Rename main.py, add new interval config

This commit also tidies up a few things.

glucose-monitor.py

@@ -1,5 +1,11 @@
 #!/usr/bin/env python3
 
+"""
+glucose_monitor.py - A script to display glucose levels on a Raspberry Pi
+
+Configurable with a config file
+"""
+
 
 import argparse
 import configparser
@@ -22,7 +28,8 @@ import yaml
 
 
 # CONSTANTS
-DEFAULT_INTERVAL = 5
+DEFAULT_DATA_REFRESH_INTERVAL = 5
+DEFAULT_SCREEN_REFRESH_INTERVAL = 1
 DEFAULT_FONT_SIZE = 9
 DEFAULT_DEBUG_SCREEN_WIDTH = 128
 DEFAULT_DEBUG_SCREEN_HEIGHT = 32
@@ -260,7 +267,8 @@ def main():
             logging.fatal("no password specified in config file")
             sys.exit(1)
 
-    delay = DEFAULT_INTERVAL
+    data_refresh_interval = DEFAULT_DATA_REFRESH_INTERVAL
+    screen_refresh_interval = DEFAULT_SCREEN_REFRESH_INTERVAL
     font = "DEFAULT"
     font_size = DEFAULT_FONT_SIZE
     lines = [
@@ -269,8 +277,10 @@ def main():
     ]
     if "general" in config:
         general_config = config["general"]
-        if "interval" in general_config:
-            delay = int(config["general"]["interval"])
+        if "data_refresh_interval" in general_config:
+            data_refresh_interval = int(config["general"]["data_refresh_interval"])
+        if "screen_refresh_interval" in general_config:
+            screen_refresh_interval = int(config["general"]["screen_refresh_interval"])
 
         # TODO: Add format specifier to check if high and low
         # if "upper_bound" in general_config:
@@ -366,8 +376,6 @@ def main():
             display.setDefaultFont()
 
     while not SHOULD_EXIT:
-        display.clearScreen()
-
         try:
             graph = libreview_session.getGraph(patient_id)
             graph["connection"]["glucoseMeasurement"]
@@ -386,13 +394,14 @@ def main():
         except KeyError:
             logging.error("the data returned from the API was not in an expected format")
 
+        for _ in range(data_refresh_interval//screen_refresh_interval):
+            display.clearScreen()
             computed_output_lines = []
             for output_line in output_lines:
                 computed_output_lines.append(eval(f"f'{output_line}'"))
             display.displayLines(computed_output_lines)
 
-        time.sleep(delay)
-
+            time.sleep(screen_refresh_interval)
 
     logging.debug("exiting now...")