Revert "Remove interrupt functionality"

This reverts commit 6300cc54.

pi_mqtt_gpio/modules/gpiod.py

@@ -66,6 +66,28 @@ class GPIO(GenericGPIO):
         pin.request(config)
         self.pins[offset] = pin
 
+    def setup_interrupt(self, handle, pin, edge, callback, bouncetime=100):
+        """
+        install interrupt callback function
+        handle:     is returned in the callback function as identification
+        pin:        gpio to watch for interrupts
+        edge:       triggering edge: RISING, FALLING or BOTH
+        callback:   the callback function to be called, when interrupt occurs
+        bouncetime: minimum time between two interrupts
+        """
+
+        config = self.io.line_request()
+        config.consumer = 'pi-mqtt-gpio'
+        config.request_type = INTERRUPT[edge]
+        
+        t = GpioThread(chip=self.chip, offset=pin, config=config, 
+                callback=callback, bouncetime=bouncetime)
+        t.start()
+
+        self.watchers[offset] = t
+        self.GPIO_INTERRUPT_CALLBACK_LOOKUP[offset] = {"handle": t.handle,
+                                                    "callback": callback}
+
     def set_pin(self, pin, value):
         offset = pin
         self.pins[offset].set_value(value)
@@ -76,3 +98,38 @@ class GPIO(GenericGPIO):
 
     def cleanup(self):
         pass
+
+class GpioThread(threading.Thread):
+    def __init__(self, chip, offset, config, callback, bouncetime):
+        super().__init__()
+        self.daemon = True
+        self._queue = queue.Queue()
+
+        self.pin = chip.get_line(offset)
+        self.pin.request(config)
+        self.callback = callback
+        self.bouncetime = timedelta(microseconds=bouncetime)
+
+    def run(self):
+        previous_event_time = datetime.now()
+        while True:
+            if self.pin.event_wait():
+                event = self.pin.event_read()
+                if event.timestamp - previous_event_time > self.bouncetime:
+                    previous_event_time = event.timestamp
+
+                    ret = self.callback()
+                    self._queue.put(
+                        {
+                            "type": event.event_type,
+                            "time": event.timestamp,
+                            "result": ret,
+                        }
+                    )
+
+    @property
+    def handle(self):
+        if self._queue.empty():
+            return None
+
+        return self._queue.get()
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