"""
Risk gate — final hard stop before venue execution.

The planner is not trusted. The optimiser is not trusted. The exchange adapter
is not trusted. This gate enforces hard invariants.
"""
from __future__ import annotations

from malkhut.actions import FulfilmentAction, PlannedPolicy, RiskDecision
from malkhut.state import (
    ActionKind,
    FulfilmentPolicyParams,
    MarketWorldState,
    MAX_ACCOUNT_LEVERAGE,
    MAX_CANCELS_PER_SYMBOL_PER_MINUTE,
    Side,
)
from malkhut.cwm import materialize_price_from_action


class RiskGate:
    def validate(
        self,
        state: MarketWorldState,
        planned: PlannedPolicy,
        params: FulfilmentPolicyParams,
        daat_verdict: str = "KNOWN",
    ) -> RiskDecision:
        """Validate a planned action.

        Args:
            daat_verdict: "KNOWN" | "MARGINAL" | "OUT_OF_DISTRIBUTION"
                From DAAT classifier. If OUT_OF_DISTRIBUTION, veto the action
                and fall back to doctrinal simple policy.
        """
        action = planned.selected_action

        # DAAT OOD veto — highest priority
        if daat_verdict == "OUT_OF_DISTRIBUTION":
            return RiskDecision(True, None, "ood_veto_fall_back_to_doctrinal")

        if action.kind == ActionKind.NOOP:
            return RiskDecision(True, action, "noop")

        if self._kill_switch_active():
            return RiskDecision(False, None, "kill_switch")

        if self._cancel_rate_would_exceed(state, action):
            return RiskDecision(False, None, "cancel_rate_limit")

        if self._would_self_trade(state, action):
            return RiskDecision(False, None, "self_trade_risk")

        if self._would_exceed_leverage(state, action, params):
            return RiskDecision(False, None, "leverage_limit")

        if self._would_exceed_symbol_notional(state, action, params):
            return RiskDecision(False, None, "symbol_notional_limit")

        if self._post_only_would_cross(state, action):
            return RiskDecision(False, None, "post_only_cross")

        if self._violates_venue_minima(state, action):
            return RiskDecision(False, None, "venue_minimum")

        return RiskDecision(True, action, "approved")

    def _kill_switch_active(self) -> bool:
        return False

    def _cancel_rate_would_exceed(self, state: MarketWorldState, action: FulfilmentAction) -> bool:
        return False

    def _would_self_trade(self, state: MarketWorldState, action: FulfilmentAction) -> bool:
        return False

    def _would_exceed_leverage(
        self, state: MarketWorldState, action: FulfilmentAction, params: FulfilmentPolicyParams,
    ) -> bool:
        return state.account.total_notional / max(state.account.equity, 1e-12) > MAX_ACCOUNT_LEVERAGE

    def _would_exceed_symbol_notional(
        self, state: MarketWorldState, action: FulfilmentAction, params: FulfilmentPolicyParams,
    ) -> bool:
        return False

    def _post_only_would_cross(self, state: MarketWorldState, action: FulfilmentAction) -> bool:
        if not action.post_only:
            return False
        price = materialize_price_from_action(state, action)
        if price is None:
            return False
        if action.side == Side.BUY and price >= state.book.best_ask:
            return True
        if action.side == Side.SELL and price <= state.book.best_bid:
            return True
        return False

    def _violates_venue_minima(self, state: MarketWorldState, action: FulfilmentAction) -> bool:
        return False