Implement cache and work on weather

.gitignore

@@ -1 +1,3 @@
 /__pycache__/
+/test*.png
+/cache.sqlite

bom.py

@@ -1,15 +1,41 @@
 from ftplib import FTP
 import xml.etree.ElementTree as ET
 
-ftp = FTP('ftp.bom.gov.au')
-file = []
-try:
+def fetch_forecast():
+    file = []
+    with FTP('ftp.bom.gov.au') as ftp:
         ftp.login()
-    ftp.cwd('anon/gen/fwo')
-    ftp.retrbinary('RETR IDV17000.xml', file.append)
-finally:
-    ftp.quit()
+        ftp.retrlines('RETR anon/gen/fwo/IDV10450.xml', file.append)
+    return ''.join(file)
 
+def parse_forecast(xml):
+    root = ET.fromstring(xml)
+    [today] = root.findall('./forecast/area[@aac="VIC_PT042"]/forecast-period[@index="0"]')
+    return today
+
+import cache
+import datetime
+with cache.open() as cache:
+    print(parse_forecast(cache.get('weather', datetime.timedelta(minutes=10), fetch_forecast)))
+
+file = []
+with FTP('ftp.bom.gov.au') as ftp:
+    ftp.login()
+    ftp.retrlines('RETR anon/gen/fwo/IDV60920.xml', file.append)
 root = ET.fromstringlist(file)
-print(root)
-print([e.attrib['description'] for e in root.findall('./forecast/area')])
+stations = root.findall('./observations/station')
+
+from math import cos, asin, sqrt, pi
+
+def distance(lat1, lon1, lat2, lon2):
+    r = 6371 # km
+    p = pi / 180
+
+    a = 0.5 - cos((lat2-lat1)*p)/2 + cos(lat1*p) * cos(lat2*p) * (1-cos((lon2-lon1)*p))/2
+    return 2 * r * asin(sqrt(a))
+def dist(station):
+    lat, lon = [float(station.attrib[k]) for k in ['lat', 'lon']]
+    return distance(lat, lon, -37.82635, 145.09653)
+stations.sort(key=dist)
+for station in stations:
+    print(station.attrib['stn-name'], dist(station))

cache.py

@@ -0,0 +1,32 @@
+import contextlib
+import datetime
+import sqlite3
+
+class Cache:
+    def __init__(self, db):
+        self.db = db
+
+    def get(self, key, timeout, f):
+        now = datetime.datetime.now()
+        earliest_acceptable = now - timeout
+        match self.db.execute(
+            'SELECT value FROM cache WHERE key = ? AND timestamp >= ?',
+            (key, earliest_acceptable.isoformat()),
+        ).fetchall():
+            case [(value,)]:
+                self.db.commit()
+                return value
+
+        value = f()
+        self.db.execute(
+            'INSERT INTO cache (key, timestamp, value) VALUES (?, ?, ?) ' +
+            'ON CONFLICT(key) DO UPDATE SET timestamp = excluded.timestamp, value = excluded.value',
+            (key, now.isoformat(), value),
+        )
+        return value
+
+@contextlib.contextmanager
+def open():
+    with sqlite3.connect('cache.sqlite', isolation_level=None) as db:
+        db.execute('CREATE TABLE IF NOT EXISTS cache (key TEXT PRIMARY KEY, timestamp TEXT NOT NULL, value TEXT NOT NULL)')
+        yield Cache(db)

demo.py

@@ -1,66 +0,0 @@
-#!/usr/bin/python
-import sys
-import os
-picdir = os.path.dirname(os.path.realpath(__file__))
-
-import logging
-import epd7in3g
-import time
-from PIL import Image, ImageDraw, ImageFont
-
-logging.basicConfig(level=logging.DEBUG)
-
-try:
-    logging.info("epd7in3g Demo")
-
-    epd = epd7in3g
-    logging.info("init and Clear")
-    epd.init()
-    #epd.clear()
-    font24 = ImageFont.truetype(os.path.join(picdir, 'Font.ttc'), 24)
-    font18 = ImageFont.truetype(os.path.join(picdir, 'Font.ttc'), 18)
-    font40 = ImageFont.truetype(os.path.join(picdir, 'Font.ttc'), 40)
-
-    # Drawing on the image
-    logging.info("1.Drawing on the image...")
-    h_image = Image.new('RGB', (epd.width, epd.height), epd.WHITE)  # 255: clear the frame
-    draw = ImageDraw.Draw(h_image)
-    draw.text((5, 0), 'hello world', font = font18, fill = epd.RED)
-    draw.text((5, 20), '7.3inch e-Paper', font = font24, fill = epd.YELLOW)
-    draw.text((5, 45), u'微雪电子', font = font40, fill = epd.BLACK)
-    draw.text((5, 85), u'微雪电子', font = font40, fill = epd.YELLOW)
-    draw.text((5, 125), u'微雪电子', font = font40, fill = epd.RED)
-
-    draw.line((5, 170, 80, 245), fill = epd.RED)
-    draw.line((80, 170, 5, 245), fill = epd.YELLOW)
-    draw.rectangle((5, 170, 80, 245), outline = epd.BLACK)
-    draw.rectangle((90, 170, 165, 245), fill = epd.YELLOW)
-    draw.arc((5, 250, 80, 325), 0, 360, fill = epd.BLACK)
-    draw.chord((90, 250, 165, 325), 0, 360, fill = epd.RED)
-    epd.display(epd.get_buffer(h_image))
-    time.sleep(3)
-
-    ## read bmp file
-    #logging.info("2.read bmp file")
-    #h_image = Image.open(os.path.join(picdir, '7.3inch-1.bmp'))
-    #epd.display(epd.get_buffer(h_image))
-    #time.sleep(3)
-
-    #logging.info("3.read bmp file")
-    #h_image = Image.open(os.path.join(picdir, '7.3inch-2.bmp'))
-    #epd.display(epd.get_buffer(h_image))
-    #time.sleep(3)
-
-    #logging.info("4.read bmp file")
-    #h_image = Image.open(os.path.join(picdir, '7.3inch-3.bmp'))
-    #epd.display(epd.getbuffer(h_image))
-    #time.sleep(3)
-
-    logging.info("Clear...")
-    epd.clear()
-
-    logging.info("Goto Sleep...")
-    epd.sleep()
-
-finally:
-    epd7in3g.epdconfig.module_exit(cleanup=True)