<?php
namespace W3TC;

/**
 * W3 CDN Base class
 */
define( 'W3TC_CDN_RESULT_HALT', -1 );
define( 'W3TC_CDN_RESULT_ERROR', 0 );
define( 'W3TC_CDN_RESULT_OK', 1 );
define( 'W3TC_CDN_HEADER_NONE', 'none' );
define( 'W3TC_CDN_HEADER_UPLOADABLE', 'uploadable' );
define( 'W3TC_CDN_HEADER_MIRRORING', 'mirroring' );

/**
 * class CdnEngine_Base
 */
class CdnEngine_Base {
	/**
	 * Engine configuration
	 *
	 * @var array
	 */
	var $_config = array();

	/**
	 * gzip extension
	 *
	 * @var string
	 */
	var $_gzip_extension = '.gzip';

	/**
	 * Last error
	 *
	 * @var string
	 */
	var $_last_error = '';

	/**
	 * PHP5 Constructor
	 *
	 * @param array   $config
	 */
	function __construct( $config = array() ) {
		$this->_config = array_merge( array(
				'debug' => false,
				'ssl' => 'auto',
				'compression' => false,
				'headers' => array()
			), $config );
	}

	/**
	 * Upload files to CDN
	 *
	 * @param array   $files         takes array consisting of array(array('local_path'=>'', 'remote_path'=>''))
	 * @param array   $results
	 * @param boolean $force_rewrite
	 * @return boolean
	 */
	function upload( $files, &$results, $force_rewrite = false,
		$timeout_time = NULL ) {
		$results = $this->_get_results( $files, W3TC_CDN_RESULT_HALT,
			'Not implemented.' );

		return false;
	}

	/**
	 * Delete files from CDN
	 *
	 * @param array   $files
	 * @param array   $results
	 * @return boolean
	 */
	function delete( $files, &$results ) {
		$results = $this->_get_results( $files, W3TC_CDN_RESULT_HALT,
			'Not implemented.' );

		return false;
	}

	/**
	 * Purge files from CDN
	 *
	 * @param array   $files
	 * @param array   $results
	 * @return boolean
	 */
	function purge( $files, &$results ) {
		return $this->upload( $files, $results, true );
	}

	/**
	 * Purge CDN completely
	 *
	 * @param unknown $results
	 * @return bool
	 */
	function purge_all( &$results ) {
		$results = $this->_get_results( array(), W3TC_CDN_RESULT_HALT,
			'Not implemented.' );

		return false;
	}

	/**
	 * Test CDN server
	 *
	 * @param string  $error
	 * @return boolean
	 */
	function test( &$error ) {
		if ( !$this->_test_domains( $error ) ) {
			return false;
		}

		return true;
	}

	/**
	 * Create bucket / container for some CDN engines
	 */
	function create_container() {
		throw new \Exception( 'Not implemented.' );
	}

	/**
	 * Returns first domain
	 *
	 * @param string  $path
	 * @return string
	 */
	function get_domain( $path = '' ) {
		$domains = $this->get_domains();
		$count = count( $domains );

		if ( $count ) {
			switch ( true ) {
				/**
				 * Reserved CSS
				 */
			case ( isset( $domains[0] ) && $this->_is_css( $path ) ):
				$domain = $domains[0];
				break;


				/**
				 * Reserved JS after body
				 */
			case ( isset( $domains[2] ) && $this->_is_js_body( $path ) ):
				$domain = $domains[2];
				break;

				/**
				 * Reserved JS before /body
				 */
			case ( isset( $domains[3] ) && $this->_is_js_footer( $path ) ):
				$domain = $domains[3];
				break;

				/**
				 * Reserved JS in head, moved here due to greedy regex
				 */
			case ( isset( $domains[1] ) && $this->_is_js( $path ) ):
				$domain = $domains[1];
				break;

			default:
				if ( !isset( $domains[0] ) ) {
					$scheme = $this->_get_scheme();
					if ( 'https' == $scheme && !empty( $domains['https_default'] ) ) {
						return $domains['https_default'];
					} else {
						return isset( $domains['http_default'] ) ? $domains['http_default'] :
							$domains['https_default'];
					}
				} elseif ( $count > 4 ) {
					$domain = $this->_get_domain( array_slice( $domains, 4 ),
						$path );
				} else {
					$domain = $this->_get_domain( $domains, $path );
				}
			}

			/**
			 * Custom host for SSL
			 */
			list( $domain_http, $domain_https ) = array_map( 'trim',
				explode( ',', $domain . ',' ) );

			$scheme = $this->_get_scheme();

			switch ( $scheme ) {
			case 'http':
				$domain = $domain_http;
				break;

			case 'https':
				$domain = ( $domain_https ? $domain_https : $domain_http );
				break;
			}

			return $domain;
		}

		return false;
	}

	/**
	 * Returns array of CDN domains
	 *
	 * @return array
	 */
	function get_domains() {
		return array();
	}

