Load argument defaults from .githubactivity.json file

To distinguish between default args and CLI args being set to the default value all argparse defaults are set to None, with the actual defaults being set separately

github_activity/cli.py

@@ -1,4 +1,5 @@
 import argparse
+import json
 import os
 import sys
 from subprocess import PIPE
@@ -71,19 +72,19 @@
 )
 parser.add_argument(
     "--include-issues",
-    default=False,
+    default=None,
     action="store_true",
     help="Include Issues in the markdown output",
 )
 parser.add_argument(
     "--include-opened",
-    default=False,
+    default=None,
     action="store_true",
     help="Include a list of opened items in the markdown output",
 )
 parser.add_argument(
     "--strip-brackets",
-    default=False,
+    default=None,
     action="store_true",
     help=(
         "If True, strip any text between brackets at the beginning of the issue/PR title. "
@@ -92,7 +93,7 @@
 )
 parser.add_argument(
     "--heading-level",
-    default=1,
+    default=None,
     type=int,
     help=(
         """Base heading level to add when generating markdown.
@@ -113,7 +114,7 @@
 )
 parser.add_argument(
     "--all",
-    default=False,
+    default=None,
     action="store_true",
     help=("""Whether to include all the GitHub tags"""),
 )
@@ -127,6 +128,33 @@
 )
 
 
+def load_config_and_defaults(args):
+    """
+    Load .githubactivity.json from the current directory,
+    override unset args with values from .githubactivity.json,
+    and set defaults for remaining args.
+    """
+    try:
+        with open(".githubactivity.json") as f:
+            config = json.load(f)
+    except FileNotFoundError:
+        config = {}
+
+    arg_defaults = {
+        "heading-level": 1,
+        "include-issues": False,
+        "include-opened": False,
+        "strip-brackets": False,
+        "all": False,
+    }
+    # Treat args as a dict
+    # https://docs.python.org/3/library/argparse.html#the-namespace-object
+    for argname in vars(args):
+        configname = argname.replace("_", "-")
+        if getattr(args, argname) is None:
+            setattr(args, argname, config.get(configname, arg_defaults.get(configname)))
+
+
 def main():
     if not _git_installed_check():
         print("git is required to run github-activity", file=sys.stderr)
@@ -140,6 +168,8 @@ def main():
     if not args.target:
         args.target = args._target
 
+    load_config_and_defaults(args)
+
     tags = args.tags.split(",") if args.tags is not None else args.tags
     # Automatically detect the target from remotes if we haven't had one passed.
     if not args.target: