#!/usr/bin/env python3
# Copyright (C) 2025 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.
"""Generates .github/CODEOWNERS from .github/CODEOWNERS.template and OWNERS.github files."""

import os
import sys

ROOT_DIR = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))

HEADER = """# ============================================================================
# THIS FILE IS AUTO-GENERATED - DO NOT EDIT DIRECTLY
#
# This file is automatically generated by tools/gen_github_codeowners
# Changes to this file will be overwritten.
#
# To modify this file, edit OWNERS.github files throughout the repository.
# ============================================================================

"""


def main():
  output = HEADER

  # Add content from root OWNERS.github
  root_owners_path = os.path.join(ROOT_DIR, 'OWNERS.github')
  with open(root_owners_path, 'r') as f:
    output += f.read().rstrip() + '\n'

  # Add separator
  output += '\n# ============================================================================\n'
  output += '# AUTO-GENERATED ENTRIES FROM OWNERS.github FILES\n'
  output += '# ============================================================================\n'

  # Find and process all OWNERS.github files
  for root, dirs, files in os.walk(ROOT_DIR):
    dirs[:] = [d for d in dirs if not d.startswith('.') and d != 'node_modules']

    if 'OWNERS.github' not in files:
      continue

    rel_dir = os.path.relpath(root, ROOT_DIR)

    # Skip root OWNERS.github as it's already processed
    if rel_dir == '.':
      continue
    base_path = '/' + rel_dir.replace(os.sep, '/')
    if not base_path.endswith('/'):
      base_path += '/'

    with open(os.path.join(root, 'OWNERS.github'), 'r') as f:
      for line in f:
        line = line.strip()
        if not line or line.startswith('#'):
          continue

        parts = line.split()
        if len(parts) < 2:
          continue

        pattern = parts[0]
        owners = ' '.join(parts[1:])

        # Security check: reject patterns with parent directory references
        if '../' in pattern or pattern.startswith('..'):
          owners_file = os.path.join(root, 'OWNERS.github')
          print(f'ERROR: Invalid pattern in {owners_file}: {pattern}')
          print('Patterns cannot contain "../" for security reasons.')
          sys.exit(1)

        # Convert relative pattern to absolute path
        if pattern == '/' or pattern == './' or pattern == '.':
          path = base_path
        elif pattern.startswith('/'):
          path = base_path + pattern[1:]
        else:
          path = base_path + pattern

        output += f'{path} {owners}\n'

  # Write output
  codeowners_path = os.path.join(ROOT_DIR, '.github', 'CODEOWNERS')
  with open(codeowners_path, 'w') as f:
    f.write(output)

  print(f'Generated {codeowners_path}')


if __name__ == '__main__':
  sys.exit(main())