fix for @demos references in headless mode

Fixes #1068

app/content/js/find-file.js

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2017 IBM Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+const debug = require('debug')('find-file')
+debug('loading')
+
+/**
+ * Maybe the given filepath is asar-relative, as indicated by a
+ * leading @ character?
+ *
+ */
+const specialPaths = [] // any special paths added via self.addPath
+const defaultSpecial = { filepath: require('path').join(__dirname, '..') } // default special is the app/ top-level
+
+exports.findFile = (filepath, safe) => {
+    if (!filepath) {
+        if (!safe) {
+            throw new Error('Please specify a file')
+        } else {
+            // caller asked us to play nice
+            return ''
+        }
+    } else if (filepath.charAt(0) === '@') {
+        // ui.js is in the /app/build directory
+        // the === '.' part handles the case where the call was e.g. ui.findFile('@demos'), i.e. the special dir itself
+        const desiredPrefix = require('path').dirname(filepath) === '.' ? filepath : require('path').dirname(filepath)
+        const special = specialPaths.find(({prefix}) => desiredPrefix.indexOf(prefix) === 0) || defaultSpecial
+        return require('path').join(special.filepath, filepath)
+    } else {
+        return require('expand-home-dir')(filepath)
+    }
+}
+
+/**
+ * Augment the module load path
+ *
+ */
+exports.addPath = filepath => {
+    const path = require('path')
+
+    // use app-module-path to augment the node module require path
+    require('app-module-path').addPath(path.resolve(filepath))
+
+    // remember this for self.findFile
+    const prefix = path.basename(filepath)
+    if (prefix.charAt(0) === '@') {
+        specialPaths.push({ prefix , filepath: path.dirname(filepath) })
+    }
+}