Implement Kraken rates provider

src/exchange/ratesProvider/index.ts

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+export type { RatesProvider } from './ratesProvider';
+export { BinanceRatesProvider } from './binance/index';
+export { KrakenRatesProvider } from './kraken/index';

src/exchange/ratesProvider/kraken/dtos.ts

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+export interface KrakenRatesDto {
+  error: string[];
+  result: Record<string, KrakenTickerInfo>;
+}
+
+export interface KrakenTickerInfo {
+  /**
+   * Ask 
+   */
+  a: [price: string, wholeLotVolume: string, lotVolume: string];
+
+  /**
+   * Bid 
+   */
+  b: [price: string, wholeLotVolume: string, lotVolume: string];
+
+  /**
+   * Last trade closed
+   */
+  c: [price: string, lotVolume: string];
+
+  /**
+   * Volume
+   */
+  v: [today: string, last24Hours: string];
+
+  /**
+   * Volume weighted average price
+   */
+  p: [today: string, last24Hours: string];
+
+  /**
+   * Number of trades
+   */
+  t: [today: number, last24Hours: number];
+
+  /**
+   * Low
+   */
+  l: [today: string, last24Hours: string];
+
+  /**
+   * High 
+   */
+  h: [today: string, last24Hours: string];
+
+  /**
+   * Today's opening price
+   */
+  o: string;
+}

src/exchange/ratesProvider/kraken/index.ts

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+export { KrakenRatesProvider } from './krakenRatesProvider';

src/exchange/ratesProvider/kraken/krakenRatesProvider.ts

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+import BigNumber from 'bignumber.js';
+
+import { HttpClient } from '../../../core';
+import type { RatesProvider } from '../ratesProvider';
+import type { KrakenRatesDto } from './dtos';
+
+export class KrakenRatesProvider implements RatesProvider {
+  private static readonly baseUrl = 'https://api.kraken.com';
+
+  private readonly httpClient: HttpClient;
+
+  constructor() {
+    this.httpClient = new HttpClient(KrakenRatesProvider.baseUrl);
+  }
+
+  async getPrice(quoteCurrency: string, baseCurrency: string): Promise<BigNumber | undefined> {
+    const symbol = `${quoteCurrency}${baseCurrency}`;
+    const urlPath = `/0/public/Ticker?pair=${symbol}`;
+    const responseDto = await this.httpClient.request<KrakenRatesDto>({ urlPath }, false);
+
+    return this.mapRatesDtoToPrice(responseDto, symbol);
+  }
+
+  private mapRatesDtoToPrice(dto: KrakenRatesDto, symbol: string): BigNumber | undefined {
+    if (dto.error)
+      return undefined;
+
+    const tickerInfo = dto.result[symbol];
+    if (!tickerInfo)
+      return undefined;
+
+    return new BigNumber(tickerInfo.c[0]);
+  }
+}

src/exchange/ratesProvider/ratesProvider.ts

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+import type BigNumber from 'bignumber.js';
+
+import type { Currency } from '../../common';
+
+export interface RatesProvider {
+  getPrice(quoteCurrency: Currency['id'], baseCurrency: Currency['id']): Promise<BigNumber | undefined>;
+}