From 8b98dcf1cea75c96faea8dddba1300e72adc01e7 Mon Sep 17 00:00:00 2001
From: Jan Tuomi <jans.tuomi@gmail.com>
Date: Sun, 24 Sep 2017 13:16:01 +0300
Subject: [PATCH] Delegate a bunch of logic to the ESP

---
 coffee_scale/mqtt.py  | 77 ++++++++++++++-----------------------------
 coffee_scale/views.py | 27 +++------------
 2 files changed, 29 insertions(+), 75 deletions(-)

diff --git a/coffee_scale/mqtt.py b/coffee_scale/mqtt.py
index 3a984fb..ad259b7 100644
--- a/coffee_scale/mqtt.py
+++ b/coffee_scale/mqtt.py
@@ -3,74 +3,47 @@ import logging
 import datetime
 from collections import deque
 
-MQTT_HOST = "mqtt.sik.party"
+MQTT_HOST = 'mqtt.sik.party'
 
-TOPIC_TEMP = "sik/kiltahuone/kahvivaaka/temperature"
-TOPIC_WEIGHT = "sik/kiltahuone/kahvivaaka/weight"
+TOPIC_BREW_TIME = 'sik/kiltahuone/kahvivaaka/brewtime'
+TOPIC_WEIGHT = 'sik/kiltahuone/kahvivaaka/weight'
+TOPIC_BREWING = 'sik/kiltahuone/kahvivaaka/brewing'
+TOPIC_CUPS = 'sik/kiltahuone/kahvivaaka/cups'
 
-BREWING_DIFFERENTIAL_MIN = 60
-# setting down the pan creates at least 800 g of weight
-BREWING_DIFFERENTIAL_MAX = 180
-
-WEIGHT_DEQUE_LENGTH = 20
-weight_deque = deque(maxlen=WEIGHT_DEQUE_LENGTH)
-latest = {
-    'last_brew': datetime.datetime.now()
-}
-
-
-def calc_averaged_weight():
-    if len(weight_deque) > 2:
-        half = []
-        for i in range(0, int(len(weight_deque) / 2)):
-            half.append(weight_deque[i])
-
-        return sum(half) / len(half)
-    else:
-        return 0
+latest = {}
 
 
 def on_connect(client, userdata, flags, rc):
-    logging.info('Subscribing to all topics on mqtt.sik.party.')
-    client.subscribe("#")
+    logging.info('Connected successfully to MQTT.')
+    logging.info('Subscribing to all topics on {}.'.format(MQTT_HOST))
+    client.subscribe('sik/kiltahuone/kahvivaaka/#')
 
 
 def on_message(client, userdata, msg):
-    if msg.topic == TOPIC_TEMP:
-        latest['temp'] = float(msg.payload.decode('utf-8'))
-    elif msg.topic == TOPIC_WEIGHT:
-        weight = float(msg.payload.decode('utf-8'))
-
-        # avoid showing erroneous data from an empty scale
-        if weight > 50:  # g
-            weight_deque.appendleft(weight)
+    payload = msg.payload.decode('utf-8')
+    if msg.topic == TOPIC_WEIGHT:
+        weight = float(payload)
+        latest['weight'] = weight
+    elif msg.topic == TOPIC_CUPS:
+        cups = float(payload)
+        latest['cups'] = cups
+    elif msg.topic == TOPIC_BREWING:
+        brewing = bool(int(payload))
+        latest['brewing'] = brewing
+    elif msg.topic == TOPIC_BREW_TIME:
+        brew_time = datetime.datetime.fromtimestamp(float(payload))
+        latest['brew_time'] = brew_time
 
 
 def on_disconnect(client, userdata, rc):
     if rc != 0:
-        logging.warning("MQTT unexpectedly disconnected.")
+        logging.warning('MQTT unexpectedly disconnected.')
     else:
         client.loop_stop(force=False)
-        logging.warning("MQTT disconnected.")
+        logging.warning('MQTT disconnected.')
 
 
 def get_latest():
-    if len(weight_deque) > 2:
-        first = weight_deque[0]
-        last = weight_deque[len(weight_deque) - 1]
-        diff = first - last  # reverse order
-
-    if len(weight_deque) < WEIGHT_DEQUE_LENGTH:
-        brewing = False
-    else:
-        if BREWING_DIFFERENTIAL_MIN < diff < BREWING_DIFFERENTIAL_MAX:
-            brewing = True
-            latest['last_brew'] = datetime.datetime.now()
-        else:
-            brewing = False
-
-    latest['brewing'] = brewing
-    latest['weight'] = calc_averaged_weight()
     return latest
 
 
@@ -82,8 +55,8 @@ client.on_disconnect = on_disconnect
 
 try:
     logging.info('Connecting to MQTT at {}...'.format(MQTT_HOST))
+    logging.info('If there is no confirmation, the MQTT connection has probably failed.')
     client.connect_async(MQTT_HOST, 1883, 60)
-    logging.info('Connected successfully to MQTT.')
 except Exception as ex:
     logging.error(ex)
     logging.error('Failed to connect to MQTT at {}'.format(MQTT_HOST))
diff --git a/coffee_scale/views.py b/coffee_scale/views.py
index fcfbc50..4d226e3 100644
--- a/coffee_scale/views.py
+++ b/coffee_scale/views.py
@@ -9,24 +9,6 @@ import logging
 from django.conf import settings
 
 
-def get_cups_from_weight(weight):
-    if not weight:
-        return 0
-
-    EMPTY = 820  # grams
-    FULL = 2000  # grams
-    cups = 10 * (weight - EMPTY) / (FULL - EMPTY)
-
-    cups = round(cups, 1)
-    if cups < 0.5:
-        cups = 0
-    if cups > 10:
-        cups = 10
-
-    # logging.debug("Coffee cups: {}, weight: {}".format(cups, weight))
-    return cups
-
-
 def coffee_view(request):
     logging.info('User navigated to coffee page!')
     return render(request, 'coffee.html')
@@ -35,12 +17,11 @@ def coffee_view(request):
 def cups_view(request):
     now = datetime.datetime.now()
     latest = get_latest()
-    cups = get_cups_from_weight(latest.get('weight'))
     data = {
         'date': now,
-        'cups': cups,
-        'temp': latest.get('temp'),
-        'last_brew': latest.get('last_brew'),
-        'brewing': latest.get('brewing')
+        'cups': latest.get('cups'),
+        'last_brew': latest.get('brew_time'),
+        'brewing': latest.get('brewing'),
+        'weight': latest.get('weight')
     }
     return JsonResponse(data)