# 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 __future__ import absolute_import

import errno

import os

import struct

import sys

import traceback

from .i18n import _

from . import (

    encoding,

    error,

    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 to out in the following format:

    data length (unsigned int),

    data

    """

    def __init__(self, out, channel):

        self.out = out

        self.channel = channel

    @property

    def name(self):

        return '<%c-channel>' % self.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', 'tell', 'seek'):

            raise AttributeError(attr)

        return getattr(self.out, 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

    @property

    def name(self):

        return '<%c-channel>' % self.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:

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

                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':

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

                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', 'tell', 'seek'):

            raise AttributeError(attr)

        return getattr(self.in_, attr)

class server(object):

    """

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

    based stream to fout.

    """

    def __init__(self, ui, repo, fin, fout):

        self.cwd = os.getcwd()

        # developer config: cmdserver.log

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

        if logpath:

            global logfile

            if logpath == '-':

                # write log on a special 'd' (debug) channel

                logfile = channeledoutput(fout, 'd')

            else:

                logfile = open(logpath, 'a')

        if repo:

            # the ui here is really the repo ui so take its baseui so we don't

            # end up with its local configuration

            self.ui = repo.baseui

            self.repo = repo

            self.repoui = repo.ui

        else:

            self.ui = ui

            self.repo = self.repoui = None

        self.cerr = channeledoutput(fout, 'e')

        self.cout = channeledoutput(fout, 'o')

        self.cin = channeledinput(fin, fout, 'I')

        self.cresult = channeledoutput(fout, 'r')

        self.client = fin

    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 _readstr(self):

        """read a string from the channel

        format:

        data length (uint32), data

        """

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

        if not length:

            return ''

        return self._read(length)

    def _readlist(self):

        """read a list of NULL separated strings from the channel"""

        s = self._readstr()

        if s:

            return s.split('\0')

        else:

            return []

    def runcommand(self):

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

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

        from . import dispatch  # avoid cycle

        args = self._readlist()

        # copy the uis so changes (e.g. --config or --verbose) don't

        # persist between requests

        copiedui = self.ui.copy()

        uis = [copiedui]

        if self.repo:

            self.repo.baseui = copiedui

            # clone ui without using ui.copy because this is protected

            repoui = self.repoui.__class__(self.repoui)

            repoui.copy = copiedui.copy # redo copy protection

            uis.append(repoui)

            self.repo.ui = self.repo.dirstate._ui = repoui

            self.repo.invalidateall()

        for ui in uis:

            ui.resetstate()

            # any kind of interaction must use server channels, but chg may

            # replace channels by fully functional tty files. so nontty is

            # enforced only if cin is a channel.

            if not util.safehasattr(self.cin, 'fileno'):

                ui.setconfig('ui', 'nontty', 'true', 'commandserver')

        req = dispatch.request(args[:], copiedui, self.repo, self.cin,

                               self.cout, self.cerr)

        ret = (dispatch.dispatch(req) or 0) & 255 # might return None

        # restore old cwd

        if '--cwd' in args:

            os.chdir(self.cwd)

        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 error.Abort(_('unknown command %s') % cmd)

        return cmd != ''

    capabilities = {'runcommand'  : runcommand,

                    'getencoding' : getencoding}

    def serve(self):

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

        hellomsg += '\n'

        hellomsg += 'encoding: ' + encoding.encoding

        hellomsg += '\n'

        hellomsg += 'pid: %d' % util.getpid()

        # 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

def _protectio(ui):

    """ duplicates streams and redirect original to null if ui uses stdio """

    ui.flush()

    newfiles = []

    nullfd = os.open(os.devnull, os.O_RDWR)

    for f, sysf, mode in [(ui.fin, sys.stdin, 'rb'),

                          (ui.fout, sys.stdout, 'wb')]:

        if f is sysf:

            newfd = os.dup(f.fileno())

            os.dup2(nullfd, f.fileno())

            f = os.fdopen(newfd, mode)

        newfiles.append(f)

    os.close(nullfd)

    return tuple(newfiles)

def _restoreio(ui, fin, fout):

    """ restores streams from duplicated ones """

    ui.flush()

    for f, uif in [(fin, ui.fin), (fout, ui.fout)]:

        if f is not uif:

            os.dup2(f.fileno(), uif.fileno())

            f.close()

class pipeservice(object):

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

        self.ui = ui

        self.repo = repo

    def init(self):

        pass

    def run(self):

        ui = self.ui

        # redirect stdio to null device so that broken extensions or in-process

        # hooks will never cause corruption of channel protocol.

        fin, fout = _protectio(ui)

        try:

            sv = server(ui, self.repo, fin, fout)

            return sv.serve()

        finally:

            _restoreio(ui, fin, fout)

    def handle(self):

        ui = self.server.ui

        repo = self.server.repo

        sv = None

        try:

            sv = server(ui, repo, self.rfile, self.wfile)

            try:

                sv.serve()

            # handle exceptions that may be raised by command server. most of

            # known exceptions are caught by dispatch.

            except error.Abort as inst:

                ui.warn(_('abort: %s\n') % inst)

            except IOError as inst:

                if inst.errno != errno.EPIPE:

                    raise

            except KeyboardInterrupt:

                pass

        except: # re-raises

            # also write traceback to error channel. otherwise client cannot

            # see it because it is written to server's stderr by default.

            if sv:

                cerr = sv.cerr

            else:

                cerr = channeledoutput(self.wfile, 'e')

            traceback.print_exc(file=cerr)

            raise

class unixservice(object):

    """

    Listens on unix domain socket and forks server per connection

    """

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

        self.ui = ui

        self.repo = repo

        self.address = opts['address']

            raise error.Abort(_('unsupported platform'))

        if not self.address:

            raise error.Abort(_('no socket path specified with --address'))

    def init(self):

            ui = self.ui

            repo = self.repo

        self.server = cls(self.address, _requesthandler)

        self.ui.status(_('listening at %s\n') % self.address)

        self.ui.flush()  # avoid buffering of status message

    def run(self):

        try:

            self.server.serve_forever()

        finally:

            os.unlink(self.address)

_servicemap = {

    'pipe': pipeservice,

    'unix': unixservice,

    }

def createservice(ui, repo, opts):

    mode = opts['cmdserver']

    try:

        return _servicemap[mode](ui, repo, opts)

    except KeyError:

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