argparse stuff

src/pricehist/cli.py

@@ -1,10 +1,42 @@
+import argparse
 import sys
+from datetime import datetime
 
 from pricehist.location import greet
 
 def cli(args=None):
-    """Process command line arguments."""
-    if not args:
-        args = sys.argv[1:]
-    tz = args[0]
-    print(greet(tz))
+    parser = build_parser()
+    args = parser.parse_args()
+
+def build_parser():
+    def valid_date(s):
+        if s == 'today':
+            return today()
+        try:
+            datetime.strptime(s, "%Y-%m-%d")
+            return s
+        except ValueError:
+            msg = "Not a valid date: '{0}'.".format(s)
+            raise argparse.ArgumentTypeError(msg)
+
+    def today():
+        return str(datetime.now().date())
+
+    parser = argparse.ArgumentParser(description='Fetch historical price data from CoinMarketCap.com.')
+
+    parser.add_argument('identifier', metavar='ID', type=str,
+                        help='currency or coin identifier from URL (example: bitcoin-cash)')
+
+    parser.add_argument('--start', dest='start', type=valid_date,
+                        default='2009-01-03',
+                        help='start date (default: 2009-01-03)')
+
+    parser.add_argument('--end', dest='end', type=valid_date,
+                        default=today(),
+                        help='end date (default: today)')
+
+    parser.add_argument('--csv', dest='csv', action='store_true',
+                        help='print full data as csv (instead of Ledger pricedb format)')
+
+    return parser
+