# commandserver.py - communicate with Mercurial's API over a pipe

#

#  Copyright Matt Mackall <mpm@selenic.com>

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

from i18n import _

import struct

import sys

import dispatch, encoding, util

logfile = None

def log(*args):

    if not logfile:

        return

    for a in args:

        logfile.write(str(a))

    logfile.flush()

class channeledoutput(object):

    """

    Write data from in_ to out in the following format:

    data length (unsigned int),

    data

    """

    def __init__(self, in_, out, channel):

        self.in_ = in_

        self.out = out

        self.channel = channel

    def write(self, data):

        if not data:

            return

        self.out.write(struct.pack('>cI', self.channel, len(data)))

        self.out.write(data)

        self.out.flush()

    def __getattr__(self, attr):

        if attr in ('isatty', 'fileno'):

            raise AttributeError, attr

        return getattr(self.in_, attr)

class channeledinput(object):

    """

    Read data from in_.

    Requests for input are written to out in the following format:

    channel identifier - 'I' for plain input, 'L' line based (1 byte)

    how many bytes to send at most (unsigned int),

    The client replies with:

    data length (unsigned int), 0 meaning EOF

    data

    """

    maxchunksize = 4 * 1024

    def __init__(self, in_, out, channel):

        self.in_ = in_

        self.out = out

        self.channel = channel

    def read(self, size=-1):

        if size < 0:

            # if we need to consume all the clients input, ask for 4k chunks

            # so the pipe doesn't fill up risking a deadlock

            size = self.maxchunksize

            s = self._read(size, self.channel)

            buf = s

            while s:

                buf += s

            return buf

        else:

            return self._read(size, self.channel)

    def _read(self, size, channel):

        if not size:

            return ''

        assert size > 0

        # tell the client we need at most size bytes

        self.out.write(struct.pack('>cI', channel, size))

        self.out.flush()

        length = self.in_.read(4)

        length = struct.unpack('>I', length)[0]

        if not length:

            return ''

        else:

            return self.in_.read(length)

    def readline(self, size=-1):

        if size < 0:

            size = self.maxchunksize

            s = self._read(size, 'L')

            buf = s

            # keep asking for more until there's either no more or

            # we got a full line

            while s and s[-1] != '\n':

                buf += s

            return buf

        else:

            return self._read(size, 'L')

    def __iter__(self):

        return self

    def next(self):

        l = self.readline()

        if not l:

            raise StopIteration

        return l

    def __getattr__(self, attr):

        if attr in ('isatty', 'fileno'):

            raise AttributeError, attr

        return getattr(self.in_, attr)

class server(object):

    """

    Listens for commands on stdin, runs them and writes the output on a channel

    based stream to stdout.

    """

    def __init__(self, ui, repo, mode):

        self.ui = ui

        logpath = ui.config("cmdserver", "log", None)

        if logpath:

            global logfile

            if logpath == '-':

                # write log on a special 'd'ebug channel

                logfile = channeledoutput(sys.stdout, sys.stdout, 'd')

            else:

                logfile = open(logpath, 'a')

        self.repo = repo

        if mode == 'pipe':

            self.cerr = channeledoutput(sys.stderr, sys.stdout, 'e')

            self.cout = channeledoutput(sys.stdout, sys.stdout, 'o')

            self.cin = channeledinput(sys.stdin, sys.stdout, 'I')

            self.cresult = channeledoutput(sys.stdout, sys.stdout, 'r')

            self.client = sys.stdin

        else:

            raise util.Abort(_('unknown mode %s') % mode)

    def _read(self, size):

        if not size:

            return ''

        data = self.client.read(size)

        # is the other end closed?

        if not data:

            raise EOFError()

        return data

    def runcommand(self):

        """ reads a list of \0 terminated arguments, executes

        and writes the return code to the result channel """

        length = struct.unpack('>I', self._read(4))[0]

        if not length:

            args = []

        else:

            args = self._read(length).split('\0')

        # copy the ui so changes to it don't persist between requests

        req = dispatch.request(args, self.ui.copy(), self.repo, self.cin,

                               self.cout, self.cerr)

        ret = dispatch.dispatch(req) or 0 # might return None

        self.cresult.write(struct.pack('>i', int(ret)))

    def getencoding(self):

        """ writes the current encoding to the result channel """

        self.cresult.write(encoding.encoding)

    def serveone(self):

        cmd = self.client.readline()[:-1]

        if cmd:

            handler = self.capabilities.get(cmd)

            if handler:

                handler(self)

            else:

                # clients are expected to check what commands are supported by

                # looking at the servers capabilities

                raise util.Abort(_('unknown command %s') % cmd)

        return cmd != ''

    capabilities = {'runcommand'  : runcommand,

                    'getencoding' : getencoding}

    def serve(self):

        hellomsg = 'capabilities: ' + ' '.join(self.capabilities.keys())

        hellomsg += '\n'

        hellomsg += 'encoding: ' + encoding.encoding

        # write the hello msg in -one- chunk

        self.cout.write(hellomsg)

        try:

            while self.serveone():

                pass

        except EOFError:

            # we'll get here if the client disconnected while we were reading

            # its request

            return 1

        return 0