# Copyright 2024 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Transport adapter for Asynchronous HTTP Requests based on aiohttp.
"""

import asyncio
from typing import AsyncGenerator, Mapping, Optional

try:
    import aiohttp  # type: ignore
except ImportError as caught_exc:  # pragma: NO COVER
    raise ImportError(
        "The aiohttp library is not installed from please install the aiohttp package to use the aiohttp transport."
    ) from caught_exc

from google.auth import _helpers
from google.auth import exceptions
from google.auth.aio import transport


class Response(transport.Response):
    """
    Represents an HTTP response and its data. It is returned by ``google.auth.aio.transport.sessions.AsyncAuthorizedSession``.

    Args:
        response (aiohttp.ClientResponse): An instance of aiohttp.ClientResponse.

    Attributes:
        status_code (int): The HTTP status code of the response.
        headers (Mapping[str, str]): The HTTP headers of the response.
    """

    def __init__(self, response: aiohttp.ClientResponse):
        self._response = response

    @property
    @_helpers.copy_docstring(transport.Response)
    def status_code(self) -> int:
        return self._response.status

    @property
    @_helpers.copy_docstring(transport.Response)
    def headers(self) -> Mapping[str, str]:
        return {key: value for key, value in self._response.headers.items()}

    @_helpers.copy_docstring(transport.Response)
    async def content(self, chunk_size: int = 1024) -> AsyncGenerator[bytes, None]:
        try:
            async for chunk in self._response.content.iter_chunked(
                chunk_size
            ):  # pragma: no branch
                yield chunk
        except aiohttp.ClientPayloadError as exc:
            raise exceptions.ResponseError(
                "Failed to read from the payload stream."
            ) from exc

    @_helpers.copy_docstring(transport.Response)
    async def read(self) -> bytes:
        try:
            return await self._response.read()
        except aiohttp.ClientResponseError as exc:
            raise exceptions.ResponseError("Failed to read the response body.") from exc

    @_helpers.copy_docstring(transport.Response)
    async def close(self):
        self._response.close()


class Request(transport.Request):
    """Asynchronous Requests request adapter.

    This class is used internally for making requests using aiohttp
    in a consistent way. If you use :class:`google.auth.aio.transport.sessions.AsyncAuthorizedSession`
    you do not need to construct or use this class directly.

    This class can be useful if you want to configure a Request callable
    with a custom ``aiohttp.ClientSession`` in :class:`AuthorizedSession` or if
    you want to manually refresh a :class:`~google.auth.aio.credentials.Credentials` instance::

        import aiohttp
        import google.auth.aio.transport.aiohttp

        # Default example:
        request = google.auth.aio.transport.aiohttp.Request()
        await credentials.refresh(request)

        # Custom aiohttp Session Example:
        session = session=aiohttp.ClientSession(auto_decompress=False)
        request = google.auth.aio.transport.aiohttp.Request(session=session)
        auth_sesion = google.auth.aio.transport.sessions.AsyncAuthorizedSession(auth_request=request)

    Args:
        session (aiohttp.ClientSession): An instance :class:`aiohttp.ClientSession` used
            to make HTTP requests. If not specified, a session will be created.

    .. automethod:: __call__
    """

    def __init__(self, session: aiohttp.ClientSession = None):
        self._session = session
        self._closed = False

    async def __call__(
        self,
        url: str,
        method: str = "GET",
        body: Optional[bytes] = None,
        headers: Optional[Mapping[str, str]] = None,
        timeout: float = transport._DEFAULT_TIMEOUT_SECONDS,
        **kwargs,
    ) -> transport.Response:
        """
        Make an HTTP request using aiohttp.

        Args:
            url (str): The URL to be requested.
            method (Optional[str]):
                The HTTP method to use for the request. Defaults to 'GET'.
            body (Optional[bytes]):
                The payload or body in HTTP request.
            headers (Optional[Mapping[str, str]]):
                Request headers.
            timeout (float): The number of seconds to wait for a
                response from the server. If not specified or if None, the
                requests default timeout will be used.
            kwargs: Additional arguments passed through to the underlying
                aiohttp :meth:`aiohttp.Session.request` method.

        Returns:
            google.auth.aio.transport.Response: The HTTP response.

        Raises:
            - google.auth.exceptions.TransportError: If the request fails or if the session is closed.
            - google.auth.exceptions.TimeoutError: If the request times out.
        """

        try:
            if self._closed:
                raise exceptions.TransportError("session is closed.")

            if not self._session:
                self._session = aiohttp.ClientSession()

            client_timeout = aiohttp.ClientTimeout(total=timeout)
            response = await self._session.request(
                method,
                url,
                data=body,
                headers=headers,
                timeout=client_timeout,
                **kwargs,
            )
            return Response(response)

        except aiohttp.ClientError as caught_exc:
            client_exc = exceptions.TransportError(f"Failed to send request to {url}.")
            raise client_exc from caught_exc

        except asyncio.TimeoutError as caught_exc:
            timeout_exc = exceptions.TimeoutError(
                f"Request timed out after {timeout} seconds."
            )
            raise timeout_exc from caught_exc

    async def close(self) -> None:
        """
        Close the underlying aiohttp session to release the acquired resources.
        """
        if not self._closed and self._session:
            await self._session.close()
        self._closed = True
