#!/usr/bin/env python2
#       vim:fileencoding=utf-8 et st=4 sts=4
# Copyright 2012-2014 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Id$

# Author: Michał Górny <mgorny@gentoo.org>
# Author: Robin H. Johnson <robbat2@gentoo.org> (hook fixups)
# Based on work of: Ulrich Müller <ulm@gentoo.org>

import datetime, os, re, subprocess, sys, fileinput

PATH_REGEX = re.compile(r'''
(?P<year> \d{4}) - (?P<month> \d{2}) - (?P<day> \d{2})
          - (?P<name> [a-z0-9+_-]+) /
(?P=year) - (?P=month) - (?P=day) - (?P=name)
          . (?P<lang> [a-z]{2}) .txt (?: .asc )?
''', re.VERBOSE)

# special git commit id
ZEROS = '0000000000000000000000000000000000000000'

def main(prog, *argv):
    if 'GIT_DIR' not in os.environ:
        return '%s: GIT_DIR unset' % (prog, )
    results = []
    for line in fileinput.input():
        # <old-value> SP <new-value> SP <ref-name> LF
        (oldrev, newrev, refname) = line.split()
        results += [validate(oldrev, newrev, refname)]
    results = filter(lambda x: x != 0, results)
    if len(results) == 0:
        return 0
    else:
        print '%s: errors in commits' % (prog, )
        print ''.join(map(lambda x: x+"\n", results))
        return 1

def validate(oldrev, newrev, refname):
    # Deletion of a branch means no work to do anyway.
    # And git-diff will fail
    if newrev == ZEROS:
        return 0

    proc = subprocess.Popen( \
            ['git', 'diff', \
                '--name-only', '--diff-filter=A',  \
                '%s..%s' % (oldrev, newrev)],
            stdout=subprocess.PIPE)
    added = proc.communicate()[0].rstrip().split('\n')

    for filename in filter(lambda f: len(f) > 0, added):
        # GLEP 42: name should take the form of:
        # yyyy-mm-dd-<name>/yyyy-mm-dd-<name>.<lang>.txt[.asc]
        # where <name>: [a-z0-9+_-]+, <lang>: [a-z][a-z]

        match = PATH_REGEX.match(filename)
        if not match:
            return 'Path syntax invalid: %s' % filename
        date = [int(match.group(x)) for x in ('year', 'month', 'day')]

        try:
            datetime.date(*date)
        except ValueError:
            return 'Date invalid: %s' % '-'.join(date)

    # return nothing if good
    return 0

if __name__ == '__main__':
    sys.exit(main(*sys.argv))