"""
Gate.io exchange connector implementation.
Supports WebSocket connections to Gate.io with their WebSocket v4 API.
"""

import json
import hmac
import hashlib
import time
from typing import Dict, List, Optional, Any
from datetime import datetime, timezone

from ..models.core import OrderBookSnapshot, TradeEvent, PriceLevel
from ..utils.logging import get_logger, set_correlation_id
from ..utils.exceptions import ValidationError, ConnectionError
from ..utils.validation import validate_symbol, validate_price, validate_volume
from .base_connector import BaseExchangeConnector

logger = get_logger(__name__)


class GateIOConnector(BaseExchangeConnector):
    """
    Gate.io WebSocket connector implementation.
    
    Supports:
    - WebSocket v4 API
    - Order book streams
    - Trade streams
    - Symbol normalization
    - Authentication for private channels
    """
    
    # Gate.io WebSocket URLs
    WEBSOCKET_URL = "wss://api.gateio.ws/ws/v4/"
    TESTNET_URL = "wss://fx-api-testnet.gateio.ws/ws/v4/"
    API_URL = "https://api.gateio.ws"
    
    def __init__(self, use_testnet: bool = False, api_key: str = None, api_secret: str = None):
        """
        Initialize Gate.io connector.
        
        Args:
            use_testnet: Whether to use testnet environment
            api_key: API key for authentication (optional)
            api_secret: API secret for authentication (optional)
        """
        websocket_url = self.TESTNET_URL if use_testnet else self.WEBSOCKET_URL
        super().__init__("gateio", websocket_url)
        
        # Authentication credentials (optional)
        self.api_key = api_key
        self.api_secret = api_secret
        self.use_testnet = use_testnet
        
        # Gate.io-specific message handlers
        self.message_handlers.update({
            'spot.order_book_update': self._handle_orderbook_update,
            'spot.trades': self._handle_trade_update,
            'spot.pong': self._handle_pong,
            'error': self._handle_error_message
        })
        
        # Subscription tracking
        self.subscribed_channels = set()
        self.request_id = 1
        
        logger.info(f"Gate.io connector initialized ({'testnet' if use_testnet else 'mainnet'})")
    
    def _get_message_type(self, data: Dict) -> str:
        """
        Determine message type from Gate.io message data.
        
        Args:
            data: Parsed message data
            
        Returns:
            str: Message type identifier
        """
        # Gate.io v4 API message format
        if 'method' in data:
            return data['method']  # 'spot.order_book_update', 'spot.trades', etc.
        elif 'error' in data:
            return 'error'
        elif 'result' in data:
            return 'result'
        
        return 'unknown'
    
    def normalize_symbol(self, symbol: str) -> str:
        """
        Normalize symbol to Gate.io format.
        
        Args:
            symbol: Standard symbol format (e.g., 'BTCUSDT')
            
        Returns:
            str: Gate.io symbol format (e.g., 'BTC_USDT')
        """
        # Gate.io uses underscore-separated format
        if symbol.upper() == 'BTCUSDT':
            return 'BTC_USDT'
        elif symbol.upper() == 'ETHUSDT':
            return 'ETH_USDT'
        elif symbol.upper().endswith('USDT'):
            base = symbol[:-4].upper()
            return f"{base}_USDT"
        elif symbol.upper().endswith('USD'):
            base = symbol[:-3].upper()
            return f"{base}_USD"
        else:
            # Assume it's already in correct format or add underscore
            if '_' not in symbol:
                # Try to split common patterns
                if len(symbol) >= 6:
                    # Assume last 4 chars are quote currency
                    base = symbol[:-4].upper()
                    quote = symbol[-4:].upper()
                    return f"{base}_{quote}"
                else:
                    return symbol.upper()
            else:
                return symbol.upper()
    
    def _denormalize_symbol(self, gateio_symbol: str) -> str:
        """
        Convert Gate.io symbol back to standard format.
        
        Args:
            gateio_symbol: Gate.io symbol format (e.g., 'BTC_USDT')
            
        Returns:
            str: Standard symbol format (e.g., 'BTCUSDT')
        """
        if '_' in gateio_symbol:
            return gateio_symbol.replace('_', '')
        return gateio_symbol
    
    async def subscribe_orderbook(self, symbol: str) -> None:
        """
        Subscribe to order book updates for a symbol.
        
