stock-bot/apps/portfolio-service/src/portfolio/portfolio-manager.ts

import { createLogger } from '@stock-bot/logger';

export interface Position {
  symbol: string;
  quantity: number;
  averagePrice: number;
  currentPrice: number;
  marketValue: number;
  unrealizedPnL: number;
  unrealizedPnLPercent: number;
  costBasis: number;
  lastUpdated: Date;
}

export interface PortfolioSnapshot {
  timestamp: Date;
  totalValue: number;
  cashBalance: number;
  positions: Position[];
  totalReturn: number;
  totalReturnPercent: number;
  dayChange: number;
  dayChangePercent: number;
}

export interface Trade {
  id: string;
  symbol: string;
  quantity: number;
  price: number;
  side: 'buy' | 'sell';
  timestamp: Date;
  commission: number;
}

export class PortfolioManager {
  private logger = createLogger('PortfolioManager');
  private positions: Map<string, Position> = new Map();
  private trades: Trade[] = [];
  private cashBalance: number = 100000; // Starting cash
  
  constructor(initialCash: number = 100000) {
    this.cashBalance = initialCash;
  }

  addTrade(trade: Trade): void {
    this.trades.push(trade);
    this.updatePosition(trade);
    logger.info(`Trade added: ${trade.symbol} ${trade.side} ${trade.quantity} @ ${trade.price}`);
  }

  private updatePosition(trade: Trade): void {
    const existing = this.positions.get(trade.symbol);
    
    if (!existing) {
      // New position
      if (trade.side === 'buy') {
        this.positions.set(trade.symbol, {
          symbol: trade.symbol,
          quantity: trade.quantity,
          averagePrice: trade.price,
          currentPrice: trade.price,
          marketValue: trade.quantity * trade.price,
          unrealizedPnL: 0,
          unrealizedPnLPercent: 0,
          costBasis: trade.quantity * trade.price + trade.commission,
          lastUpdated: trade.timestamp
        });
        this.cashBalance -= (trade.quantity * trade.price + trade.commission);
      }
      return;
    }

    // Update existing position
    if (trade.side === 'buy') {
      const newQuantity = existing.quantity + trade.quantity;
      const newCostBasis = existing.costBasis + (trade.quantity * trade.price) + trade.commission;
      
      existing.quantity = newQuantity;
      existing.averagePrice = (newCostBasis - this.getTotalCommissions(trade.symbol)) / newQuantity;
      existing.costBasis = newCostBasis;
      existing.lastUpdated = trade.timestamp;
      
      this.cashBalance -= (trade.quantity * trade.price + trade.commission);
      
    } else if (trade.side === 'sell') {
      existing.quantity -= trade.quantity;
      existing.lastUpdated = trade.timestamp;
      
      const proceeds = trade.quantity * trade.price - trade.commission;
      this.cashBalance += proceeds;
      
      // Remove position if quantity is zero
      if (existing.quantity <= 0) {
        this.positions.delete(trade.symbol);
      }
    }
  }

  updatePrice(symbol: string, price: number): void {
    const position = this.positions.get(symbol);
    if (position) {
      position.currentPrice = price;
      position.marketValue = position.quantity * price;
      position.unrealizedPnL = position.marketValue - (position.quantity * position.averagePrice);
      position.unrealizedPnLPercent = position.unrealizedPnL / (position.quantity * position.averagePrice) * 100;
      position.lastUpdated = new Date();
    }
  }

  getPosition(symbol: string): Position | undefined {
    return this.positions.get(symbol);
  }

  getAllPositions(): Position[] {
    return Array.from(this.positions.values());
  }

  getPortfolioSnapshot(): PortfolioSnapshot {
    const positions = this.getAllPositions();
    const totalMarketValue = positions.reduce((sum, pos) => sum + pos.marketValue, 0);
    const totalValue = totalMarketValue + this.cashBalance;
    const totalUnrealizedPnL = positions.reduce((sum, pos) => sum + pos.unrealizedPnL, 0);
    
    return {
      timestamp: new Date(),
      totalValue,
      cashBalance: this.cashBalance,
      positions,
      totalReturn: totalUnrealizedPnL, // Simplified - should include realized gains
      totalReturnPercent: (totalUnrealizedPnL / (totalValue - totalUnrealizedPnL)) * 100,
      dayChange: 0, // TODO: Calculate from previous day
      dayChangePercent: 0
    };
  }

  getTrades(symbol?: string): Trade[] {
    if (symbol) {
      return this.trades.filter(trade => trade.symbol === symbol);
    }
    return this.trades;
  }

  private getTotalCommissions(symbol: string): number {
    return this.trades
      .filter(trade => trade.symbol === symbol)
      .reduce((sum, trade) => sum + trade.commission, 0);
  }

  getCashBalance(): number {
    return this.cashBalance;
  }

  getNetLiquidationValue(): number {
    const positions = this.getAllPositions();
    const positionValue = positions.reduce((sum, pos) => sum + pos.marketValue, 0);
    return positionValue + this.cashBalance;
  }
}