Feature: ESM Import Maps

app/code/core/Mage/Core/Model/Design/Package.php

@@ -792,6 +792,7 @@ public function cleanMergedJsCss()
     {
         $result = (bool)$this->_initMergerDir('js', true);
         $result = (bool)$this->_initMergerDir('css', true) && $result;
+        $result = (bool)$this->_initMergerDir('importmap', true) && $result;
         return (bool)$this->_initMergerDir('css_secure', true) && $result;
     }
 
@@ -933,6 +934,121 @@ protected function _prepareUrl($uri)
         return $uri;
     }
 
+    /**
+     * @param array $allItems
+     * @param array $itemUrls
+     * @param bool $inline
+     * @return string
+     * @throws JsonException
+     */
+    public function renderImportMap(array $allItems, array $itemUrls, bool $inline): string
+    {
+        $importMap = [];
+        $cacheKey = [];
+        $fileHashKey = []; // No timestamps in hash key in production mode
+        $useCache = Mage::app()->useCache('import_map');
+        foreach ($allItems as $item) {
+            if (!preg_match('#^(static|skin)_import(_map)?$#', $item['type']) || !isset($itemUrls[$item['type']][$item['name']])) {
+                continue;
+            }
+            $fileOrUrl = $itemUrls[$item['type']][$item['name']];
+            switch ($item['type']) {
+                case 'static_import_map':
+                case 'skin_import_map':
+                    if ($item['type'] === 'skin_import_map') {
+                        $filePath = $this->getFilename($fileOrUrl, ['_type' => 'skin']);
+                    } else {
+                        $filePath = Mage::getBaseDir() . DS . 'js' . DS . $fileOrUrl;
+                    }
+                    $fileHashKey [] = $item['name'];
+                    if ($useCache) {
+                        $cacheKey[] = Mage::getIsDeveloperMode() ? $filePath . '-' . filemtime($filePath) : $filePath;
+                    }
+                    $importData = json_decode($filePath, true, 3, JSON_THROW_ON_ERROR);
+                    if (isset($importData['imports'])) {
+                        $importMap['imports'] = array_merge($importMap['imports'] ?? [], $importData['imports']);
+                    }
+                    if (isset($importData['scopes'])) {
+                        $importMap['scopes'] = array_merge($importMap['scopes'] ?? [], $importData['scopes']);
+                    }
+                    break;
+                case 'static_import':
+                case 'skin_import':
+                    $fileHashKey [] = $fileOrUrl;
+                    if (!preg_match('#^https?://#', $fileOrUrl)) {
+                        if ($item['type'] === 'skin_import') {
+                            $fileOrUrl = $this->getSkinUrl($fileOrUrl) . '?v=' . filemtime($this->getFilename($fileOrUrl, ['_type' => 'skin']));
+                        } else {
+                            $fileOrUrl = Mage::getBaseUrl('js') . $fileOrUrl . '?v=' . filemtime(Mage::getBaseDir() . DS . 'js' . DS . $fileOrUrl);
+                        }
+                    }
+                    $importMap['imports'][$item['name']] = $fileOrUrl;
+                    break;
+            }
+        }
+        if (!$importMap) {
+            return '';
+        }
+
+        $html = '';
+        if ($useCache) {
+            $cacheKey = md5('LAYOUT_' . $this->getArea() . '_STORE' . $this->getStore()->getId() . '_'
+            . $this->getPackageName() . '_' . $this->getTheme('layout') . '_'
+            . (Mage::app()->getRequest()->isSecure() ? 's' : 'u') . '_' . implode('|', $cacheKey));
+            $html = Mage::app()->loadCache($cacheKey);
+        }
+
+        // Allow devs to bypass cache in browser
+        if ($useCache && Mage::getIsDeveloperMode() && isset($_SERVER['HTTP_CACHE_CONTROL'])
+            && strpos($_SERVER['HTTP_CACHE_CONTROL'], 'no-cache') !== false
+        ) {
+            $html = null;
+        }
+
+        if (!$html) {
+            if ($inline) {
+                $html = '<script type="importmap">' . json_encode($importMap) . '</script>';
+            } else {
+                $filePrefix = md5(implode('|', $fileHashKey));
+                $targetFilename = $filePrefix . '.json';
+                if ($this->_writeImportMap(json_encode($importMap), $targetFilename)) {
+                    $url = Mage::getBaseUrl('media', Mage::app()->getRequest()->isSecure()) . 'importmap/' . $targetFilename . '?v=' . time();
+                    $html = '<script type="importmap" src="' . $url . '"></script>';
+                } else {
+                    $html = '<script type="importmap">' . json_encode($importMap) . '</script>';
+                }
+            }
+            if ($useCache) {
+                // Cache with infinite lifetime since we have filemtime in cache key in dev mode
+                Mage::app()->saveCache($html, $cacheKey, ['import_map'], null);
+            }
+        }
+        return $html;
+    }
+
+    protected function _writeImportMap(string $data, string $targetFile): bool
+    {
+        try {
+            $targetDir = Mage::getBaseDir('media') . DS . 'importmap';
+            if (!is_dir($targetDir)) {
+                if (!mkdir($targetDir)) {
+                    throw new Exception(sprintf('Could not create directory %s.', $targetDir));
+                }
+            }
+            if (!is_writable($targetDir)) {
+                throw new Exception(sprintf('Path %s is not writeable.', $targetDir));
+            }
+            file_put_contents($targetDir . DS . $targetFile, $data, LOCK_EX);
+            if (Mage::helper('core/file_storage_database')->checkDbUsage()) {
+                Mage::helper('core/file_storage_database')->saveFile($targetDir . DS . $targetFile);
+            }
+            return true;
+        } catch (Exception $e) {
+            Mage::logException($e);
+            return false;
+        }
+    }
+
     /**
      * Default theme getter
      * @return string

