"""Canonical v2 contracts for the DITAv2 execution kernel."""

from __future__ import annotations

from dataclasses import dataclass, field
from datetime import datetime
from enum import Enum
from typing import Any, Dict, Mapping, Optional, Sequence, Tuple


class TradeSide(str, Enum):
    """Trade side."""

    LONG = "LONG"
    SHORT = "SHORT"
    FLAT = "FLAT"


class TradeStage(str, Enum):
    """Execution stage for a trade slot."""

    IDLE = "IDLE"
    DECISION_CREATED = "DECISION_CREATED"
    INTENT_CREATED = "INTENT_CREATED"
    ORDER_REQUESTED = "ORDER_REQUESTED"
    ORDER_SENT = "ORDER_SENT"
    ORDER_ACKED = "ORDER_ACKED"
    ORDER_REJECTED = "ORDER_REJECTED"
    ENTRY_WORKING = "ENTRY_WORKING"
    PARTIAL_FILL = "PARTIAL_FILL"
    POSITION_OPENED = "POSITION_OPENED"
    POSITION_OPEN = "POSITION_OPEN"
    EXIT_REQUESTED = "EXIT_REQUESTED"
    EXIT_SENT = "EXIT_SENT"
    EXIT_ACKED = "EXIT_ACKED"
    EXIT_REJECTED = "EXIT_REJECTED"
    EXIT_WORKING = "EXIT_WORKING"
    POSITION_PARTIALLY_CLOSED = "POSITION_PARTIALLY_CLOSED"
    POSITION_CLOSED = "POSITION_CLOSED"
    CLOSED = "CLOSED"
    TRADE_TERMINAL_WRITTEN = "TRADE_TERMINAL_WRITTEN"
    STALE_STATE_RECONCILING = "STALE_STATE_RECONCILING"


class KernelCommandType(str, Enum):
    """Kernel command types."""

    ENTER = "ENTER"
    EXIT = "EXIT"
    MARK_PRICE = "MARK_PRICE"
    RECONCILE = "RECONCILE"
    CONTROL = "CONTROL"
    CANCEL = "CANCEL"


class KernelEventKind(str, Enum):
    """Normalized venue event kinds."""

    ORDER_ACK = "ORDER_ACK"
    ORDER_REJECT = "ORDER_REJECT"
    RATE_LIMITED = "RATE_LIMITED"
    PARTIAL_FILL = "PARTIAL_FILL"
    FULL_FILL = "FULL_FILL"
    CANCEL_ACK = "CANCEL_ACK"
    CANCEL_REJECT = "CANCEL_REJECT"
    MARK_PRICE = "MARK_PRICE"
    RECONCILE = "RECONCILE"
    CONTROL = "CONTROL"


class KernelDiagnosticCode(str, Enum):
    """Structured diagnostic codes emitted by the kernel."""

    OK = "OK"
    RATE_LIMITED = "RATE_LIMITED"
    INVALID_SLOT_ID = "INVALID_SLOT_ID"
    INVALID_INTENT = "INVALID_INTENT"
    UNSUPPORTED_INTENT = "UNSUPPORTED_INTENT"
    SLOT_BUSY = "SLOT_BUSY"
    NO_OPEN_POSITION = "NO_OPEN_POSITION"
    NO_ACTIVE_EXIT_ORDER = "NO_ACTIVE_EXIT_ORDER"
    UNKNOWN_EVENT_KIND = "UNKNOWN_EVENT_KIND"
    ORDER_REJECTED = "ORDER_REJECTED"
    ENTRY_ORDER_REJECTED = "ENTRY_ORDER_REJECTED"
    EXIT_ORDER_REJECTED = "EXIT_ORDER_REJECTED"
    CANCEL_REJECTED = "CANCEL_REJECTED"
    STALE_STATE_RECONCILE = "STALE_STATE_RECONCILE"
    RECONCILED = "RECONCILED"
    DUPLICATE_EVENT = "DUPLICATE_EVENT"
    UNRESOLVED_SLOT = "UNRESOLVED_SLOT"
    INVALID_TRANSITION = "INVALID_TRANSITION"
    TERMINAL_STATE = "TERMINAL_STATE"


class KernelSeverity(str, Enum):
    """Severity classification for kernel outcomes."""

