Fixes access error using file cache

ycast/__main__.py

@@ -3,6 +3,7 @@
 import argparse
 import logging
 import sys
+import ycast.generic as generic
 
 from ycast import __version__
 from ycast import server
@@ -23,6 +24,8 @@ def launch_server():
         logging.debug("Debug logging enabled")
     else:
         logging.getLogger('werkzeug').setLevel(logging.WARNING)
+    # TODO Should cleaning cache be optional?
+    generic.clear_cache()
     server.run(arguments.config, arguments.address, arguments.port)
 
 

ycast/generic.py

@@ -1,9 +1,12 @@
 import logging
 import os
+import shutil
+import hashlib
 
 USER_AGENT = 'YCast'
 VAR_PATH = os.path.expanduser("~") + '/.ycast'
 CACHE_PATH = VAR_PATH + '/cache'
+CACHE_NAME = 'shortid'
 
 
 class Directory:
@@ -23,6 +26,11 @@ def generate_stationid_with_prefix(uid, prefix):
     if not uid:
         logging.error("Missing station id for full station id generation")
         return None
+    if prefix != 'MY':
+        uid = write_uuid(str(uid))
+        if not uid:
+            logging.error("Unable to store uuid. See previous errors")
+            return None
     return str(prefix) + '_' + str(uid)
 
 
@@ -37,7 +45,10 @@ def get_stationid_without_prefix(uid):
     if len(uid) < 4:
         logging.error("Could not extract stationid (Invalid station id length)")
         return None
-    return uid[3:]
+    wopid = uid[3:]
+    if get_stationid_prefix(uid) != 'MY':
+        return read_uuid(wopid)
+    return wopid
 
 
 def get_cache_path(cache_name):
@@ -50,3 +61,54 @@ def get_cache_path(cache_name):
         logging.error("Could not create cache folders (%s) because of access permissions", cache_path)
         return None
     return cache_path
+
+
+def get_checksum(feed, charlimit=12):
+    hash_feed = feed.encode()
+    hash_object = hashlib.md5(hash_feed)
+    digest = hash_object.digest()
+    xor_fold = bytearray(digest[:8])
+    for i, b in enumerate(digest[8:]):
+        xor_fold[i] ^= b
+    digest_xor_fold = ''.join(format(x, '02x') for x in bytes(xor_fold))
+    return digest_xor_fold[:charlimit]
+
+
+def write_uuid(uid):
+    cache_path = get_cache_path(CACHE_NAME)
+    if not cache_path:
+        return None
+    shortid = get_checksum(uid)
+    id_file = cache_path + '/' + shortid
+    try:
+        with open(id_file, 'w') as file:
+            file.write(uid)
+    except PermissionError:
+        logging.error("Could not access station id file in cache (%s) because of access permissions",
+                      id_file)
+        return None
+    return shortid
+
+
+def read_uuid(shortid):
+    cache_path = get_cache_path(CACHE_NAME)
+    if not cache_path:
+        return None
+    id_file = cache_path + '/' + shortid
+    try:
+        with open(id_file, 'r') as file:
+            uid = file.read()
+    except PermissionError:
+        logging.error("Could not access station id file in cache (%s) because of access permissions",
+                      id_file)
+        return None
+    return uid
+
+
+def clear_cache():
+    try:
+        for root, dirs, files in os.walk(CACHE_PATH):
+            for d in dirs:
+                shutil.rmtree(os.path.join(root, d))
+    except OSError:
+        logging.error("Could not clean cache)")

ycast/my_stations.py

@@ -1,5 +1,4 @@
 import logging
-import hashlib
 
 import yaml
 
@@ -71,17 +70,6 @@ def get_stations_by_category(category):
     if my_stations_yaml and category in my_stations_yaml:
         for station_name in my_stations_yaml[category]:
             station_url = my_stations_yaml[category][station_name]
-            station_id = str(get_checksum(station_name + station_url)).upper()
+            station_id = str(generic.get_checksum(station_name + station_url)).upper()
             stations.append(Station(station_id, station_name, station_url, category))
     return stations
-
-
-def get_checksum(feed, charlimit=12):
-    hash_feed = feed.encode()
-    hash_object = hashlib.md5(hash_feed)
-    digest = hash_object.digest()
-    xor_fold = bytearray(digest[:8])
-    for i, b in enumerate(digest[8:]):
-        xor_fold[i] ^= b
-    digest_xor_fold = ''.join(format(x, '02x') for x in bytes(xor_fold))
-    return digest_xor_fold[:charlimit]