import asyncio
import signal
import socket
import warnings
from abc import ABC, abstractmethod
from typing import Any, Awaitable, Callable, List, Optional, Set

from yarl import URL

from .typedefs import PathLike
from .web_app import Application
from .web_server import Server

try:
    from ssl import SSLContext
except ImportError:
    SSLContext = object  # type: ignore[misc,assignment]


__all__ = (
    "BaseSite",
    "TCPSite",
    "UnixSite",
    "NamedPipeSite",
    "SockSite",
    "BaseRunner",
    "AppRunner",
    "ServerRunner",
    "GracefulExit",
)


class GracefulExit(SystemExit):
    code = 1


def _raise_graceful_exit() -> None:
    raise GracefulExit()


class BaseSite(ABC):
    __slots__ = ("_runner", "_ssl_context", "_backlog", "_server")

    def __init__(
        self,
        runner: "BaseRunner",
        *,
        shutdown_timeout: float = 60.0,
        ssl_context: Optional[SSLContext] = None,
        backlog: int = 128,
    ) -> None:
        if runner.server is None:
            raise RuntimeError("Call runner.setup() before making a site")
        if shutdown_timeout != 60.0:
            msg = "shutdown_timeout should be set on BaseRunner"
            warnings.warn(msg, DeprecationWarning, stacklevel=2)
            runner._shutdown_timeout = shutdown_timeout
        self._runner = runner
        self._ssl_context = ssl_context
        self._backlog = backlog
        self._server: Optional[asyncio.AbstractServer] = None

    @property
    @abstractmethod
    def name(self) -> str:
        pass  # pragma: no cover

    @abstractmethod
    async def start(self) -> None:
        self._runner._reg_site(self)

    async def stop(self) -> None:
        self._runner._check_site(self)
        if self._server is not None:  # Maybe not started yet
            self._server.close()

        self._runner._unreg_site(self)


class TCPSite(BaseSite):
    __slots__ = ("_host", "_port", "_reuse_address", "_reuse_port")

    def __init__(
        self,
        runner: "BaseRunner",
        host: Optional[str] = None,
        port: Optional[int] = None,
        *,
        shutdown_timeout: float = 60.0,
        ssl_context: Optional[SSLContext] = None,
        backlog: int = 128,
        reuse_address: Optional[bool] = None,
        reuse_port: Optional[bool] = None,
    ) -> None:
        super().__init__(
            runner,
            shutdown_timeout=shutdown_timeout,
            ssl_context=ssl_context,
            backlog=backlog,
        )
        self._host = host
        if port is None:
            port = 8443 if self._ssl_context else 8080
        self._port = port
        self._reuse_address = reuse_address
        self._reuse_port = reuse_port

    @property
    def name(self) -> str:
        scheme = "https" if self._ssl_context else "http"
        host = "0.0.0.0" if self._host is None else self._host
        return str(URL.build(scheme=scheme, host=host, port=self._port))

    async def start(self) -> None:
        await super().start()
        loop = asyncio.get_event_loop()
        server = self._runner.server
        assert server is not None
        self._server = await loop.create_server(
            server,
            self._host,
            self._port,
            ssl=self._ssl_context,
            backlog=self._backlog,
            reuse_address=self._reuse_address,
            reuse_port=self._reuse_port,
        )


class UnixSite(BaseSite):
    __slots__ = ("_path",)

    def __init__(
        self,
        runner: "BaseRunner",
        path: PathLike,
        *,
        shutdown_timeout: float = 60.0,
        ssl_context: Optional[SSLContext] = None,
        backlog: int = 128,
    ) -> None:
        super().__init__(
            runner,
            shutdown_timeout=shutdown_timeout,
            ssl_context=ssl_context,
            backlog=backlog,
        )
        self._path = path

    @property
    def name(self) -> str:
        scheme = "https" if self._ssl_context else "http"
        return f"{scheme}://unix:{self._path}:"

    async def start(self) -> None:
        await super().start()
        loop = asyncio.get_event_loop()
        server = self._runner.server
        assert server is not None
        self._server = await loop.create_unix_server(
            server,
            self._path,
            ssl=self._ssl_context,
            backlog=self._backlog,
        )


class NamedPipeSite(BaseSite):
    __slots__ = ("_path",)

    def __init__(
        self, runner: "BaseRunner", path: str, *, shutdown_timeout: float = 60.0
    ) -> None:
        loop = asyncio.get_event_loop()
        if not isinstance(
            loop, asyncio.ProactorEventLoop  # type: ignore[attr-defined]
        ):
            raise RuntimeError(
                "Named Pipes only available in proactor" "loop under windows"
            )
        super().__init__(runner, shutdown_timeout=shutdown_timeout)
        self._path = path

    @property
    def name(self) -> str:
        return self._path

    async def start(self) -> None:
        await super().start()
        loop = asyncio.get_event_loop()
        server = self._runner.server
        assert server is not None
        _server = await loop.start_serving_pipe(  # type: ignore[attr-defined]
            server, self._path
        )
        self._server = _server[0]


class SockSite(BaseSite):
    __slots__ = ("_sock", "_name")

    def __init__(
        self,
        runner: "BaseRunner",
        sock: socket.socket,
        *,
        shutdown_timeout: float = 60.0,
        ssl_context: Optional[SSLContext] = None,
        backlog: int = 128,
    ) -> None:
        super().__init__(
            runner,
            shutdown_timeout=shutdown_timeout,
            ssl_context=ssl_context,
            backlog=backlog,
        )
        self._sock = sock
        scheme = "https" if self._ssl_context else "http"
        if hasattr(socket, "AF_UNIX") and sock.family == socket.AF_UNIX:
            name = f"{scheme}://unix:{sock.getsockname()}:"
        else:
            host, port = sock.getsockname()[:2]
            name = str(URL.build(scheme=scheme, host=host, port=port))
        self._name = name

