deploy-ng: Add initial support for creating .app bundles for macOS

The actual bundling is currently commented out in the bottom of
build_apps.build_runtimes(). Generating the .app was tested from a Linux
host and looks mostly correct upon a visual inspection of the contents.
However, no testing was done for actually running the .app on macOS,
which is why it is commented out. This was also not tested on Python 2.

There are also some TODO comments that need to be addressed.

direct/src/showutil/dist.py

@@ -3,6 +3,7 @@ from __future__ import print_function
 import collections
 import os
 import pip
+import plistlib
 import sys
 import subprocess
 import zipfile
@@ -44,6 +45,7 @@ class build_apps(distutils.core.Command):
         self.build_base = os.path.join(os.getcwd(), 'build')
         self.gui_apps = {}
         self.console_apps = {}
+        self.macos_main_app = None
         self.rename_paths = {}
         self.include_patterns = []
         self.exclude_patterns = []
@@ -116,6 +118,19 @@ class build_apps(distutils.core.Command):
         self.exclude_modules = _parse_list(self.exclude_modules)
         self.plugins = _parse_list(self.plugins)
 
+        num_gui_apps = len(self.gui_apps)
+        num_console_apps = len(self.console_apps)
+
+        if self.macos_main_app is None:
+            if num_gui_apps > 1:
+                assert True, 'macos_main_app must be defined if more than one gui_app is defined'
+            elif num_gui_apps == 1:
+                self.macos_main_app = list(self.gui_apps.keys())[0]
+            elif num_console_apps > 1:
+                assert True, 'macos_main_app must be defined if more than one console_app is defined with no gui_apps'
+            elif num_console_apps == 1:
+                self.macos_main_app = list(self.console_apps.keys())[0]
+
         assert os.path.exists(self.requirements_path), 'Requirements.txt path does not exist: {}'.format(self.requirements_path)
         assert num_gui_apps + num_console_apps != 0, 'Must specify at least one app in either gui_apps or console_apps'
 
@@ -169,6 +184,55 @@ class build_apps(distutils.core.Command):
         wheelpaths = [os.path.join(whldir,i) for i in os.listdir(whldir) if platform in i]
         return wheelpaths
 
+    def bundle_macos_app(self, builddir):
+        """Bundle built runtime into a .app for macOS"""
+
+        appname = '{}.app'.format(self.macos_main_app)
+        appdir = os.path.join(builddir, appname)
+        contentsdir = os.path.join(appdir, 'Contents')
+        macosdir = os.path.join(contentsdir, 'MacOS')
+        fwdir = os.path.join(contentsdir, 'Frameworks')
+        resdir = os.path.join(contentsdir, 'Resources')
+
+        self.announce('Bundling macOS app into {}'.format(appdir), distutils.log.INFO)
+
+        # Create initial directory structure
+        os.makedirs(macosdir)
+        os.makedirs(fwdir)
+        os.makedirs(resdir)
+
+        # Move files over
+        for fname in os.listdir(builddir):
+            src = os.path.join(builddir, fname)
+            if appdir in src:
+                continue
+
+            if fname in self.gui_apps or self.console_apps:
+                dst = macosdir
+            elif src.endswith('.so') or src.endswith('dylib'):
+                dst = fwdir
+            else:
+                # TODO Cg still shows up in Resources when it should be in Frameworks
+                dst = resdir
+            shutil.move(src, dst)
+
+        # Write out Info.plist
+        plist = {
+            'CFBundleName': appname,
+            'CFBundleDisplayName': appname, #TODO use name from setup.py/cfg
+            'CFBundleIdentifier': '', #TODO
+            'CFBundleVersion': '0.0.0', #TODO get from setup.py
+            'CFBundlePackageType': 'APPL',
+            'CFBundleSignature': '', #TODO
+            'CFBundleExecutable': self.macos_main_app,
+        }
+        with open(os.path.join(contentsdir, 'Info.plist'), 'wb') as f:
+            if hasattr(plistlib, 'dump'):
+                plistlib.dump(plist, f)
+            else:
+                plistlib.writePlist(plist, f)
+
+
     def build_runtimes(self, platform, use_wheels):
         """ Builds the distributions for the given platform. """
 
@@ -400,6 +464,10 @@ class build_apps(distutils.core.Command):
 
                 copy_file(src, dst)
 
+        # Bundle into an .app on macOS
+        #if 'macosx' in platform:
+        #    self.bundle_macos_app(builddir)
+
     def add_dependency(self, name, target_dir, search_path, referenced_by):
         """ Searches for the given DLL on the search path.  If it exists,
         copies it to the target_dir. """