republisher/repub/entrypoint.py

from __future__ import annotations

import argparse
import asyncio
import logging
import os
import signal
import sys
from contextlib import suppress

from hypercorn.asyncio import serve as hypercorn_serve
from hypercorn.config import Config as HypercornConfig

import repub.crawl as crawl_module
from repub.web import SHUTDOWN_EVENT_KEY, create_app

FeedNameFilter = crawl_module.FeedNameFilter
check_runtime = crawl_module.check_runtime

__all__ = ["FeedNameFilter", "check_runtime", "entrypoint", "parse_args"]

logger = logging.getLogger(__name__)
logger.setLevel(logging.DEBUG)
logger.propagate = False
if not logger.handlers:
    handler = logging.StreamHandler()
    handler.setLevel(logging.DEBUG)
    handler.setFormatter(
        logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
    )
    logger.addHandler(handler)


def parse_args(argv: list[str] | None = None) -> tuple[str, argparse.Namespace]:
    raw_args = list(argv) if argv is not None else sys.argv[1:]

    parser = argparse.ArgumentParser(description="Mirror RSS and Atom feeds")
    subparsers = parser.add_subparsers(dest="command")

    serve_parser = subparsers.add_parser("serve", help="Start the republisher web UI")
    serve_parser.add_argument(
        "--host",
        default=os.environ.get("REPUBLISHER_HOST", "127.0.0.1"),
        help="Host interface for the web UI",
    )
    serve_parser.add_argument(
        "--port",
        default=os.environ.get("REPUBLISHER_PORT", "8080"),
        help="Port for the web UI",
    )
    serve_parser.add_argument(
        "--dev-mode",
        action="store_true",
        help="Serve published feeds from /feeds for local development",
    )

    crawl_parser = subparsers.add_parser("crawl", help="Run the feed crawler once")
    crawl_parser.add_argument(
        "-c",
        "--config",
        default="repub.toml",
        help="Path to runtime config TOML file",
    )
    if not raw_args:
        raw_args = ["serve", "--dev-mode"]
    elif raw_args[0] in {"-c", "--config"}:
        raw_args = ["crawl", *raw_args]
    elif raw_args[0] not in {"serve", "crawl"}:
        raw_args = ["serve", "--dev-mode", *raw_args]

    args = parser.parse_args(raw_args)
    command = args.command or "serve"
    return command, args


def _install_signal_handlers(stop_event: asyncio.Event) -> None:
    loop = asyncio.get_running_loop()

    def request_stop(*_: object) -> None:
        if not stop_event.is_set():
            stop_event.set()

    for signum in (signal.SIGINT, signal.SIGTERM):
        try:
            loop.add_signal_handler(signum, request_stop)
        except NotImplementedError:
            signal.signal(signum, request_stop)


async def _serve_app(*, host: str, port: int, dev_mode: bool) -> None:
    stop_event = asyncio.Event()
    _install_signal_handlers(stop_event)

    app = create_app(dev_mode=dev_mode)
    app.extensions[SHUTDOWN_EVENT_KEY] = stop_event

    config = HypercornConfig()
    config.bind = [f"{host}:{port}"]
    config.use_reloader = False
    config.accesslog = "-"
    config.errorlog = "-"

    async def shutdown_trigger() -> None:
        await stop_event.wait()

    try:
        await hypercorn_serve(app, config, shutdown_trigger=shutdown_trigger)
    finally:
        stop_event.set()


def entrypoint(argv: list[str] | None = None) -> int:
    command, args = parse_args(argv)

    if command == "crawl":
        crawl_module.check_runtime = check_runtime
        return crawl_module.crawl_from_config(args.config)

    try:
        port = int(args.port)
    except ValueError:
        logger.error("Invalid REPUBLISHER_PORT/--port value: %s", args.port)
        return 2

    with suppress(KeyboardInterrupt):
        asyncio.run(_serve_app(host=args.host, port=port, dev_mode=bool(args.dev_mode)))
    return 0


if __name__ == "__main__":
    sys.exit(entrypoint())