"""CCXT-based exchange client wrapper for FUTURES trading.

Provides a unified async interface to any CCXT-supported exchange
with automatic sandbox/testnet support. Configured for futures
(perpetual swaps) with leverage and margin mode management.
"""

from __future__ import annotations

import asyncio
from typing import Any, Dict, List, Optional

import ccxt.pro as ccxtpro
import pandas as pd
from loguru import logger

from config import settings


class ExchangeClient:
    """Async exchange client wrapping ccxt.pro for live and sandbox trading."""

    def __init__(
        self,
        exchange_id: str | None = None,
        api_key: str | None = None,
        api_secret: str | None = None,
        sandbox: bool | None = None,
    ):
        self._exchange_id = exchange_id or settings.EXCHANGE_ID
        self._api_key = api_key or settings.API_KEY
        self._api_secret = api_secret or settings.API_SECRET
        self._sandbox = sandbox if sandbox is not None else settings.SANDBOX_MODE
        self._exchange: Optional[ccxtpro.Exchange] = None

    # ------------------------------------------------------------------
    # Connection lifecycle
    # ------------------------------------------------------------------

    async def connect(self) -> None:
        """Initialise and authenticate the exchange connection."""
        exchange_class = getattr(ccxtpro, self._exchange_id, None)
        if exchange_class is None:
            raise ValueError(f"Exchange '{self._exchange_id}' is not supported by ccxt.pro")

        self._exchange = exchange_class(
            {
                "apiKey": self._api_key,
                "secret": self._api_secret,
                "enableRateLimit": True,
                "options": {"defaultType": "future"},
            }
        )

        if self._sandbox:
            self._exchange.set_sandbox_mode(True)
            logger.info("Exchange connected in SANDBOX mode ({})", self._exchange_id)
        else:
            logger.info("Exchange connected in LIVE mode ({})", self._exchange_id)

    async def disconnect(self) -> None:
        """Gracefully close the exchange connection."""
        if self._exchange:
            await self._exchange.close()
            logger.info("Exchange disconnected")

    async def is_connected(self) -> bool:
        """Return True if the exchange instance is initialised."""
        return self._exchange is not None

    @property
    def exchange(self) -> ccxtpro.Exchange:
        if self._exchange is None:
            raise RuntimeError("Exchange not connected. Call connect() first.")
        return self._exchange

    # ------------------------------------------------------------------
    # Market data
    # ------------------------------------------------------------------

    async def watch_ohlcv(self, symbol: str, timeframe: str = "1m") -> List:
        """Watch real-time OHLCV candles via WebSocket."""
        return await self.exchange.watch_ohlcv(symbol, timeframe)

    async def fetch_ohlcv(
        self,
        symbol: str,
        timeframe: str = "1h",
        since: int | None = None,
        limit: int = 500,
    ) -> pd.DataFrame:
        """Fetch historical OHLCV data and return as a DataFrame."""
        data = await self.exchange.fetch_ohlcv(symbol, timeframe, since=since, limit=limit)
        df = pd.DataFrame(data, columns=["timestamp", "open", "high", "low", "close", "volume"])
        df["timestamp"] = pd.to_datetime(df["timestamp"], unit="ms")
        df.set_index("timestamp", inplace=True)
        return df

    async def fetch_balance(self) -> Dict[str, Any]:
        """Fetch account balance."""
        return await self.exchange.fetch_balance()

    async def fetch_ticker(self, symbol: str) -> Dict[str, Any]:
        """Fetch current ticker information."""
        return await self.exchange.fetch_ticker(symbol)

    # ------------------------------------------------------------------
    # Order management
    # ------------------------------------------------------------------

    async def create_limit_buy(self, symbol: str, amount: float, price: float) -> Dict:
        """Place a limit buy order."""
        logger.info("LIMIT BUY {} {} @ {}", symbol, amount, price)
        return await self.exchange.create_limit_buy_order(symbol, amount, price)

    async def create_limit_sell(self, symbol: str, amount: float, price: float) -> Dict:
        """Place a limit sell order."""
        logger.info("LIMIT SELL {} {} @ {}", symbol, amount, price)
        return await self.exchange.create_limit_sell_order(symbol, amount, price)

    async def create_market_buy(self, symbol: str, amount: float) -> Dict:
        """Place a market buy order."""
        logger.info("MARKET BUY {} {}", symbol, amount)
        return await self.exchange.create_market_buy_order(symbol, amount)

    async def create_market_sell(self, symbol: str, amount: float) -> Dict:
        """Place a market sell order."""
        logger.info("MARKET SELL {} {}", symbol, amount)
        return await self.exchange.create_market_sell_order(symbol, amount)

    async def create_stop_loss(
        self, symbol: str, side: str, amount: float, stop_price: float
    ) -> Dict:
        """Place a stop-loss order (stop-market)."""
        logger.info("STOP {} {} {} trigger={}", side, symbol, amount, stop_price)
        params = {"stopPrice": stop_price}
        return await self.exchange.create_order(
            symbol, "stop", side, amount, stop_price, params
        )

    async def cancel_order(self, order_id: str, symbol: str) -> Dict:
        """Cancel an existing order."""
        logger.info("CANCEL order {} on {}", order_id, symbol)
        return await self.exchange.cancel_order(order_id, symbol)

    async def fetch_order(self, order_id: str, symbol: str) -> Dict:
        """Fetch a single order by id."""
        return await self.exchange.fetch_order(order_id, symbol)

    async def fetch_open_orders(self, symbol: str | None = None) -> List[Dict]:
        """Fetch all open orders, optionally filtered by symbol."""
        return await self.exchange.fetch_open_orders(symbol)

    # ------------------------------------------------------------------
    # Futures-specific
    # ------------------------------------------------------------------

    async def set_leverage(self, symbol: str, leverage: int) -> None:
        """Set leverage for a futures symbol."""
        try:
            await self.exchange.set_leverage(leverage, symbol)
            logger.info("Set leverage {} = {}x", symbol, leverage)
        except Exception as e:
            logger.warning("set_leverage failed for {} (may already be set): {}", symbol, e)

    async def set_margin_mode(self, symbol: str, mode: str = "isolated") -> None:
        """Set margin mode (isolated/cross) for a futures symbol."""
        try:
            await self.exchange.set_margin_mode(mode, symbol)
            logger.info("Set margin mode {} = {}", symbol, mode)
        except Exception as e:
            logger.warning("set_margin_mode failed for {} (may already be set): {}", symbol, e)