currency: Improved exception handling

Co-authored-by: dgw <dgw@technobabbl.es>
Co-authored-by: Humorous Baby <humorbaby@humorbaby.net>

sopel/modules/currency.py

@@ -39,26 +39,45 @@
 
 class CurrencySection(StaticSection):
     fixer_io_key = ValidatedAttribute('fixer_io_key', default=None)
+    """Optional API key for Fixer.io (increases currency support)"""
     auto_convert = ValidatedAttribute('auto_convert', parse=bool, default=False)
+    """Whether to convert currencies without an explicit command"""
 
 
 def configure(config):
+    """
+    | name | example | purpose |
+    | ---- | ------- | ------- |
+    | auto\\_convert | False | Whether to convert currencies without an explicit command |
+    | fixer\\_io\\_key | 0123456789abcdef0123456789abcdef | Optional API key for Fixer.io (increases currency support) |
+    """
     config.define_section('currency', CurrencySection, validate=False)
     config.currency.configure_setting('fixer_io_key', 'Optional API key for Fixer.io (leave blank to use exchangeratesapi.io):')
-    config.currency.configure_setting('auto_convert', 'Automatically respond to currency conversion lines?')
+    config.currency.configure_setting('auto_convert', 'Whether to convert currencies without an explicit command?')
 
 
 def setup(bot):
     bot.config.define_section('currency', CurrencySection)
 
 
+class FixerError(Exception):
+    """A Fixer.io API Error Exception"""
+    def __init__(self, status):
+        super(FixerError, self).__init__("FixerError: {}".format(status))
+
+
+class UnsupportedCurrencyError(Exception):
+    """A currency is currently not supported by the API"""
+    def __init__(self, currency):
+        super(UnsupportedCurrencyError, self).__init__(currency)
+
+
 def update_rates(bot):
     global rates_fiat_json, rates_btc_json, rates_updated
 
-    # If we have data that are less than 24h old, return
-    if 'date' in rates_fiat_json:
-        if time.time() - rates_updated < 24 * 60 * 60:
-            return
+    # If we have data that is less than 24h old, return
+    if time.time() - rates_updated < 24 * 60 * 60:
+        return
 
     # Update crypto rates
     response = requests.get(CRYPTO_URL)
@@ -69,8 +88,7 @@ def update_rates(bot):
     if bot.config.currency.fixer_io_key is not None:
         response = requests.get(FIXER_URL.format(bot.config.currency.fixer_io_key))
         if not response.json()['success']:
-            LOGGER.error(str(response.json()['error']))
-            return bot.reply('Sorry, something went wrong')
+            raise FixerError('Fixer.io request failed with error: {}'.format(response.json()['error']))
     else:
         response = requests.get(FIAT_URL)
 
@@ -86,7 +104,7 @@ def btc_rate(code, reverse=False):
     if search in rates_btc_json:
         rate = rates_btc_json[search]['averages']['day']
     else:
-        return UNSUPPORTED_CURRENCY.format(code)
+        raise UnsupportedCurrencyError(code)
 
     if reverse:
         return 1 / rate
@@ -98,21 +116,16 @@ def get_rate(of, to):
     of = of.upper()
     to = to.upper()
 
-    if of == 'BTC' or to == 'BTC':
-        if of == 'BTC':
-            code = to
-            reverse = False
-        else:
-            code = of
-            reverse = True
-
-        return btc_rate(code, reverse)
+    if of == 'BTC':
+        return btc_rate(to, False)
+    elif to == 'BTC':
+        return btc_rate(of, True)
 
     if of not in rates_fiat_json['rates']:
-        return UNSUPPORTED_CURRENCY.format(of)
+        raise UnsupportedCurrencyError(of)
 
     if to not in rates_fiat_json['rates']:
-        return UNSUPPORTED_CURRENCY.format(to)
+        raise UnsupportedCurrencyError(to)
 
     return (1 / rates_fiat_json['rates'][of]) * rates_fiat_json['rates'][to]
 
@@ -125,14 +138,18 @@ def exchange(bot, match):
 
     try:
         update_rates(bot)  # Try and update rates. Rate-limiting is done in update_rates()
-    except requests.exceptions.RequestException as e:
+    except requests.exceptions.RequestException as err:
         bot.reply("Something went wrong while I was getting the exchange rate.")
-        LOGGER.error("Error in GET request: {}".format(e))
+        LOGGER.error("Error in GET request: {}".format(err))
         return NOLIMIT
     except ValueError:
         bot.reply("Error: Got malformed data.")
         LOGGER.error("Invalid json on update_rates")
         return NOLIMIT
+    except FixerError as err:
+        bot.reply('Sorry, something went wrong with Fixer')
+        LOGGER.error(err)
+        return NOLIMIT
 
     query = match.string
 
@@ -151,11 +168,24 @@ def exchange(bot, match):
     except OverflowError:
         bot.reply("Sorry, input amount was out of range.")
 
+    if not amount:
+        bot.reply("Zero is zero, no matter what country you're in.")
+        return NOLIMIT
+
     out_string = '{} {} is'.format(amount, of.upper())
+
     for to in others:
         try:
-            out_string = build_reply(bot, amount, of.upper(), to.upper(), out_string)
+            out_string = build_reply(amount, of.upper(), to.upper(), out_string)
         except ValueError:
+            LOGGER.error("Raw rate wasn't a float")
+            return NOLIMIT
+        except KeyError as err:
+            bot.reply("Error: Invalid rates")
+            LOGGER.error("No key: {} in json".format(err))
+            return NOLIMIT
+        except UnsupportedCurrencyError as cur:
+            bot.reply(UNSUPPORTED_CURRENCY.format(cur))
             return NOLIMIT
 
     bot.reply(out_string[0:-1])
@@ -183,18 +213,9 @@ def exchange_re(bot, trigger):
         exchange(bot, match)
 
 
-def build_reply(bot, amount, of, to, out_string):
-    if not amount:
-        bot.reply("Zero is zero, no matter what country you're in.")
-
-    rate_raw = ''
-    try:
-        rate_raw = get_rate(of, to)
-        rate = float(rate_raw)
-    except ValueError:
-        bot.reply(rate_raw)
-        raise
-
+def build_reply(amount, of, to, out_string):
+    rate_raw = get_rate(of, to)
+    rate = float(rate_raw)
     result = float(rate * amount)
 
     if to == 'BTC':