from dataclasses import dataclass
from typing import Mapping


@dataclass(frozen=True)
class AbriConfig:
    endpoint_url: str
    username: str
    password: str
    default_resource: str

    @classmethod
    def from_env(cls, env: Mapping[str, str]) -> "AbriConfig":
        # A blank default_resource does not error at the relay — OpenHousing
        # logs the job but silently drops the appointment — so reject it here
        # rather than let the misconfiguration ship an empty resource.
        default_resource = env["ABRI_RELAY_DEFAULT_RESOURCE"]
        if not default_resource.strip():
            raise ValueError("ABRI_RELAY_DEFAULT_RESOURCE must not be blank")

        return cls(
            endpoint_url=env["ABRI_RELAY_URL"],
            username=env["ABRI_RELAY_USERNAME"],
            password=env["ABRI_RELAY_PASSWORD"],
            default_resource=default_resource,
        )