from __future__ import annotations as _annotations

import functools
from asyncio import Lock
from collections.abc import AsyncGenerator, Mapping
from pathlib import Path
from typing import Literal, overload

import anyio.to_thread
import httpx
from typing_extensions import deprecated

from .. import ModelProfile
from ..exceptions import UserError
from ..models import cached_async_http_client
from ..profiles.google import google_model_profile
from ..providers import Provider

try:
    import google.auth
    from google.auth.credentials import Credentials as BaseCredentials
    from google.auth.transport.requests import Request
    from google.oauth2.service_account import Credentials as ServiceAccountCredentials
except ImportError as _import_error:
    raise ImportError(
        'Please install the `google-auth` package to use the Google Vertex AI provider, '
        'you can use the `vertexai` optional group — `pip install "pydantic-ai-slim[vertexai]"`'
    ) from _import_error


__all__ = ('GoogleVertexProvider',)


@deprecated('`GoogleVertexProvider` is deprecated, use `GoogleProvider` with `GoogleModel` instead.')
class GoogleVertexProvider(Provider[httpx.AsyncClient]):
    """Provider for Vertex AI API."""

    @property
    def name(self) -> str:
        return 'google-vertex'

    @property
    def base_url(self) -> str:
        return (
            f'https://{self.region}-aiplatform.googleapis.com/v1'
            f'/projects/{self.project_id}'
            f'/locations/{self.region}'
            f'/publishers/{self.model_publisher}/models/'
        )

    @property
    def client(self) -> httpx.AsyncClient:
        return self._client

    def model_profile(self, model_name: str) -> ModelProfile | None:
        return google_model_profile(model_name)

    @overload
    def __init__(
        self,
        *,
        service_account_file: Path | str | None = None,
        project_id: str | None = None,
        region: VertexAiRegion = 'us-central1',
        model_publisher: str = 'google',
        http_client: httpx.AsyncClient | None = None,
    ) -> None: ...

    @overload
    def __init__(
        self,
        *,
        service_account_info: Mapping[str, str] | None = None,
        project_id: str | None = None,
        region: VertexAiRegion = 'us-central1',
        model_publisher: str = 'google',
        http_client: httpx.AsyncClient | None = None,
    ) -> None: ...

    def __init__(
        self,
        *,
        service_account_file: Path | str | None = None,
        service_account_info: Mapping[str, str] | None = None,
        project_id: str | None = None,
        region: VertexAiRegion = 'us-central1',
        model_publisher: str = 'google',
        http_client: httpx.AsyncClient | None = None,
    ) -> None:
        """Create a new Vertex AI provider.

        Args:
            service_account_file: Path to a service account file.
                If not provided, the service_account_info or default environment credentials will be used.
            service_account_info: The loaded service_account_file contents.
                If not provided, the service_account_file or default environment credentials will be used.
            project_id: The project ID to use, if not provided it will be taken from the credentials.
            region: The region to make requests to.
            model_publisher: The model publisher to use, I couldn't find a good list of available publishers,
                and from trial and error it seems non-google models don't work with the `generateContent` and
                `streamGenerateContent` functions, hence only `google` is currently supported.
                Please create an issue or PR if you know how to use other publishers.
            http_client: An existing `httpx.AsyncClient` to use for making HTTP requests.
        """
        if service_account_file and service_account_info:
            raise ValueError('Only one of `service_account_file` or `service_account_info` can be provided.')

        self._client = http_client or cached_async_http_client(provider='google-vertex')
        self.service_account_file = service_account_file
        self.service_account_info = service_account_info
        self.project_id = project_id
        self.region = region
        self.model_publisher = model_publisher

        self._client.auth = _VertexAIAuth(service_account_file, service_account_info, project_id, region)
        self._client.base_url = self.base_url


class _VertexAIAuth(httpx.Auth):
    """Auth class for Vertex AI API."""