        Args:
            symbol: Trading symbol (e.g., 'BTCUSDT')
        """
        try:
            set_correlation_id()
            gateio_symbol = self.normalize_symbol(symbol)
            
            # Create subscription message
            subscription_msg = {
                "method": "spot.order_book",
                "params": [gateio_symbol, 20, "0"],  # symbol, limit, interval
                "id": self.request_id
            }
            self.request_id += 1
            
            # Send subscription
            success = await self._send_message(subscription_msg)
            if success:
                # Track subscription
                if symbol not in self.subscriptions:
                    self.subscriptions[symbol] = []
                if 'orderbook' not in self.subscriptions[symbol]:
                    self.subscriptions[symbol].append('orderbook')
                
                self.subscribed_channels.add(f"spot.order_book:{gateio_symbol}")
                
                logger.info(f"Subscribed to order book for {symbol} ({gateio_symbol}) on Gate.io")
            else:
                logger.error(f"Failed to subscribe to order book for {symbol} on Gate.io")
                
        except Exception as e:
            logger.error(f"Error subscribing to order book for {symbol}: {e}")
            raise
    
    async def subscribe_trades(self, symbol: str) -> None:
        """
        Subscribe to trade updates for a symbol.
        
        Args:
            symbol: Trading symbol (e.g., 'BTCUSDT')
        """
        try:
            set_correlation_id()
            gateio_symbol = self.normalize_symbol(symbol)
            
            # Create subscription message
            subscription_msg = {
                "method": "spot.trades",
                "params": [gateio_symbol],
                "id": self.request_id
            }
            self.request_id += 1
            
            # Send subscription
            success = await self._send_message(subscription_msg)
            if success:
                # Track subscription
                if symbol not in self.subscriptions:
                    self.subscriptions[symbol] = []
                if 'trades' not in self.subscriptions[symbol]:
                    self.subscriptions[symbol].append('trades')
                
                self.subscribed_channels.add(f"spot.trades:{gateio_symbol}")
                
                logger.info(f"Subscribed to trades for {symbol} ({gateio_symbol}) on Gate.io")
            else:
                logger.error(f"Failed to subscribe to trades for {symbol} on Gate.io")
                
        except Exception as e:
            logger.error(f"Error subscribing to trades for {symbol}: {e}")
            raise
    
    async def unsubscribe_orderbook(self, symbol: str) -> None:
        """
        Unsubscribe from order book updates for a symbol.
        
        Args:
            symbol: Trading symbol (e.g., 'BTCUSDT')
        """
        try:
            gateio_symbol = self.normalize_symbol(symbol)
            
            # Create unsubscription message
            unsubscription_msg = {
                "method": "spot.unsubscribe",
                "params": [f"spot.order_book", gateio_symbol],
                "id": self.request_id
            }
            self.request_id += 1
            
            # Send unsubscription
            success = await self._send_message(unsubscription_msg)
            if success:
                # Remove from tracking
                if symbol in self.subscriptions and 'orderbook' in self.subscriptions[symbol]:
                    self.subscriptions[symbol].remove('orderbook')
                    if not self.subscriptions[symbol]:
                        del self.subscriptions[symbol]
                
                self.subscribed_channels.discard(f"spot.order_book:{gateio_symbol}")
                
                logger.info(f"Unsubscribed from order book for {symbol} ({gateio_symbol}) on Gate.io")
            else:
                logger.error(f"Failed to unsubscribe from order book for {symbol} on Gate.io")
                
        except Exception as e:
            logger.error(f"Error unsubscribing from order book for {symbol}: {e}")
            raise
    
    async def unsubscribe_trades(self, symbol: str) -> None:
        """
        Unsubscribe from trade updates for a symbol.
        
        Args:
            symbol: Trading symbol (e.g., 'BTCUSDT')
        """
        try:
            gateio_symbol = self.normalize_symbol(symbol)
            
            # Create unsubscription message
            unsubscription_msg = {
                "method": "spot.unsubscribe",
                "params": ["spot.trades", gateio_symbol],
                "id": self.request_id
            }
            self.request_id += 1
            
            # Send unsubscription
            success = await self._send_message(unsubscription_msg)
            if success:
                # Remove from tracking
                if symbol in self.subscriptions and 'trades' in self.subscriptions[symbol]:
                    self.subscriptions[symbol].remove('trades')
                    if not self.subscriptions[symbol]:
                        del self.subscriptions[symbol]
                
                self.subscribed_channels.discard(f"spot.trades:{gateio_symbol}")
                
                logger.info(f"Unsubscribed from trades for {symbol} ({gateio_symbol}) on Gate.io")
            else:
                logger.error(f"Failed to unsubscribe from trades for {symbol} on Gate.io")
                
        except Exception as e:
            logger.error(f"Error unsubscribing from trades for {symbol}: {e}")
            raise
    
    async def get_symbols(self) -> List[str]:
        """
        Get list of available trading symbols from Gate.io.
        
