From 43b096f98226f9a52c75ea49c07ef63ce5bdf890 Mon Sep 17 00:00:00 2001
From: tyleroooo <tyler@dydx.exchange>
Date: Tue, 15 Oct 2024 12:45:07 -0400
Subject: [PATCH] fix: help users not leave dust in the vault (#709)

---
 build.gradle.kts                              |  2 +-
 .../vault/VaultDepositWithdrawForm.kt         | 24 ++---
 .../functional/vault/VaultFormTests.kt        | 88 +++++++++++++++++++
 v4_abacus.podspec                             |  2 +-
 4 files changed, 103 insertions(+), 13 deletions(-)

diff --git a/build.gradle.kts b/build.gradle.kts
index 799e48df6..b8405a825 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -52,7 +52,7 @@ allprojects {
 }
 
 group = "exchange.dydx.abacus"
-version = "1.12.24"
+version = "1.12.25"
 
 repositories {
     google()
diff --git a/src/commonMain/kotlin/exchange.dydx.abacus/functional/vault/VaultDepositWithdrawForm.kt b/src/commonMain/kotlin/exchange.dydx.abacus/functional/vault/VaultDepositWithdrawForm.kt
index 822510a9d..901465672 100644
--- a/src/commonMain/kotlin/exchange.dydx.abacus/functional/vault/VaultDepositWithdrawForm.kt
+++ b/src/commonMain/kotlin/exchange.dydx.abacus/functional/vault/VaultDepositWithdrawForm.kt
@@ -17,7 +17,6 @@ import kollections.toIList
 import kotlinx.serialization.Serializable
 import kotlin.js.JsExport
 import kotlin.math.abs
-import kotlin.math.floor
 
 @JsExport
 @Serializable
@@ -245,7 +244,17 @@ object VaultDepositWithdrawFormValidator {
         if (shareValue == 0.0) {
             return 0.0
         }
-        return (amount / shareValue).toLong().toDouble()
+
+        val amountToUse = if (vaultAccount?.withdrawableUsdc != null &&
+            vaultAccount.withdrawableUsdc - amount >= 0 &&
+            vaultAccount.withdrawableUsdc - amount <= 0.01
+        ) {
+            vaultAccount.withdrawableUsdc
+        } else {
+            amount
+        }
+
+        return (amountToUse / shareValue).toLong().toDouble()
     }
 
     fun validateVaultForm(
@@ -260,15 +269,8 @@ object VaultDepositWithdrawFormValidator {
         var submissionData: VaultDepositWithdrawSubmissionData? = null
 
         // Calculate post-operation values and slippage
-        val amount = formData.amount ?: 0.0
-
-        val shareValue = vaultAccount?.shareValue
-        val sharesToAttemptWithdraw = if (amount > 0 && shareValue != null && shareValue > 0) {
-            // shares must be whole numbers
-            floor(amount / shareValue)
-        } else {
-            null
-        }
+        val sharesToAttemptWithdraw = calculateSharesToWithdraw(vaultAccount, formData.amount ?: 0.0)
+        val amount = sharesToAttemptWithdraw * (vaultAccount?.shareValue ?: 0.0)
 
         val withdrawnAmountIncludingSlippage = slippageResponse?.expectedQuoteQuantums?.let { it / 1_000_000.0 }
         val postOpVaultBalance = when (formData.action) {
diff --git a/src/commonTest/kotlin/exchange.dydx.abacus/functional/vault/VaultFormTests.kt b/src/commonTest/kotlin/exchange.dydx.abacus/functional/vault/VaultFormTests.kt
index 25e481928..4577094e5 100644
--- a/src/commonTest/kotlin/exchange.dydx.abacus/functional/vault/VaultFormTests.kt
+++ b/src/commonTest/kotlin/exchange.dydx.abacus/functional/vault/VaultFormTests.kt
@@ -38,6 +38,94 @@ class VaultFormTests {
         )
     }
 
+    @Test
+    fun testShareCalculationCloseToZero() {
+        assertEquals(
+            VaultDepositWithdrawFormValidator.calculateSharesToWithdraw(
+                vaultAccount = makeVaultAccount(
+                    balanceUsdc = 600.0,
+                    balanceShares = 600000.0,
+                    withdrawableUsdc = 500.0,
+                ),
+                amount = 500.0,
+            ),
+            500000.0,
+        )
+
+        assertEquals(
+            VaultDepositWithdrawFormValidator.calculateSharesToWithdraw(
+                vaultAccount = makeVaultAccount(
+                    balanceUsdc = 600.0,
+                    balanceShares = 600000.0,
+                    withdrawableUsdc = 500.0,
+                ),
+                amount = 499.02,
+            ),
+            499020.0,
+        )
+
+        assertEquals(
+            VaultDepositWithdrawFormValidator.calculateSharesToWithdraw(
+                vaultAccount = makeVaultAccount(
+                    balanceUsdc = 600.0,
+                    balanceShares = 600000.0,
+                    withdrawableUsdc = 500.0,
+                ),
+                amount = 499.07,
+            ),
+            499070.0,
+        )
+
+        assertEquals(
+            VaultDepositWithdrawFormValidator.calculateSharesToWithdraw(
+                vaultAccount = makeVaultAccount(
+                    balanceUsdc = 600.0,
+                    balanceShares = 600000.0,
+                    withdrawableUsdc = 500.0,
+                ),
+                amount = 499.02,
+            ),
+            499020.0,
+        )
+
+        assertEquals(
+            VaultDepositWithdrawFormValidator.calculateSharesToWithdraw(
+                vaultAccount = makeVaultAccount(
+                    balanceUsdc = 600.0,
+                    balanceShares = 600000.0,
+                    withdrawableUsdc = 500.0,
+                ),
+                amount = 499.989,
+            ),
+            // actually off by one because of double precision + cast to long
+            499988.0,
+        )
+
+        assertEquals(
+            VaultDepositWithdrawFormValidator.calculateSharesToWithdraw(
+                vaultAccount = makeVaultAccount(
+                    balanceUsdc = 600.0,
+                    balanceShares = 600000.0,
+                    withdrawableUsdc = 500.0,
+                ),
+                amount = 499.99,
+            ),
+            500000.0,
+        )
+
+        assertEquals(
+            VaultDepositWithdrawFormValidator.calculateSharesToWithdraw(
+                vaultAccount = makeVaultAccount(
+                    balanceUsdc = 600.0,
+                    balanceShares = 600000.0,
+                    withdrawableUsdc = 500.0,
+                ),
+                amount = 499.992,
+            ),
+            500000.0,
+        )
+    }
+
     @Test
     fun testDepositValidation() {
         val result = VaultDepositWithdrawFormValidator.validateVaultForm(
diff --git a/v4_abacus.podspec b/v4_abacus.podspec
index 94d2ddbf0..1651704e4 100644
--- a/v4_abacus.podspec
+++ b/v4_abacus.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |spec|
     spec.name                     = 'v4_abacus'
-    spec.version                  = '1.12.24'
+    spec.version                  = '1.12.25'
     spec.homepage                 = 'https://github.com/dydxprotocol/v4-abacus'
     spec.source                   = { :http=> ''}
     spec.authors                  = ''