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"""A library to get the version info from version definition file.

Here "mozc_version.txt" file has to be the following format:
MAJOR=0
MINOR=9
BUILD=248
REVISION=0
"""

import datetime
import os
import re
import sys


def IsWindows():
  """Returns true if the platform is Windows."""
  return os.name == 'nt'


def IsMac():
  """Returns true if the platform is Mac."""
  return os.name == 'posix' and os.uname()[0] == 'Darwin'


def IsLinux():
  """Returns true if the platform is Linux."""
  return os.name == 'posix' and os.uname()[0] == 'Linux'


def CalculateRevisionForPlatform(revision):
  """Returns the revision for the current platform."""
  if not revision:
    return revision
  if IsWindows():
    last_digit = '0'
  elif IsMac():
    last_digit = '1'
  elif IsLinux():
    last_digit = '2'
  if last_digit:
    return revision[0:-1] + last_digit

  # If not supported, just use the specified version.
  return revision


class MozcVersion(object):
  """A class to parse the version definition file and maintain the
  version data.
  """
  def __init__(self, path, expand_daily):
    self.ParseVersionFile(path, expand_daily)

  def ParseVersionFile(self, path, expand_daily):
    """Parses a version definition file.

    Args:
      path: A filename which has the version definition
    """
    self._dict = {}
    for line in open(path):
      matchobj = re.match(r'(\w+)=(.*)', line.strip())
      if matchobj:
        var = matchobj.group(1)
        val = matchobj.group(2)
        if not self._dict.has_key(var):
          self._dict[var] = val

    # Set the actual version from the parsed data.
    self._major = self._dict['MAJOR']
    self._minor = self._dict['MINOR']
    self._build = self._dict['BUILD']
    self._revision = CalculateRevisionForPlatform(self._dict['REVISION'])
    if expand_daily and self._build == 'daily':
      zero_day = datetime.date(2009, 5, 24)
      self._build = str(
          datetime.date.today().toordinal() - zero_day.toordinal())

  def IsDevChannel(self):
    """Returns true if the parsed version is dev-channel."""
    if len(self._revision) >= 3 and self._revision[-3] == '1':
      return True

    return False

  def GetVersionString(self):
    """Returns the normal version info string.

    Returns:
      a string in format of "MAJOR.MINOR.BUILD.REVISION"
    """
    return self.GetVersionInFormat('@MAJOR@.@MINOR@.@BUILD@.@REVISION@')

  def GetVersionInFormat(self, format):
    """Returns the version string based on the specified format.

    format can contains @MAJOR@, @MINOR@, @BUILD@ and @REVISION@ which are
    replaced by self._major, self._minor, self._build, and self._revision
    respectively.

    Args:
      format: a string which contains version patterns.

    Returns:
      Return the version string in the format of format.
    """
    replacements = [('@MAJOR@', self._major), ('@MINOR@', self._minor),
                    ('@BUILD@', self._build), ('@REVISION@', self._revision)]
    result = format
    for r in replacements:
      result = result.replace(r[0], r[1])
    return result


def main():
  """A sample main function"""
  if len(sys.argv) < 2:
    logging.error('The number of argument is not enough')
    exit(1)

  version = MozcVersion(sys.argv[1], expand_daily=True)
  print version.GetVersionString()

if __name__ == '__main__':
  main()