Fix dca swap amount logic (#1109)

* Fix dca swap amount logic

* Fix to HNT decimals

* fix tests

Author: ChewingGlass

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "dc-auto-top"
-version = "0.0.6"
+version = "0.0.7"
 # Trigger deployment - timestamp: 03-31-2025 #3
 description = "Created with Anchor"
 edition = "2021"

programs/dc-auto-top/Cargo.toml

@@ -240,11 +240,22 @@ pub fn handler<'info>(
           .ok_or(ErrorCode::ArithmeticError)?,
       };
 
-      msg!("hnt_per_swap: {}", hnt_per_swap);
+      // Convert HNT per swap to HNT decimals from DCA decimals
+      let hnt_per_swap_hnt_decimals = match ctx.accounts.dca_mint.decimals.cmp(&8u8) {
+        std::cmp::Ordering::Greater => hnt_per_swap
+          .checked_div(10_u64.pow(u32::from(ctx.accounts.dca_mint.decimals - 8)))
+          .ok_or(ErrorCode::ArithmeticError)?,
+        std::cmp::Ordering::Less => hnt_per_swap
+          .checked_mul(10_u64.pow(u32::from(8 - ctx.accounts.dca_mint.decimals)))
+          .ok_or(ErrorCode::ArithmeticError)?,
+        std::cmp::Ordering::Equal => hnt_per_swap,
+      };
+
+      msg!("hnt_per_swap: {}", hnt_per_swap_hnt_decimals);
 
       // Now calculate number of orders needed using ceiling division
-      if hnt_per_swap > 0 {
-        hnt_needed.div_ceil(hnt_per_swap)
+      if hnt_per_swap_hnt_decimals > 0 {
+        hnt_needed.div_ceil(hnt_per_swap_hnt_decimals)
       } else {
         0
       }

programs/dc-auto-top/src/instructions/top_off_hnt_v0.rs

@@ -510,6 +510,7 @@ describe("dc-auto-topoff", () => {
 
       // Calculate required input amount per swap to get exactly hntNeeded/numOrders HNT per swap
       // Formula: outputAmount = inputAmount * (inputPrice / outputPrice)
+      // (dollars / dollars) / (dollars / hnt) = hnt / dollars
       // So: inputAmount = outputAmount * (outputPrice / inputPrice)
       const hntPerSwap = hntNeeded.divn(numOrders); // 10 HNT per swap
 
@@ -525,17 +526,23 @@ describe("dc-auto-topoff", () => {
           .mul(outputPrice)
           .div(inputPrice)
           .div(new anchor.BN(10).pow(new anchor.BN(Math.abs(expoDiff))))
+          // Decimal difference between USDC and HNT
+          .div(new anchor.BN(100))
           .add(new anchor.BN(1));
       } else if (expoDiff < 0) {
         dcaSwapAmount = hntPerSwap
           .mul(outputPrice)
           .div(inputPrice)
           .mul(new anchor.BN(10).pow(new anchor.BN(Math.abs(expoDiff))))
+          // Decimal difference between USDC and HNT
+          .div(new anchor.BN(100))
           .add(new anchor.BN(1));
       } else {
         dcaSwapAmount = hntPerSwap
           .mul(outputPrice)
           .div(inputPrice)
+          // Decimal difference between USDC and HNT
+          .div(new anchor.BN(100))
           .add(new anchor.BN(1));
       }
 
@@ -669,6 +676,10 @@ describe("dc-auto-topoff", () => {
       const actualAmount = new anchor.BN(
         hntAccountAfterFirstSwap.amount.toString()
       );
+      console.log(`Actual amount after first swap: ${actualAmount.toString()}`);
+      console.log(
+        `Expected amount after first swap: ${expectedAfterFirstSwap.toString()}`
+      );
       const difference = actualAmount.gt(expectedAfterFirstSwap)
         ? actualAmount.sub(expectedAfterFirstSwap)
         : expectedAfterFirstSwap.sub(actualAmount);

tests/dc-auto-topoff.ts

@@ -49,7 +49,8 @@ function calculateExpectedOutput(
       .div(outputPriceWithConf);
   }
 
-  return expectedOutput;
+  // Extra two decimals on HNT
+  return expectedOutput.mul(new BN(100));
 }
 
 export interface DcaServerConfig {
@@ -117,11 +118,13 @@ export async function createDcaServer(
         );
 
       console.log(
-        `Input Price: ${inputPriceUpdate.priceMessage.price.toString()} (expo: ${inputPriceUpdate.priceMessage.exponent
+        `Input Price: ${inputPriceUpdate.priceMessage.price.toString()} (expo: ${
+          inputPriceUpdate.priceMessage.exponent
         })`
       );
       console.log(
-        `Output Price: ${outputPriceUpdate.priceMessage.price.toString()} (expo: ${outputPriceUpdate.priceMessage.exponent
+        `Output Price: ${outputPriceUpdate.priceMessage.price.toString()} (expo: ${
+          outputPriceUpdate.priceMessage.exponent
         })`
       );
 
@@ -231,9 +234,7 @@ export async function runAllTasks(
   taskQueue: PublicKey,
   crankTurner: Keypair
 ) {
-  const taskQueueAcc = await tuktukProgram.account.taskQueueV0.fetch(
-    taskQueue
-  );
+  const taskQueueAcc = await tuktukProgram.account.taskQueueV0.fetch(taskQueue);
 
   // Find all task IDs that need to be executed (have a 1 in the bitmap)
   const taskIds: number[] = [];
@@ -251,8 +252,9 @@ export async function runAllTasks(
     const task = taskKey(taskQueue, taskId)[0];
     const taskAcc = await tuktukProgram.account.taskV0.fetch(task);
     if (
-      ((taskAcc.trigger.timestamp?.[0]?.toNumber() || 0) >
-        new Date().getTime() / 1000) || taskAcc.transaction.remoteV0?.url?.includes(".helium.io")
+      (taskAcc.trigger.timestamp?.[0]?.toNumber() || 0) >
+        new Date().getTime() / 1000 ||
+      taskAcc.transaction.remoteV0?.url?.includes(".helium.io")
     ) {
       continue;
     }
@@ -276,4 +278,3 @@ export async function runAllTasks(
 }
 
 export { calculateExpectedOutput };
-