import secrets
import warnings
import logging
from typing import Annotated, Any, Literal

from pydantic import (
    AnyUrl,
    BeforeValidator,
    EmailStr,
    PostgresDsn,
    computed_field,
    model_validator,
)
from pydantic_core import MultiHostUrl
from pydantic_settings import BaseSettings, SettingsConfigDict
from typing_extensions import Self


def parse_cors(v: Any) -> list[str] | str:
    if isinstance(v, str) and not v.startswith("["):
        return [i.strip() for i in v.split(",")]
    elif isinstance(v, list | str):
        return v
    raise ValueError(v)


class Settings(BaseSettings):
    model_config = SettingsConfigDict(
        env_file="../.env",
        env_ignore_empty=True,
        extra="ignore",
    )
    PORT: int = 8000
    SECRET_KEY: str = secrets.token_urlsafe(32)

    VERBOSITY: Literal[*logging.getLevelNamesMapping().keys()] = "DEBUG"

    # 60 minutes * 24 hours * 8 days = 8 days
    ACCESS_TOKEN_EXPIRE_MINUTES: int = 60 * 24 * 8
    FRONTEND_HOST: str
    ENVIRONMENT: Literal["local", "staging", "production"] = "local"

    BACKEND_CORS_ORIGINS: Annotated[
        list[AnyUrl] | str, BeforeValidator(parse_cors)
    ] = []

    @computed_field
    @property
    def all_cors_origins(self) -> list[str]:
        return [str(origin).rstrip("/") for origin in self.BACKEND_CORS_ORIGINS] + [self.FRONTEND_HOST]

    POSTGRES_SERVER: str
    POSTGRES_PORT: int = 5432
    POSTGRES_USER: str
    POSTGRES_PASSWORD: str = ""
    POSTGRES_DB: str = ""

    @computed_field
    @property
    def SQLALCHEMY_DATABASE_URI(self) -> PostgresDsn:
        return MultiHostUrl.build(
            scheme='postgresql+psycopg2',
            username=self.POSTGRES_USER,
            password=self.POSTGRES_PASSWORD,
            host=self.POSTGRES_SERVER,
            port=self.POSTGRES_PORT,
            path=self.POSTGRES_DB,
        )

    SMTP_TLS: bool = True
    SMTP_SSL: bool = False
    SMTP_PORT: int = 587
    SMTP_HOST: str | None = None
    SMTP_USER: str | None = None
    SMTP_PASSWORD: str | None = None
    EMAILS_FROM_EMAIL: EmailStr | None = None
    EMAILS_FROM_NAME: EmailStr | None = None

    EMAIL_RESET_TOKEN_EXPIRE_HOURS: int = 48

    @computed_field
    @property
    def emails_enabled(self) -> bool:
        return bool(self.SMTP_HOST and self.EMAILS_FROM_EMAIL)

    @computed_field
    @property
    def is_local_environment(self) -> bool:
        return self.ENVIRONMENT == "local"

    EMAIL_TEST_USER: EmailStr = "test@example.com"
    FIRST_SUPERUSER: EmailStr
    FIRST_SUPERUSER_PASSWORD: str

    def _check_default_secret(self, var_name: str, value: str | None) -> None:
        if value == "changethis":
            message = f'The value of {var_name} is "changethis", '"for security, please change it, at least for deployments."
            if self.ENVIRONMENT == "local":
                warnings.warn(message, stacklevel=1)
            else:
                raise ValueError(message)

    @model_validator(mode="after")
    def _enforce_non_default_secrets(self) -> Self:
        self._check_default_secret("SECRET_KEY", self.SECRET_KEY)
        self._check_default_secret("POSTGRES_PASSWORD", self.POSTGRES_PASSWORD)
        self._check_default_secret("FIRST_SUPERUSER_PASSWORD", self.FIRST_SUPERUSER_PASSWORD)

        return self


settings = Settings()