Merge branch 'feature-withdrawal-fee'

7 files changed, 112 insertions, 24 deletions

diff --git a/README.md b/README.md
index 1b3c832d..ad1a6724 100644
--- a/README.md
+++ b/README.md
@@ -25,7 +25,7 @@ docker network create net
 docker run -it -v $(pwd):/app --entrypoint yarn asoltys/coinos-server
 docker-compose -f docker-compose.yml -f docker-compose.dev.yml up -d
 docker exec -i mariadb mysql -u root -ppassword < db/schema.sql   
-docker exec -it liquid elements-cli -conf=/config/elements.conf sendtoaddress AzpsKhC6xE9FEK4aWAzMnbvueMLiSa5ym1xpuYogFkHzWgMHSt8B79aNNbFppQzCSQ2yZ9E4nL6RQJU7 1000000
+docker exec -it liquid elements-cli -conf=/home/elements/.elements/elements.conf sendtoaddress AzpsKhC6xE9FEK4aWAzMnbvueMLiSa5ym1xpuYogFkHzWgMHSt8B79aNNbFppQzCSQ2yZ9E4nL6RQJU7 1000000
 ```
 
 then run this and keep reference to the result for the forthcoming [Config changes] 
@@ -266,4 +266,4 @@ To purchase a commercial license or to inquire about customized, managed instanc
 [pwd file]:./sampleconfig/lnd/pwd
 [licensed]:./LICENSE.md
 [[email protected]]:mailto:[email protected]
-[generate some BTC]:./doc/fund-server-bitcoin-cli.md
\ No newline at end of file
+[generate some BTC]:./doc/fund-server-bitcoin-cli.md
diff --git a/db/models/accounts.js b/db/models/accounts.js
index 12fef548..88ad2d44 100644
--- a/db/models/accounts.js
+++ b/db/models/accounts.js
@@ -124,6 +124,15 @@ const attributes = {
     comment: null,
     field: "balance"
   },
+  fee_credits: {
+    type: DataTypes.DOUBLE,
+    allowNull: true,
+    defaultValue: 0.0,
+    primaryKey: false,
+    autoIncrement: false,
+    comment: "Credits that can be used towards paying withdrawal fees",
+    field: "fee_credits"
+  },
   pending: {
     type: DataTypes.DOUBLE,
     allowNull: true,
diff --git a/doc/fund-server-bitcoin-cli.md b/doc/fund-server-bitcoin-cli.md
index 093c537c..e0a2c5e3 100644
--- a/doc/fund-server-bitcoin-cli.md
+++ b/doc/fund-server-bitcoin-cli.md
@@ -14,7 +14,7 @@ bitcoin-cli -regtest -rpcuser=admin1 -rpcpassword=123 getnewaddress
 > bcrt1qzneawwyxe0fts5p8a6tsp4gu2mfnqzs92235hm # (example)
 
 # mine a block to the new address 
-bitcoin-cli -regtest -datadir=/config generatetoaddress 101  theaddressgeneratedabove
+bitcoin-cli -regtest -datadir=/home/bitcoin/.bitcoin generatetoaddress 101  theaddressgeneratedabove
 
 # verify you got the reward by doing: 
 bitcoin-cli -regtest -rpcuser=admin1 -rpcpassword=123 getbalance
diff --git a/routes/bitcoin/receive.js b/routes/bitcoin/receive.js
index 5d8e21e7..5bdbcb72 100644
--- a/routes/bitcoin/receive.js
+++ b/routes/bitcoin/receive.js
@@ -21,6 +21,9 @@ const network =
 const queue = {};
 const seen = [];
 
+// used to calculate how many credits to give
+const withdrawalFeeMultiplier = 0.01;
+
 zmqRawTx.on("message", async (topic, message, sequence) => {
   const hex = message.toString("hex");
   let tx = bitcoin.Transaction.fromHex(message);
@@ -192,6 +195,7 @@ setInterval(async () => {
             { pending: Math.min(account.pending, total) },
             { transaction }
           );
+          await account.increment({ fee_credits: Math.floor(total * withdrawalFeeMultiplier) }, { transaction });
           await account.reload({ transaction });
           await p.save({ transaction });
 
diff --git a/routes/bitcoin/send.js b/routes/bitcoin/send.js
index cf7e89ef..a9c95b31 100644
--- a/routes/bitcoin/send.js
+++ b/routes/bitcoin/send.js
@@ -34,7 +34,7 @@ module.exports = ah(async (req, res) => {
   // get withdrawal fee
   // 'total' refers to the total before the withdrawal fee
   // (i.e. the total bitcoin that leaves this server)
-  let withdrawalFee = amount * withdrawalFeeMultiplier;
+  let withdrawalFee = Math.floor(amount * withdrawalFeeMultiplier);
 
   try {
     // withdraw bitcoin
@@ -67,6 +67,14 @@ module.exports = ah(async (req, res) => {
         throw new Error("low balance (after withdrawal 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 });
+        await account.reload({ transaction });
+        withdrawalFee -= withdrawalFeeDeduction;
+      }
+
       await account.decrement({ balance: (total + withdrawalFee) }, { transaction });
       await account.reload({ transaction });
 
@@ -84,25 +92,26 @@ module.exports = ah(async (req, res) => {
         transaction
       });
 
-      await receiverAccount.increment({ balance: withdrawalFee }, { transaction });
-      await receiverAccount.reload({ transaction });
-      let fee_payment = await db.Payment.create({
-        amount: withdrawalFee,
-        fee: 0,
-        memo: "Bitcoin withdrawal fee",
-        account_id: receiverAccount.id,
-        user_id: receiverAccount.user_id,
-        rate: app.get("rates")[receiverAccount.user.currency],
-        currency: receiverAccount.user.currency,
-        confirmed: true,
-        received: true,
-        network: "COINOS"
-        },
-        { transaction }
-      );
+      let fee_payment_id = null;
+      if (withdrawalFee) {
+        await receiverAccount.increment({ balance: withdrawalFee }, { transaction });
+        await receiverAccount.reload({ transaction });
+        let fee_payment = await db.Payment.create({
+          amount: withdrawalFee,
+          fee: 0,
+          memo: "Bitcoin withdrawal fee",
+          account_id: receiverAccount.id,
