"""Assemble and run the live trading engine."""

from __future__ import annotations

import asyncio
import logging
import signal
import time
from decimal import Decimal
from functools import partial

import structlog
from structlog import dev as structlog_dev
from structlog import processors as structlog_processors
from structlog import stdlib as structlog_stdlib

from tradefinder.adapters.binance_usdm import BinanceUSDMAdapter
from tradefinder.adapters.types import (
    MarginType,
    Order,
    OrderRequest,
    OrderType,
    PositionSide,
    Side,
)
from tradefinder.core.config import LogFormat, Settings, get_settings
from tradefinder.core.regime import RegimeClassifier
from tradefinder.core.risk import PortfolioRisk, RiskEngine
from tradefinder.data.fetcher import DataFetcher
from tradefinder.data.storage import DataStorage
from tradefinder.strategies.signals import SignalType
from tradefinder.strategies.supertrend import SupertrendStrategy

logger = structlog.get_logger(__name__)

DEFAULT_LOOP_INTERVAL = 60
FETCH_LIMIT = 512
MAX_FETCH_ATTEMPTS = 3
MAX_ORDER_ATTEMPTS = 3
RETRY_DELAY_SECONDS = 2


def _configure_logging(settings: Settings) -> None:
    """Set up structlog and the underlying stdlib logger."""

    level = getattr(logging, settings.log_level, logging.INFO)
    logging.basicConfig(level=level)

    renderer = (
        structlog_dev.ConsoleRenderer()
        if settings.log_format == LogFormat.CONSOLE
        else structlog_processors.JSONRenderer()
    )

    structlog.configure(
        processors=[
            structlog_stdlib.add_logger_name,
            structlog_stdlib.add_log_level,
            structlog_processors.TimeStamper(fmt="iso"),
            structlog_processors.StackInfoRenderer(),
            structlog_processors.format_exc_info,
            renderer,
        ],
        context_class=dict,
        logger_factory=structlog_stdlib.LoggerFactory(),
        wrapper_class=structlog_stdlib.BoundLogger,
        cache_logger_on_first_use=True,
    )

    global logger
    logger = structlog.get_logger(__name__)


async def _async_main() -> None:
    """Asynchronous entry point that orchestrates the trading loop."""

    settings = get_settings()
    _configure_logging(settings)

    storage = DataStorage(settings.duckdb_path)
    storage.connect()
    storage.initialize_schema()

    adapter: BinanceUSDMAdapter | None = None
    fetcher: DataFetcher | None = None
    shutdown_event = asyncio.Event()

    try:
        _register_signal_handlers(shutdown_event)

        if settings.is_paper_trading:
            logger.info(
                "Paper trading enabled, skipping exchange connectivity",
                mode=settings.trading_mode.value,
                symbols=settings.symbols_list,
            )
        else:
            adapter = BinanceUSDMAdapter(settings)
            await _initialize_adapter(adapter, settings.symbols_list)
            fetcher = DataFetcher(adapter, storage)

        strategy = SupertrendStrategy()
        risk_engine = RiskEngine(PortfolioRisk())
        regime_classifier = RegimeClassifier()

        logger.info(
            "Starting trading loop",
            mode=settings.trading_mode.value,
            loop_interval=DEFAULT_LOOP_INTERVAL,
            symbols=settings.symbols_list,
        )

        await _run_trading_loop(
            settings,
            storage,
            strategy,
            regime_classifier,
            risk_engine,
            adapter,
            fetcher,
            shutdown_event,
        )
    except asyncio.CancelledError:
        logger.info("Trading loop cancelled")
        raise
    except Exception as error:
        logger.exception("Trading engine failed", error=str(error))
        raise
    finally:
        if adapter is not None:
            await adapter.disconnect()
        storage.disconnect()
        logger.info("Trading engine shutdown")


def main() -> None:
    """Sync wrapper that starts the async trading engine."""
    asyncio.run(_async_main())


async def _run_trading_loop(
    settings: Settings,
    storage: DataStorage,
    strategy: SupertrendStrategy,
    regime_classifier: RegimeClassifier,
    risk_engine: RiskEngine,
    adapter: BinanceUSDMAdapter | None,
    fetcher: DataFetcher | None,
    shutdown_event: asyncio.Event,
) -> None:
    """Perform trading cycles until a shutdown signal is received."""

