#!/usr/bin/python
#-*- coding: utf-8 -*-

# SAT communication bridge
# Copyright (C) 2009-2016 Jérôme Poisson (goffi@goffi.org)

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.

# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from sat.core.i18n import _
from bridge_frontend import BridgeFrontend, BridgeException
import dbus
from sat.core.log import getLogger
log = getLogger(__name__)
from sat.core.exceptions import BridgeExceptionNoService, BridgeInitError

from dbus.mainloop.glib import DBusGMainLoop
DBusGMainLoop(set_as_default=True)

import ast

const_INT_PREFIX = "org.goffi.SAT"  # Interface prefix
const_ERROR_PREFIX = const_INT_PREFIX + ".error"
const_OBJ_PATH = '/org/goffi/SAT/bridge'
const_CORE_SUFFIX = ".core"
const_PLUGIN_SUFFIX = ".plugin"
const_TIMEOUT = 120


def dbus_to_bridge_exception(dbus_e):
    """Convert a DBusException to a BridgeException.

    @param dbus_e (DBusException)
    @return: BridgeException
    """
    full_name = dbus_e.get_dbus_name()
    if full_name.startswith(const_ERROR_PREFIX):
        name = dbus_e.get_dbus_name()[len(const_ERROR_PREFIX) + 1:]
    else:
        name = full_name
    # XXX: dbus_e.args doesn't contain the original DBusException args, but we
    # receive its serialized form in dbus_e.args[0]. From that we can rebuild
    # the original arguments list thanks to ast.literal_eval (secure eval).
    message = dbus_e.get_dbus_message()  # similar to dbus_e.args[0]
    try:
        message, condition = ast.literal_eval(message)
    except (SyntaxError, ValueError, TypeError):
        condition = ''
    return BridgeException(name, message, condition)


class DBusBridgeFrontend(BridgeFrontend):
    def __init__(self):
        try:
            self.sessions_bus = dbus.SessionBus()
            self.db_object = self.sessions_bus.get_object(const_INT_PREFIX,
                                                          const_OBJ_PATH)
            self.db_core_iface = dbus.Interface(self.db_object,
                                                dbus_interface=const_INT_PREFIX + const_CORE_SUFFIX)
            self.db_plugin_iface = dbus.Interface(self.db_object,
                                                  dbus_interface=const_INT_PREFIX + const_PLUGIN_SUFFIX)
        except dbus.exceptions.DBusException, e:
            if e._dbus_error_name == 'org.freedesktop.DBus.Error.ServiceUnknown':
                raise BridgeExceptionNoService
            elif e._dbus_error_name == 'org.freedesktop.DBus.Error.NotSupported':
                log.error(_(u"D-Bus is not launched, please see README to see instructions on how to launch it"))
                raise BridgeInitError
            else:
                raise e
        #props = self.db_core_iface.getProperties()

    def register(self, functionName, handler, iface="core"):
        if iface == "core":
            self.db_core_iface.connect_to_signal(functionName, handler)
        elif iface == "plugin":
            self.db_plugin_iface.connect_to_signal(functionName, handler)
        else:
            log.error(_('Unknown interface'))

    def __getattribute__(self, name):
        """ usual __getattribute__ if the method exists, else try to find a plugin method """
        try:
            return object.__getattribute__(self, name)
        except AttributeError:
            # The attribute is not found, we try the plugin proxy to find the requested method

            def getPluginMethod(*args, **kwargs):
                # We first check if we have an async call. We detect this in two ways:
                #   - if we have the 'callback' and 'errback' keyword arguments
                #   - or if the last two arguments are callable

                async = False

                if kwargs:
                    if 'callback' in kwargs:
                        async = True
                        _callback = kwargs.pop('callback')
                        _errback = kwargs.pop('errback', lambda failure: log.error(unicode(failure)))
                elif len(args) >= 2 and callable(args[-1]) and callable(args[-2]):
                    async = True
                    args = list(args)
                    _errback = args.pop()
                    _callback = args.pop()

                method = getattr(self.db_plugin_iface, name)

                if async:
                    kwargs['timeout'] = const_TIMEOUT
                    kwargs['reply_handler'] = _callback
                    kwargs['error_handler'] = lambda err: _errback(dbus_to_bridge_exception(err))

                return method(*args, **kwargs)

            return getPluginMethod

##METHODS_PART##