app/code/core/Mage/Page/Block/Html/Head.php

@@ -206,7 +206,9 @@ public function getCssJsHtml()
         // prepare HTML
         $shouldMergeJs = Mage::getStoreConfigFlag('dev/js/merge_files');
         $shouldMergeCss = Mage::getStoreConfigFlag('dev/css/merge_css_files');
+        $externalImportMap = Mage::getStoreConfigFlag('dev/import_map/external'); // "External import maps are not yet supported."
         $html   = '';
+        $html   .= $this->_prepareImportMap(!$externalImportMap) . "\n";
         foreach ($lines as $if => $items) {
             if (empty($items)) {
                 continue;
@@ -578,4 +580,78 @@ protected function _sortItems($referenceName, $before, $type)
             $this->_data['items'] = $newItems;
         }
     }
+
+    /***************
+     * Import Maps *
+     ***************/
+
+    /**
+     * @param string $name A unique name for the import map found in a static path (e.g. "main")
+     * @param string $path The path to the import map file to be merged (relative to the /js/ directory - e.g. bundle/importmap.json)
+     * @param string|null $devPath An alternative file to use in developer mode
+     * @param string $referenceName The name of the item to insert the element before. If name is not found, insert at the end, * has special meaning (all)
+     * @param bool $before If true insert before the $referenceName instead of after
+     * @return $this
+     */
+    public function addStaticImportMap($name, $path, $devPath = null, $referenceName = '*', $before = false)
+    {
+        $this->_data['imports']['static_import_map'][$name] = Mage::getIsDeveloperMode() && $devPath ? $devPath : $path;
+        $this->addItem('static_import_map', $name, null, null, null, $referenceName, $before);
+        return $this;
+    }
+
+    /**
+     * @param string $name A unique name for the import map found in a skin path (e.g. "main")
+     * @param string $path The path to the import map file to be merged (relative to the skin path - e.g. js/importmap.json)
+     * @param string|null $devPath An alternative file to use in developer mode
+     * @param string $referenceName The name of the item to insert the element before. If name is not found, insert at the end, * has special meaning (all)
+     * @param bool $before If true insert before the $referenceName instead of after
+     * @return $this
+     */
+    public function addSkinImportMap($name, $path, $devPath = null, $referenceName = '*', $before = false)
+    {
+        $this->_data['imports']['skin_import_map'][$name] = Mage::getIsDeveloperMode() && $devPath ? $devPath : $path;
+        $this->addItem('skin_import_map', $name, null, null, null, $referenceName, $before);
+        return $this;
+    }
+
+    /**
+     * @param string $specifier The specifier to use when importing the resource (e.g. "vue")
+     * @param string $fileOrUrl The path to the file (relative to the /js/ directory) or a CDN url
+     * @param string|null $devFileOrUrl An alternative file or url to use in developer mode
+     * @param string $referenceName The name of the item to insert the element before. If name is not found, insert at the end, * has special meaning (all)
