move cli functionality to a separate file

cli.py

@@ -0,0 +1,44 @@
+import argparse
+import http.server
+import socketserver
+import sys
+import os
+
+import recipes
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser()
+    subparsers = parser.add_subparsers(required=True, dest="subcommand")
+
+    parser_build = subparsers.add_parser("build")
+    parser_build.add_argument("directory", type=str)
+
+    parser_serve = subparsers.add_parser("serve")
+    parser_serve.add_argument("directory", type=str)
+    parser_serve.add_argument("--port", type=int, default=8000)
+    parser_serve.add_argument("--address", type=str, default="127.0.0.1")
+
+    args = parser.parse_args()
+
+    ret = 0
+    if args.subcommand == "build":
+        ret = recipes.Builder().build(args.directory)
+    elif args.subcommand == "serve":
+        os.chdir(f"{args.directory}/out/html")
+        httpd = socketserver.TCPServer(
+            (args.address, args.port), http.server.SimpleHTTPRequestHandler
+        )
+        print(f"serving at http://{args.address}:{args.port}")
+        try:
+            httpd.serve_forever()
+        except KeyboardInterrupt:
+            pass
+    else:
+        # unhandled, but valid subcommand
+        assert False
+    sys.exit(ret)
+
+
+if __name__ == "__main__":
+    main()

recipes.py

@@ -1,6 +1,5 @@
 from abc import abstractmethod
 import collections
-import sys
 from typing import Dict, List, Any, Optional, Self, Set
 import os
 import json
@@ -689,24 +688,3 @@ class Builder:
                 print("ERROR:", e)
                 return 1
         return 0
-
-
-def help() -> None:
-    print(f"usage: {sys.argv[0]} build DIR - build pages in DIR/out")
-    print(f"       {sys.argv[0]} -h        - show help")
-
-
-def main() -> None:
-    if len(sys.argv) == 2 and sys.argv[1] == "-h":
-        help()
-        sys.exit(0)
-    elif len(sys.argv) == 3 and sys.argv[1] == "build":
-        ret = Builder().build(sys.argv[2])
-        sys.exit(ret)
-    else:
-        help()
-        sys.exit(1)
-
-
-if __name__ == "__main__":
-    main()