# -*- coding: utf-8 -*-
# Free Software Foundation; either version 2.1 of the License, or (at your
# option) any later version.

# This library 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 Lesser General Public License
# for more details.

# You should have received a copy of the GNU Lesser General Public License
# along with this library; if not, write to the Free Software Foundation,
# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

"""
    pyudev.wx
    =========

    Provides :class:`~pyudev.wx.WXUDevMonitorObserver` to integrate a
    :class:`~pyudev.Monitor` into a :meth:`wx.App.MainLoop`.

    To use this module, :mod:`wx` from wxPython must be available.

    .. moduleauthor::  Tobias Eberle  <tobias.eberle@gmx.de>
    .. versionadded:: 0.14
"""


from __future__ import (print_function, division, unicode_literals,
                        absolute_import)

from wx import EvtHandler, PostEvent
from wx.lib.newevent import NewEvent

from pyudev.monitor import MonitorObserver


DeviceEvent, EVT_DEVICE_EVENT = NewEvent()
DeviceAddedEvent, EVT_DEVICE_ADDED = NewEvent()
DeviceRemovedEvent, EVT_DEVICE_REMOVED = NewEvent()
DeviceChangedEvent, EVT_DEVICE_CHANGED = NewEvent()
DeviceMovedEvent, EVT_DEVICE_MOVED = NewEvent()


class WxUDevMonitorObserver(EvtHandler):
    """
    Observe a :class:`~pyudev.Monitor` and post wx events upon device events:

    >>> context = pyudev.Context()
    >>> monitor = pyudev.Monitor.from_netlink(context)
    >>> monitor.filter_by(subsystem='input')
    >>> observer = pyudev.wx.WxUDevMonitorObserver(monitor)
    >>> def device_connected(event):
    ...     print('{0!r} added'.format(event.device))
    >>> observer.Bind(EVT_DEVICE_ADDED, device_connected)
    >>> monitor.start()

    This class is a child of :class:`wx.EvtHandler`.
    """

    _action_event_map = {
        'add': DeviceAddedEvent,
        'remove': DeviceRemovedEvent,
        'change': DeviceChangedEvent,
        'move': DeviceMovedEvent
    }

    def __init__(self, monitor):
        EvtHandler.__init__(self)
        self.monitor = monitor
        self._observer_thread = None
        self.start()

    @property
    def enabled(self):
        """
        Whether this observer is enabled or not.

        If ``True`` (the default), this observer is enabled, and emits events.
        Otherwise it is disabled and does not emit any events.
        """
        return self._observer_thread is not None

    @enabled.setter
    def enabled(self, value):
        if value:
            self.start()
        else:
            self.stop()

    def start(self):
        """
        Enable this observer.

        Do nothing, if the observer is already enabled.
        """
        if self._observer_thread is not None:
            return
        self._observer_thread = MonitorObserver(
            self.monitor, self._emit_events, name='wx-observer-thread')
        self._observer_thread.start()

    def stop(self):
        """
        Disable this observer.

        Do nothing, if the observer is already disabled.
        """
        if self._observer_thread is None:
            return
        self._observer_thread.stop()

    def _emit_events(self, action, device):
        PostEvent(self, DeviceEvent(action=action, device=device))
        event_class = self._action_event_map[action]
        PostEvent(self, event_class(device=device))