"""Settlement validators — Phase 10.8."""
from __future__ import annotations

from decimal import Decimal

from shared.exceptions import AppError

from app.models.types import SettlementIntentStatus

ALLOWED_TRANSITIONS: dict[str, set[SettlementIntentStatus]] = {
    "submit": {SettlementIntentStatus.DRAFT},
    "settle": {SettlementIntentStatus.SUBMITTED},
    "fail": {SettlementIntentStatus.SUBMITTED},
    "cancel": {SettlementIntentStatus.DRAFT, SettlementIntentStatus.PENDING},
}

TARGET_STATUS: dict[str, SettlementIntentStatus] = {
    "submit": SettlementIntentStatus.SUBMITTED,
    "settle": SettlementIntentStatus.SETTLED,
    "fail": SettlementIntentStatus.FAILED,
    "cancel": SettlementIntentStatus.CANCELLED,
}

TERMINAL = frozenset(
    {
        SettlementIntentStatus.SETTLED,
        SettlementIntentStatus.FAILED,
        SettlementIntentStatus.CANCELLED,
    }
)


def ensure_settlement_transition(*, action: str, current: SettlementIntentStatus) -> None:
    if current in TERMINAL:
        raise AppError(
            "تسویه در وضعیت پایانی است",
            status_code=409,
            error_code="settlement_terminal",
            details={"status": current.value, "action": action},
        )
    allowed = ALLOWED_TRANSITIONS.get(action, set())
    if current not in allowed:
        raise AppError(
            "انتقال وضعیت تسویه مجاز نیست",
            status_code=409,
            error_code="invalid_settlement_transition",
            details={
                "from_status": current.value,
                "action": action,
                "allowed_from": sorted(s.value for s in allowed),
            },
        )


def target_settlement_status(action: str) -> SettlementIntentStatus:
    return TARGET_STATUS[action]


def validate_settlement_amount(amount: Decimal) -> Decimal:
    if amount <= 0:
        raise AppError(
            "مبلغ تسویه باید بزرگ‌تر از صفر باشد",
            status_code=422,
            error_code="invalid_settlement_amount",
        )
    return amount