From 63b0ad3c76bf2929df5d359b92f89a2a5f4350d6 Mon Sep 17 00:00:00 2001
From: Brett Smith <brettcsmith@brettcsmith.org>
Date: Wed, 17 May 2017 15:34:51 -0400
Subject: [PATCH] Configuration: Improve --help output throughout.

---
 oxrlib/config.py | 52 +++++++++++++++++++++++++++++-------------------
 1 file changed, 32 insertions(+), 20 deletions(-)

diff --git a/oxrlib/config.py b/oxrlib/config.py
index e4db88d..af712ad 100644
--- a/oxrlib/config.py
+++ b/oxrlib/config.py
@@ -57,7 +57,11 @@ class Configuration:
         )
         subparsers = prog_parser.add_subparsers()
 
-        hist_parser = subparsers.add_parser('historical', aliases=['hist'])
+        hist_parser = subparsers.add_parser(
+            'historical', aliases=['hist'],
+            usage='%(prog)s historical YYYY-MM-DD [[amount] code] [[in] code]',
+            help="Show a currency conversion or rate from a past date",
+        )
         hist_parser.set_defaults(
             command='historical',
             amount=None,
@@ -70,12 +74,24 @@ class Configuration:
         )
         hist_parser.add_argument(
             'date',
-            type=date_from('%Y-%m-%d'), metavar='YYYY-MM-DD',
+            type=date_from('%Y-%m-%d'),
+            help="Use rates from this date, in YYYY-MM-DD format"
         )
         hist_parser.add_argument(
-            'remainder',
-            nargs=argparse.REMAINDER,
+            'word1', nargs='?', metavar='first code',
+            help="Convert or show rates from this currency, in three-letter code format. "
+            "If not specified, show all rates on the given date.",
         )
+        hist_parser.add_argument(
+            'word2', nargs='?', metavar='amount',
+            help="Convert this amount of currency. If not specified, show rates.",
+        )
+        hist_parser.add_argument(
+            'word3', nargs='?', metavar='second code',
+            help="Convert to this currency, in three-letter code format. "
+            "If not specified, defaults to the base currency.",
+        )
+        hist_parser.add_argument('word4', nargs='?', help=argparse.SUPPRESS)
 
         return prog_parser
 
@@ -101,25 +117,21 @@ class Configuration:
         if self.args.base is None:
             self.args.base = self.conffile.get('Historical', 'base')
         self.args.to_currency = self.args.base
-        remain_len = len(self.args.remainder)
-        if (remain_len > 3) and (self.args.remainder[2].lower() in self.PREPOSITIONS):
-            del self.args.remainder[2]
-            remain_len -= 1
-        if remain_len == 0:
+        if self.args.word4 and (self.args.word3.lower() in self.PREPOSITIONS):
+            self.args.word3 = self.args.word4
+        if self.args.word1 is None:
             pass
-        elif remain_len == 1:
+        elif self.args.word2 is None:
             self.args.from_currency = self._convert_or_error(
-                currency_code, self.args.remainder[0])
-        elif remain_len < 4:
-            self.args.amount = self._convert_or_error(
-                decimal.Decimal, self.args.remainder[0])
-            self.args.from_currency = self._convert_or_error(
-                currency_code, self.args.remainder[1])
-            if remain_len == 3:
-                self.args.to_currency = self._convert_or_error(
-                    currency_code, self.args.remainder[2])
+                currency_code, self.args.word1)
         else:
-            self.error("too many arguments")
+            self.args.amount = self._convert_or_error(
+                decimal.Decimal, self.args.word1)
+            self.args.from_currency = self._convert_or_error(
+                currency_code, self.args.word2)
+            if self.args.word3 is not None:
+                self.args.to_currency = self._convert_or_error(
+                    currency_code, self.args.word3 or self.args.base)
 
     def _build_cache_loader(self):
         kwargs = dict(self.conffile.items('Cache'))