#!/usr/bin/env python3
# Copyright 2014 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Create files with copyright boilerplate and header include guards.

Usage: tools/boilerplate.py path/to/file.{h,cc}
"""

from __future__ import print_function, unicode_literals

from datetime import date
import io
import os
import os.path
import sys

LINES = [
  f'Copyright {date.today().year} The Chromium Authors',
  'Use of this source code is governed by a BSD-style license that can be',
  'found in the LICENSE file.',
]

NO_COMPILE_LINES = [
  'This is a "No Compile Test" suite.',
  'https://dev.chromium.org/developers/testing/no-compile-tests',
]

EXTENSIONS_TO_COMMENTS = {
  'cc': '//',
  'gn': '#',
  'gni': '#',
  'h': '//',
  'js': '//',
  'mm': '//',
  'mojom': '//',
  'nc': '//',
  'proto': '//',
  'py': '#',
  'swift': '//',
  'ts': '//',
  'typemap': '#',
}


def _GetHeaderImpl(filename, lines):
  _, ext = os.path.splitext(filename)
  ext = ext[1:]
  comment = EXTENSIONS_TO_COMMENTS[ext] + ' '
  return '\n'.join([comment + line for line in lines])


def _GetHeader(filename):
  return _GetHeaderImpl(filename, LINES)


def _GetNoCompileHeader(filename):
  assert filename.endswith(".nc")
  return '\n' + _GetHeaderImpl(filename, NO_COMPILE_LINES)


def _CppHeader(filename):
  guard = filename.upper() + '_'
  for char in '/\\.+':
    guard = guard.replace(char, '_')
  return '\n'.join(
    ['', '#ifndef ' + guard, '#define ' + guard, '', '#endif  // ' + guard, '']
  )


def _RemoveCurrentDirectoryPrefix(filename):
  current_dir_prefixes = [os.curdir + os.sep]
  if os.altsep is not None:
    current_dir_prefixes.append(os.curdir + os.altsep)
  for prefix in current_dir_prefixes:
    if filename.startswith(prefix):
      return filename[len(prefix) :]
  return filename


def _RemoveTestSuffix(filename):
  base, _ = os.path.splitext(filename)
  suffixes = ['_test', '_unittest', '_browsertest']
  for suffix in suffixes:
    l = len(suffix)
    if base[-l:] == suffix:
      return base[:-l]
  return base


def _IsIOSFile(filename):
  if os.path.splitext(os.path.basename(filename))[0].endswith('_ios'):
    return True
  if 'ios' in filename.split(os.path.sep):
    return True
  return False


def _FilePathSlashesToCpp(filename):
  return filename.replace('\\', '/')


def _CppImplementation(filename):
  return (
    '\n#include "'
    + _FilePathSlashesToCpp(_RemoveTestSuffix(filename))
    + '.h"\n'
  )


def _ObjCppImplementation(filename):
  return (
    '\n#import "' + _FilePathSlashesToCpp(_RemoveTestSuffix(filename)) + '.h"\n'
  )


def _CreateFile(filename):
  filename = _RemoveCurrentDirectoryPrefix(filename)

  contents = _GetHeader(filename) + '\n'

  if filename.endswith('.h'):
    contents += _CppHeader(filename)
  elif filename.endswith('.cc'):
    contents += _CppImplementation(filename)
  elif filename.endswith('.nc'):
    contents += _GetNoCompileHeader(filename) + '\n'
    contents += _CppImplementation(filename)
  elif filename.endswith('.mm'):
    contents += _ObjCppImplementation(filename)

  with io.open(filename, mode='w', newline='\n') as fd:
    fd.write(contents)


# A file is safe to overwrite if it's an empty file we can write to.
def _IsSafeToOverwrite(path):
  return (
    os.path.isfile(path)
    and os.path.getsize(path) == 0
    and os.access(path, os.W_OK)
  )


def Main():
  files = sys.argv[1:]
  if len(files) < 1:
    print(
      'Usage: boilerplate.py path/to/file.h path/to/file.cc', file=sys.stderr
    )
    return 1

  # Perform checks first so that the entire operation is atomic.
  for f in files:
    _, ext = os.path.splitext(f)
    if not ext[1:] in EXTENSIONS_TO_COMMENTS:
      print('Unknown file type for %s' % f, file=sys.stderr)
      return 2

    if os.path.exists(f) and not _IsSafeToOverwrite(f):
      print('A file at path %s already exists' % f, file=sys.stderr)
      return 2

  for f in files:
    _CreateFile(f)


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