From 8d79599a1f0e6715204c069f13077d2798e55c1c Mon Sep 17 00:00:00 2001
From: Alek Ratzloff <alekratz@gmail.com>
Date: Wed, 21 Jun 2023 00:05:24 -0700
Subject: [PATCH] Add arg parsing and subcommands

* pull - will download thumbnails and update the database
* serve - (in the future) will run an HTTP frontend server to display
  the pulled data

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>
---
 chanbans/__main__.py | 42 +++++++++++++++++++++++++++++++++++++++++-
 chanbans/pull.py     |  4 ++++
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/chanbans/__main__.py b/chanbans/__main__.py
index f861ec2..acb22e5 100644
--- a/chanbans/__main__.py
+++ b/chanbans/__main__.py
@@ -1,6 +1,46 @@
 import asyncio
+import argparse
 
 from .pull import pull
 
 
-asyncio.run(pull())
+def parse_args():
+    parser = argparse.ArgumentParser(description="Run 4chan bans archiver")
+    subparsers = parser.add_subparsers(title="Commands", dest="command")
+
+    subcommands = set()
+
+    def add_subcommand(subcommand: str, *args, **kwargs):
+        nonlocal subparsers, subcommands
+        assert (
+            subcommand not in subcommands
+        ), f"subcommand {subcommand} was already registered"
+        subcommands |= {subcommand}
+        return subparsers.add_parser(subcommand, *args, **kwargs)
+
+    _pull_parser = add_subcommand(
+        "pull",
+        help="Pull bans from 4chan, save thumbnails, update the database, and exit",
+    )
+    _serve_parser = add_subcommand("serve", help="Start HTTP server")
+    _help_parser = add_subcommand("help", help="Show this help message")
+
+    args = parser.parse_args()
+
+    if args.command not in subcommands or args.command == "help":
+        parser.print_help()
+
+    return args
+
+
+async def main():
+    args = parse_args()
+    match args.command:
+        case "pull":
+            await pull()
+        case "serve":
+            print("TODO: HTTP server")
+        case command:
+            assert False, f"unknown command {command} that was not caught in add_subcommand"
+
+asyncio.run(main())
diff --git a/chanbans/pull.py b/chanbans/pull.py
index bb58460..754f981 100644
--- a/chanbans/pull.py
+++ b/chanbans/pull.py
@@ -12,7 +12,11 @@ from .files import file_cache
 
 BANS_URL = "https://4chan.org/bans"
 PREVIEW_RE = re.compile(r"var postPreviews = (.+)")
+# TODO(args) --thumbs-dir arg
 THUMBS_DIR = Path("thumbs")
+# TODO(args) --cache-dir arg
+# this is kind of hard to do because it's set in a decorator. I think the best option would be to
+# make a global "config" object
 CACHE_DIR = Path("bans")