# A minimal client for Mercurial's command server

import sys, struct, subprocess, cStringIO

def connect(path=None):

    cmdline = ['hg', 'serve', '--cmdserver', 'pipe']

    if path:

        cmdline += ['-R', path]

    server = subprocess.Popen(cmdline, stdin=subprocess.PIPE,

                              stdout=subprocess.PIPE)

    return server

def writeblock(server, data):

    server.stdin.write(struct.pack('>I', len(data)))

    server.stdin.write(data)

    server.stdin.flush()

def readchannel(server):

    data = server.stdout.read(5)

    if not data:

        raise EOFError

    channel, length = struct.unpack('>cI', data)

    if channel in 'IL':

        return channel, length

    else:

        return channel, server.stdout.read(length)

def sep(text):

    return text.replace('\\', '/')

def runcommand(server, args, output=sys.stdout, error=sys.stderr, input=None,

               outfilter=lambda x: x):

    print '*** runcommand', ' '.join(args)

    sys.stdout.flush()

    server.stdin.write('runcommand\n')

    writeblock(server, '\0'.join(args))

    if not input:

        input = cStringIO.StringIO()

    while True:

        ch, data = readchannel(server)

        if ch == 'o':

            output.write(outfilter(data))

            output.flush()

        elif ch == 'e':

            error.write(data)

            error.flush()

        elif ch == 'I':

            writeblock(server, input.read(data))

        elif ch == 'L':

            writeblock(server, input.readline(data))

        elif ch == 'r':

            ret, = struct.unpack('>i', data)

            if ret != 0:

                print ' [%d]' % ret

            return ret

        else:

            print "unexpected channel %c: %r" % (ch, data)

            if ch.isupper():

                return

    sys.stdout.flush()

    try:

        return func(server)

    finally:

        server.stdin.close()

        server.wait()