config: add a basic storage backend

$XDG_DATA_HOME/tuhi/<mac address>/settings.ini

And that file contains a [Device] section with two entries, address and uuid.

example.ini

@@ -0,0 +1,3 @@
+[Device]
+Address=E2:43:03:67:0E:01
+UUID=dead00beef00

tuhi.py

@@ -20,6 +20,7 @@ from gi.repository import GObject
 from tuhi.dbusserver import TuhiDBusServer
 from tuhi.ble import BlueZDeviceManager
 from tuhi.wacom import WacomDevice, Stroke
+from tuhi.config import TuhiConfig
 
 logging.basicConfig(format='%(levelname)s: %(name)s: %(message)s',
                     level=logging.INFO)
@@ -76,14 +77,16 @@ class TuhiDevice(GObject.Object):
     over Tuhi's DBus interface
     """
 
-    def __init__(self, bluez_device, tuhi_dbus_device, paired=True):
+    def __init__(self, bluez_device, tuhi_dbus_device, uuid=None, paired=True):
         GObject.Object.__init__(self)
         self._tuhi_dbus_device = tuhi_dbus_device
-        self._wacom_device = WacomDevice(bluez_device)
+        self._wacom_device = WacomDevice(bluez_device, uuid)
         self._wacom_device.connect('drawing', self._on_drawing_received)
         self._wacom_device.connect('done', self._on_fetching_finished, bluez_device)
         self._wacom_device.connect('button-press-required', self._on_button_press_required)
         self.drawings = []
+        # We need either uuid or paired as false
+        assert uuid is not None or paired is False
         self.paired = paired
 
         bluez_device.connect('connected', self._on_bluez_device_connected)
@@ -165,6 +168,8 @@ class Tuhi(GObject.Object):
         self.bluez.connect('discovery-started', self._on_bluez_discovery_started)
         self.bluez.connect('discovery-stopped', self._on_bluez_discovery_stopped)
 
+        self.config = TuhiConfig()
+
         self.devices = {}
 
         self._search_stop_handler = None
@@ -199,8 +204,16 @@ class Tuhi(GObject.Object):
         if Tuhi._is_pairing_device(bluez_device):
             return
 
+        try:
+            config = self.config.devices[bluez_device.address]
+            uuid = config['uuid']
+        except KeyError:
+            logger.info('{}: device without config, must be paired first'.format(bluez_device.address))
+            return
+
+        logger.debug('{}: uuid {}'.format(bluez_device.address, uuid))
         tuhi_dbus_device = self.server.create_device(bluez_device)
-        d = TuhiDevice(bluez_device, tuhi_dbus_device)
+        d = TuhiDevice(bluez_device, tuhi_dbus_device, uuid=uuid)
         self.devices[bluez_device.address] = d
 
     def _on_bluez_discovery_started(self, manager):

tuhi/config.py

@@ -0,0 +1,64 @@
+#!/usr/bin/env python3
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 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 General Public License for more details.
+#
+
+from gi.repository import GObject
+
+import xdg.BaseDirectory
+import os
+import configparser
+import re
+import logging
+
+logger = logging.getLogger('tuhi.config')
+
+ROOT_PATH = os.path.join(xdg.BaseDirectory.xdg_data_home, 'tuhi')
+
+
+class TuhiConfig(GObject.Object):
+    def __init__(self):
+        GObject.Object.__init__(self)
+        try:
+            os.mkdir(ROOT_PATH)
+        except FileExistsError:
+            pass
+
+        self._devices = {}
+        self._scan_config_dir()
+
+    @property
+    def devices(self):
+        """
+        Returns a dictionary with the bluetooth address as key
+        """
+        return self._devices
+
+    def _scan_config_dir(self):
+        with os.scandir(ROOT_PATH) as it:
+            for entry in it:
+                if entry.is_file():
+                    continue
+
+                if not re.match('^([0-9A-F]{2}[:-]){5}([0-9A-F]{2})$', entry.name):
+                    continue
+
+                path = os.path.join(ROOT_PATH, entry.name, 'settings.ini')
+                if not os.path.isfile(path):
+                    continue
+
+                logger.debug("{}: configuration found".format(entry.name))
+                config = configparser.ConfigParser()
+                config.read(path)
+
+                assert config['Device']['Address'] == entry.name
+                self._devices[entry.name] = config['Device']
+