"""Gateway operations whose responses must be interpreted conservatively."""

from django.conf import settings
import requests


class PaymentVerificationUncertain(Exception):
    """The gateway response does not prove either payment success or failure."""


def request_payment_verification(payment):
    try:
        response = requests.post(
            settings.ZARINPAL_VERIFY_URL,
            json={
                "merchant_id": settings.ZARINPAL_MERCHANT_ID,
                "amount": payment.amount,
                "authority": payment.authority,
            },
            headers={"accept": "application/json", "content-type": "application/json"},
            timeout=15,
        )
        status_code = getattr(response, "status_code", 200)
        if isinstance(status_code, int) and status_code >= 400:
            raise PaymentVerificationUncertain(
                f"ZarinPal verification returned HTTP {status_code}"
            )
        body = response.json()
    except PaymentVerificationUncertain:
        raise
    except Exception as exc:
        raise PaymentVerificationUncertain("ZarinPal verification request failed") from exc

    if not isinstance(body, dict) or not isinstance(body.get("data"), dict):
        raise PaymentVerificationUncertain("ZarinPal returned an invalid verification response")

    code = body["data"].get("code")
    try:
        code = int(code)
    except (TypeError, ValueError) as exc:
        raise PaymentVerificationUncertain("ZarinPal returned no verification code") from exc

    if code not in (100, 101, -51):
        raise PaymentVerificationUncertain(
            f"ZarinPal returned an inconclusive verification code: {code}"
        )

    return code, body["data"]