	/**
	 * Returns via string
	 *
	 * @return string
	 */
	function get_via() {
		$domain = $this->get_domain();

		if ( $domain ) {
			return $domain;
		}

		return 'N/A';
	}

	/**
	 * Formats URL
	 *
	 * @param string  $path
	 * @return string
	 */
	function format_url( $path ) {
		$url = $this->_format_url( $path );

		if ( $url && $this->_config['compression'] && ( isset( $_SERVER['HTTP_ACCEPT_ENCODING'] ) ? stristr( sanitize_text_field( wp_unslash( $_SERVER['HTTP_ACCEPT_ENCODING'] ) ), 'gzip' ) !== false : false ) && $this->_may_gzip( $path ) ) {
			if ( ( $qpos = strpos( $url, '?' ) ) !== false ) {
				$url = substr_replace( $url, $this->_gzip_extension, $qpos, 0 );
			} else {
				$url .= $this->_gzip_extension;
			}
		}

		return $url;
	}

	/**
	 * Returns prepend path
	 *
	 * @param string  $path
	 * @return string
	 */
	function get_prepend_path( $path ) {
		$domain = $this->get_domain( $path );

		if ( $domain ) {
			$scheme = $this->_get_scheme();
			$url = sprintf( '%s://%s', $scheme, $domain );

			return $url;
		}

		return false;
	}

	/**
	 * Formats URL
	 *
	 * @param string  $path
	 * @return string
	 */
	function _format_url( $path ) {
		$domain = $this->get_domain( $path );

		if ( $domain ) {
			$scheme = $this->_get_scheme();
			$url = sprintf( '%s://%s/%s', $scheme, $domain, $path );

			return $url;
		}

		return false;
	}

	/**
	 * Returns results
	 *
	 * @param array   $files
	 * @param integer $result
	 * @param string  $error
	 * @return array
	 */
	function _get_results( $files, $result = W3TC_CDN_RESULT_OK,
		$error = 'OK' ) {
		$results = array();

		foreach ( $files as $key => $file ) {
			if ( is_array( $file ) ) {
				$local_path = $file['local_path'];
				$remote_path = $file['remote_path'];
			} else {
				$local_path = $key;
				$remote_path = $file;
			}

			$results[] = $this->_get_result( $local_path, $remote_path, $result,
				$error, $file );
		}

		return $results;
	}

	/**
	 * Returns file process result
	 *
	 * @param string  $local_path
	 * @param string  $remote_path
	 * @param integer $result
	 * @param string  $error
	 * @return array
	 */
	function _get_result( $local_path, $remote_path,
		$result = W3TC_CDN_RESULT_OK, $error = 'OK', $descriptor = null ) {
		if ( $this->_config['debug'] ) {
			$this->_log( $local_path, $remote_path, $error );
		}

		return array(
			'local_path' => $local_path,
			'remote_path' => $remote_path,
			'result' => $result,
			'error' => $error,
			'descriptor' => $descriptor
		);
	}

	/**
	 * Check for errors
	 *
	 * @param array   $results
	 * @return bool
	 */
	function _is_error( $results ) {
		foreach ( $results as $result ) {
			if ( $result['result'] != W3TC_CDN_RESULT_OK ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Returns headers for file
	 *
	 * @param array   $file CDN file array
	 * @param array   $whitelist which expensive headers to calculate
	 * @return array
	 */
	function get_headers_for_file( $file, $whitelist = array() ) {
		$local_path = $file['local_path'];
		$mime_type = Util_Mime::get_mime_type( $local_path );

		$link = $file['original_url'];

		$headers = array(
			'Content-Type' => $mime_type,
			'Last-Modified' => Util_Content::http_date( time() ),
			'Access-Control-Allow-Origin' => '*',
			'Link' => '<' . $link  .'>; rel="canonical"'
		);

		$section = Util_Mime::mime_type_to_section( $mime_type );

		if ( isset( $this->_config['headers'][$section] ) ) {
			$hc = $this->_config['headers'][$section];

			if ( isset( $whitelist['ETag'] ) && $hc['etag'] ) {
				$headers['ETag'] = '"' . @md5_file( $local_path ) . '"';
			}

			if ( $hc['expires'] ) {
				$headers['Expires'] = Util_Content::http_date( time() +
					$hc['lifetime'] );
				$expires_set = true;
			}

			$headers = array_merge( $headers, $hc['static'] );
		}

		return $headers;
	}

	/**
	 * Use gzip compression only for text-based files
	 *
	 * @param string  $file
	 * @return boolean
	 */
	function _may_gzip( $file ) {
		/**
		 * Remove query string
		 */
		$file = preg_replace( '~\?.*$~', '', $file );

