Further externalization and exceptions

some more methods for easier accessing the steps done to give the answer
now also includes exeptions with handlers

bot.py

@@ -4,6 +4,8 @@ import re
 from telegram import InlineQueryResultArticle, InputTextMessageContent
 from telegram.ext import Updater, CommandHandler, InlineQueryHandler
 
+from exceptions import *
+
 token_file = open("token", "r")
 updater = Updater(token=token_file.read(), use_context=True)
 token_file.close()
@@ -41,23 +43,27 @@ def search_station(query):
 
 
 def handle_vvs(update, context):
-    for reply in get_vvs_departures(context.args):
+    query = parse_station(context.args)
+    departures = get_vvs_departures(query)
+
+    for reply in departures:
         update.message.reply_text(reply)
 
 
-def get_vvs_departures(args):
-    reply = []
+def parse_station(args):
     if len(args) == 0:
-        reply.append("No argument specified")
-        return reply
+        raise NoArgError
     query = Query(args)
     if query.station_id == -1:
-        reply.append("No station matching this name found!")
-        return reply
+        raise StationNotFoundError
+    return query
+
+
+def get_vvs_departures(query):
+    reply = []
     request = requests.get("https://efa-api.asw.io/api/v1/station/" + query.station_id + "/departures")
     if request.status_code != 200:
-        reply.append("Error with server communication")
-        return reply
+        raise ServerCommunicationError
     reply.append("Next departures:")
     printed_departures = 0
     for station in request.json():
@@ -95,11 +101,25 @@ def get_station_id_list(name):
     return request.json()
 
 
+def error_callback(update, context):
+    try:
+        raise context.error
+    except NoArgError:
+        update.message.reply_text('No argument specified!')
+        return
+    except StationNotFoundError:
+        update.message.reply_text('No station matching this name found!')
+        return
+    except ServerCommunicationError:
+        update.message.reply_text('Error with server communication')
+        return
+
+
 inline_station_search_handler = InlineQueryHandler(inline_station_search)
 
 dispatcher.add_handler(inline_station_search_handler)
-
-updater.dispatcher.add_handler(CommandHandler('vvs', handle_vvs))
+dispatcher.add_handler(CommandHandler('vvs', handle_vvs))
+dispatcher.add_error_handler(error_callback)
 
 updater.start_polling()
 updater.idle()

exceptions.py

@@ -0,0 +1,10 @@
+class NoArgError(Exception):
+    pass
+
+
+class StationNotFoundError(Exception):
+    pass
+
+
+class ServerCommunicationError(Exception):
+    pass