Caterpillar now generates app.info.js, a metadata script. Resolves #12.

src/caterpillar.py

 #!/usr/bin/env python2
 # -*- coding: utf-8 -*-
 
 # Copyright 2015 Google Inc. All Rights Reserved.
 #
 # 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
@@ skipping 51 matching lines @@
 
 # Name of the service worker static script.
 SW_STATIC_SCRIPT_NAME = 'sw_static.js'
 
 # Largest number that the cache version can be.
 MAX_CACHE_VERSION = 1000000
 
 # Where this file is located (so we can find resources).
 SCRIPT_DIR = os.path.dirname(__file__)
 
+# Name of the app info script.
+INFO_SCRIPT_NAME = 'app.info.js'
+
 # Maps dependency managers to the folder they install dependencies into.
 DEPENDENCY_MANAGER_INSTALL_FOLDER = {
   'bower': 'bower_components',
   'npm': 'node_modules',
 }
 
 SW_FORMAT_STRING = """/**
  * @file Service worker generated by Caterpillar.
  */
 
@@ skipping 351 matching lines @@
   sw_js = generate_service_worker(output_dir, ca_manifest, required_js_paths,
                                   boilerplate_dir)
 
   # We can now write the service worker. Note that it must be in the root.
   sw_path = os.path.join(output_dir, SW_SCRIPT_NAME)
   logging.debug('Writing service worker to `%s`.', sw_path)
   with open(sw_path, 'w') as sw_file:
     sw_file.write(surrogateescape.encode(sw_js))
 
 
+def add_app_info(output_dir, ca_manifest, config):
+  """Adds an app info script, containing metadata, to a web app.
+
+  Args:
+    output_dir: Path to web app to add app info script to.
+    ca_manifest: Chrome App manifest dictionary.
+    config: Configuration dictionary.
+  """
+  logging.debug('Generating app info script.')
+  js_manifest = json.dumps(
+      ca_manifest, sort_keys=True, indent=2).replace('"', "'")
+  app_id = config['id']
+  app_info_js = ('chrome.caterpillar.manifest = {manifest};\n'
+                 'chrome.caterpillar.appId = \'{app_id}\';\n').format(
+                 manifest=js_manifest,
+                 app_id=app_id)
+  app_info_path = os.path.join(output_dir, INFO_SCRIPT_NAME)
+  logging.debug('Writing app info script to `%s`.', app_info_path)
+  with open(app_info_path, 'w') as app_info_file:
+    app_info_file.write(app_info_js.encode('utf-8'))
+
+
 class InstallationError(Exception):
   """Exception raised when a dependency fails to install."""
 
   pass
 
 
 def install_dependency(call, output_dir):
   """Installs a dependency into a directory.
 
   Assumes that there is no output on stdout if installation fails.
@@ skipping 165 matching lines @@
   for dependency in dependencies:
     # Note that dependencies are installed into the root, but we need paths
     # relative to Caterpillar's boilerplate directory.
     dependency_path = os.path.join('..',
         DEPENDENCY_MANAGER_INSTALL_FOLDER[dependency['manager']],
         dependency['name'], dependency['path'])
     required_dependency_paths.append(dependency_path)
 
   required_polyfill_paths = polyfill_paths(polyfillable)
 
+  # Additionally, we may generate some files we want to use in HTML script tags,
+  # but we don't want to install as a dependency or copy from a static JS file.
+  required_generated_paths = []
+
   # Read in and check the manifest file.
   try:
     ca_manifest = chrome_app.manifest.get(input_dir)
     chrome_app.manifest.localize(ca_manifest, input_dir)
     chrome_app.manifest.verify(ca_manifest)
   except ValueError as e:
     logging.error(e.message)
     return
 
   # TODO(alger): Identify background scripts and determine start_url.
   start_url = config['start_url']
   logging.info('Got start URL from config file: `%s`', start_url)
 
   # Generate a progressive web app manifest.
   pwa_manifest = generate_web_manifest(ca_manifest, start_url)
   pwa_manifest_path = os.path.join(output_dir, PWA_MANIFEST_FILENAME)
   with open(pwa_manifest_path, 'w') as pwa_manifest_file:
     json.dump(pwa_manifest, pwa_manifest_file, indent=4, sort_keys=True)
   logging.debug('Wrote `%s` to `%s`.', PWA_MANIFEST_FILENAME, pwa_manifest_path)
 
+  # Generate and write an app info file so we can access Chrome App metadata
+  # from polyfills and scripts.
+  add_app_info(output_dir, ca_manifest, config)
+  required_generated_paths.append(os.path.join('..', INFO_SCRIPT_NAME))
+
   # Remove unnecessary files from the output web app. This must be done before
   # the service worker is generated, or these files will be cached.
   cleanup_output_dir(output_dir)
 
   # Edit the HTML and JS code of the output web app.
   # This is adding TODOs, injecting tags, etc. - anything that involves editing
   # user code directly. This must be done before the static code is copied
   # across, or the polyfills will have TODOs added to them.
   # Order is significant here - always, then dependencies, then polyfills.
-  required_script_paths = (required_always_paths + required_dependency_paths
-                           + required_polyfill_paths)
+  required_script_paths = (required_always_paths + required_generated_paths +
+                           required_dependency_paths + required_polyfill_paths)
   edit_code(output_dir, required_script_paths, ca_manifest, config)
 
   # We want the static SW file to be copied in too, so we add it here.
   # We have to add it after edit_code or it would be included in the HTML, but
   # this is service worker-only code, and shouldn't be included there.
   required_always_paths.append(SW_STATIC_SCRIPT_NAME)
 
   # Copy static code from Caterpillar into the output web app.
   # This must be done before the service worker is generated, or these files
   # will not be cached.
@@ skipping 78 matching lines @@
   if args.mode == 'config':
     configuration.generate_and_save(args.output, args.interactive)
 
   elif args.mode == 'convert':
     config = configuration.load(args.config)
     convert_app(args.input, args.output, config, args.force)
 
 
 if __name__ == '__main__':
   sys.exit(main())