Add support for creating private CTF channels

Fix issue OpenToAllCTF#125

Add util method for parsing args for options. This method takes an array and
searches for any strings in that array beginning with a hyphen. If it
encounters such a string it strips the leading punctuation from that string and
puts it into a new array. After iterating the given array it returns a 2-tuple
containing the new array of options sans leading punctuation and the original
array minus those extracted options.

handlers/challenge_handler.py

@@ -95,6 +95,10 @@ class AddCTFCommand(Command):
     @classmethod
     def execute(cls, slack_wrapper, args, timestamp, channel_id, user_id, user_is_admin):
         """Execute AddCTF command."""
+
+        # Pull options out into its own array
+        opts, args = parse_opts(args)
+
         name = args[0].lower()
         long_name = " ".join(args[1:])
 
@@ -110,7 +114,8 @@ def execute(cls, slack_wrapper, args, timestamp, channel_id, user_id, user_is_ad
             raise InvalidCommand("Add CTF failed: Invalid characters for CTF name found.")
 
         # Create the channel
-        response = slack_wrapper.create_channel(name)
+        is_private = True if 'private' in opts else False
+        response = slack_wrapper.create_channel(name, is_private)
 
         # Validate that the channel was successfully created.
         if not response['ok']:

util/util.py

@@ -1,13 +1,30 @@
 import json
 import pickle
 import re
+from string import punctuation
 
 from bottypes.invalid_command import InvalidCommand
 
 #######
 # Helper functions
 #######
 
+def parse_opts(_args):
+    """
+    Filter an array of args and extract those beginning with a hyphen into a
+    new array called opts, removing any/all leading punctuation in the process.
+    Return a 2-tuple like ([opts], [args])
+    """
+    opts = []
+    args = []
+    for arg in _args:
+        if arg.startswith('-'):
+            arg = arg.strip(punctuation)
+            opts.append(arg)
+        else:
+            args.append(arg)
+    return (opts,args)
+
 
 def load_json(string):
     """