Stock Price MCP Server

import { MarketState, StockPriceResponse, YahooFinanceChart } from './types.js'; export class StockAPIClient { private readonly baseUrl = 'https://query2.finance.yahoo.com/v8/finance/chart'; private readonly maxRetries = 3; private readonly retryDelay = 1000; async getStockPrice(ticker: string): Promise<StockPriceResponse> { if (!ticker || ticker.trim() === '') { throw new Error('Ticker symbol is required'); } const normalizedTicker = ticker.trim().toUpperCase(); let lastError: Error | null = null; for (let attempt = 1; attempt <= this.maxRetries; attempt++) { try { const url = `${this.baseUrl}/${normalizedTicker}`; const response = await fetch(url, { headers: { 'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36' } }); if (!response.ok) { throw new Error(`HTTP error! status: ${response.status}`); } const data = await response.json() as YahooFinanceChart; if (data.chart.error) { throw new Error(`Yahoo Finance API error: ${data.chart.error.description}`); } if (!data.chart.result || data.chart.result.length === 0) { throw new Error(`Invalid ticker symbol: ${normalizedTicker}`); } const result = data.chart.result[0]; const meta = result.meta; return { ticker: meta.symbol, last_price: meta.regularMarketPrice, timestamp: new Date(meta.regularMarketTime * 1000).toISOString(), market_state: this.normalizeMarketState(meta.marketState), currency: meta.currency }; } catch (error) { lastError = error as Error; if (attempt < this.maxRetries) { await this.sleep(this.retryDelay * attempt); continue; } } } throw new Error(`Failed to fetch stock price after ${this.maxRetries} attempts: ${lastError?.message}`); } private normalizeMarketState(state: string): MarketState { if (!state) return MarketState.CLOSED; const normalized = state.toUpperCase(); switch (normalized) { case 'PRE': case 'PREPRE': return MarketState.PRE; case 'REGULAR': return MarketState.REGULAR; case 'POST': case 'POSTPOST': return MarketState.POST; case 'AFTER': return MarketState.AFTER; case 'CLOSED': default: return MarketState.CLOSED; } } private sleep(ms: number): Promise<void> { return new Promise(resolve => setTimeout(resolve, ms)); } }