Refs #4052 Reprocess CSS file if any of merged files has changed

NOTE: does not support @import'ed less files, could be added in prepareMergedCssFile @diosmosis

2 files changed, 88 insertions, 35 deletions

diff --git a/core/AssetManager.php b/core/AssetManager.php
index a87db2a3f0..307ad4a99a 100644
--- a/core/AssetManager.php
+++ b/core/AssetManager.php
@@ -62,7 +62,7 @@ class Piwik_AssetManager
      */
     public static function getJsAssets()
     {
-        if (self::getDisableMergedAssets()) {
+        if (self::isMergedAssetsDisabled()) {
             // Individual includes mode
             self::removeMergedAsset(self::MERGED_JS_FILE);
             return self::getIndividualJsIncludes();
@@ -88,54 +88,110 @@ class Piwik_AssetManager
      *
      * @throws Exception if a file can not be opened in write mode
      */
-    private static function generateMergedCssFile()
+    private static function prepareMergedCssFile()
     {
-        $mergedContent = "";
+        $mergedCssAlreadyGenerated = self::isGenerated(self::MERGED_CSS_FILE);
+        $isDevelopingPiwik = self::isMergedAssetsDisabled();
 
-        // absolute path to doc root
-        $rootDirectory = realpath(PIWIK_DOCUMENT_ROOT);
-        if ($rootDirectory != '/' && substr_compare($rootDirectory, '/', -1)) {
-            $rootDirectory .= '/';
+        if ($mergedCssAlreadyGenerated
+            && !$isDevelopingPiwik
+        ) {
+            return;
         }
-        $rootDirectoryLen = strlen($rootDirectory);
 
-        if(!class_exists("lessc")) {
-            throw new Exception("Less was added to composer during 2.0. ==> Execute this command to update composer packages: \$ php composer.phar update");
-        }
-        $less = new lessc;
+        $less = self::makeLess();
 
         // Loop through each css file
         $files = self::getCssFiles();
+        $mergedContent = "";
         foreach ($files as $file) {
 
             self::validateCssFile($file);
 
             $fileLocation = self::getAbsoluteLocation($file);
             $less->addImportDir(dirname($fileLocation));
+
             $content = file_get_contents($fileLocation);
 
-            // Rewrite css url directives
-            // - assumes these are all relative paths
-            // - rewrite windows directory separator \\ to /
-            $baseDirectory = dirname($file);
-            $content = preg_replace_callback(
-                "/(url\(['\"]?)([^'\")]*)/",
-                create_function(
-                    '$matches',
-                    "return \$matches[1] . str_replace('\\\\', '/', substr(realpath(PIWIK_DOCUMENT_ROOT . '/$baseDirectory/' . \$matches[2]), $rootDirectoryLen));"
-                ),
-                $content
-            );
+            $content = self::rewriteCssPathsDirectives($file, $content);
+
             $mergedContent = $mergedContent . $content;
         }
 
+        $fileHash = md5($mergedContent);
+        $firstLineCompileHash = "/* compile_me_once=$fileHash */";
+
+        // Disable Merged Assets ==> Check on each request if file needs re-compiling
+        if ($mergedCssAlreadyGenerated
+            && $isDevelopingPiwik
+        ) {
+            $pathMerged = self::getAbsoluteMergedFileLocation(self::MERGED_CSS_FILE);
+            $f = fopen($pathMerged, 'r');
+            $firstLine = fgets($f);
+            fclose($f);
+            if (!empty($firstLine)
+                && trim($firstLine) == trim($firstLineCompileHash)) {
+                return;
+            }
+            // Some CSS file in the merge, has changed since last merged asset was generated
+            // Note: we do not detect changes in @import'ed LESS files
+        }
+
         $mergedContent = $less->compile($mergedContent);
 
         Piwik_PostEvent('AssetManager.filterMergedCss', array(&$mergedContent));
 
+        $mergedContent =
+              $firstLineCompileHash . "\n"
+            . "/* Piwik CSS file is compiled with Less. You may be interested in writing a custom Theme for Piwik! */\n"
+            . $mergedContent;
+
         self::writeAssetToFile($mergedContent, self::MERGED_CSS_FILE);
     }
 