    @property
    def name(self) -> str:
        return self._name

    async def start(self) -> None:
        await super().start()
        loop = asyncio.get_event_loop()
        server = self._runner.server
        assert server is not None
        self._server = await loop.create_server(
            server, sock=self._sock, ssl=self._ssl_context, backlog=self._backlog
        )


class BaseRunner(ABC):
    __slots__ = (
        "shutdown_callback",
        "_handle_signals",
        "_kwargs",
        "_server",
        "_sites",
        "_shutdown_timeout",
    )

    def __init__(
        self,
        *,
        handle_signals: bool = False,
        shutdown_timeout: float = 60.0,
        **kwargs: Any,
    ) -> None:
        self.shutdown_callback: Optional[Callable[[], Awaitable[None]]] = None
        self._handle_signals = handle_signals
        self._kwargs = kwargs
        self._server: Optional[Server] = None
        self._sites: List[BaseSite] = []
        self._shutdown_timeout = shutdown_timeout

    @property
    def server(self) -> Optional[Server]:
        return self._server

    @property
    def addresses(self) -> List[Any]:
        ret: List[Any] = []
        for site in self._sites:
            server = site._server
            if server is not None:
                sockets = server.sockets  # type: ignore[attr-defined]
                if sockets is not None:
                    for sock in sockets:
                        ret.append(sock.getsockname())
        return ret

    @property
    def sites(self) -> Set[BaseSite]:
        return set(self._sites)

    async def setup(self) -> None:
        loop = asyncio.get_event_loop()

        if self._handle_signals:
            try:
                loop.add_signal_handler(signal.SIGINT, _raise_graceful_exit)
                loop.add_signal_handler(signal.SIGTERM, _raise_graceful_exit)
            except NotImplementedError:  # pragma: no cover
                # add_signal_handler is not implemented on Windows
                pass

        self._server = await self._make_server()

    @abstractmethod
    async def shutdown(self) -> None:
        """Call any shutdown hooks to help server close gracefully."""

    async def cleanup(self) -> None:
        # The loop over sites is intentional, an exception on gather()
        # leaves self._sites in unpredictable state.
        # The loop guaranties that a site is either deleted on success or
        # still present on failure
        for site in list(self._sites):
            await site.stop()

        if self._server:  # If setup succeeded
            # Yield to event loop to ensure incoming requests prior to stopping the sites
            # have all started to be handled before we proceed to close idle connections.
            await asyncio.sleep(0)
            self._server.pre_shutdown()
            await self.shutdown()

            if self.shutdown_callback:
                await self.shutdown_callback()

            await self._server.shutdown(self._shutdown_timeout)
        await self._cleanup_server()

        self._server = None
        if self._handle_signals:
            loop = asyncio.get_running_loop()
            try:
                loop.remove_signal_handler(signal.SIGINT)
                loop.remove_signal_handler(signal.SIGTERM)
            except NotImplementedError:  # pragma: no cover
                # remove_signal_handler is not implemented on Windows
                pass

    @abstractmethod
    async def _make_server(self) -> Server:
        pass  # pragma: no cover

    @abstractmethod
    async def _cleanup_server(self) -> None:
        pass  # pragma: no cover

    def _reg_site(self, site: BaseSite) -> None:
        if site in self._sites:
            raise RuntimeError(f"Site {site} is already registered in runner {self}")
        self._sites.append(site)

    def _check_site(self, site: BaseSite) -> None:
        if site not in self._sites:
            raise RuntimeError(f"Site {site} is not registered in runner {self}")

    def _unreg_site(self, site: BaseSite) -> None:
        if site not in self._sites:
            raise RuntimeError(f"Site {site} is not registered in runner {self}")
        self._sites.remove(site)


class ServerRunner(BaseRunner):
    """Low-level web server runner"""

    __slots__ = ("_web_server",)

    def __init__(
        self, web_server: Server, *, handle_signals: bool = False, **kwargs: Any
    ) -> None:
        super().__init__(handle_signals=handle_signals, **kwargs)
        self._web_server = web_server

    async def shutdown(self) -> None:
        pass

    async def _make_server(self) -> Server:
        return self._web_server

    async def _cleanup_server(self) -> None:
        pass


class AppRunner(BaseRunner):
    """Web Application runner"""

    __slots__ = ("_app",)

    def __init__(
        self, app: Application, *, handle_signals: bool = False, **kwargs: Any
    ) -> None:
        super().__init__(handle_signals=handle_signals, **kwargs)
        if not isinstance(app, Application):
            raise TypeError(
                "The first argument should be web.Application "
                "instance, got {!r}".format(app)
            )
        self._app = app

    @property
    def app(self) -> Application:
        return self._app

    async def shutdown(self) -> None:
        await self._app.shutdown()

    async def _make_server(self) -> Server:
        loop = asyncio.get_event_loop()
        self._app._set_loop(loop)
        self._app.on_startup.freeze()
        await self._app.startup()
        self._app.freeze()

        return self._app._make_handler(loop=loop, **self._kwargs)

    async def _cleanup_server(self) -> None:
        await self._app.cleanup()