Bugfix/exchange rate calculation when converting derived currencies (#5961)

* Fix exchange rate calculation when converting derived currencies

* Update changelog

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Fixed
+
+- Fixed an issue with the exchange rate calculation when converting between derived currencies and their root currencies
+
 ## 2.219.0 - 2025-11-23
 
 ### Added

apps/api/src/services/exchange-rate-data/exchange-rate-data.service.ts

@@ -30,6 +30,7 @@ import ms from 'ms';
 export class ExchangeRateDataService {
   private currencies: string[] = [];
   private currencyPairs: DataGatheringItem[] = [];
+  private derivedCurrencyFactors: { [currencyPair: string]: number } = {};
   private exchangeRates: { [currencyPair: string]: number } = {};
 
   public constructor(
@@ -135,8 +136,14 @@ export class ExchangeRateDataService {
   public async initialize() {
     this.currencies = await this.prepareCurrencies();
     this.currencyPairs = [];
+    this.derivedCurrencyFactors = {};
     this.exchangeRates = {};
 
+    for (const { currency, factor, rootCurrency } of DERIVED_CURRENCIES) {
+      this.derivedCurrencyFactors[`${currency}${rootCurrency}`] = 1 / factor;
+      this.derivedCurrencyFactors[`${rootCurrency}${currency}`] = factor;
+    }
+
     for (const {
       currency1,
       currency2,
@@ -266,10 +273,14 @@ export class ExchangeRateDataService {
       return this.toCurrency(aValue, aFromCurrency, aToCurrency);
     }
 
+    const derivedCurrencyFactor =
+      this.derivedCurrencyFactors[`${aFromCurrency}${aToCurrency}`];
     let factor: number;
 
     if (aFromCurrency === aToCurrency) {
       factor = 1;
+    } else if (derivedCurrencyFactor) {
+      factor = derivedCurrencyFactor;
     } else {
       const dataSource =
         this.dataProviderService.getDataSourceForExchangeRates();
@@ -357,9 +368,22 @@ export class ExchangeRateDataService {
       for (const date of dates) {
         factors[format(date, DATE_FORMAT)] = 1;
       }
-    } else {
-      const dataSource =
-        this.dataProviderService.getDataSourceForExchangeRates();
+
+      return factors;
+    }
+
+    const derivedCurrencyFactor =
+      this.derivedCurrencyFactors[`${currencyFrom}${currencyTo}`];
+
+    if (derivedCurrencyFactor) {
+      for (const date of dates) {
+        factors[format(date, DATE_FORMAT)] = derivedCurrencyFactor;
+      }
+
+      return factors;
+    }
+
+    const dataSource = this.dataProviderService.getDataSourceForExchangeRates();
     const symbol = `${currencyFrom}${currencyTo}`;
 
     const marketData = await this.marketDataService.getRange({
@@ -389,8 +413,7 @@ export class ExchangeRateDataService {
       try {
         if (currencyFrom === DEFAULT_CURRENCY) {
           for (const date of dates) {
-              marketPriceBaseCurrencyFromCurrency[format(date, DATE_FORMAT)] =
-                1;
+            marketPriceBaseCurrencyFromCurrency[format(date, DATE_FORMAT)] = 1;
           }
         } else {
           const marketData = await this.marketDataService.getRange({
@@ -440,9 +463,7 @@ export class ExchangeRateDataService {
         try {
           const factor =
             (1 /
-                marketPriceBaseCurrencyFromCurrency[
-                  format(date, DATE_FORMAT)
-                ]) *
+              marketPriceBaseCurrencyFromCurrency[format(date, DATE_FORMAT)]) *
             marketPriceBaseCurrencyToCurrency[format(date, DATE_FORMAT)];
 
           if (isNaN(factor)) {
@@ -464,7 +485,6 @@ export class ExchangeRateDataService {
         }
       }
     }
-    }
 
     return factors;
   }