#!/usr/bin/python
#

# Copyright (C) 2011 Google Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.


"""Script to check NEWS file.

"""

import sys
import time
import datetime
import locale
import fileinput
import re


DASHES_RE = re.compile(r"^\s*-+\s*$")
RELEASED_RE = re.compile(r"^\*\(Released (?P<day>[A-Z][a-z]{2}),"
                         r" (?P<date>.+)\)\*$")
UNRELEASED_RE = re.compile(r"^\*\(unreleased\)\*$")
VERSION_RE = re.compile(r"^Version \d+(\.\d+)+( (beta|rc)\d+)?$")


def main():
  # Ensure "C" locale is used
  curlocale = locale.getlocale()
  if curlocale != (None, None):
    raise Exception("Invalid locale %s" % curlocale)

  prevline = None
  expect_date = False
  count_empty = 0

  for line in fileinput.input():
    line = line.rstrip("\n")

    if VERSION_RE.match(line):
      if count_empty != 2:
        raise Exception("Line %s: Missing 2 empty lines before %s" %
                        (fileinput.filelineno(), line))

    if UNRELEASED_RE.match(line) or RELEASED_RE.match(line):
      if count_empty != 1:
        raise Exception("Line %s: Missing 1 empty line before %s" %
                        (fileinput.filelineno(), line))

    if line:
      count_empty = 0
    else:
      count_empty += 1

    if DASHES_RE.match(line):
      if not VERSION_RE.match(prevline):
        raise Exception("Line %s: Invalid title" %
                        (fileinput.filelineno() - 1))
      if len(line) != len(prevline):
        raise Exception("Line %s: Invalid dashes length" %
                        (fileinput.filelineno()))
      expect_date = True

    elif expect_date:
      if not line:
        # Ignore empty lines
        continue

      if UNRELEASED_RE.match(line):
        # Ignore unreleased versions
        expect_date = False
        continue

      m = RELEASED_RE.match(line)
      if not m:
        raise Exception("Line %s: Invalid release line" %
                        fileinput.filelineno())

      # Including the weekday in the date string does not work as time.strptime
      # would return an inconsistent result if the weekday is incorrect.
      parsed_ts = time.mktime(time.strptime(m.group("date"), "%d %b %Y"))
      parsed = datetime.date.fromtimestamp(parsed_ts)
      weekday = parsed.strftime("%a")

      # Check weekday
      if m.group("day") != weekday:
        raise Exception("Line %s: %s was/is a %s, not %s" %
                        (fileinput.filelineno(), parsed, weekday,
                         m.group("day")))

      expect_date = False

    prevline = line

  sys.exit(0)


if __name__ == "__main__":
  main()