+    protected static function makeLess()
+    {
+        if (!class_exists("lessc")) {
+            throw new Exception("Less was added to composer during 2.0. ==> Execute this command to update composer packages: \$ php composer.phar update");
+        }
+        $less = new lessc;
+        return $less;
+    }
+
+    /*
+     * Rewrite css url directives
+     * - assumes these are all relative paths
+     *  - rewrite windows directory separator \\ to /
+     */
+    protected static function rewriteCssPathsDirectives($relativePath, $content)
+    {
+        static $rootDirectoryLength = null;
+        if (is_null($rootDirectoryLength)) {
+            $rootDirectoryLength = self::countDirectoriesInPathToRoot();
+        }
+
+        $baseDirectory = dirname($relativePath);
+        $content = preg_replace_callback(
+            "/(url\(['\"]?)([^'\")]*)/",
+            create_function(
+                '$matches',
+                "return \$matches[1] . str_replace('\\\\', '/', substr(realpath(PIWIK_DOCUMENT_ROOT . '/$baseDirectory/' . \$matches[2]), $rootDirectoryLength));"
+            ),
+            $content
+        );
+        return $content;
+    }
+
+    protected static function countDirectoriesInPathToRoot()
+    {
+        $rootDirectory = realpath(PIWIK_DOCUMENT_ROOT);
+        if ($rootDirectory != '/' && substr_compare($rootDirectory, '/', -1)) {
+            $rootDirectory .= '/';
+        }
+        $rootDirectoryLen = strlen($rootDirectory);
+        return $rootDirectoryLen;
+    }
+
     private static function writeAssetToFile($mergedContent, $name)
     {
         // Remove the previous file
@@ -320,9 +376,9 @@ class Piwik_AssetManager
      *
      * @return string
      */
-    private static function getDisableMergedAssets()
+    private static function isMergedAssetsDisabled()
     {
-        return Piwik_Config::getInstance()->Debug['disable_merged_assets'];
+        return (bool)Piwik_Config::getInstance()->Debug['disable_merged_assets'];
     }
 
     /**
@@ -333,12 +389,7 @@ class Piwik_AssetManager
      */
     public static function getMergedCssFileLocation()
     {
-        $isGenerated = self::isGenerated(self::MERGED_CSS_FILE);
-
-        if (!$isGenerated) {
-            self::generateMergedCssFile();
-        }
-
+        self::prepareMergedCssFile();
         return self::getAbsoluteMergedFileLocation(self::MERGED_CSS_FILE);
     }
 
diff --git a/core/testMinimumPhpVersion.php b/core/testMinimumPhpVersion.php
index 0f9b8b0529..e44c39ea1e 100644
--- a/core/testMinimumPhpVersion.php
+++ b/core/testMinimumPhpVersion.php
@@ -58,9 +58,11 @@ if ($minimumPhpInvalid) {
     if(!file_exists($autoloader)) {
         $piwik_errorMessage .= "<p>It appears the <a href='https://getcomposer.org/' target='_blank'>composer</a> tool is not yet installed.
         You can install Composer in a few easy steps. In the piwik directory, run in the command line the following (eg. via ssh):
-                    <pre>curl -sS https://getcomposer.org/installer | php".
-                    "\nphp composer.phar install</pre> </p><p>This will download and install composer, and initialize composer for Piwik (eg. download the twig library in vendor/twig).
-                    <br/>Then reload this page to access your analytics reports.</p>";
+                    <pre> curl -sS https://getcomposer.org/installer | php".
+                    "\n php composer.phar install</pre> </p><p>This will download and install composer, and initialize composer for Piwik (eg. download the twig library in vendor/twig).
+                    <br/>Then reload this page to access your analytics reports.
+                    <br/><br/>Note: if for some reasons you cannot execute this command, install the latest Piwik release from <a
+                    href='http://builds.piwik.org/latest.zip'>builds.piwik.org</a>.</p>";
     }
 }