    _refresh_lock: Lock = Lock()

    credentials: BaseCredentials | ServiceAccountCredentials | None

    def __init__(
        self,
        service_account_file: Path | str | None = None,
        service_account_info: Mapping[str, str] | None = None,
        project_id: str | None = None,
        region: VertexAiRegion = 'us-central1',
    ) -> None:
        self.service_account_file = service_account_file
        self.service_account_info = service_account_info
        self.project_id = project_id
        self.region = region

        self.credentials = None

    async def async_auth_flow(self, request: httpx.Request) -> AsyncGenerator[httpx.Request, httpx.Response]:
        if self.credentials is None:  # pragma: no branch
            self.credentials = await self._get_credentials()
        if self.credentials.token is None:  # type: ignore[reportUnknownMemberType]
            await self._refresh_token()
        request.headers['Authorization'] = f'Bearer {self.credentials.token}'  # type: ignore[reportUnknownMemberType]
        # NOTE: This workaround is in place because we might get the project_id from the credentials.
        request.url = httpx.URL(str(request.url).replace('projects/None', f'projects/{self.project_id}'))
        response = yield request

        if response.status_code == 401:
            await self._refresh_token()
            request.headers['Authorization'] = f'Bearer {self.credentials.token}'  # type: ignore[reportUnknownMemberType]
            yield request

    async def _get_credentials(self) -> BaseCredentials | ServiceAccountCredentials:
        if self.service_account_file is not None:
            creds = await _creds_from_file(self.service_account_file)
            assert creds.project_id is None or isinstance(creds.project_id, str)  # type: ignore[reportUnknownMemberType]
            creds_project_id: str | None = creds.project_id
            creds_source = 'service account file'
        elif self.service_account_info is not None:
            creds = await _creds_from_info(self.service_account_info)
            assert creds.project_id is None or isinstance(creds.project_id, str)  # type: ignore[reportUnknownMemberType]
            creds_project_id: str | None = creds.project_id
            creds_source = 'service account info'
        else:
            creds, creds_project_id = await _async_google_auth()
            creds_source = '`google.auth.default()`'

        if self.project_id is None:  # pragma: no branch
            if creds_project_id is None:
                raise UserError(f'No project_id provided and none found in {creds_source}')  # pragma: no cover
            self.project_id = creds_project_id
        return creds

    async def _refresh_token(self) -> str:  # pragma: no cover
        async with self._refresh_lock:
            assert self.credentials is not None
            await anyio.to_thread.run_sync(self.credentials.refresh, Request())  # type: ignore[reportUnknownMemberType]
            assert isinstance(self.credentials.token, str), (  # type: ignore[reportUnknownMemberType]
                f'Expected token to be a string, got {self.credentials.token}'  # type: ignore[reportUnknownMemberType]
            )
            return self.credentials.token


async def _async_google_auth() -> tuple[BaseCredentials, str | None]:
    return await anyio.to_thread.run_sync(google.auth.default, ['https://www.googleapis.com/auth/cloud-platform'])  # type: ignore


async def _creds_from_file(service_account_file: str | Path) -> ServiceAccountCredentials:
    service_account_credentials_from_file = functools.partial(
        ServiceAccountCredentials.from_service_account_file,  # type: ignore[reportUnknownMemberType]
        scopes=['https://www.googleapis.com/auth/cloud-platform'],
    )
    return await anyio.to_thread.run_sync(service_account_credentials_from_file, str(service_account_file))


async def _creds_from_info(service_account_info: Mapping[str, str]) -> ServiceAccountCredentials:
    service_account_credentials_from_string = functools.partial(
        ServiceAccountCredentials.from_service_account_info,  # type: ignore[reportUnknownMemberType]
        scopes=['https://www.googleapis.com/auth/cloud-platform'],
    )
    return await anyio.to_thread.run_sync(service_account_credentials_from_string, service_account_info)


VertexAiRegion = Literal[
    'asia-east1',
    'asia-east2',
    'asia-northeast1',
    'asia-northeast3',
    'asia-south1',
    'asia-southeast1',
    'australia-southeast1',
    'europe-central2',
    'europe-north1',
    'europe-southwest1',
    'europe-west1',
    'europe-west2',
    'europe-west3',
    'europe-west4',
    'europe-west6',
    'europe-west8',
    'europe-west9',
    'me-central1',
    'me-central2',
    'me-west1',
    'northamerica-northeast1',
    'southamerica-east1',
    'us-central1',
    'us-east1',
    'us-east4',
    'us-east5',
    'us-south1',
    'us-west1',
    'us-west4',
]
"""Regions available for Vertex AI.

More details [here](https://cloud.google.com/vertex-ai/generative-ai/docs/learn/locations#genai-locations).
"""