        Returns:
            List[str]: List of available symbols in standard format
        """
        try:
            import aiohttp
            
            api_url = "https://fx-api-testnet.gateio.ws" if self.use_testnet else self.API_URL
            
            async with aiohttp.ClientSession() as session:
                async with session.get(f"{api_url}/api/v4/spot/currency_pairs") as response:
                    if response.status == 200:
                        data = await response.json()
                        
                        symbols = []
                        
                        for pair_info in data:
                            if pair_info.get('trade_status') == 'tradable':
                                pair_id = pair_info.get('id', '')
                                # Convert to standard format
                                standard_symbol = self._denormalize_symbol(pair_id)
                                symbols.append(standard_symbol)
                        
                        logger.info(f"Retrieved {len(symbols)} symbols from Gate.io")
                        return symbols
                    else:
                        logger.error(f"Failed to get symbols from Gate.io: HTTP {response.status}")
                        return []
                        
        except Exception as e:
            logger.error(f"Error getting symbols from Gate.io: {e}")
            return []
    
    async def get_orderbook_snapshot(self, symbol: str, depth: int = 20) -> Optional[OrderBookSnapshot]:
        """
        Get current order book snapshot from Gate.io REST API.
        
        Args:
            symbol: Trading symbol
            depth: Number of price levels to retrieve
            
        Returns:
            OrderBookSnapshot: Current order book or None if unavailable
        """
        try:
            import aiohttp
            
            gateio_symbol = self.normalize_symbol(symbol)
            api_url = "https://fx-api-testnet.gateio.ws" if self.use_testnet else self.API_URL
            
            # Gate.io supports various depths
            api_depth = min(depth, 100)
            
            url = f"{api_url}/api/v4/spot/order_book"
            params = {
                'currency_pair': gateio_symbol,
                'limit': api_depth
            }
            
            async with aiohttp.ClientSession() as session:
                async with session.get(url, params=params) as response:
                    if response.status == 200:
                        data = await response.json()
                        return self._parse_orderbook_snapshot(data, symbol)
                    else:
                        logger.error(f"Failed to get order book for {symbol}: HTTP {response.status}")
                        return None
                        
        except Exception as e:
            logger.error(f"Error getting order book snapshot for {symbol}: {e}")
            return None   
 
    def _parse_orderbook_snapshot(self, data: Dict, symbol: str) -> OrderBookSnapshot:
        """
        Parse Gate.io order book data into OrderBookSnapshot.
        
        Args:
            data: Raw Gate.io order book data
            symbol: Trading symbol
            
        Returns:
            OrderBookSnapshot: Parsed order book
        """
        try:
            # Parse bids and asks
            bids = []
            for bid_data in data.get('bids', []):
                price = float(bid_data[0])
                size = float(bid_data[1])
                
                if validate_price(price) and validate_volume(size):
                    bids.append(PriceLevel(price=price, size=size))
            
            asks = []
            for ask_data in data.get('asks', []):
                price = float(ask_data[0])
                size = float(ask_data[1])
                
                if validate_price(price) and validate_volume(size):
                    asks.append(PriceLevel(price=price, size=size))
            
            # Create order book snapshot
            orderbook = OrderBookSnapshot(
                symbol=symbol,
                exchange=self.exchange_name,
                timestamp=datetime.now(timezone.utc),  # Gate.io doesn't provide timestamp in snapshot
                bids=bids,
                asks=asks,
                sequence_id=data.get('id')
            )
            
            return orderbook
            
        except Exception as e:
            logger.error(f"Error parsing order book snapshot: {e}")
            raise ValidationError(f"Invalid order book data: {e}", "PARSE_ERROR")
    
    async def _handle_orderbook_update(self, data: Dict) -> None:
        """
        Handle order book update from Gate.io.
        
        Args:
            data: Order book update data
        """
        try:
            set_correlation_id()
            
            params = data.get('params', [])
            if len(params) < 2:
                logger.warning("Invalid order book update format")
                return
            
            # Gate.io format: [symbol, order_book_data]
            gateio_symbol = params[0]
            symbol = self._denormalize_symbol(gateio_symbol)
            book_data = params[1]
            
            # Parse bids and asks
            bids = []
            for bid_data in book_data.get('bids', []):
                price = float(bid_data[0])
                size = float(bid_data[1])
                
                if validate_price(price) and validate_volume(size):
                    bids.append(PriceLevel(price=price, size=size))
            
            asks = []
            for ask_data in book_data.get('asks', []):
                price = float(ask_data[0])
                size = float(ask_data[1])
                
                if validate_price(price) and validate_volume(size):
                    asks.append(PriceLevel(price=price, size=size))
            
