From f7a13a0436badbf46be38c5b578b8543c7743d07 Mon Sep 17 00:00:00 2001
From: Lauri Vuorela <lauri.vuorela@gmail.com>
Date: Tue, 13 Feb 2024 20:35:57 +0100
Subject: Round totals rather than expense by expense (#88)

* do balance rounding only on full balances rather than on every expense

* use "public balances" calculated from reimbursements to show on balance page

* fixes for totals that did not work as expected

* prettier
---
 src/lib/balances.ts | 34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

(limited to 'src/lib/balances.ts')

diff --git a/src/lib/balances.ts b/src/lib/balances.ts
index 0bcd915..aa8d26f 100644
--- a/src/lib/balances.ts
+++ b/src/lib/balances.ts
@@ -24,7 +24,6 @@ export function getBalances(
 
     if (!balances[paidBy]) balances[paidBy] = { paid: 0, paidFor: 0, total: 0 }
     balances[paidBy].paid += expense.amount
-    balances[paidBy].total += expense.amount
 
     const totalPaidForShares = paidFors.reduce(
       (sum, paidFor) => sum + paidFor.shares,
@@ -46,13 +45,40 @@ export function getBalances(
 
       const dividedAmount = isLast
         ? remaining
-        : Math.floor((expense.amount * shares) / totalShares)
+        : (expense.amount * shares) / totalShares
       remaining -= dividedAmount
       balances[paidFor.participantId].paidFor += dividedAmount
-      balances[paidFor.participantId].total -= dividedAmount
     })
   }
 
+  // rounding and add total
+  for (const participantId in balances) {
+    // add +0 to avoid negative zeros
+    balances[participantId].paidFor =
+      Math.round(balances[participantId].paidFor) + 0
+    balances[participantId].paid = Math.round(balances[participantId].paid) + 0
+
+    balances[participantId].total =
+      balances[participantId].paid - balances[participantId].paidFor
+  }
+  return balances
+}
+
+export function getPublicBalances(reimbursements: Reimbursement[]): Balances {
+  const balances: Balances = {}
+  reimbursements.forEach((reimbursement) => {
+    if (!balances[reimbursement.from])
+      balances[reimbursement.from] = { paid: 0, paidFor: 0, total: 0 }
+
+    if (!balances[reimbursement.to])
+      balances[reimbursement.to] = { paid: 0, paidFor: 0, total: 0 }
+
+    balances[reimbursement.from].paidFor += reimbursement.amount
+    balances[reimbursement.from].total -= reimbursement.amount
+
+    balances[reimbursement.to].paid += reimbursement.amount
+    balances[reimbursement.to].total += reimbursement.amount
+  })
   return balances
 }
 
@@ -86,5 +112,5 @@ export function getSuggestedReimbursements(
       balancesArray.shift()
     }
   }
-  return reimbursements.filter(({ amount }) => amount !== 0)
+  return reimbursements.filter(({ amount }) => Math.round(amount) + 0 !== 0)
 }
-- 
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