import { db } from '../db.js';
import { notify } from '../notify.js';

/**
 * Paper Trading Engine.
 * Executes virtual trades, tracks PnL, stores in SurrealDB.
 */
export class PaperEngine {
  constructor(initialBalance = 1000) {
    this.balance = initialBalance;
    this.openPositions = new Map(); // ticker -> [positions]
    this.tradeHistory = [];
    this.totalPnL = 0;
    this.wins = 0;
    this.losses = 0;
  }

  async init() {
    // Load state from SurrealDB
    try {
      const state = await db.query('SELECT * FROM paper_state ORDER BY timestamp DESC LIMIT 1');
      const saved = state[0]?.[0];
      if (saved) {
        this.balance = saved.balance;
        this.totalPnL = saved.totalPnL;
        this.wins = saved.wins;
        this.losses = saved.losses;
        console.log(`[Paper] Restored state: $${this.balance.toFixed(2)} balance, ${this.wins}W/${this.losses}L`);
      }

      // Load open positions
      const positions = await db.query('SELECT * FROM paper_positions WHERE settled = false');
      if (positions[0]) {
        for (const pos of positions[0]) {
          const list = this.openPositions.get(pos.ticker) || [];
          list.push(pos);
          this.openPositions.set(pos.ticker, list);
        }
        console.log(`[Paper] Restored ${this.openPositions.size} open position(s)`);
      }
    } catch (e) {
      console.error('[Paper] Init error (fresh start):', e.message);
    }
  }

  /**
   * Execute a paper trade from a strategy signal.
   */
  async executeTrade(signal, marketState) {
    const cost = signal.size; // Each contract costs signal.price cents, but we simplify: $1 per contract unit
    if (this.balance < cost) {
      console.log(`[Paper] Insufficient balance ($${this.balance.toFixed(2)}) for $${cost} trade`);
      return null;
    }

    const trade = {
      id: `pt_${Date.now()}_${Math.random().toString(36).slice(2, 8)}`,
      strategy: signal.strategy,
      ticker: signal.ticker,
      side: signal.side,
      price: signal.price, // Entry price in cents
      size: signal.size,
      cost,
      reason: signal.reason,
      entryTime: Date.now(),
      settled: false,
      result: null,
      pnl: null,
      marketState: {
        yesPct: marketState.yesPct,
        noPct: marketState.noPct,
        yesOdds: marketState.yesOdds,
        noOdds: marketState.noOdds
      }
    };

    this.balance -= cost;

    const list = this.openPositions.get(trade.ticker) || [];
    list.push(trade);
    this.openPositions.set(trade.ticker, list);

    // Store in SurrealDB
    try {
      await db.create('paper_positions', trade);
      await this._saveState();
    } catch (e) {
      console.error('[Paper] DB write error:', e.message);
    }

    const msg = `📝 PAPER ${trade.side.toUpperCase()} @ ${trade.price}¢ ($${cost}) | ${trade.strategy} | ${trade.reason}`;
    console.log(`[Paper] ${msg}`);
    await notify(msg, 'Paper Trade');

    return trade;
  }

  /**
   * Settle all positions for a ticker when the market resolves.
   */
  async settle(ticker, result) {
    const positions = this.openPositions.get(ticker);
    if (!positions || positions.length === 0) return;

    console.log(`[Paper] Settling ${positions.length} position(s) for ${ticker}, result: ${result}`);

    for (const pos of positions) {
      const won = pos.side === result;
      // Payout: if won, pay out at $1 per contract (100¢), minus cost
      // If lost, lose the cost
      const payout = won ? (100 / pos.price) * pos.cost : 0;
      const pnl = payout - pos.cost;

      pos.settled = true;
      pos.result = result;
      pos.pnl = parseFloat(pnl.toFixed(2));
      pos.settleTime = Date.now();

      this.balance += payout;
      this.totalPnL += pnl;

      if (won) this.wins++;
      else this.losses++;

      // Update in SurrealDB
      try {
        await db.query(`UPDATE paper_positions SET settled = true, result = $result, pnl = $pnl, settleTime = $settleTime WHERE id = $id`, {
          id: pos.id,
          result,
          pnl: pos.pnl,
          settleTime: pos.settleTime
        });
      } catch (e) {
        console.error('[Paper] Settle DB error:', e.message);
      }

      const emoji = won ? '✅' : '❌';
      const msg = `${emoji} ${pos.strategy} ${pos.side.toUpperCase()} ${won ? 'WON' : 'LOST'} | PnL: $${pnl.toFixed(2)} | Balance: $${this.balance.toFixed(2)}`;
      console.log(`[Paper] ${msg}`);
      await notify(msg, won ? 'Paper Win!' : 'Paper Loss');
    }

    this.openPositions.delete(ticker);
    await this._saveState();

    return positions;
  }

  getStats() {
    const openPositionsList = [];
    for (const [ticker, positions] of this.openPositions) {
      openPositionsList.push(...positions);
    }

    return {
      balance: parseFloat(this.balance.toFixed(2)),
      totalPnL: parseFloat(this.totalPnL.toFixed(2)),
      wins: this.wins,
      losses: this.losses,
      winRate: this.wins + this.losses > 0
        ? parseFloat(((this.wins / (this.wins + this.losses)) * 100).toFixed(1))
        : 0,
      openPositions: openPositionsList,
      totalTrades: this.wins + this.losses
    };
  }

  async _saveState() {
    try {
      await db.create('paper_state', {
        balance: this.balance,
        totalPnL: this.totalPnL,
        wins: this.wins,
        losses: this.losses,
        timestamp: Date.now()
      });
    } catch (e) {
      console.error('[Paper] State save error:', e.message);
    }
  }
}