#!/usr/bin/env python3

#

# Dumps output generated by Mercurial's command server in a formatted style to a

# given file or stderr if '-' is specified. Output is also written in its raw

# format to stdout.

#

# $ ./hg serve --cmds pipe | ./contrib/debugcmdserver.py -

# o, 52   -> 'capabilities: getencoding runcommand\nencoding: UTF-8'

from __future__ import absolute_import, print_function

import struct

import sys

if len(sys.argv) != 2:

    print('usage: debugcmdserver.py FILE')

    sys.exit(1)

outputfmt = '>cI'

outputfmtsize = struct.calcsize(outputfmt)

if sys.argv[1] == '-':

    log = sys.stderr

else:

    log = open(sys.argv[1], 'a')

def read(size):

    data = sys.stdin.read(size)

    if not data:

        raise EOFError

    sys.stdout.write(data)

    sys.stdout.flush()

    return data

try:

    while True:

        header = read(outputfmtsize)

        channel, length = struct.unpack(outputfmt, header)

        log.write('%s, %-4d' % (channel, length))

        if channel in 'IL':

            log.write(' -> waiting for input\n')

        else:

            data = read(length)

            log.write(' -> %r\n' % data)

        log.flush()

except EOFError:

    pass

finally:

    if log != sys.stderr:

        log.close()