import datetime

from typing import Any, Annotated
from pydantic import (
    AwareDatetime,
    BaseModel,
    ConfigDict,
    field_serializer,
    field_validator,
    StringConstraints,
    PositiveInt,
)

DUMMY_VAL = "dummy"
DUMMY_EXPIRES_IN_SECONDS = 60 * 60 * 12  # 12 hours
EXPIRATION_FORMAT = "%Y-%m-%d %H:%M:%S.%f%z"


class M2MToken(BaseModel):
    """Representation of an M2M Token."""

    token: str
    expires_at: AwareDatetime
    client_credentials_secret_arn: str

    model_config = ConfigDict(
        str_strip_whitespace=True,
    )

    @field_validator("token", "client_credentials_secret_arn")
    @classmethod
    def check_action_not_empty(cls, v: Any) -> Any:
        """Validate token is not empty."""
        assert v != "", "Empty strings are not allowed."
        return v

    @field_serializer("expires_at", mode="plain")
    @classmethod
    def expires_at_serializer(cls, expires_at: datetime.datetime) -> str:
        """Serialize expires_at conforming to `EXPIRATION_FORMAT`."""
        return expires_at.strftime(EXPIRATION_FORMAT)

    def is_expired(self, leeway_seconds: int | None = None) -> bool:
        """Return True if the M2M Token is expired."""
        return self.expires_at <= (
            datetime.datetime.now(datetime.UTC)
            + datetime.timedelta(seconds=leeway_seconds or 0)
        )


def create_dummy_m2m_token(client_credentials_secret_arn: str) -> M2MToken:
    return M2MToken(
        token=DUMMY_VAL,
        client_credentials_secret_arn=client_credentials_secret_arn,
        expires_at=datetime.datetime.now(datetime.UTC)
        + datetime.timedelta(seconds=DUMMY_EXPIRES_IN_SECONDS),
    )


class ClientCredentials(BaseModel):
    """Representation client credentials to send to AUTH0"""

    audience: Annotated[str, StringConstraints(min_length=1)]
    client_id: Annotated[str, StringConstraints(min_length=1)]
    client_secret: Annotated[str, StringConstraints(min_length=1)]
    grant_type: Annotated[str, StringConstraints(min_length=1)]

    model_config = ConfigDict(str_strip_whitespace=True)


class OAuthToken(BaseModel):
    """Representation of an OAuth Token."""

    access_token: Annotated[str, StringConstraints(min_length=1)]
    expires_in: PositiveInt
    token_type: Annotated[str, StringConstraints(min_length=1)]

    model_config = ConfigDict(str_strip_whitespace=True)

    def convert_to_m2m_token(self, client_credentials_secret_arn: str) -> M2MToken:
        return M2MToken.model_validate(
            {
                "client_credentials_secret_arn": client_credentials_secret_arn,
                "token": self.access_token,
                "expires_at": datetime.datetime.now(datetime.UTC)
                + datetime.timedelta(seconds=self.expires_in),
            }
        )