Add support for file exclusion in ktfmt.py

This CL adds support for file exclusion in ktfmt.py. This will allow to
include all files in a directory but exclude those that are not
currently formatted properly.

This CL also adds the generate_includes_file.py to generate such a file
from a list of directories.

Bug: 235461679
Test: Manual
Change-Id: I17e17de40d4c558c617e06a55d27eaeb2743f368
diff --git a/generate_includes_file.py b/generate_includes_file.py
new file mode 100755
index 0000000..be9ebff
--- /dev/null
+++ b/generate_includes_file.py
@@ -0,0 +1,95 @@
+#!/usr/bin/env python3
+
+#
+# Copyright 2022, The Android Open Source Project
+#
+# 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.
+#
+"""Script to generate an include file that can be passed to ktfmt.py.
+
+The include file is generated from one or more folders containing one or more
+Kotlin files. The generated include file will exclude all Kotlin files that
+currently don't follow ktfmt format. This way, we can easily start formatting
+all new files in a project/directory.
+"""
+
+import argparse
+import os
+import subprocess
+import sys
+
+
+def main():
+  parser = argparse.ArgumentParser(
+      'Generate an include file that can be passed to ktfmt.py')
+  parser.add_argument(
+      '--output', '-o', required=True, help='The output include file.')
+  parser.add_argument(
+      'files',
+      nargs='*',
+      help='The files or directories that should be included.')
+  args = parser.parse_args()
+
+  # Add a line preprended with '+' for included files/folders.
+  with open(args.output, 'w+') as out:
+    includes = args.files
+    includes.sort()
+    for include in includes:
+      out.write('+' + include + '\n')
+
+    # Retrieve all Kotlin files.
+    kt_files = []
+    for file in args.files:
+      if os.path.isdir(file):
+        for root, dirs, files in os.walk(file):
+          for f in files:
+            if is_kotlin_file(f):
+              kt_files += [os.path.join(root, f)]
+
+      if is_kotlin_file(file):
+        kt_files += [file]
+
+    # Check all files with ktfmt.
+    ktfmt_args = ['--kotlinlang-style', '--set-exit-if-changed', '--dry-run'
+                 ] + kt_files
+    dir = os.path.dirname(__file__)
+    ktfmt_jar = os.path.normpath(
+        os.path.join(dir,
+                     '../../prebuilts/build-tools/common/framework/ktfmt.jar'))
+
+    ktlint_env = os.environ.copy()
+    ktlint_env['JAVA_CMD'] = 'java'
+    try:
+      process = subprocess.Popen(
+          ['java', '-jar', ktfmt_jar] + ktfmt_args,
+          stdout=subprocess.PIPE,
+          env=ktlint_env)
+
+      # Add a line prepended with '-' for all files that are not correctly.
+      # formatted.
+      stdout, _ = process.communicate()
+      incorrect_files = stdout.decode('utf-8').splitlines()
+      incorrect_files.sort()
+      for file in incorrect_files:
+        out.write('-' + file + '\n')
+    except OSError as e:
+      print('Error running ktfmt')
+      sys.exit(1)
+
+
+def is_kotlin_file(name):
+  return name.endswith('.kt') or name.endswith('.kts')
+
+
+if __name__ == '__main__':
+  main()