import WebSocket from 'ws';
import { signRequest } from './auth.js';
import { EventEmitter } from 'events';

const WS_URL = 'wss://api.elections.kalshi.com/trade-api/ws/v2';

export class KalshiWS extends EventEmitter {
  constructor() {
    super();
    this.ws = null;
    this.subscribedTickers = new Set();
    this.alive = false;
    this.reconnectTimer = null;
    this.pingInterval = null;
  }

  connect() {
    if (this.ws) this.disconnect();

    const path = '/trade-api/ws/v2';
    const headers = signRequest('GET', path);

    this.ws = new WebSocket(WS_URL, { headers });

    this.ws.on('open', () => {
      console.log('[WS] Connected to Kalshi');
      this.alive = true;
      this._startPing();
      // Resubscribe to any tickers we were watching
      for (const ticker of this.subscribedTickers) {
        this._sendSubscribe(ticker);
      }
      this.emit('connected');
    });

    this.ws.on('message', (raw) => {
      try {
        const msg = JSON.parse(raw.toString());
        this._handleMessage(msg);
      } catch (e) {
        console.error('[WS] Parse error:', e.message);
      }
    });

    this.ws.on('close', (code) => {
      console.log(`[WS] Disconnected (code: ${code}). Reconnecting in 3s...`);
      this.alive = false;
      this._stopPing();
      this._scheduleReconnect();
    });

    this.ws.on('error', (err) => {
      console.error('[WS] Error:', err.message);
    });
  }

  subscribeTicker(ticker) {
    this.subscribedTickers.add(ticker);
    if (this.alive) this._sendSubscribe(ticker);
  }

  unsubscribeTicker(ticker) {
    this.subscribedTickers.delete(ticker);
    if (this.alive) {
      this.ws.send(JSON.stringify({
        id: Date.now(),
        cmd: 'unsubscribe',
        params: { channels: ['orderbook_delta', 'ticker'], market_tickers: [ticker] }
      }));
    }
  }

  disconnect() {
    this._stopPing();
    clearTimeout(this.reconnectTimer);
    if (this.ws) {
      this.ws.removeAllListeners();
      this.ws.close();
      this.ws = null;
    }
    this.alive = false;
  }

  _sendSubscribe(ticker) {
    this.ws.send(JSON.stringify({
      id: Date.now(),
      cmd: 'subscribe',
      params: { channels: ['orderbook_delta', 'ticker'], market_tickers: [ticker] }
    }));
  }

  _handleMessage(msg) {
    const { type } = msg;
    if (type === 'orderbook_snapshot' || type === 'orderbook_delta') {
      this.emit('orderbook', msg);
    } else if (type === 'ticker') {
      this.emit('ticker', msg);
    } else if (type === 'subscribed') {
      console.log(`[WS] Subscribed to: ${msg.msg?.channels || 'unknown'}`);
    }
  }

  _startPing() {
    this.pingInterval = setInterval(() => {
      if (this.alive && this.ws?.readyState === WebSocket.OPEN) {
        this.ws.ping();
      }
    }, 15000);
  }

  _stopPing() {
    clearInterval(this.pingInterval);
  }

  _scheduleReconnect() {
    clearTimeout(this.reconnectTimer);
    this.reconnectTimer = setTimeout(() => this.connect(), 3000);
  }
}