		/**
		 * Check by file extension
		 */
		if ( preg_match( '~\.(ico|js|css|xml|xsd|xsl|svg|htm|html|txt)$~i',
				$file ) ) {
			return true;
		}

		return false;
	}

	/**
	 * Test domains
	 *
	 * @param string  $error
	 * @return boolean
	 */
	function _test_domains( &$error ) {
		$domains = $this->get_domains();

		if ( !count( $domains ) ) {
			$error = 'Empty hostname / CNAME list.';

			return false;

		}

		foreach ( $domains as $domain ) {
			$_domains = array_map( 'trim', explode( ',', $domain ) );

			foreach ( $_domains as $_domain ) {
				$matches = null;

				if ( preg_match( '~^([a-z0-9\-\.]*)~i', $_domain, $matches ) ) {
					$hostname = $matches[1];
				} else {
					$hostname = $_domain;
				}

				if ( empty( $hostname ) ) {
					continue;
				}

				if ( gethostbyname( $hostname ) === $hostname ) {
					$error = sprintf( 'Unable to resolve hostname: %s.',
						$hostname );

					return false;
				}
			}
		}

		return true;
	}

	/**
	 * Check if css file
	 *
	 * @param string  $path
	 * @return boolean
	 */
	function _is_css( $path ) {
		return preg_match( '~[a-zA-Z0-9\-_]*(\.include\.[0-9]+)?\.css$~',
			$path );
	}

	/**
	 * Check if JS file in heeader
	 *
	 * @param string  $path
	 * @return boolean
	 */
	function _is_js( $path ) {
		return preg_match( '~([a-z0-9\-_]+(\.include\.[a-z0-9]+)\.js)$~',
			$path ) ||
			preg_match( '~[\w\d\-_]+\.js~', $path );
	}

	/**
	 * Check if JS file after body
	 *
	 * @param string  $path
	 * @return boolean
	 */
	function _is_js_body( $path ) {
		return preg_match( '~[a-z0-9\-_]+(\.include-body\.[a-z0-9]+)\.js$~',
			$path );
	}

	/**
	 * Check if JS file before /body
	 *
	 * @param string  $path
	 * @return boolean
	 */
	function _is_js_footer( $path ) {
		return preg_match( '~[a-z0-9\-_]+(\.include-footer\.[a-z0-9]+)\.js$~',
			$path );
	}

	/**
	 * Returns domain for path
	 *
	 * @param array   $domains
	 * @param string  $path
	 * @return string
	 */
	function _get_domain( $domains, $path ) {
		$count = count( $domains );
		if ( isset( $domains['http_default'] ) )
			$count--;
		if ( isset( $domains['https_default'] ) )
			$count--;

		if ( $count ) {
			/**
			 * Use for equal URLs same host to allow caching by browser
			 */
			$hash = $this->_get_hash( $path );
			$domain = $domains[$hash % $count];

			return $domain;
		}

		return false;
	}

	/**
	 * Returns integer hash for key
	 *
	 * @param string  $key
	 * @return integer
	 */
	function _get_hash( $key ) {
		$hash = abs( crc32( $key ) );

		return $hash;
	}

	/**
	 * Returns scheme
	 *
	 * @return string
	 */
	function _get_scheme() {
		switch ( $this->_config['ssl'] ) {
		default:
		case 'auto':
			$scheme = ( Util_Environment::is_https() ? 'https' : 'http' );
			break;

		case 'enabled':
			$scheme = 'https';
			break;

		case 'disabled':
			$scheme = 'http';
			break;
		case 'rejected':
			$scheme = 'http';
			break;
		}

		return $scheme;
	}

	/**
	 * Write log entry
	 *
	 * @param string  $local_path
	 * @param string  $remote_path
	 * @param string  $error
	 * @return bool|int
	 */
	function _log( $local_path, $remote_path, $error ) {
		$data = sprintf( "[%s] [%s => %s] %s\n", date( 'r' ), $local_path,
			$remote_path, $error );
		$data = strtr( $data, '<>', '..' );

		$filename = Util_Debug::log_filename( 'cdn' );

		return @file_put_contents( $filename, $data, FILE_APPEND );
	}

	/**
	 * Our error handler
	 *
	 * @param integer $errno
	 * @param string  $errstr
	 * @return boolean
	 */
	function _error_handler( $errno, $errstr ) {
		$this->_last_error = $errstr;

		return false;
	}

	/**
	 * Returns last error
	 *
	 * @return string
	 */
	function _get_last_error() {
		return $this->_last_error;
	}

	/**
	 * Set our error handler
	 *
	 * @return void
	 */
	function _set_error_handler() {
		set_error_handler( array(
				$this,
				'_error_handler'
			) );
	}

	/**
	 * Restore prev error handler
	 *
	 * @return void
	 */
	function _restore_error_handler() {
		restore_error_handler();
	}

	/**
	 * How and if headers should be set
	 *
	 * @return string W3TC_CDN_HEADER_NONE, W3TC_CDN_HEADER_UPLOADABLE,
	 * W3TC_CDN_HEADER_MIRRORING
	 */
	function headers_support() {
		return W3TC_CDN_HEADER_NONE;
	}
}