from __future__ import annotations

import json
from dataclasses import asdict, dataclass
from pathlib import Path
import re
from typing import Literal

from okx_codex_trader.models import InstrumentMeta, Position
from okx_codex_trader.okx_client import OkxClient, build_contract_size


PositionSide = Literal["flat", "long", "short"]


@dataclass(frozen=True)
class TargetPosition:
    side: PositionSide
    unit: float
    known: bool
    reason: str
    contracts: float | None = None


@dataclass(frozen=True)
class RuntimeState:
    last_candle_ts: int | None
    nextgen_active_legs: tuple[str, ...]
    micro_side: Literal["long", "short"] | None


@dataclass(frozen=True)
class PlannedAction:
    action: Literal["noop", "open", "increase", "reduce", "close", "reverse"]
    side: PositionSide
    unit: float
    reduce_only: bool


@dataclass(frozen=True)
class ExecutionPlan:
    target: TargetPosition
    current: TargetPosition
    actions: tuple[PlannedAction, ...]


@dataclass(frozen=True)
class RenderedOrder:
    action: str
    margin_usdt: float
    body: dict[str, object]


EMPTY_STATE = RuntimeState(last_candle_ts=None, nextgen_active_legs=(), micro_side=None)
CLIENT_ORDER_ID_MAX_LENGTH = 32


def load_runtime_state(path: Path) -> RuntimeState:
    if not path.exists():
        return EMPTY_STATE
    payload = json.loads(path.read_text(encoding="utf-8"))
    return RuntimeState(
        last_candle_ts=payload["last_candle_ts"],
        nextgen_active_legs=tuple(payload["nextgen_active_legs"]),
        micro_side=payload["micro_side"],
    )


def save_runtime_state(path: Path, state: RuntimeState) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    path.write_text(json.dumps(asdict(state), indent=2, sort_keys=True) + "\n", encoding="utf-8")


def _decision_candle_ts(payload: dict[str, object]) -> int:
    active_engine = str(payload["decision"]["active_engine"])
    if active_engine == "nextgen":
        nextgen = payload["nextgen"]
        if "data" in nextgen:
            return int(nextgen["data"]["decision_candle_ts"])
        return int(nextgen["decision"]["decision_candle_ts"])
    return int(payload["micro"]["decision_candle_ts"])


def target_from_signal(payload: dict[str, object], state: RuntimeState) -> tuple[RuntimeState, TargetPosition]:
    candle_ts = _decision_candle_ts(payload)
    if state.last_candle_ts is not None and candle_ts <= state.last_candle_ts:
        return state, target_from_state(payload, state)

    active_engine = str(payload["decision"]["active_engine"])
    if active_engine == "nextgen":
        active = set(state.nextgen_active_legs)
        weights: dict[str, float] = {}
        for leg in payload["nextgen"]["legs"]:
            leg_id = str(leg["leg_id"])
            weights[leg_id] = float(leg["suggested_weight"])
            if bool(leg["signal"]):
                active.add(leg_id)
            elif leg_id in active and bool(leg["exit_signal"]):
                active.remove(leg_id)
        next_state = RuntimeState(last_candle_ts=candle_ts, nextgen_active_legs=tuple(sorted(active)), micro_side=None)
        return next_state, _nextgen_target(next_state, weights)

    return (
        RuntimeState(last_candle_ts=candle_ts, nextgen_active_legs=(), micro_side=state.micro_side),
        TargetPosition(
            side="flat",
            unit=0.0,
            known=False,
            reason="micro target position requires persistent micro exit state before live execution",
        ),
    )


def target_from_state(payload: dict[str, object], state: RuntimeState) -> TargetPosition:
    active_engine = str(payload["decision"]["active_engine"])
    if active_engine != "nextgen":
        return TargetPosition(
            side="flat",
            unit=0.0,
            known=False,
            reason="micro target position requires persistent micro exit state before live execution",
        )
    weights = {str(leg["leg_id"]): float(leg["suggested_weight"]) for leg in payload["nextgen"]["legs"]}
    return _nextgen_target(state, weights)


def _nextgen_target(state: RuntimeState, weights: dict[str, float]) -> TargetPosition:
    unit = sum(weights[leg_id] for leg_id in state.nextgen_active_legs)
    if unit <= 0.0:
        return TargetPosition(side="flat", unit=0.0, known=True, reason="no active nextgen virtual legs")
    return TargetPosition(side="long", unit=unit, known=True, reason="active nextgen virtual legs net to one long ETH target")


def plan_position_delta(current: TargetPosition, target: TargetPosition) -> ExecutionPlan:
    if not current.known or not target.known:
        return ExecutionPlan(target=target, current=current, actions=())
    if current.side == target.side and current.unit == target.unit:
        return ExecutionPlan(target=target, current=current, actions=(PlannedAction("noop", target.side, 0.0, False),))
    if current.side == "flat":
        return ExecutionPlan(target=target, current=current, actions=(PlannedAction("open", target.side, target.unit, False),))
    if target.side == "flat":
        return ExecutionPlan(target=target, current=current, actions=(PlannedAction("close", current.side, current.unit, True),))
    if current.side == target.side:
        if target.unit > current.unit:
            return ExecutionPlan(target=target, current=current, actions=(PlannedAction("increase", target.side, target.unit - current.unit, False),))
        return ExecutionPlan(target=target, current=current, actions=(PlannedAction("reduce", current.side, current.unit - target.unit, True),))
    return ExecutionPlan(
        target=target,
        current=current,
        actions=(
            PlannedAction("close", current.side, current.unit, True),
            PlannedAction("reverse", target.side, target.unit, False),
        ),
    )


