llm-token-tracker

/** * Exchange rate management with caching */ import * as fs from 'fs'; import * as path from 'path'; import * as os from 'os'; export interface ExchangeRateCache { rate: number; lastUpdated: string; source: string; } export class ExchangeRateManager { private cachePath: string; private cacheExpiryHours: number; private fallbackRate: number = 1380; // Default fallback rate constructor(cacheExpiryHours: number = 24) { const homeDir = os.homedir(); const cacheDir = path.join(homeDir, '.llm-token-tracker'); if (!fs.existsSync(cacheDir)) { fs.mkdirSync(cacheDir, { recursive: true }); } this.cachePath = path.join(cacheDir, 'exchange-rate.json'); this.cacheExpiryHours = cacheExpiryHours; } /** * Get current USD to KRW exchange rate */ async getUSDtoKRW(): Promise<number> { // Try to get from cache first const cached = this.loadFromCache(); if (cached && !this.isCacheExpired(cached.lastUpdated)) { return cached.rate; } // Fetch fresh rate try { const rate = await this.fetchExchangeRate(); this.saveToCache(rate, 'exchangerate-api'); return rate; } catch (error) { console.error('Failed to fetch exchange rate:', error); // Use cached rate even if expired if (cached) { console.log('Using expired cache due to API failure'); return cached.rate; } // Fall back to default rate console.log(`Using fallback rate: ${this.fallbackRate}`); return this.fallbackRate; } } /** * Fetch exchange rate from API */ private async fetchExchangeRate(): Promise<number> { // Using exchangerate-api.com (free tier, no API key required) const url = 'https://api.exchangerate-api.com/v4/latest/USD'; const response = await fetch(url); if (!response.ok) { throw new Error(`API request failed: ${response.status}`); } const data: any = await response.json(); if (!data.rates || !data.rates.KRW) { throw new Error('Invalid API response format'); } return data.rates.KRW as number; } /** * Load exchange rate from cache */ private loadFromCache(): ExchangeRateCache | null { try { if (!fs.existsSync(this.cachePath)) { return null; } const data = fs.readFileSync(this.cachePath, 'utf-8'); return JSON.parse(data) as ExchangeRateCache; } catch (error) { console.error('Failed to load exchange rate cache:', error); return null; } } /** * Save exchange rate to cache */ private saveToCache(rate: number, source: string): void { try { const cache: ExchangeRateCache = { rate, lastUpdated: new Date().toISOString(), source }; fs.writeFileSync(this.cachePath, JSON.stringify(cache, null, 2), 'utf-8'); } catch (error) { console.error('Failed to save exchange rate cache:', error); } } /** * Check if cache is expired */ private isCacheExpired(lastUpdated: string): boolean { const lastUpdateTime = new Date(lastUpdated).getTime(); const now = Date.now(); const expiryMs = this.cacheExpiryHours * 60 * 60 * 1000; return (now - lastUpdateTime) > expiryMs; } /** * Force refresh exchange rate */ async forceRefresh(): Promise<number> { try { const rate = await this.fetchExchangeRate(); this.saveToCache(rate, 'exchangerate-api'); return rate; } catch (error) { console.error('Failed to force refresh exchange rate:', error); throw error; } } /** * Get cached rate info */ getCacheInfo(): ExchangeRateCache | null { return this.loadFromCache(); } /** * Clear cache */ clearCache(): boolean { try { if (fs.existsSync(this.cachePath)) { fs.unlinkSync(this.cachePath); } return true; } catch (error) { console.error('Failed to clear exchange rate cache:', error); return false; } } /** * Set fallback rate */ setFallbackRate(rate: number): void { this.fallbackRate = rate; } /** * Get fallback rate */ getFallbackRate(): number { return this.fallbackRate; } }