#!/usr/bin/env python
import os
import subprocess
import sys
import tempfile

_PATCHHDR = '# HG changeset patch'


def main(argv):
    tf = tempfile.NamedTemporaryFile(suffix='.diff')
    d = sys.stdin.read()
    if _PATCHHDR in d:
        junk, d = d.split(_PATCHHDR, 1)
        d = _PATCHHDR + d
    tf.write(d)
    tf.flush()
    subprocess.check_call([os.environ['EDITOR'], tf.name],
                          stdout=sys.stderr)
    sys.stdout.write(open(tf.name).read())


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