Moved conversion fee calculation to a single file per currency

3 files changed, 32 insertions, 21 deletions

diff --git a/routes/bitcoin/conversionFee.js b/routes/bitcoin/conversionFee.js
new file mode 100644
index 00000000..8a6bfce6
--- /dev/null
+++ b/routes/bitcoin/conversionFee.js
@@ -0,0 +1,12 @@
+// Code for the conversion fee
+// This is in a separate file so that the same function can be used by ./send and ./receive
+
+const conversionFeeMultiplier = 0.01;
+export const conversionFeeReceiver = "coinosfees";  // account that receives the fees
+
+/**
+ * Returns the fee you have to pay for withdrawing 'amount' bitcoin.
+ */
+export function computeConversionFee(amount) {
+  return Math.floor(amount * conversionFeeMultiplier);
+}
diff --git a/routes/bitcoin/receive.js b/routes/bitcoin/receive.js
index 5bdbcb72..02deb58f 100644
--- a/routes/bitcoin/receive.js
+++ b/routes/bitcoin/receive.js
@@ -21,8 +21,7 @@ const network =
 const queue = {};
 const seen = [];
 
-// used to calculate how many credits to give
-const withdrawalFeeMultiplier = 0.01;
+import { computeConversionFee } from './conversionFee.js';
 
 zmqRawTx.on("message", async (topic, message, sequence) => {
   const hex = message.toString("hex");
@@ -195,7 +194,8 @@ setInterval(async () => {
             { pending: Math.min(account.pending, total) },
             { transaction }
           );
-          await account.increment({ fee_credits: Math.floor(total * withdrawalFeeMultiplier) }, { transaction });
+          // get the # of fee credits you would need to pay off this amount of bitcoin
+          await account.increment({ fee_credits: computeConversionFee(total) }, { transaction });
           await account.reload({ transaction });
           await p.save({ transaction });
 
diff --git a/routes/bitcoin/send.js b/routes/bitcoin/send.js
index a9c95b31..72d34317 100644
--- a/routes/bitcoin/send.js
+++ b/routes/bitcoin/send.js
@@ -1,6 +1,5 @@
 const btc = config.liquid.btcasset;
-const withdrawalFeeMultiplier = 0.01;  // 1% withdrawal fee
-const withdrawalFeeReceiver = "coinosfees";  // account that receives the fees
+import { computeConversionFee, conversionFeeReceiver } from './conversionFee.js';
 
 module.exports = ah(async (req, res) => {
   let { user } = req;
@@ -31,10 +30,10 @@ module.exports = ah(async (req, res) => {
   total = total - change + fee;
   let amount = total - fee;
 
-  // get withdrawal fee
-  // 'total' refers to the total before the withdrawal fee
+  // get conversion fee
+  // 'total' refers to the total before the conversion fee
   // (i.e. the total bitcoin that leaves this server)
-  let withdrawalFee = Math.floor(amount * withdrawalFeeMultiplier);
+  let conversionFee = computeConversionFee(amount);
 
   try {
     // withdraw bitcoin
@@ -62,25 +61,25 @@ module.exports = ah(async (req, res) => {
       if (total > account.balance) {
         l.error("amount exceeds balance", amount, fee, account.balance);
         throw new Error("low balance");
-      } else if (total + withdrawalFee > account.balance) {
-        l.error("total (after withdrawal fee) exceeds balance", amount, fee, account.balance);
-        throw new Error("low balance (after withdrawal fee)");
+      } else if (total + conversionFee > account.balance) {
+        l.error("total (after conversion fee) exceeds balance", amount, fee, account.balance);
+        throw new Error("low balance (after conversion fee)");
       }
 
       // use user's credits to reduce fee, if available
-      let withdrawalFeeDeduction = Math.min(account.fee_credits, withdrawalFee);
-      if (withdrawalFeeDeduction) {
-        await account.decrement({ fee_credits: withdrawalFeeDeduction }, { transaction });
+      let conversionFeeDeduction = Math.min(account.fee_credits, conversionFee);
+      if (conversionFeeDeduction) {
+        await account.decrement({ fee_credits: conversionFeeDeduction }, { transaction });
         await account.reload({ transaction });
-        withdrawalFee -= withdrawalFeeDeduction;
+        conversionFee -= conversionFeeDeduction;
       }
 
-      await account.decrement({ balance: (total + withdrawalFee) }, { transaction });
+      await account.decrement({ balance: (total + conversionFee) }, { transaction });
       await account.reload({ transaction });
 
       let receiverAccount = await db.Account.findOne({
         where: {
-          "$user.username$": withdrawalFeeReceiver
+          "$user.username$": conversionFeeReceiver
         },
         include: [
           {
@@ -93,13 +92,13 @@ module.exports = ah(async (req, res) => {
       });
 
       let fee_payment_id = null;
-      if (withdrawalFee) {
-        await receiverAccount.increment({ balance: withdrawalFee }, { transaction });
+      if (conversionFee) {
+        await receiverAccount.increment({ balance: conversionFee }, { transaction });
         await receiverAccount.reload({ transaction });
         let fee_payment = await db.Payment.create({
-          amount: withdrawalFee,
+          amount: conversionFee,
           fee: 0,
-          memo: "Bitcoin withdrawal fee",
+          memo: "Bitcoin conversion fee",
           account_id: receiverAccount.id,
           user_id: receiverAccount.user_id,
           rate: app.get("rates")[receiverAccount.user.currency],