def current_position_from_okx(
    *,
    positions: list[Position],
    mark_price: float,
    metadata: InstrumentMeta,
    leverage: int,
    margin_per_unit_usdt: float,
) -> TargetPosition:
    if leverage <= 0 or margin_per_unit_usdt <= 0.0 or mark_price <= 0.0 or metadata.ct_val <= 0.0:
        raise ValueError("position normalization inputs are invalid")
    active = [position for position in positions if position.size > 0.0]
    if not active:
        return TargetPosition(side="flat", unit=0.0, known=True, reason="no open OKX position", contracts=0.0)
    sides = {position.pos_side for position in active}
    if len(sides) != 1:
        return TargetPosition(side="flat", unit=0.0, known=False, reason="both OKX hedge sides are open")
    side = active[0].pos_side
    if side not in {"long", "short"}:
        return TargetPosition(side="flat", unit=0.0, known=False, reason="OKX position side is unsupported")
    contracts = sum(position.size for position in active)
    notional = contracts * metadata.ct_val * mark_price
    margin = notional / leverage
    unit = margin / margin_per_unit_usdt
    return TargetPosition(side=side, unit=unit, known=True, reason="OKX position normalized by configured strategy unit margin", contracts=contracts)


def render_market_order_bodies(
    *,
    plan: ExecutionPlan,
    symbol: str,
    mark_price: float,
    metadata: InstrumentMeta,
    leverage: int,
    margin_per_unit_usdt: float,
    max_new_margin_usdt: float,
    max_total_margin_usdt: float,
    client_order_id_prefix: str,
    stop_loss_pct: float | None = None,
    take_profit_pct: float | None = None,
) -> tuple[RenderedOrder, ...]:
    if leverage <= 0 or margin_per_unit_usdt <= 0.0 or max_new_margin_usdt < 0.0 or max_total_margin_usdt < 0.0:
        raise ValueError("order rendering inputs are invalid")
    if stop_loss_pct is not None and stop_loss_pct <= 0.0:
        raise ValueError("stop_loss_pct is invalid")
    if take_profit_pct is not None and take_profit_pct <= 0.0:
        raise ValueError("take_profit_pct is invalid")
    if plan.target.known and plan.target.unit * margin_per_unit_usdt > max_total_margin_usdt:
        raise ValueError("target margin exceeds max_total_margin_usdt")
    rendered: list[RenderedOrder] = []
    new_margin = 0.0
    index = 1
    for action in plan.actions:
        if action.action == "noop":
            continue
        margin = action.unit * margin_per_unit_usdt
        if margin <= 0.0 or action.side == "flat":
            raise ValueError("planned action is invalid")
        if not action.reduce_only:
            new_margin += margin
            if new_margin > max_new_margin_usdt:
                raise ValueError("new margin exceeds max_new_margin_usdt")
        side = _okx_side(action)
        if action.action == "close":
            if plan.current.contracts is None or plan.current.contracts <= 0.0:
                raise ValueError("current contracts are required for close orders")
            size = plan.current.contracts
        else:
            size = build_contract_size(margin * leverage, mark_price, metadata)
        stop_loss_trigger_price = None
        take_profit_trigger_price = None
        if not action.reduce_only and stop_loss_pct is not None:
            stop_loss_trigger_price = mark_price * (1.0 - stop_loss_pct if action.side == "long" else 1.0 + stop_loss_pct)
        if not action.reduce_only and take_profit_pct is not None:
            take_profit_trigger_price = mark_price * (1.0 + take_profit_pct if action.side == "long" else 1.0 - take_profit_pct)
        rendered.append(
            RenderedOrder(
                action=action.action,
                margin_usdt=margin,
                body=OkxClient.build_market_order_body(
                    symbol=symbol,
                    side=side,
                    pos_side=action.side,
                    size=size,
                    client_order_id=market_client_order_id(client_order_id_prefix, index, action.action),
                    reduce_only=action.reduce_only,
                    stop_loss_trigger_price=stop_loss_trigger_price,
                    take_profit_trigger_price=take_profit_trigger_price,
                ),
            )
        )
        index += 1
    return tuple(rendered)


def market_client_order_id(prefix: str, index: int, action: str) -> str:
    compact = re.sub(r"[^A-Za-z0-9]", "", f"{prefix}{index}{action}")
    if not compact:
        raise ValueError("client order id prefix is invalid")
    return compact[:CLIENT_ORDER_ID_MAX_LENGTH]


def _okx_side(action: PlannedAction) -> str:
    if action.reduce_only:
        return "sell" if action.side == "long" else "buy"
    return "buy" if action.side == "long" else "sell"