    INFO = "INFO"
    WARNING = "WARNING"
    ERROR = "ERROR"
    CRITICAL = "CRITICAL"


class VenueOrderStatus(str, Enum):
    """Order status surface mirrored from venue truth."""

    NEW = "NEW"
    ACKED = "ACKED"
    PARTIALLY_FILLED = "PARTIALLY_FILLED"
    FILLED = "FILLED"
    CANCELED = "CANCELED"
    REJECTED = "REJECTED"


class VenueEventStatus(str, Enum):
    """Status alias for normalized venue events."""

    ACKED = "ACKED"
    REJECTED = "REJECTED"
    RATE_LIMITED = "RATE_LIMITED"
    PARTIALLY_FILLED = "PARTIALLY_FILLED"
    FILLED = "FILLED"
    CANCELED = "CANCELED"
    CANCELED_REJECTED = "CANCEL_REJECTED"


@dataclass(frozen=True)
class VenueOrder:
    """Venue-specific order identity and fill state."""

    internal_trade_id: str
    venue_order_id: str
    venue_client_id: str
    side: TradeSide
    intended_size: float
    filled_size: float = 0.0
    average_fill_price: float = 0.0
    status: VenueOrderStatus = VenueOrderStatus.NEW
    metadata: Dict[str, Any] = field(default_factory=dict)

    @property
    def remaining_size(self) -> float:
        return max(0.0, float(self.intended_size) - float(self.filled_size))


@dataclass
class TradeSlot:
    """A single execution slot managed by the v2 kernel."""

    slot_id: int
    trade_id: str = ""
    asset: str = ""
    side: TradeSide = TradeSide.FLAT
    entry_price: float = 0.0
    size: float = 0.0
    initial_size: float = 0.0
    leverage: float = 0.0
    entry_time: Optional[datetime] = None
    unrealized_pnl: float = 0.0
    realized_pnl: float = 0.0
    closed: bool = False
    exit_leg_ratios: Tuple[float, ...] = (1.0,)
    active_leg_index: int = 0
    active_exit_order: Optional[VenueOrder] = None
    active_entry_order: Optional[VenueOrder] = None
    fsm_state: TradeStage = TradeStage.IDLE
    close_reason: str = ""
    last_event_time: Optional[datetime] = None
    seen_event_ids: Tuple[str, ...] = ()
    metadata: Dict[str, Any] = field(default_factory=dict)

    def is_free(self) -> bool:
        return self.fsm_state in {TradeStage.IDLE, TradeStage.CLOSED} and float(self.size or 0.0) <= 0.0 and not self.active_entry_order and not self.active_exit_order

    def is_open(self) -> bool:
        return self.fsm_state in {
            TradeStage.ENTRY_WORKING,
            TradeStage.POSITION_OPENED,
            TradeStage.POSITION_OPEN,
            TradeStage.EXIT_WORKING,
        } and not self.closed

    def mark_price(self, price: float) -> None:
        if price is None or price != price or price <= 0:
            return
        self.entry_price = self.entry_price or price
        if self.entry_price <= 0 or self.size <= 0:
            self.unrealized_pnl = 0.0
            return
        delta = (price - self.entry_price) / self.entry_price
        if self.side == TradeSide.SHORT:
            delta = -delta
        self.unrealized_pnl = delta * self.size * self.entry_price * self.leverage

    def next_exit_ratio(self) -> float:
        if self.active_leg_index < len(self.exit_leg_ratios):
            ratio = float(self.exit_leg_ratios[self.active_leg_index])
            return max(0.0, min(1.0, ratio))
        return 1.0

    def consume_exit_leg(self) -> float:
        ratio = self.next_exit_ratio()
        self.active_leg_index = min(self.active_leg_index + 1, max(len(self.exit_leg_ratios), 1))
        return ratio

    def remaining_size(self) -> float:
        return max(0.0, float(self.size))

    def attach_entry_order(self, order: VenueOrder) -> None:
        self.active_entry_order = order