    timeframe = settings.signal_timeframe

    while not shutdown_event.is_set():
        loop_start = time.monotonic()

        for symbol in settings.symbols_list:
            if shutdown_event.is_set():
                break

            await _process_symbol(
                settings,
                storage,
                strategy,
                regime_classifier,
                risk_engine,
                adapter,
                fetcher,
                symbol,
                timeframe,
                shutdown_event,
            )

        if shutdown_event.is_set():
            break

        elapsed = time.monotonic() - loop_start
        await _sleep_or_cancel(DEFAULT_LOOP_INTERVAL - elapsed, shutdown_event)


async def _process_symbol(
    settings: Settings,
    storage: DataStorage,
    strategy: SupertrendStrategy,
    regime_classifier: RegimeClassifier,
    risk_engine: RiskEngine,
    adapter: BinanceUSDMAdapter | None,
    fetcher: DataFetcher | None,
    symbol: str,
    timeframe: str,
    shutdown_event: asyncio.Event,
) -> None:
    """Fetch candles, classify the regime, and execute signals for a single symbol."""

    if shutdown_event.is_set():
        return

    await _fetch_latest_candles(fetcher, symbol, timeframe)

    candles = storage.get_candles(symbol, timeframe, limit=FETCH_LIMIT)
    if not candles:
        logger.debug("Skipping symbol with no candles", symbol=symbol, timeframe=timeframe)
        return

    regime = regime_classifier.classify(candles)
    signal = strategy.generate_signal(candles)
    if signal is None or not signal.is_entry:
        logger.debug(
            "No actionable signal",
            symbol=symbol,
            regime=regime.name,
            strategy=strategy.name,
        )
        return

    signal_symbol = signal.symbol or symbol

    try:
        equity = await _determine_equity(settings, adapter)
    except RuntimeError as error:
        logger.warning("Unable to determine equity", error=str(error))
        return

    risk_pct = Decimal(str(settings.risk.per_trade_pct))

    try:
        position_size = risk_engine.calculate_position_size(
            equity, signal.price, signal.stop_loss, risk_pct
        )
    except ValueError as error:
        logger.warning("Position sizing failed", symbol=symbol, error=str(error))
        return

    if position_size <= Decimal("0"):
        logger.warning("Computed non-positive position size", symbol=symbol)
        return

    risk_amount = risk_engine.calculate_risk_amount(position_size, signal.price, signal.stop_loss)

    strategy_cap_pct = Decimal(str(settings.risk.max_equity_per_strategy_pct))
    total_cap_pct = Decimal("100")

    if not risk_engine.can_allocate_strategy(
        strategy.name,
        risk_amount,
        equity,
        max_per_strategy_pct=strategy_cap_pct,
        max_total_exposure_pct=total_cap_pct,
    ):
        logger.warning(
            "Risk limits block allocation",
            symbol=symbol,
            strategy=strategy.name,
        )
        return

    if adapter is None:
        logger.info(
            "Paper trading signal",
            symbol=signal_symbol,
            signal_type=signal.signal_type.value,
            regime=regime.name,
            strategy=strategy.name,
        )
        return

    entry_side, position_side = _map_signal_to_sides(signal.signal_type)

    entry_request = OrderRequest(
        symbol=signal_symbol,
        side=entry_side,
        position_side=position_side,
        order_type=OrderType.LIMIT,
        quantity=position_size,
        price=signal.price,
    )

    try:
        entry_order = await _safe_create_order(adapter, entry_request)
        logger.info(
            "Entry order placed",
            order_id=entry_order.id,
            symbol=entry_order.symbol,
            side=entry_order.side.value,
            strategy=strategy.name,
        )
    except Exception as error:
        logger.error(
            "Failed to place entry order",
            symbol=signal_symbol,
            error=str(error),
        )
        return

