#!/usr/bin/env python
# Copyright (c) 2012 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.

'''Reads the Webkit Version.xcconfig file looking for MAJOR_VERSION and
MINOR_VERSION, emitting them into a webkit_version.h header file as
WEBKIT_MAJOR_VERSION and WEBKIT_MINOR_VERSION macros.
'''

import os
import re
import sys

# Get the full path of the current script which would be something like
# src/webkit/build/webkit_version.py and navigate backwards twice to strip the
# last two path components to get to the srcroot.
# This is to ensure that the script can load the lastchange module by updating
# the sys.path variable with the desired location.
path = os.path.dirname(os.path.realpath(__file__))
path = os.path.dirname(os.path.dirname(path))
path = os.path.join(path, 'build', 'util')

sys.path.insert(0, path)
import lastchange

def ReadVersionFile(fname):
  '''Reads the Webkit Version.xcconfig file looking for MAJOR_VERSION and
     MINOR_VERSION.  This function doesn't attempt to support the full syntax
     of xcconfig files.'''
  re_major = re.compile('MAJOR_VERSION\s*=\s*(\d+).*')
  re_minor = re.compile('MINOR_VERSION\s*=\s*(\d+).*')
  major = -1
  minor = -1
  f = open(fname, 'rb')
  line = "not empty"
  while line and not (major >= 0 and minor >= 0):
    line = f.readline()
    if major == -1:
      match = re_major.match(line)
      if match:
        major = int(match.group(1))
        continue
    if minor == -1:
      match = re_minor.match(line)
      if match:
        minor = int(match.group(1))
        continue
  assert(major >= 0 and minor >= 0)
  return (major, minor)


def GetWebKitRevision(webkit_dir, version_file):
  """Get the WebKit revision, in the form 'trunk@1234'."""

  # "svn info" tells us what we want, but third_party/WebKit does *not*
  # point at the upstream repo.  So instead we run svn info on the directory
  # containing the versioning file (which is some subdirectory of WebKit).
  version_file_dir = os.path.dirname(version_file)
  version_info = lastchange.FetchVersionInfo(
      default_lastchange=None,
      directory=os.path.join(webkit_dir, version_file_dir),
      directory_regex_prior_to_src_url='webkit')

  if version_info.url == None:
    version_info.url = 'Unknown URL'
  version_info.url = version_info.url.strip('/')

  if version_info.revision == None:
    version_info.revision = '0'

  return "%s@%s" % (version_info.url, version_info.revision)


def EmitVersionHeader(webkit_dir, version_file, output_dir):
  '''Given webkit's version file, emit a header file that we can use from
  within webkit_glue.cc.
  '''

  # See .gypi file for discussion of this workaround for the version file.
  assert version_file[0] == '/'
  version_file = version_file[1:]

  major, minor = ReadVersionFile(os.path.join(webkit_dir, version_file))

  webkit_revision = GetWebKitRevision(webkit_dir, version_file)

  fname = os.path.join(output_dir, "webkit_version.h")
  f = open(fname, 'wb')
  template = """// webkit_version.h
// generated from %s

#define WEBKIT_VERSION_MAJOR %d
#define WEBKIT_VERSION_MINOR %d
#define WEBKIT_SVN_REVISION "%s"
""" % (version_file, major, minor, webkit_revision)
  f.write(template)
  f.close()
  return 0


def main():
  return EmitVersionHeader(*sys.argv[1:])


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