    def attach_exit_order(self, order: VenueOrder) -> None:
        self.active_exit_order = order

    def to_dict(self) -> Dict[str, Any]:
        def _order_dict(order: Optional[VenueOrder]) -> Optional[Dict[str, Any]]:
            if order is None:
                return None
            return {
                "internal_trade_id": order.internal_trade_id,
                "venue_order_id": order.venue_order_id,
                "venue_client_id": order.venue_client_id,
                "side": order.side.value,
                "intended_size": float(order.intended_size or 0.0),
                "filled_size": float(order.filled_size or 0.0),
                "average_fill_price": float(order.average_fill_price or 0.0),
                "status": order.status.value,
                "metadata": dict(order.metadata),
            }

        return {
            "slot_id": self.slot_id,
            "trade_id": self.trade_id,
            "asset": self.asset,
            "side": self.side.value,
            "entry_price": float(self.entry_price or 0.0),
            "size": float(self.size or 0.0),
            "initial_size": float(self.initial_size or 0.0),
            "leverage": float(self.leverage or 0.0),
            "entry_time": self.entry_time.isoformat() if hasattr(self.entry_time, "isoformat") else None,
            "unrealized_pnl": float(self.unrealized_pnl or 0.0),
            "realized_pnl": float(self.realized_pnl or 0.0),
            "closed": bool(self.closed),
            "exit_leg_ratios": [float(r) for r in self.exit_leg_ratios],
            "active_leg_index": int(self.active_leg_index or 0),
            "active_exit_order": _order_dict(self.active_exit_order),
            "active_entry_order": _order_dict(self.active_entry_order),
            "fsm_state": self.fsm_state.value,
            "close_reason": self.close_reason,
            "last_event_time": self.last_event_time.isoformat() if hasattr(self.last_event_time, "isoformat") else None,
            "seen_event_ids": list(self.seen_event_ids),
            "metadata": dict(self.metadata),
        }


@dataclass(frozen=True)
class KernelIntent:
    """Command emitted by the algo and written to the hot-path intent region."""

    timestamp: datetime
    intent_id: str
    trade_id: str
    slot_id: int
    asset: str
    side: TradeSide
    action: KernelCommandType
    reference_price: float
    target_size: float
    leverage: float
    exit_leg_ratios: Tuple[float, ...] = (1.0,)
    reason: str = ""
    metadata: Dict[str, Any] = field(default_factory=dict)
    stage: TradeStage = TradeStage.INTENT_CREATED
    order_type: str = "MARKET"
    limit_price: float = 0.0


@dataclass(frozen=True)
class VenueEvent:
    """Normalized venue truth mapped into DITAv2 semantics."""

    timestamp: datetime
    event_id: str
    trade_id: str
    slot_id: int
    kind: KernelEventKind
    status: VenueEventStatus
    venue_order_id: str = ""
    venue_client_id: str = ""
    side: TradeSide = TradeSide.FLAT
    asset: str = ""
    price: float = 0.0
    size: float = 0.0
    filled_size: float = 0.0
    remaining_size: float = 0.0
    reason: str = ""
    raw_payload: Dict[str, Any] = field(default_factory=dict)
    metadata: Dict[str, Any] = field(default_factory=dict)


@dataclass(frozen=True)
class KernelTransition:
    """Durable kernel transition used for debug journaling."""

    timestamp: datetime
    trade_id: str
    slot_id: int
    prev_state: TradeStage
    next_state: TradeStage
    trigger: str
    intent_id: str = ""
    event_id: str = ""
    control_mode: str = ""
    control_verbosity: str = ""
    details: Dict[str, Any] = field(default_factory=dict)


@dataclass(frozen=True)
class KernelOutcome:
    """Result of applying a command or venue event."""

    accepted: bool
    slot_id: int
    trade_id: str
    state: TradeStage
    diagnostic_code: KernelDiagnosticCode = KernelDiagnosticCode.OK
    severity: KernelSeverity = KernelSeverity.INFO
    transitions: Tuple[KernelTransition, ...] = ()
    emitted_events: Tuple[VenueEvent, ...] = ()
    details: Dict[str, Any] = field(default_factory=dict)