# ========================================================================== #
#                                                                            #
#    KVMD - The main PiKVM daemon.                                           #
#                                                                            #
#    Copyright (C) 2020  Maxim Devaev <mdevaev@gmail.com>                    #
#                                                                            #
#    This program is free software: you can redistribute it and/or modify    #
#    it under the terms of the GNU General Public License as published by    #
#    the Free Software Foundation, either version 3 of the License, or       #
#    (at your option) any later version.                                     #
#                                                                            #
#    This program is distributed in the hope that it will be useful,         #
#    but WITHOUT ANY WARRANTY; without even the implied warranty of          #
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           #
#    GNU General Public License for more details.                            #
#                                                                            #
#    You should have received a copy of the GNU General Public License       #
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.  #
#                                                                            #
# ========================================================================== #


import contextlib
import types

from typing import Callable
from typing import Awaitable
from typing import Generator
from typing import AsyncGenerator

import aiohttp
import ustreamer

from .. import tools
from .. import aiotools
from .. import htclient


# =====
class StreamerError(Exception):
    pass


class StreamerTempError(StreamerError):
    pass


class StreamerPermError(StreamerError):
    pass


# =====
class StreamFormats:
    JPEG = 1195724874    # V4L2_PIX_FMT_JPEG
    H264 = 875967048     # V4L2_PIX_FMT_H264
    _MJPEG = 1196444237  # V4L2_PIX_FMT_MJPEG


class BaseStreamerClient:
    def get_format(self) -> int:
        raise NotImplementedError()

    @contextlib.asynccontextmanager
    async def reading(self) -> AsyncGenerator[Callable[[bool], Awaitable[dict]], None]:
        if self is not None:  # XXX: Vulture and pylint hack
            raise NotImplementedError()
        yield


# =====
@contextlib.contextmanager
def _http_handle_errors() -> Generator[None, None, None]:
    try:
        yield
    except Exception as err:  # Тут бывают и ассерты, и KeyError, и прочая херня
        if isinstance(err, StreamerTempError):
            raise
        raise StreamerTempError(tools.efmt(err))


class HttpStreamerClient(BaseStreamerClient):
    def __init__(
        self,
        name: str,
        unix_path: str,
        timeout: float,
        user_agent: str,
    ) -> None:

        self.__name = name
        self.__unix_path = unix_path
        self.__timeout = timeout
        self.__user_agent = user_agent

    def get_format(self) -> int:
        return StreamFormats.JPEG

    @contextlib.asynccontextmanager
    async def reading(self) -> AsyncGenerator[Callable[[bool], Awaitable[dict]], None]:
        with _http_handle_errors():
            async with self.__make_http_session() as session:
                async with session.get(
                    url=self.__make_url("stream"),
                    params={"extra_headers": "1"},
                ) as response:
                    htclient.raise_not_200(response)
                    reader = aiohttp.MultipartReader.from_response(response)
                    self.__patch_stream_reader(reader.resp.content)

                    async def read_frame(key_required: bool) -> dict:
                        _ = key_required
                        with _http_handle_errors():
                            frame = await reader.next()  # pylint: disable=not-callable
                            if not isinstance(frame, aiohttp.BodyPartReader):
                                raise StreamerTempError("Expected body part")

                            data = bytes(await frame.read())
                            if not data:
                                raise StreamerTempError("Reached EOF")

                            return {
                                "online": (frame.headers["X-UStreamer-Online"] == "true"),
                                "width": int(frame.headers["X-UStreamer-Width"]),
                                "height": int(frame.headers["X-UStreamer-Height"]),
                                "data": data,
                                "format": StreamFormats.JPEG,
                            }

                    yield read_frame

    def __make_http_session(self) -> aiohttp.ClientSession:
        kwargs: dict = {
            "headers": {"User-Agent": self.__user_agent},
            "connector": aiohttp.UnixConnector(path=self.__unix_path),
            "timeout": aiohttp.ClientTimeout(
                connect=self.__timeout,
                sock_read=self.__timeout,
            ),
        }
        return aiohttp.ClientSession(**kwargs)

    def __make_url(self, handle: str) -> str:
        assert not handle.startswith("/"), handle
        return f"http://localhost:0/{handle}"

    def __patch_stream_reader(self, reader: aiohttp.StreamReader) -> None:
        # https://github.com/pikvm/pikvm/issues/92
        # Infinite looping in BodyPartReader.read() because _at_eof flag.

        orig_read = reader.read

        async def read(self: aiohttp.StreamReader, n: int=-1) -> bytes:  # pylint: disable=invalid-name
            if self.is_eof():
                raise StreamerTempError("StreamReader.read(): Reached EOF")
            return (await orig_read(n))

        reader.read = types.MethodType(read, reader)  # type: ignore

    def __str__(self) -> str:
        return f"HttpStreamerClient({self.__name})"


# =====
@contextlib.contextmanager
def _memsink_handle_errors() -> Generator[None, None, None]:
    try:
        yield
    except StreamerPermError:
        raise
    except FileNotFoundError as err:
        raise StreamerTempError(tools.efmt(err))
    except Exception as err:
        raise StreamerPermError(tools.efmt(err))


class MemsinkStreamerClient(BaseStreamerClient):
    def __init__(
        self,
        name: str,
        fmt: int,
        obj: str,
        lock_timeout: float,
        wait_timeout: float,
        drop_same_frames: float,
    ) -> None:

        self.__name = name
        self.__fmt = fmt
        self.__kwargs: dict = {
            "obj": obj,
            "lock_timeout": lock_timeout,
            "wait_timeout": wait_timeout,
            "drop_same_frames": drop_same_frames,
        }

    def get_format(self) -> int:
        return self.__fmt

    @contextlib.asynccontextmanager
    async def reading(self) -> AsyncGenerator[Callable[[bool], Awaitable[dict]], None]:
        with _memsink_handle_errors():
            with ustreamer.Memsink(**self.__kwargs) as sink:
                async def read_frame(key_required: bool) -> dict:
                    key_required = (key_required and self.__fmt == StreamFormats.H264)
                    with _memsink_handle_errors():
                        while True:
                            frame = await aiotools.run_async(sink.wait_frame, key_required)
                            if frame is not None:
                                self.__check_format(frame["format"])
                                return frame
                yield read_frame

    def __check_format(self, fmt: int) -> None:
        if fmt == StreamFormats._MJPEG:  # pylint: disable=protected-access
            fmt = StreamFormats.JPEG
        if fmt != self.__fmt:
            raise StreamerPermError("Invalid sink format")

    def __str__(self) -> str:
        return f"MemsinkStreamerClient({self.__name})"