    stop_side = Side.SELL if entry_side == Side.BUY else Side.BUY

    stop_request = OrderRequest(
        symbol=signal_symbol,
        side=stop_side,
        position_side=position_side,
        order_type=OrderType.STOP_MARKET,
        quantity=position_size,
        stop_price=signal.stop_loss,
        reduce_only=True,
    )

    try:
        stop_order = await _safe_create_order(adapter, stop_request)
        logger.info(
            "Stop loss order placed",
            order_id=stop_order.id,
            symbol=stop_order.symbol,
            stop_price=stop_order.stop_price,
        )
    except Exception as error:
        logger.error(
            "Failed to place stop loss order",
            symbol=signal_symbol,
            error=str(error),
        )


async def _fetch_latest_candles(fetcher: DataFetcher | None, symbol: str, timeframe: str) -> None:
    """Fetch new candles if possible and read the latest batch from storage."""

    if fetcher is None:
        return

    last_error: Exception | None = None

    for attempt in range(1, MAX_FETCH_ATTEMPTS + 1):
        try:
            await fetcher.fetch_latest_candles(symbol, timeframe, limit=FETCH_LIMIT)
            return
        except Exception as error:
            last_error = error
            logger.warning(
                "Candle sync failed",
                symbol=symbol,
                attempt=attempt,
                error=str(error),
            )
            await asyncio.sleep(RETRY_DELAY_SECONDS * attempt)

    if last_error is not None:
        logger.error("Unable to synchronize candles", symbol=symbol, error=str(last_error))


async def _safe_create_order(adapter: BinanceUSDMAdapter, request: OrderRequest) -> Order:
    """Retry order creation to handle transient exchange errors."""

    last_error: Exception | None = None

    for attempt in range(1, MAX_ORDER_ATTEMPTS + 1):
        try:
            return await adapter.create_order(request)
        except Exception as error:
            last_error = error
            logger.warning(
                "Order attempt failed",
                symbol=request.symbol,
                attempt=attempt,
                error=str(error),
            )
            await asyncio.sleep(RETRY_DELAY_SECONDS * attempt)

    logger.error(
        "Max retries reached while creating order",
        symbol=request.symbol,
        error=str(last_error) if last_error else "unknown",
    )
    raise last_error or RuntimeError("Order request failed without exception details")


def _map_signal_to_sides(signal_type: SignalType) -> tuple[Side, PositionSide]:
    """Map a signal direction to a trade side."""

    if signal_type == SignalType.ENTRY_LONG:
        return Side.BUY, PositionSide.LONG
    return Side.SELL, PositionSide.SHORT


async def _determine_equity(settings: Settings, adapter: BinanceUSDMAdapter | None) -> Decimal:
    """Return the equity that should be used for sizing positions."""

    if settings.is_paper_trading:
        return Decimal(str(settings.paper_equity_usdt))

    if adapter is None:
        raise RuntimeError("Adapter is required for non-paper trading")

    balance = await adapter.get_balance()
    return balance.total_equity


def _register_signal_handlers(shutdown_event: asyncio.Event) -> None:
    """Register signal handlers that trigger a graceful shutdown."""

    loop = asyncio.get_running_loop()

    def _handle(sig: signal.Signals) -> None:
        logger.info("Shutdown signal received", signal=sig.name)
        shutdown_event.set()

    def _handle_signal(signum: int, frame: object) -> None:
        shutdown_event.set()

    for sig in (signal.SIGINT, signal.SIGTERM):
        try:
            loop.add_signal_handler(sig, partial(_handle, sig))
        except (NotImplementedError, RuntimeError):
            signal.signal(sig, _handle_signal)


async def _sleep_or_cancel(delay: float, shutdown_event: asyncio.Event) -> None:
    """Sleep but exit early if a shutdown signal is received."""
    if delay <= 0:
        return

    try:
        await asyncio.wait_for(shutdown_event.wait(), timeout=delay)
    except TimeoutError:
        pass


async def _initialize_adapter(adapter: BinanceUSDMAdapter, symbols: list[str]) -> None:
    """Configure the adapter for hedge mode and isolated margin symbols."""

    await adapter.connect()
    await adapter.configure_hedge_mode(True)
    for symbol in symbols:
        await adapter.configure_margin_type(symbol, MarginType.ISOLATED)