#!/usr/bin/python3
import Xlib
import Xlib.display

from zope import interface
from interfaces import desktopEvent
from threading import Thread

from interfaces.message import IMessage, Debug
from zope import component

@interface.implementer(desktopEvent.IDesktop)
class Listener(Thread):

    def __init__(self, mapping, queue):
        Thread.__init__(self)
        self.queue = queue
        self.mapping = mapping
        self.active_window = None
        self.last_code = None
        self.running = False

    def getForegroundWindowTitle(self):
        """ Return the name of the selected window
        """
        return self.active_window

    def run(self):
        disp = Xlib.display.Display()
        NET_WM_NAME = disp.intern_atom('_NET_WM_NAME')
        WM_CLASS = disp.intern_atom('WM_CLASS')
        NET_ACTIVE_WINDOW = disp.intern_atom('_NET_ACTIVE_WINDOW')
        root = disp.screen().root
        root.change_attributes(event_mask=Xlib.X.PropertyChangeMask)

        component.handle(Debug("Waiting for xlib event"))
        self.running = True
        while self.running:
            event = disp.next_event()
            try:
                window_id = root.get_full_property(NET_ACTIVE_WINDOW, Xlib.X.AnyPropertyType).value[0]
                window = disp.create_resource_object('window', window_id)
                window.change_attributes(event_mask=Xlib.X.PropertyChangeMask)
                window_prop = window.get_full_property(NET_WM_NAME, 0)
                if window_prop is None:
                    continue
                window_name = str(window_prop.value).lower()
                class_name = str(window.get_full_property(WM_CLASS, 0).value).lower()
            except Xlib.error.XError:
                continue

            if window_name is None or window_name == self.active_window:
                continue

            self.active_window = window_name
            found = False
            for pattern, code in self.mapping.items():
                # Ignore the default layout
                if pattern == "default":
                    continue
                if not (pattern in window_name or pattern in class_name):
                    continue
                # We found something. At this point, even if we do not update
                # the layer (because it is the same as the previous) we do not
                # switch back to the default layer.
                found = True
                if  code != self.last_code:

                    component.handle(Debug("Switching to '%s' for '%s'" % (code, window_name)))
                    self.queue.put ( (code, None) )
                    self.last_code = code
                    break
            if not found and self.last_code != "default":
                default = self.mapping.get("default", None)
                if default is None:
                    continue

                self.queue.put ( (default, None) )
                self.last_code = "default"

    def stop(self):
        self.running = False