#!/usr/bin/env python
# Copyright 2016 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import argparse
import os
import re
import sys


_HERE_PATH = os.path.join(os.path.dirname(__file__))

# The name of a dummy file to be updated always after all other files have been
# written. This file is declared as the "output" for GN's purposes
_TIMESTAMP_FILENAME = os.path.join('unpack.stamp')


_SRC_PATH = os.path.normpath(os.path.join(_HERE_PATH, '..', '..', '..'))
sys.path.insert(1, os.path.join(_SRC_PATH, 'tools', 'grit'))
from grit.format import data_pack


def ParseLine(line):
  return re.match('  {"([^"]+)", ([^},]+)', line)

def UnpackResource(root_dir, out_path, excludes, resource_path, resource_text):
    dirname = os.path.dirname(resource_path)
    # When files are generated, |dirname| becomes
    # @out_folder@/<gen_path>/path_to_resource. To make the structure look as if
    # this file was not generated, remove @out_folder@ and <gen_path>.
    if ('@out_folder@' in dirname):
      dirname = os.path.relpath(dirname, os.path.join('@out_folder@', root_dir))
    filename = os.path.basename(resource_path)
    resource_path = os.path.join(dirname, filename).replace('\\', '/')
    if (resource_path in excludes):
      return

    out_dir = os.path.normpath(
        os.path.join(out_path, dirname)).replace('\\', '/')
    assert out_dir.startswith(out_path), \
           'Cannot unpack files to locations not in %s. %s should be removed ' \
           'from the pak file or excluded from unpack.' \
           % (out_path, resource_path)

    if not os.path.exists(out_dir):
      os.makedirs(out_dir)
    with open(os.path.join(out_dir, filename), 'w') as file:
      file.write(resource_text)

def Unpack(pak_path, out_path, pak_base_dir, excludes):
  pak_dir = os.path.dirname(pak_path)
  pak_id = os.path.splitext(os.path.basename(pak_path))[0]

  data = data_pack.ReadDataPack(pak_path)

  # Associate numerical grit IDs to strings.
  # For example 120045 -> 'IDR_SETTINGS_ABOUT_PAGE_HTML'
  resource_ids = dict()
  resources_path = os.path.join(pak_dir, 'grit', pak_id + '.h')
  with open(resources_path) as resources_file:
    for line in resources_file:
      res = re.match('^#define (\S*).* (\d+)\)?$', line)
      if res:
        resource_ids[int(res.group(2))] = res.group(1)
  assert resource_ids

  # Associate numerical string IDs to files.
  resource_filenames = dict()
  resources_map_path = os.path.join(pak_dir, 'grit', pak_id + '_map.cc')
  with open(resources_map_path) as resources_map:
    for line in resources_map:
      res = ParseLine(line)
      if res:
        resource_filenames[res.group(2)] = res.group(1)
  assert resource_filenames

  root_dir = pak_base_dir if pak_base_dir else pak_dir
  # Extract packed files, while preserving directory structure.
  for (resource_id, text) in data.resources.iteritems():
    UnpackResource(root_dir, out_path, excludes or [],
                   resource_filenames[resource_ids[resource_id]], text)

def main():
  parser = argparse.ArgumentParser()
  parser.add_argument('--pak_file')
  parser.add_argument('--out_folder')
  # The expected reference point/root path for files appearing in the pak file.
  # If this argument is not provided, the location of the pak file will be used
  # by default.
  parser.add_argument('--pak_base_dir')
  # Resources in the pak file which should not be unpacked.
  parser.add_argument('--excludes', nargs='*')
  args = parser.parse_args()

  Unpack(args.pak_file, args.out_folder, args.pak_base_dir, args.excludes)

  timestamp_file_path = os.path.join(args.out_folder, _TIMESTAMP_FILENAME)
  with open(timestamp_file_path, 'a'):
    os.utime(timestamp_file_path, None)


if __name__ == '__main__':
  main()