From f7d78a9a73ac8e976b72d85e379d97cac04ba21a Mon Sep 17 00:00:00 2001
From: Reto Kaul <retokaul@sublimd.com>
Date: Sat, 12 Mar 2022 15:05:19 +0100
Subject: [PATCH] Improve percentage performance algorithm

---
 .../app/portfolio/portfolio-calculator-new.ts   | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/apps/api/src/app/portfolio/portfolio-calculator-new.ts b/apps/api/src/app/portfolio/portfolio-calculator-new.ts
index d627474ea..7d7c2dc04 100644
--- a/apps/api/src/app/portfolio/portfolio-calculator-new.ts
+++ b/apps/api/src/app/portfolio/portfolio-calculator-new.ts
@@ -691,6 +691,7 @@ export class PortfolioCalculatorNew {
     let grossPerformanceAtStartDate = new Big(0);
     let grossPerformanceFromSells = new Big(0);
     let initialValue: Big;
+    let investmentAtStartDate: Big;
     let lastAveragePrice = new Big(0);
     let lastTransactionInvestment = new Big(0);
     let lastValueOfInvestmentBeforeTransaction = new Big(0);
@@ -773,6 +774,10 @@ export class PortfolioCalculatorNew {
         averagePriceAtStartDate = totalInvestment.div(totalUnits);
       }
 
+      if (!investmentAtStartDate && i >= indexOfStartOrder) {
+        investmentAtStartDate = totalInvestment ?? new Big(0);
+      }
+
       const valueOfInvestmentBeforeTransaction = totalUnits.mul(
         order.unitPrice
       );
@@ -901,13 +906,17 @@ export class PortfolioCalculatorNew {
       .minus(grossPerformanceAtStartDate)
       .minus(fees.minus(feesAtStartDate));
 
+    const maxInvestmentBetweenStartAndEndDate = initialValue.plus(
+      maxTotalInvestment.minus(investmentAtStartDate)
+    );
+
     const grossPerformancePercentage =
       PortfolioCalculatorNew.CALCULATE_PERCENTAGE_PERFORMANCE_WITH_MAX_INVESTMENT ||
       averagePriceAtStartDate.eq(0) ||
       averagePriceAtEndDate.eq(0) ||
       orders[indexOfStartOrder].unitPrice.eq(0)
-        ? maxTotalInvestment.gt(0)
-          ? totalGrossPerformance.div(maxTotalInvestment)
+        ? maxInvestmentBetweenStartAndEndDate.gt(0)
+          ? totalGrossPerformance.div(maxInvestmentBetweenStartAndEndDate)
           : new Big(0)
         : // This formula has the issue that buying more units with a price
           // lower than the average buying price results in a positive
@@ -928,8 +937,8 @@ export class PortfolioCalculatorNew {
       averagePriceAtStartDate.eq(0) ||
       averagePriceAtEndDate.eq(0) ||
       orders[indexOfStartOrder].unitPrice.eq(0)
-        ? maxTotalInvestment.gt(0)
-          ? totalNetPerformance.div(maxTotalInvestment)
+        ? maxInvestmentBetweenStartAndEndDate.gt(0)
+          ? totalNetPerformance.div(maxInvestmentBetweenStartAndEndDate)
           : new Big(0)
         : // This formula has the issue that buying more units with a price
           // lower than the average buying price results in a positive