Port MPRIS plugin to new API

There's still no support for telling Kaylee that a handler failed, so
errors pass silently now.  The plugin got much more long-winded, but at
least we only have to get the MPRIS proxy object once instead of three
separate times like we did before.

kayleevc/plugins/mpris.py

@@ -19,9 +19,10 @@ this plugin.  Recognition while music is playing may still be mediocre,
 but without module-echo-cancel it has almost no chance of working.
 """
 
+from gi.repository import GLib
 from pydbus import SessionBus
 
-from .pluginbase import PluginBase
+from . import PluginBase, Handler
 
 
 class Plugin(PluginBase):
@@ -36,14 +37,14 @@ class Plugin(PluginBase):
         self._dbus_proxy = self._bus.get('.DBus')
 
         self.commands = {
-            'next song': self._next,
-            'next video': self._next,
-            'pause music': self._pause,
-            'pause video': self._pause,
-            'play music': self._play,
-            'play video': self._play,
-            'previous song': self._previous,
-            'previous video': self._previous
+            'next song': MPRISNextHandler,
+            'next video': MPRISNextHandler,
+            'pause music': MPRISPauseHandler,
+            'pause video': MPRISPauseHandler,
+            'play music': MPRISPlayHandler,
+            'play video': MPRISPlayHandler,
+            'previous song': MPRISPreviousHandler,
+            'previous video': MPRISPreviousHandler
         }
 
         self.corpus_strings.update(self.commands)
@@ -59,39 +60,77 @@ class Plugin(PluginBase):
         except IndexError:
             return None
 
-    def _next(self):
+    def get_handler(self, text):
+        """Return a handler if a recognized command is heard"""
+        if text not in self.corpus_strings:
+            return None
         p = self._mpris_proxy()
-        if p is not None:
-            p.Next()
+        if p is None:
+            return None
+        # Make a handler for the command we heard
+        return self.commands[text](1, p)
 
-    def _pause(self):
-        p = self._mpris_proxy()
-        if p is not None:
-            p.Pause()
 
-    def _play(self):
-        p = self._mpris_proxy()
-        if p is not None:
-            p.Play()
+class MPRISHandler(Handler):
+    """Base class for MPRIS plugin handlers"""
 
-    def _previous(self):
-        p = self._mpris_proxy()
-        if p is not None:
-            p.Previous()
+    def __init__(self, confidence, proxy):
+        """Store the MPRIS proxy object"""
+        super().__init__(confidence)
+        self.proxy = proxy
 
-    def confidence(self, text):
-        """Return whether or not the command can be handled"""
-        if text not in self.corpus_strings:
-            return 0
-        if self._mpris_proxy() is None:
-            return 0
-        return 1
-
-    def handle(self, text):
-        """Print and speak the phrase when it is heard"""
-        # Is there a matching command?
-        if self.confidence(text):
-            self.commands[text]()
-            return True
-        else:
-            return False
+
+class MPRISNextHandler(MPRISHandler):
+    """Handler for the MPRIS Next method"""
+
+    def __call__(self, tts):
+        """Call the MPRIS Next method"""
+        try:
+            self.proxy.Next()
+        except GLib.Error:
+            # This error is raised if the media player was closed after we got
+            # the proxy but before we called next.
+            # FIXME raise a different exception to tell Kaylee that we failed
+            pass
+
+
+class MPRISPauseHandler(MPRISHandler):
+    """Handler for the MPRIS Pause method"""
+
+    def __call__(self, tts):
+        """Call the MPRIS Pause method"""
+        try:
+            self.proxy.Pause()
+        except GLib.Error:
+            # This error is raised if the media player was closed after we got
+            # the proxy but before we called pause.
+            # FIXME raise a different exception to tell Kaylee that we failed
+            pass
+
+
+class MPRISPlayHandler(MPRISHandler):
+    """Handler for the MPRIS Play method"""
+
+    def __call__(self, tts):
+        """Call the MPRIS Play method"""
+        try:
+            self.proxy.Play()
+        except GLib.Error:
+            # This error is raised if the media player was closed after we got
+            # the proxy but before we called play.
+            # FIXME raise a different exception to tell Kaylee that we failed
+            pass
+
+
+class MPRISPreviousHandler(MPRISHandler):
+    """Handler for the MPRIS Previous method"""
+
+    def __call__(self, tts):
+        """Call the MPRIS Previous method"""
+        try:
+            self.proxy.Previous()
+        except GLib.Error:
+            # This error is raised if the media player was closed after we got
+            # the proxy but before we called previous.
+            # FIXME raise a different exception to tell Kaylee that we failed
+            pass