Environment::is_litespeed():
			return $this->rules_no404wp_generate_apache( $config );
		}

		return false;
	}

	/**
	 * Generate rules related to prevent for media 404 error by WP
	 *
	 * @param Config  $config
	 * @return string
	 */
	private function rules_no404wp_generate_apache( $config ) {
		$a = $this->get_mime_types();
		$cssjs_types = $a['cssjs'];
		$html_types = $a['html'];
		$other_types = $a['other'];

		$extensions = array_merge( array_keys( $cssjs_types ),
			array_keys( $html_types ), array_keys( $other_types ) );

		$permalink_structure = get_option( 'permalink_structure' );
		$permalink_structure_ext = ltrim( strrchr( $permalink_structure, '.' ),
			'.' );

		if ( $permalink_structure_ext != '' ) {
			foreach ( $extensions as $index => $extension ) {
				if ( strstr( $extension, $permalink_structure_ext ) !== false ) {
					$extensions[$index] = preg_replace( '~\|?' .
						Util_Environment::preg_quote( $permalink_structure_ext ) .
						'\|?~', '', $extension );
				}
			}
		}

		$exceptions = $config->get_array( 'browsercache.no404wp.exceptions' );
		$wp_uri = network_home_url( '', 'relative' );
		$wp_uri = rtrim( $wp_uri, '/' );

		$rules = '';
		$rules .= W3TC_MARKER_BEGIN_BROWSERCACHE_NO404WP . "\n";
		$rules .= "<IfModule mod_rewrite.c>\n";
		$rules .= "    RewriteEngine On\n";

		// in subdir - rewrite theme files and similar to upper folder if file exists
		if ( Util_Environment::is_wpmu() &&
			!Util_Environment::is_wpmu_subdomain() ) {
			$rules .= "    RewriteCond %{REQUEST_FILENAME} !-f\n";
			$rules .= "    RewriteCond %{REQUEST_FILENAME} !-d\n";
			$rules .= "    RewriteCond %{REQUEST_URI} ^$wp_uri/([_0-9a-zA-Z-]+/)(.*\.)(" .
				implode( '|', $extensions ) . ")$ [NC]\n";
			$document_root = Util_Rule::apache_docroot_variable();
			$rules .= '    RewriteCond "' . $document_root . $wp_uri .
				'/%2%3" -f' . "\n";
			$rules .= "    RewriteRule .* $wp_uri/%2%3 [L]\n\n";
		}


		$rules .= "    RewriteCond %{REQUEST_FILENAME} !-f\n";
		$rules .= "    RewriteCond %{REQUEST_FILENAME} !-d\n";

		$imploded = implode( '|', $exceptions );
		if ( !empty( $imploded ) )
			$rules .= "    RewriteCond %{REQUEST_URI} !(" . $imploded. ")\n";

		$rules .= "    RewriteCond %{REQUEST_URI} \\.(" .
			implode( '|', $extensions ) . ")$ [NC]\n";
		$rules .= "    RewriteRule .* - [L]\n";
		$rules .= "</IfModule>\n";
		$rules .= W3TC_MARKER_END_BROWSERCACHE_NO404WP . "\n";

		return $rules;
	}

	/**
	 * Takes an array of extensions single per row and/or extensions delimited by |
	 *
	 * @param unknown $extensions
	 * @param unknown $ext
	 * @return array
	 */
	private function _remove_extension_from_list( $extensions, $ext ) {
		for ( $i = 0; $i < sizeof( $extensions ); $i++ ) {
			if ( $extensions[$i] == $ext ) {
				unset( $extensions[$i] );
				return $extensions;
			} elseif ( strpos( $extensions[$i], $ext ) !== false &&
				strpos( $extensions[$i], '|' ) !== false ) {
				$exts = explode( '|', $extensions[$i] );
				$key = array_search( $ext, $exts );
				unset( $exts[$key] );
				$extensions[$i] = implode( '|', $exts );
				return $extensions;
			}
		}
		return $extensions;
	}
}