Improve option parsing

gl-sak

@@ -7,9 +7,11 @@ entities (issues, labels, milestones, etc) in a GitLab project.
 
 Usage
 
-  $ ./gl-sak --root OWNER[/PROJECT_PATH] COMMAND [ARGS...]
+  $ ./gl-sak --gitlab=GL_SERVER --user USER [--root PROJECT_PATH] COMMAND [ARGS...]
 
-OWNER/PROJECT_PATH is something like "jrandom/foo/bar/myproj".
+E.g., 
+
+  $ ./gl-sak --user jrandom --gitlab=https://code.librehq.com --root foo/bar/myproj baz qux quux
 
 TBD: Document some commands, some of which take further arguments.
 
@@ -76,26 +78,39 @@ def main():
         # here would be RawDescriptionHelpFormatter.
         formatter_class=argparse.RawTextHelpFormatter)
     arg_parser.add_argument(
+        '--gitlab',
+        help="The URL of the GitLab server (not with path appended)")
+    arg_parser.add_argument(
+        '--root',
+        help="The root path of the project to operate on")
+    arg_parser.add_argument(
+        '--user',
+        help="The username to log in to GitLab with")
+    authn_token_arg = arg_parser.add_mutually_exclusive_group()
+    authn_token_arg.add_argument(
         '-T', '--authn-token',
-        # TBD: This next one is not implemented yet.  Also, how to
-        # tell argparse that two options are mutually incompatible?
-        # Do we just have to do that with post-parsing code, or does
-        # argparse have a built-in way to handle it?
-        '-F', '--authn-token-file',
         help="The GitLab access token to use for this operation")
+    authn_token_arg.add_argument(
+        '-F', '--authn-token-file',
+        help="File containing the GitLab access token to use for this operation")
+
     args = arg_parser.parse_args()
 
+    if args.authn_token_file is not None:
+        with open(args.authn_token_file, "r") as f:
+            args.authn_token = f.readline().rstrip()
+
     # Set up the GitLab instance.
-    lhq = gitlab.Gitlab(url='https://code.librehq.com', 
+    gl = gitlab.Gitlab(url=args.gitlab,
                         private_token=args.authn_token)
-    lhq.auth()
+    gl.auth()
 
     # WARNING: Turning on debugging can cause credentials and other
     # sensitive data to be printed on the console.
     #
-    # lhq.enable_debug()
+    # gl.enable_debug()
 
-    projects = lhq.projects.list(iterator=True)
+    projects = gl.projects.list(iterator=True)
     for project in projects:
         print(f"*** {project.name_with_namespace} ({project.id}):")
         issues = project.issues.list(get_all=True)
@@ -103,13 +118,13 @@ def main():
         #     print(f"{issue}")
         print("")
     
-    groups = lhq.groups.list(iterator=True)
+    groups = gl.groups.list(iterator=True)
     for group in groups:
         print(f"{group}")
 
     # This isn't quite right yet:
     # 
-    # boards = lhq.boards.list(iterator=True)
+    # boards = gl.boards.list(iterator=True)
     # for board in boards:
     #     print(f"*** {board} ({board.id}):")