            # Create order book snapshot
            orderbook = OrderBookSnapshot(
                symbol=symbol,
                exchange=self.exchange_name,
                timestamp=datetime.fromtimestamp(int(book_data.get('t', 0)) / 1000, tz=timezone.utc),
                bids=bids,
                asks=asks,
                sequence_id=book_data.get('id')
            )
            
            # Notify callbacks
            self._notify_data_callbacks(orderbook)
            
            logger.debug(f"Processed order book update for {symbol}")
            
        except Exception as e:
            logger.error(f"Error handling order book update: {e}")
    
    async def _handle_trade_update(self, data: Dict) -> None:
        """
        Handle trade update from Gate.io.
        
        Args:
            data: Trade update data
        """
        try:
            set_correlation_id()
            
            params = data.get('params', [])
            if len(params) < 2:
                logger.warning("Invalid trade update format")
                return
            
            # Gate.io format: [symbol, [trade_data]]
            gateio_symbol = params[0]
            symbol = self._denormalize_symbol(gateio_symbol)
            trades_data = params[1]
            
            # Process each trade
            for trade_data in trades_data:
                price = float(trade_data.get('price', 0))
                amount = float(trade_data.get('amount', 0))
                
                # Validate data
                if not validate_price(price) or not validate_volume(amount):
                    logger.warning(f"Invalid trade data: price={price}, amount={amount}")
                    continue
                
                # Determine side (Gate.io uses 'side' field)
                side = trade_data.get('side', 'unknown').lower()
                
                # Create trade event
                trade = TradeEvent(
                    symbol=symbol,
                    exchange=self.exchange_name,
                    timestamp=datetime.fromtimestamp(int(trade_data.get('time', 0)), tz=timezone.utc),
                    price=price,
                    size=amount,
                    side=side,
                    trade_id=str(trade_data.get('id', ''))
                )
                
                # Notify callbacks
                self._notify_data_callbacks(trade)
                
                logger.debug(f"Processed trade for {symbol}: {side} {amount} @ {price}")
            
        except Exception as e:
            logger.error(f"Error handling trade update: {e}")
    
    async def _handle_pong(self, data: Dict) -> None:
        """
        Handle pong response from Gate.io.
        
        Args:
            data: Pong response data
        """
        logger.debug("Received Gate.io pong")
    
    async def _handle_error_message(self, data: Dict) -> None:
        """
        Handle error message from Gate.io.
        
        Args:
            data: Error message data
        """
        error_info = data.get('error', {})
        code = error_info.get('code', 'unknown')
        message = error_info.get('message', 'Unknown error')
        
        logger.error(f"Gate.io error {code}: {message}")
    
    def _get_auth_signature(self, method: str, url: str, query_string: str, 
                           payload: str, timestamp: str) -> str:
        """
        Generate authentication signature for Gate.io.
        
        Args:
            method: HTTP method
            url: Request URL
            query_string: Query string
            payload: Request payload
            timestamp: Request timestamp
            
        Returns:
            str: Authentication signature
        """
        if not self.api_key or not self.api_secret:
            return ""
        
        try:
            # Create signature string
            message = f"{method}\n{url}\n{query_string}\n{hashlib.sha512(payload.encode()).hexdigest()}\n{timestamp}"
            
            # Generate signature
            signature = hmac.new(
                self.api_secret.encode('utf-8'),
                message.encode('utf-8'),
                hashlib.sha512
            ).hexdigest()
            
            return signature
            
        except Exception as e:
            logger.error(f"Error generating auth signature: {e}")
            return ""
    
    async def _send_ping(self) -> None:
        """Send ping to keep connection alive."""
        try:
            ping_msg = {
                "method": "spot.ping",
                "params": [],
                "id": self.request_id
            }
            self.request_id += 1
            
            await self._send_message(ping_msg)
            logger.debug("Sent ping to Gate.io")
            
        except Exception as e:
            logger.error(f"Error sending ping: {e}")
    
    def get_gateio_stats(self) -> Dict[str, Any]:
        """Get Gate.io-specific statistics."""
        base_stats = self.get_stats()
        
        gateio_stats = {
            'subscribed_channels': list(self.subscribed_channels),
            'use_testnet': self.use_testnet,
            'authenticated': bool(self.api_key and self.api_secret),
            'next_request_id': self.request_id
        }
        
        base_stats.update(gateio_stats)
        return base_stats