Add CRC support to the FiatApi

Bridged via USD rates from Coingecko.

src/fiat-api/FiatApi.ts

@@ -77,6 +77,10 @@ export enum FiatApiSupportedFiatCurrency {
     ZAR = 'zar', // South African Rand
 }
 
+export enum FiatApiBridgedFiatCurrency {
+    CRC = 'crc', // Costa Rican Colón
+}
+
 const API_URL = 'https://api.coingecko.com/api/v3';
 const COINGECKO_COIN_IDS = {
     [FiatApiSupportedCryptoCurrency.NIM]: 'nimiq-2',
@@ -135,7 +139,7 @@ export async function getHistoricExchangeRatesByRange(
  */
 export async function getHistoricExchangeRates(
     cryptoCurrency: FiatApiSupportedCryptoCurrency,
-    vsCurrency: FiatApiSupportedFiatCurrency | FiatApiSupportedCryptoCurrency,
+    vsCurrency: FiatApiSupportedFiatCurrency | FiatApiBridgedFiatCurrency | FiatApiSupportedCryptoCurrency,
     timestamps: number[],
     disableMinutlyData = false,
 ): Promise<Map<number, number|undefined>> {
@@ -180,9 +184,45 @@ export async function getHistoricExchangeRates(
         timestampIndex = searchEndIndex;
     }
 
-    // 2. Query Coingecko Api
+    // 2a. If we have a bridged currency, fetch the historic exchange rates for it
+    let bridgedCurrency: FiatApiBridgedFiatCurrency | undefined;
+    let bridgedExchangeRatePromise: Promise<Record<string, number>> | undefined;
+    if (Object.values(FiatApiBridgedFiatCurrency).includes(vsCurrency as FiatApiBridgedFiatCurrency)) {
+        bridgedCurrency = vsCurrency as FiatApiBridgedFiatCurrency;
+
+        switch (bridgedCurrency) {
+            case FiatApiBridgedFiatCurrency.CRC: {
+                // Use USD as the intermediate currency
+                vsCurrency = FiatApiSupportedFiatCurrency.USD;
+
+                // Find first and last date requested
+                const fromDate = new Date(timestamps[0]);
+                const untilDate = new Date(timestamps[timestamps.length - 1]);
+                // Adapt dates to Costa Rica timezone (UTC-6, all year round)
+                fromDate.setHours(fromDate.getHours() - 6);
+                untilDate.setHours(untilDate.getHours() - 6);
+                // Get the day portion
+                const from = fromDate.toISOString().split('T')[0];
+                const until = untilDate.toISOString().split('T')[0];
+
+                bridgedExchangeRatePromise = _fetch(
+                    `https://usd-crc-historic-rate.deno.dev/api/rates/${from}/${until}`,
+                );
+                break;
+            }
+            default:
+                throw new Error(`Unsupported bridged currency: ${bridgedCurrency}`);
+        }
+    }
+
+    // 2b. Query Coingecko Api
     const fetchPromises = chunks.map(
-        (chunk) => getHistoricExchangeRatesByRange(cryptoCurrency, vsCurrency, chunk.start, chunk.end),
+        (chunk) => getHistoricExchangeRatesByRange(
+            cryptoCurrency,
+            vsCurrency as FiatApiSupportedFiatCurrency | FiatApiSupportedCryptoCurrency,
+            chunk.start,
+            chunk.end,
+        ),
     );
     const prices = (await Promise.all(fetchPromises)).reduce(
         (accumulated, singleResult) => [...singleResult, ...accumulated],
@@ -226,6 +266,31 @@ export async function getHistoricExchangeRates(
         }
         ++timestampIndex; // Continue with next timestamp and check same priceIndex
     }
+
+    // 4. If bridged, convert the prices from the intermediate currency
+    if (bridgedCurrency && bridgedExchangeRatePromise) {
+        const bridgedExchangeRates = await bridgedExchangeRatePromise;
+        for (const [timestamp, price] of result) {
+            if (price) {
+                switch (bridgedCurrency) {
+                    case FiatApiBridgedFiatCurrency.CRC: {
+                        // Find first and last date requested
+                        const date = new Date(timestamps[0]);
+                        // Adapt date to Costa Rica timezone (UTC-6, all year round)
+                        date.setHours(date.getHours() - 6);
+                        // Get the day portion
+                        const day = date.toISOString().split('T')[0];
+                        // Convert from USD to CRC
+                        result.set(timestamp, price * bridgedExchangeRates[day]);
+                        break;
+                    }
+                    default:
+                        throw new Error(`Unsupported bridged currency: ${bridgedCurrency}`);
+                }
+            }
+        }
+    }
+
     return result;
 }
 

