Improve cli, add subcommands and flags.

omicron/ssg/cli.py

@@ -1,10 +1,56 @@
+import argparse
 import logging
 import sys
-from omicron.ssg.site import Site
+from omicron.ssg.output import OutputError
+from omicron.ssg.site import ConfigError, Site
 from pathlib import Path
 
 
-def setup_logging(verbose: bool = False, log_file: str | None = None) -> None:
+class CliError(RuntimeError):
+    pass
+
+
+def setup_argparse() -> argparse.ArgumentParser:
+    # base options
+    help_formatter = argparse.ArgumentDefaultsHelpFormatter
+    parser = argparse.ArgumentParser(prog="ossg", formatter_class=help_formatter)
+    parser.add_argument(
+        "--site", type=Path, default=Path("."), help="path to site directory"
+    )
+    parser.add_argument(
+        "--verbose", "-v", action="count", default=0, help="increase log verbosity"
+    )
+    parser.add_argument(
+        "--log-file",
+        type=Path,
+        default=argparse.SUPPRESS,
+        help="write logs to this file (default: <site>/build.log)",
+    )
+
+    subparsers = parser.add_subparsers(dest="command", required=True)
+
+    # build command
+    build = subparsers.add_parser(
+        "build", help="build the site", formatter_class=help_formatter
+    )
+    build.add_argument(
+        "--clean",
+        action=argparse.BooleanOptionalAction,
+        default=True,
+        help="remove output directory before building",
+    )
+    build.add_argument(
+        "--drafts",
+        action=argparse.BooleanOptionalAction,
+        default=False,
+        help="include draft content",
+    )
+    subparsers.add_parser("clean", help="remove the output directory")
+
+    return parser
+
+
+def setup_logging(verbose: bool = False, log_file: Path | None = None) -> None:
     logger = logging.getLogger("omicron.ssg")
     logger.setLevel(logging.DEBUG)
 
@@ -13,8 +59,46 @@ def setup_logging(verbose: bool = False, log_file: str | None = None) -> None:
     console.setFormatter(logging.Formatter("%(levelname)s: %(message)s"))
     logger.addHandler(console)
 
+    if log_file is not None:
+        try:
+            file_handler = logging.FileHandler(log_file)
+        except FileNotFoundError as e:
+            raise CliError("log file can't be written") from e
+        file_handler.setLevel(logging.DEBUG)
+        file_handler.setFormatter(
+            logging.Formatter("%(asctime)s %(levelname)s: %(message)s")
+        )
+        logger.addHandler(file_handler)
+
+
+def build(args: argparse.Namespace) -> None:
+    site = Site(args.site, args.drafts)
+    if args.clean:
+        site.clean()
+    site.build()
+
+
+def clean(args: argparse.Namespace) -> None:
+    site = Site(args.site)
+    site.clean()
+
+
+def cli() -> None:
+    parser = setup_argparse()
+    args = parser.parse_args()
+    log_file = getattr(args, "log_file", args.site / "build.log")
+    setup_logging(verbose=bool(args.verbose), log_file=log_file)
+    if args.command == "build":
+        build(args)
+    elif args.command == "clean":
+        clean(args)
+    else:
+        raise NotImplementedError(f"'{args.command}' command not implemented yet")
+
 
 def main() -> None:
-    setup_logging(verbose=True)
-    site = Site(Path("."))
-    site.build()
+    try:
+        cli()
+    except (ConfigError, OutputError, CliError) as e:
+        print(e)
+        sys.exit(1)

omicron/ssg/site.py

@@ -1,4 +1,5 @@
 import logging
+import shutil
 from typing import Any, cast
 from urllib.parse import urlparse
 
@@ -31,7 +32,7 @@ class ConfigError(RuntimeError):
 
 
 class Site:
-    def __init__(self, site: Path):
+    def __init__(self, site: Path, drafts: bool = False):
         self.site_path = site.resolve()
         self.content: list[Content] = []
         self.directories: list[Directory] = []
@@ -54,8 +55,11 @@ class Site:
     def read_config(self) -> dict[str, Any]:
         config_path = self.site_path / "config.yml"
         log.debug("Reading config file %s", config_path)
-        with open(config_path, "r") as f:
-            config = yaml.safe_load(f)
+        try:
+            with open(config_path, "r") as f:
+                config = yaml.safe_load(f)
+        except FileNotFoundError:
+            raise ConfigError("config file missing, not a valid ossg directory")
         if not isinstance(config, dict) or not all(isinstance(k, str) for k in config):
             raise ConfigError("config file must be a YAML mapping with string keys")
         if "name" not in config:
@@ -188,6 +192,12 @@ class Site:
         self.other_outputs.append(tags_page)
         log.info("Discovered %d content items", len(self.content))
 
+    def clean(self) -> None:
+        if not self.output_path.exists():
+            return
+        shutil.rmtree(self.output_path)
+        log.info("Removed %s", self.output_path)
+
     def build(self) -> None:
         if not self.origin:
             log.warning(