+          user_id: receiverAccount.user_id,
+          rate: app.get("rates")[receiverAccount.user.currency],
+          currency: receiverAccount.user.currency,
+          confirmed: true,
+          received: true,
+          network: "COINOS"
+        }, { transaction });
+        fee_payment_id = fee_payment.id;
+      }
 
       // record the external bitcoin transaction
-      // no need to record the withdrawal fee - since that is internal only
       let params = {
         amount: -amount,
         fee,
@@ -115,7 +124,7 @@ module.exports = ah(async (req, res) => {
         confirmed: true,
         received: false,
         network: "bitcoin",
-        fee_payment_id: fee_payment.id
+        fee_payment_id: fee_payment_id
       };
 
       if (config.bitcoin.walletpass)
diff --git a/routes/liquid/receive.js b/routes/liquid/receive.js
index d2864872..0eed35fd 100644
--- a/routes/liquid/receive.js
+++ b/routes/liquid/receive.js
@@ -13,6 +13,9 @@ const network =
     config.liquid.network === "mainnet" ? "liquid" : config.liquid.network
   ];
 
+// used to calculate how many credits to give
+const withdrawalFeeMultiplier = 0.01;
+
 const getAccount = async (params, transaction) => {
   let account = await db.Account.findOne({
     where: params,
@@ -341,6 +344,7 @@ setInterval(async () => {
             { pending: Math.min(p.account.pending, total) },
             { transaction }
           );
+          await account.increment({ fee_credits: Math.floor(total * withdrawalFeeMultiplier) }, { transaction });
           await p.account.reload({ transaction });
 
           await p.save({ transaction });
diff --git a/routes/liquid/send.js b/routes/liquid/send.js
index 6f3616e8..fcb05942 100644
--- a/routes/liquid/send.js
+++ b/routes/liquid/send.js
@@ -84,6 +84,11 @@ sendLiquid = async ({ asset, amount, user, address, memo, tx, limit }) => {
           total += fee - covered;
         }
 
+        // get withdrawal fee
+        // 'total' refers to the total before the withdrawal fee
+        // (i.e. the total liquid bitcoin that leaves this server)
+        var withdrawalFee = Math.floor(amount * withdrawalFeeMultiplier);
+
         if (limit && total > limit + fee)
           throw new Error("Tx amount exceeds authorized amount");
 
@@ -112,11 +117,67 @@ sendLiquid = async ({ asset, amount, user, address, memo, tx, limit }) => {
                 account.ticker === "BTC" ? "SAT" : account.ticker
               }, have ${account.balance}`
             );
+          } else if (total + withdrawalFee > account.balance) {
+            l.warn("amount plus withdrawal fee exceeds balance", {
+              total,
+              fee,
+              withdrawalFee,
+              balance: account.balance
+            });
+            throw new Error(
+              `Insufficient funds, need ${total + withdrawalFee} ${
+                account.ticker === "BTC" ? "SAT" : account.ticker
+              }, have ${account.balance}`
+            );
+          }
+
+          // use user's credits to reduce fee, if available
+          console.log(account.fee_credits);
+          let withdrawalFeeDeduction = Math.min(account.fee_credits, withdrawalFee);
+          if (withdrawalFeeDeduction) {
+            await account.decrement({ fee_credits: withdrawalFeeDeduction }, { transaction });
+            await account.reload({ transaction });
+            withdrawalFee -= withdrawalFeeDeduction;
           }
 
-          await account.decrement({ balance: total }, { transaction });
+          await account.decrement({ balance: (total + withdrawalFee)}, { transaction });
           await account.reload({ transaction });
 
+          let receiverAccount = await db.Account.findOne({
+            where: {
+              "$user.username$": withdrawalFeeReceiver
+            },
+            include: [
+              {
+                model: db.User,
+                as: "user"
+              },
+            ],
+            lock: transaction.LOCK.UPDATE,
+            transaction
+          });
+
+          let fee_payment_id = null;
+          if (withdrawalFee) {
+            await receiverAccount.increment({ balance: withdrawalFee }, { transaction });
+            await receiverAccount.reload({ transaction });
+            let fee_payment = {
+              amount: withdrawalFee,
+              fee: 0,
+              memo: "Liquid withdrawal fee",
+              account_id: receiverAccount.id,
+              user_id: receiverAccount.user_id,
+              rate: app.get("rates")[receiverAccount.user.currency],
+              currency: receiverAccount.user.currency,
+              confirmed: true,
+              received: true,
+              network: "COINOS"
+            };
+            fee_payment.account = receiverAccount;
+            payments.push(fee_payment);
+            fee_payment_id = fee_payment.id;
+          }
+
           let payment = {
             amount: -amount,
             account_id: account.id,
@@ -128,7 +189,8 @@ sendLiquid = async ({ asset, amount, user, address, memo, tx, limit }) => {
             address,
             confirmed: true,
             received: false,
-            network: "liquid"
+            network: "liquid",
+            fee_payment_id: fee_payment_id
           };
 
           payment.account = account;