tests/FiatApi.spec.ts

@@ -0,0 +1,64 @@
+/**
+ * @jest-environment node
+ */
+
+/* global describe, it, expect */
+
+import {
+    FiatApiBridgedFiatCurrency,
+    FiatApiSupportedCryptoCurrency,
+    FiatApiSupportedFiatCurrency,
+    getHistoricExchangeRates,
+} from '../src/fiat-api/FiatApi';
+
+describe('FiatApi', () => {
+    it('can fetch historic USD rates for BTC', async () => {
+        const timestamps = [
+            new Date('2023-01-01T00:00:00.000Z').getTime(),
+            new Date('2023-01-01T01:00:00.000Z').getTime(),
+            new Date('2023-01-01T02:00:00.000Z').getTime(),
+            new Date('2023-01-01T03:00:00.000Z').getTime(),
+            new Date('2023-01-01T04:00:00.000Z').getTime(),
+            new Date('2023-10-13T05:00:00.000Z').getTime(),
+            new Date('2023-10-13T06:00:00.000Z').getTime(),
+            new Date('2023-10-13T07:00:00.000Z').getTime(),
+            new Date('2023-10-13T08:00:00.000Z').getTime(),
+            new Date('2023-10-13T09:00:00.000Z').getTime(),
+        ];
+        const rates = await getHistoricExchangeRates(
+            FiatApiSupportedCryptoCurrency.BTC,
+            FiatApiSupportedFiatCurrency.USD,
+            timestamps,
+        );
+        expect(rates.size).toBe(10);
+        expect(rates.get(timestamps[0])).toBeDefined();
+        expect(rates.get(timestamps[5])).toBeDefined();
+        expect(rates.get(timestamps[1])).toBeGreaterThan(16500);
+        expect(rates.get(timestamps[6])).toBeGreaterThan(16800);
+    }, 30e3);
+
+    it('can fetch historic CRC (bridged) rates for BTC', async () => {
+        const timestamps = [
+            new Date('2023-01-01T00:00:00.000Z').getTime(),
+            new Date('2023-01-01T01:00:00.000Z').getTime(),
+            new Date('2023-01-01T02:00:00.000Z').getTime(),
+            new Date('2023-01-01T03:00:00.000Z').getTime(),
+            new Date('2023-01-01T04:00:00.000Z').getTime(),
+            new Date('2023-10-13T05:00:00.000Z').getTime(),
+            new Date('2023-10-13T06:00:00.000Z').getTime(),
+            new Date('2023-10-13T07:00:00.000Z').getTime(),
+            new Date('2023-10-13T08:00:00.000Z').getTime(),
+            new Date('2023-10-13T09:00:00.000Z').getTime(),
+        ];
+        const rates = await getHistoricExchangeRates(
+            FiatApiSupportedCryptoCurrency.BTC,
+            FiatApiBridgedFiatCurrency.CRC,
+            timestamps,
+        );
+        expect(rates.size).toBe(10);
+        expect(rates.get(timestamps[0])).toBeDefined();
+        expect(rates.get(timestamps[5])).toBeDefined();
+        expect(rates.get(timestamps[1])).toBeGreaterThan(165000); // ~price in BTC * 10
+        expect(rates.get(timestamps[6])).toBeGreaterThan(168000); // ~price in BTC * 10
+    }, 30e3);
+});