import os
from datetime import datetime, timedelta

import requests

from .exceptions import AuthError


class AtlasClient:
    """
    Atlas API client.

    Provides base generic interface to Atlas API
    and maintains auth tokens freshness.
    """

    def __init__(
        self,
        host: str = "",
        client_id: str = "",
        client_secret: str = "",
        audience: str = "",
        schema: str = "https",
    ):
        self._host = host or os.environ.get("ATLAS_HOST")
        self._schema = schema
        self._api_root = f"{self._schema}://{self._host}/api/v1"
        self._client_id = client_id or os.environ.get("ATLAS_CLIENT_ID")
        self._client_secret = client_secret or os.environ.get("ATLAS_CLIENT_SECRET")
        self._audience = audience or os.environ.get("ATLAS_AUDIENCE")
        self._token = ""
        self._token_expires_at = None

    def request(self, url: str, method: str = "GET", **kwargs):
        url = url[1:] if url.startswith("/") else url
        headers = kwargs.get("headers") or dict()
        headers.update({f"Authorization": f"Bearer {self.get_token()}"})
        return requests.request(
            url=f"{self._api_root}/{url}", method=method, headers=headers, **kwargs
        )

    def get_token(self):
        if (
            self._token
            and self._token_expires_at - timedelta(seconds=60) > datetime.now()
        ):
            return self._token

        url = f"{self._schema}://{self._host}/oauth/token"
        resp = requests.post(
            url,
            data={
                "audience": self._audience,
                "grant_type": "client_credentials",
                "client_id": self._client_id,
                "client_secret": self._client_secret,
            },
        )
        if not resp.ok:
            raise AuthError("Unable to get access token")
        data = resp.json()
        self._token = data.get("access_token")
        self._token_expires_at = datetime.now() + timedelta(
            seconds=data.get("expires_in")
        )
        return self._token