<?php

/**
 * @addtogroup Media
 */
class DjVuHandler extends ImageHandler {
	function isEnabled() {
		global $wgDjvuRenderer, $wgDjvuDump, $wgDjvuToXML;
		if ( !$wgDjvuRenderer || ( !$wgDjvuDump && !$wgDjvuToXML ) ) {
			wfDebug( "DjVu is disabled, please set \$wgDjvuRenderer and \$wgDjvuDump\n" );
			return false;
		} else {
			return true;
		}
	}

	function mustRender() { return true; }
	function isMultiPage() { return true; }

	function getParamMap() {
		return array(
			'img_width' => 'width',
			'img_page' => 'page',
		);
	}

	function validateParam( $name, $value ) {
		if ( in_array( $name, array( 'width', 'height', 'page' ) ) ) {
			if ( $value <= 0 ) {
				return false;
			} else {
				return true;
			}
		} else {
			return false;
		}
	}

	function makeParamString( $params ) {
		$page = isset( $params['page'] ) ? $params['page'] : 1;
		if ( !isset( $params['width'] ) ) {
			return false;
		}
		return "page{$page}-{$params['width']}px";
	}

	function parseParamString( $str ) {
		$m = false;
		if ( preg_match( '/^page(\d+)-(\d+)px$/', $str, $m ) ) {
			return array( 'width' => $m[2], 'page' => $m[1] );
		} else {
			return false;
		}
	}

	function getScriptParams( $params ) {
		return array(
			'width' => $params['width'],
			'page' => $params['page'],
		);
	}

	function doTransform( $image, $dstPath, $dstUrl, $params, $flags = 0 ) {
		global $wgDjvuRenderer, $wgDjvuPostProcessor;

		// Fetch XML and check it, to give a more informative error message than the one which 
		// normaliseParams will inevitably give.
		$xml = $image->getMetadata();
		if ( !$xml ) {
			return new MediaTransformError( 'thumbnail_error', @$params['width'], @$params['height'], 
				wfMsg( 'djvu_no_xml' ) );
		}
		
		if ( !$this->normaliseParams( $image, $params ) ) {
			return new TransformParameterError( $params );
		}
		$width = $params['width'];
		$height = $params['height'];
		$srcPath = $image->getPath();
		$page = $params['page'];
		if ( $page > $this->pageCount( $image ) ) {
			return new MediaTransformError( 'thumbnail_error', $width, $height, wfMsg( 'djvu_page_error' ) );
		}
		
		if ( $flags & self::TRANSFORM_LATER ) {
			return new ThumbnailImage( $image, $dstUrl, $width, $height, $dstPath, $page );
		}

		if ( !wfMkdirParents( dirname( $dstPath ) ) ) {
			return new MediaTransformError( 'thumbnail_error', $width, $height, wfMsg( 'thumbnail_dest_directory' ) );
		}

		# Use a subshell (brackets) to aggregate stderr from both pipeline commands 
		# before redirecting it to the overall stdout. This works in both Linux and Windows XP.
		$cmd = '(' . wfEscapeShellArg( $wgDjvuRenderer ) . " -format=ppm -page={$page} -size={$width}x{$height} " .
			wfEscapeShellArg( $srcPath );
		if ( $wgDjvuPostProcessor ) {
			$cmd .= " | {$wgDjvuPostProcessor}";
		}
		$cmd .= ' > ' . wfEscapeShellArg($dstPath) . ') 2>&1';
		wfProfileIn( 'ddjvu' );
		wfDebug( __METHOD__.": $cmd\n" );
		$err = wfShellExec( $cmd, $retval );
		wfProfileOut( 'ddjvu' );

		$removed = $this->removeBadFile( $dstPath, $retval );
		if ( $retval != 0 || $removed ) {
			wfDebugLog( 'thumbnail',
				sprintf( 'thumbnail failed on %s: error %d "%s" from "%s"',
					wfHostname(), $retval, trim($err), $cmd ) );
			return new MediaTransformError( 'thumbnail_error', $width, $height, $err );
		} else {
			return new ThumbnailImage( $image, $dstUrl, $width, $height, $dstPath, $page );
		}
	}

	/**
	 * Cache an instance of DjVuImage in an Image object, return that instance
	 */
	function getDjVuImage( $image, $path ) {
		if ( !$image ) {
			$deja = new DjVuImage( $path );
		} elseif ( !isset( $image->dejaImage ) ) {
			$deja = $image->dejaImage = new DjVuImage( $path );
		} else {
			$deja = $image->dejaImage;
		}
		return $deja;
	}

	/**
	 * Cache a document tree for the DjVu XML metadata
	 */
	function getMetaTree( $image ) {
		if ( isset( $image->dejaMetaTree ) ) {
			return $image->dejaMetaTree;
		}

		$metadata = $image->getMetadata();
		if ( !$this->isMetadataValid( $image, $metadata ) ) {
			wfDebug( "DjVu XML metadata is invalid or missing, should have been fixed in upgradeRow\n" );
			return false;
		}
		wfProfileIn( __METHOD__ );

		wfSuppressWarnings();
		try {
			$image->dejaMetaTree = new SimpleXMLElement( $metadata );
		} catch( Exception $e ) {
			wfDebug( "Bogus multipage XML metadata on '$image->name'\n" );
			// Set to false rather than null to avoid further attempts
			$image->dejaMetaTree = false;
		}
		wfRestoreWarnings();
		wfProfileOut( __METHOD__ );
		return $image->dejaMetaTree;
	}

	function getImageSize( $image, $path ) {
		return $this->getDjVuImage( $image, $path )->getImageSize();
	}

	function getThumbType( $ext, $mime ) {
		global $wgDjvuOutputExtension;
		static $mime;
		if ( !isset( $mime ) ) {
			$magic = MimeMagic::singleton();
			$mime = $magic->guessTypesForExtension( $wgDjvuOutputExtension );
		}
		return array( $wgDjvuOutputExtension, $mime );
	}

	function getMetadata( $image, $path ) {
		wfDebug( "Getting DjVu metadata for $path\n" );
		return $this->getDjVuImage( $image, $path )->retrieveMetaData();
	}

	function getMetadataType( $image ) {
		return 'djvuxml';
	}

	function isMetadataValid( $image, $metadata ) {
		return !empty( $metadata ) && $metadata != serialize(array());
	}

	function pageCount( $image ) {
		$tree = $this->getMetaTree( $image );
		if ( !$tree ) {
			return false;
		}
		return count( $tree->xpath( '//OBJECT' ) );
	}

	function getPageDimensions( $image, $page ) {
		$tree = $this->getMetaTree( $image );
		if ( !$tree ) {
			return false;
		}

		$o = $tree->BODY[0]->OBJECT[$page-1];
		if ( $o ) {
			return array(
				'width' => intval( $o['width'] ),
				'height' => intval( $o['height'] )
			);
		} else {
			return false;
		}
	}
}