From 4511f6fa9fa059d3a4afdc029e20d7764cd6fc2b Mon Sep 17 00:00:00 2001
From: Gilles Dubuc <gilles@wikimedia.org>
Date: Thu, 11 May 2017 13:12:55 +0200
Subject: [PATCH] Add X-Content-Dimensions support to DjVu

Bug: T150741
Change-Id: I4a3bae9bf056a7ba332f2f0a330697cdf59b4d04
---
 includes/media/DjVu.php | 119 ++++++++++++++++++++++++++++++----------
 1 file changed, 89 insertions(+), 30 deletions(-)

diff --git a/includes/media/DjVu.php b/includes/media/DjVu.php
index a852215ca8..374e166b19 100644
--- a/includes/media/DjVu.php
+++ b/includes/media/DjVu.php
@@ -304,11 +304,28 @@ class DjVuHandler extends ImageHandler {
 			return false;
 		}
 
+		$trees = $this->extractTreesFromMetadata( $metadata );
+		$image->djvuTextTree = $trees['TextTree'];
+		$image->dejaMetaTree = $trees['MetaTree'];
+
+		if ( $gettext ) {
+			return $image->djvuTextTree;
+		} else {
+			return $image->dejaMetaTree;
+		}
+	}
+
+	/**
+	 * Extracts metadata and text trees from metadata XML in string form
+	 * @param string $metadata XML metadata as a string
+	 * @return array
+	 */
+	protected function extractTreesFromMetadata( $metadata ) {
 		MediaWiki\suppressWarnings();
 		try {
 			// Set to false rather than null to avoid further attempts
-			$image->dejaMetaTree = false;
-			$image->djvuTextTree = false;
+			$metaTree = false;
+			$textTree = false;
 			$tree = new SimpleXMLElement( $metadata, LIBXML_PARSEHUGE );
 			if ( $tree->getName() == 'mw-djvu' ) {
 				/** @var SimpleXMLElement $b */
@@ -316,23 +333,20 @@ class DjVuHandler extends ImageHandler {
 					if ( $b->getName() == 'DjVuTxt' ) {
 						// @todo File::djvuTextTree and File::dejaMetaTree are declared
 						// dynamically. Add a public File::$data to facilitate this?
-						$image->djvuTextTree = $b;
+						$textTree = $b;
 					} elseif ( $b->getName() == 'DjVuXML' ) {
-						$image->dejaMetaTree = $b;
+						$metaTree = $b;
 					}
 				}
 			} else {
-				$image->dejaMetaTree = $tree;
+				$metaTree = $tree;
 			}
 		} catch ( Exception $e ) {
-			wfDebug( "Bogus multipage XML metadata on '{$image->getName()}'\n" );
+			wfDebug( "Bogus multipage XML metadata\n" );
 		}
 		MediaWiki\restoreWarnings();
-		if ( $gettext ) {
-			return $image->djvuTextTree;
-		} else {
-			return $image->dejaMetaTree;
-		}
+
+		return [ 'MetaTree' => $metaTree, 'TextTree' => $textTree ];
 	}
 
 	function getImageSize( $image, $path ) {
@@ -394,30 +408,39 @@ class DjVuHandler extends ImageHandler {
 			$cache::TTL_INDEFINITE,
 			function () use ( $file ) {
 				$tree = $this->getMetaTree( $file );
-				if ( !$tree ) {
-					return false;
-				}
-
-				$dimsByPage = [];
-				$count = count( $tree->xpath( '//OBJECT' ) );
-				for ( $i = 0; $i < $count; $i++ ) {
-					$o = $tree->BODY[0]->OBJECT[$i];
-					if ( $o ) {
-						$dimsByPage[$i] = [
-							'width' => (int)$o['width'],
-							'height' => (int)$o['height'],
-						];
-					} else {
-						$dimsByPage[$i] = false;
-					}
-				}
-
-				return [ 'pageCount' => $count, 'dimensionsByPage' => $dimsByPage ];
+				return $this->getDimensionInfoFromMetaTree( $tree );
 			},
 			[ 'pcTTL' => $cache::TTL_INDEFINITE ]
 		);
 	}
 
+	/**
+	 * Given an XML metadata tree, returns dimension information about the document
+	 * @param bool|SimpleXMLElement $metatree The file's XML metadata tree
+	 * @return bool|array
+	 */
+	protected function getDimensionInfoFromMetaTree( $metatree ) {
+		if ( !$metatree ) {
+			return false;
+		}
+
+		$dimsByPage = [];
+		$count = count( $metatree->xpath( '//OBJECT' ) );
+		for ( $i = 0; $i < $count; $i++ ) {
+			$o = $metatree->BODY[0]->OBJECT[$i];
+			if ( $o ) {
+				$dimsByPage[$i] = [
+					'width' => (int)$o['width'],
+					'height' => (int)$o['height'],
+				];
+			} else {
+				$dimsByPage[$i] = false;
+			}
+		}
+
+		return [ 'pageCount' => $count, 'dimensionsByPage' => $dimsByPage ];
+	}
+
 	/**
 	 * @param File $image
 	 * @param int $page Page number to get information for
@@ -438,4 +461,40 @@ class DjVuHandler extends ImageHandler {
 			return false;
 		}
 	}
+
+	/**
+	* Get useful response headers for GET/HEAD requests for a file with the given metadata
+	* @param $metadata Array Contains this handler's unserialized getMetadata() for a file
+	* @return array
+	*/
+	public function getContentHeaders( $metadata ) {
+		if ( !is_array( $metadata ) || !isset( $metadata['xml'] ) ) {
+			return [];
+		}
+
+		$trees = $this->extractTreesFromMetadata( $metadata['xml'] );
+		$dimensionInfo = $this->getDimensionInfoFromMetaTree( $trees['MetaTree'] );
+
+		if ( !$dimensionInfo ) {
+			return [];
+		}
+
+		$pagesByDimensions = [];
+		$count = $dimensionInfo['pageCount'];
+
+		for ( $i = 1; $i <= $count; $i++ ) {
+			$dimensions = $dimensionInfo['dimensionsByPage'][ $i - 1 ];
+			$dimensionString = $dimensions['width'] . 'x' . $dimensions['height'];
+
+			if ( isset ( $pagesByDimensions[ $dimensionString ] ) ) {
+				$pagesByDimensions[ $dimensionString ][] = $i;
+			} else {
+				$pagesByDimensions[ $dimensionString ] = [ $i ];
+			}
+		}
+
+		$pageRangesByDimensions = MediaHandler::getPageRangesByDimensions( $pagesByDimensions );
+
+		return [ 'X-Content-Dimensions' => $pageRangesByDimensions ];
+	}
 }
-- 
2.20.1