+     * @param bool $before If true insert before the $referenceName instead of after
+     * @return $this
+     */
+    public function addStaticImport($specifier, $fileOrUrl, $devFileOrUrl = null, $referenceName = '*', $before = false)
+    {
+        $this->_data['imports']['static_import'][$specifier] = Mage::getIsDeveloperMode() && $devFileOrUrl ? $devFileOrUrl : $fileOrUrl;
+        $this->addItem('static_import', $specifier, null, null, null, $referenceName, $before);
+        return $this;
+    }
+
+    /**
+     * @param string $specifier The specifier to use when importing the resource (e.g. "vue")
+     * @param string $fileOrUrl The path to the file (relative to skin) or a CDN url
+     * @param string|null $devFileOrUrl An alternative file or url to use in developer mode
+     * @param string $referenceName The name of the item to insert the element before. If name is not found, insert at the end, * has special meaning (all)
+     * @param bool $before If true insert before the $referenceName instead of after
+     * @return $this
+     */
+    public function addSkinImport($specifier, $fileOrUrl, $devFileOrUrl = null, $referenceName = '*', $before = false)
+    {
+        $this->_data['imports']['skin_import'][$specifier] = Mage::getIsDeveloperMode() && $devFileOrUrl ? $devFileOrUrl : $fileOrUrl;
+        $this->addItem('skin_import', $specifier, null, null, null, $referenceName, $before);
+        return $this;
+    }
+
+    /**
+     * @param bool $inline
+     * @return string
+     * @throws JsonException
+     */
+    public function _prepareImportMap(bool $inline): string
+    {
+        return Mage::getSingleton('core/design_package')->renderImportMap($this->_data['items'], $this->_data['imports'] ?? [], $inline);
+    }
 }

dev/openmage/nginx-admin.conf

@@ -74,6 +74,13 @@ server {
         limit_req zone=media burst=50 nodelay;
         root /var/www/html;
         gzip on;
+        location ~* importmap/.*\.json$ {
+            add_header Cache-Control "public";
+            expires +1y;
+            types {
+                application/importmap+json json;
+            }
+        }
         location ~* \.(eot|ttf|otf|woff|woff2|svg)$ {
             add_header Access-Control-Allow-Origin "*";
             add_header Cache-Control "public";

dev/openmage/nginx-frontend.conf

@@ -117,6 +117,13 @@ server {
         limit_req zone=media burst=100 nodelay;
         root /var/www/html;
         gzip on;
+        location ~* importmap/.*\.json$ {
+            add_header Cache-Control "public";
+            expires +1y;
+            types {
+                application/importmap+json json;
+            }
+        }
         location ~* \.(eot|ttf|otf|woff|woff2|svg)$ {
             add_header Access-Control-Allow-Origin "*";
             add_header Cache-Control "public";

media/.htaccess

@@ -17,6 +17,12 @@ Options All -Indexes
     AddHandler cgi-script .php .pl .py .jsp .asp .sh .cgi
     Options -ExecCGI
 
+############################################
+## Serve import maps with correct content type
+<FilesMatch "importmap/.*\.json$">
+    AddType application/importmap+json .json
+</FilesMatch>
+
 <IfModule mod_rewrite.c>
 
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