Cancel any current phrase when Talon is waking (talonhub#1435)

When Talon wakes we set a timestamp threshold. On the next command we
will compare the phrase timestamp to the threshold and cancel any phrase
started before wakeup. This is to prevent commands from being executed
if the user wakes Talon using a noise or keypress.

---------

Co-authored-by: Nicholas Riley <com-github@sabi.net>

plugin/cancel/cancel.py

@@ -1,20 +1,72 @@
 # to disable command cancellation, comment out this entire file.
 # you may also wish to adjust the commands in misc/cancel.talon.
-from talon import actions, speech_system
+
+import time
+
+from talon import Context, Module, actions, speech_system
+from talon.grammar import Phrase
 
 # To change the phrase used to cancel commands, you must also adjust misc/cancel.talon
 cancel_phrase = "cancel cancel".split()
 
+mod = Module()
+ctx = Context()
 
-def pre_phrase(d):
-    n = len(cancel_phrase)
-    if "text" in d and "parsed" in d:
-        before, after = d["text"][:-n], d["text"][-n:]
-        if after != cancel_phrase:
+ts_threshold: float = 0
+
+
+@ctx.action_class("speech")
+class SpeechActions:
+    # When Talon wakes we set the timestamp threshold. On the next command we
+    # will compare the phrase timestamp to the threshold and cancel any phrase
+    # started before wakeup. This is to prevent speech said before wake-up to
+    # be interpreted as a command if the user wakes Talon using a noise or
+    # keypress.
+    def enable():
+        actions.user.cancel_current_phrase()
+        actions.next()
+
+
+@mod.action_class
+class Actions:
+    def cancel_current_phrase():
+        """Cancel/abort current spoken phrase"""
+        global ts_threshold
+        ts_threshold = time.perf_counter()
+
+
+def pre_phrase(phrase: Phrase):
+    global ts_threshold
+
+    words = phrase["phrase"]
+
+    if not words:
+        return
+
+    # Check if the phrase is before the threshold
+    if ts_threshold != 0:
+        start = getattr(words[0], "start", phrase["_ts"])
+        phrase_starts_before_threshold = start < ts_threshold
+        ts_threshold = 0
+        # Start of phrase is before threshold timestamp
+        if phrase_starts_before_threshold:
+            print(f"Canceled phrase: {' '.join(words)}")
+            cancel_entire_phrase(phrase)
             return
-        # cancel the command
-        d["parsed"]._sequence = []
+
+    # Check if the phrase is a cancel command
+    n = len(cancel_phrase)
+    before, after = words[:-n], words[-n:]
+    if after == cancel_phrase:
         actions.app.notify(f"Command canceled: {' '.join(before)!r}")
+        cancel_entire_phrase(phrase)
+        return
+
+
+def cancel_entire_phrase(phrase: Phrase):
+    phrase["phrase"] = []
+    if "parsed" in phrase:
+        phrase["parsed"]._sequence = []
 
 
 speech_system.register("pre:phrase", pre_phrase)