import os
import logging
import signal
import sys
from typing import List
import ssl
from asyncio import run, gather
import asyncio

from lib.backend import Backend
from lib.metrics import Metrics
from aiohttp import web

log = logging.getLogger(__file__)


def _setup_signal_handlers():
    """Setup signal handlers to log when process receives termination signals."""
    def signal_handler(signum, frame):
        sig_name = signal.Signals(signum).name
        log.error(f"SIGNAL RECEIVED: {sig_name} ({signum}) - process is being terminated")
        sys.stdout.flush()
        sys.stderr.flush()
        sys.exit(128 + signum)
    
    # Handle common termination signals
    for sig in [signal.SIGTERM, signal.SIGINT, signal.SIGHUP]:
        try:
            signal.signal(sig, signal_handler)
        except (OSError, ValueError):
            pass  # Some signals may not be available


def start_server(backend: Backend, routes: List[web.RouteDef], **kwargs):
    _setup_signal_handlers()
    try:
        log.debug("getting certificate...")
        use_ssl = os.environ.get("USE_SSL", "false") == "true"
        if use_ssl is True:
            ssl_context = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
            ssl_context.load_cert_chain(
                certfile="/etc/instance.crt",
                keyfile="/etc/instance.key",
            )
        else:
            ssl_context = None

        async def main():
            log.debug("starting server...")
            app = web.Application()
            app.add_routes(routes)
            runner = web.AppRunner(app)
            await runner.setup()
            site = web.TCPSite(
                runner,
                ssl_context=ssl_context,
                port=int(os.environ["WORKER_PORT"]),
                **kwargs
            )
            await gather(site.start(), backend._start_tracking())

        run(main())

    except Exception as e:
        err_msg = f"PyWorker failed to launch: {e}"
        log.error(err_msg)

        async def beacon():
            metrics = Metrics()
            metrics._set_version(getattr(backend, "version", "0"))
            metrics._set_mtoken(getattr(backend, "mtoken", ""))
            try:
                while True:
                    metrics._model_errored(err_msg)
                    await metrics._Metrics__send_metrics_and_reset()
                    await asyncio.sleep(10)
            finally:
                await metrics.aclose()

        run(beacon())