From d9bd07c397d814c510be6374e98e03ab1fe8e968 Mon Sep 17 00:00:00 2001
From: Maxim Kucherov <maxima-net@bk.ru>
Date: Tue, 23 Aug 2022 15:58:52 +0300
Subject: [PATCH] Implement Kraken rates provider

---
 src/exchange/ratesProvider/index.ts           |  3 ++
 src/exchange/ratesProvider/kraken/dtos.ts     | 51 +++++++++++++++++++
 src/exchange/ratesProvider/kraken/index.ts    |  1 +
 .../kraken/krakenRatesProvider.ts             | 34 +++++++++++++
 src/exchange/ratesProvider/ratesProvider.ts   |  7 +++
 5 files changed, 96 insertions(+)
 create mode 100644 src/exchange/ratesProvider/index.ts
 create mode 100644 src/exchange/ratesProvider/kraken/dtos.ts
 create mode 100644 src/exchange/ratesProvider/kraken/index.ts
 create mode 100644 src/exchange/ratesProvider/kraken/krakenRatesProvider.ts
 create mode 100644 src/exchange/ratesProvider/ratesProvider.ts

diff --git a/src/exchange/ratesProvider/index.ts b/src/exchange/ratesProvider/index.ts
new file mode 100644
index 00000000..3e4f0e45
--- /dev/null
+++ b/src/exchange/ratesProvider/index.ts
@@ -0,0 +1,3 @@
+export type { RatesProvider } from './ratesProvider';
+export { BinanceRatesProvider } from './binance/index';
+export { KrakenRatesProvider } from './kraken/index';
diff --git a/src/exchange/ratesProvider/kraken/dtos.ts b/src/exchange/ratesProvider/kraken/dtos.ts
new file mode 100644
index 00000000..1a65a792
--- /dev/null
+++ b/src/exchange/ratesProvider/kraken/dtos.ts
@@ -0,0 +1,51 @@
+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;
+}
diff --git a/src/exchange/ratesProvider/kraken/index.ts b/src/exchange/ratesProvider/kraken/index.ts
new file mode 100644
index 00000000..882bb11d
--- /dev/null
+++ b/src/exchange/ratesProvider/kraken/index.ts
@@ -0,0 +1 @@
+export { KrakenRatesProvider } from './krakenRatesProvider';
diff --git a/src/exchange/ratesProvider/kraken/krakenRatesProvider.ts b/src/exchange/ratesProvider/kraken/krakenRatesProvider.ts
new file mode 100644
index 00000000..b43d0d17
--- /dev/null
+++ b/src/exchange/ratesProvider/kraken/krakenRatesProvider.ts
@@ -0,0 +1,34 @@
+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]);
+  }
+}
diff --git a/src/exchange/ratesProvider/ratesProvider.ts b/src/exchange/ratesProvider/ratesProvider.ts
new file mode 100644
index 00000000..169c2862
--- /dev/null
+++ b/src/exchange/ratesProvider/ratesProvider.ts
@@ -0,0 +1,7 @@
+import type BigNumber from 'bignumber.js';
+
+import type { Currency } from '../../common';
+
+export interface RatesProvider {
+  getPrice(quoteCurrency: Currency['id'], baseCurrency: Currency['id']): Promise<BigNumber | undefined>;
+}