Messed up previous commit. This commit adds discount support.

* invoices now support a discounts array
* discount line items support a description and a percentage or amount
* renamed balance_due, total_paid, and remaining_balance to match
  invoice view
* mocha test written for discount total calculations
* changed roundToDecimal function to actually round instead of truncate

db/index.js

@@ -272,12 +272,28 @@ var createInvoice = function(invoice, callback) {
       invoice.api_key = undefined;
       invoice.created = new Date().getTime();
       invoice.type = 'invoice';
-      var balanceDue = new BigNumber(0);
+      var invoiceTotal = new BigNumber(0);
       invoice.line_items.forEach(function(item) {
         var lineCost = new BigNumber(item.amount).times(item.quantity);
-        balanceDue = balanceDue.plus(lineCost);
+        invoiceTotal = invoiceTotal.plus(lineCost);
       });
-      invoice.balance_due = Number(balanceDue.valueOf());
+      var isUSD = invoice.currency.toUpperCase() === 'USD';
+      var discountTotal = new BigNumber(0);
+      invoice.discounts.forEach(function(item) {
+        var roundedAmount = 0;
+        if (item.amount) {
+          roundedAmount = isUSD ? helper.roundToDecimal(item.amount, 2) : item.amount;
+        }
+        else if (item.percentage) {
+          var percentage = new BigNumber(item.percentage).dividedBy(100);
+          var discountAmount = Number(invoiceTotal.times(percentage).valueOf());
+          roundedAmount = isUSD ? helper.roundToDecimal(discountAmount, 2) : discountAmount;
+        }
+        discountTotal = discountTotal.plus(roundedAmount);
+      });
+      invoiceTotal = invoiceTotal.minus(discountTotal);
+      invoice.invoice_total = Number(invoiceTotal.valueOf());
+      invoice.invoice_total = isUSD ? helper.roundToDecimal(invoice.invoice_total, 2) : Number(invoice.invoice_total);
       if (invoice.text) {
         invoice.text = sanitizeHtml(invoice.text); // remove hostile elements
       }

lib/helper.js

@@ -34,8 +34,7 @@ var getLastFourDecimals = function(number) {
 
 // Round to decimal place
 var roundToDecimal = function(number, decimalPlaces) {
-  var offset = Math.pow(10, decimalPlaces);
-  return (Math.round(number * offset) / offset).toFixed(decimalPlaces);
+  return Number(Math.round(number + 'e+' + decimalPlaces)  + 'e-' + decimalPlaces).toFixed(decimalPlaces);
 };
 
 // Returns receiveDetail portion of transaction json from wallet notify

lib/invoices.js

@@ -8,7 +8,7 @@ var helper = require(__dirname + '/helper');
 // Calculates line totals for invoice line items
 var calculateLineTotals = function(invoice) {
   var isUSD = invoice.currency.toUpperCase() === 'USD';
-  invoice.line_items.forEach(function (item){
+  invoice.line_items.forEach(function (item) {
     item.line_total = Number(new BigNumber(item.amount).times(item.quantity).valueOf());
     if (isUSD) { // Round USD to two decimals
       item.amount = helper.roundToDecimal(item.amount, 2);
@@ -21,6 +21,32 @@ var calculateLineTotals = function(invoice) {
   });
 };
 
+// Calculates discount totals for invoice
+var calculateDiscountTotals = function(invoice) {
+  if (invoice.discounts && invoice.discounts.length > 0) {
+    var isUSD = invoice.currency.toUpperCase() === 'USD';
+    var invoiceTotal = new BigNumber(0);
+    invoice.line_items.forEach(function(item) {
+      var lineCost = new BigNumber(item.amount).times(item.quantity);
+      invoiceTotal = invoiceTotal.plus(lineCost);
+    });
+    invoice.discounts.forEach(function (item) {
+      if (item.amount) {
+        return;
+      }
+      var percentage = new BigNumber(item.percentage).dividedBy(100);
+      item.amount = invoiceTotal.times(percentage);
+      if (isUSD) { // Round USD to two decimals
+        item.amount = helper.roundToDecimal(item.amount, 2);
+      }
+      // If our calculated discount total has more than 8 decimals round to 8
+      else if (helper.decimalPlaces(item.amount) > 8) {
+        item.amount = helper.roundToDecimal(item.amount, 8);
+      }
+    });
+  }
+};
+
 // Returns the latest payment object for invoice
 var getActivePayment = function(paymentsArr) {
   var activePayment;
@@ -86,7 +112,7 @@ var getAmountDue = function(balanceDue, totalPaid, currency) {
 var getAmountDueBTC = function(invoice, paymentsArr, cb) {
   var isUSD = invoice.currency.toUpperCase() === 'USD';
   var totalPaid = getTotalPaid(invoice, paymentsArr);
-  var remainingBalance = new BigNumber(invoice.balance_due).minus(totalPaid);
+  var remainingBalance = new BigNumber(invoice.invoice_total).minus(totalPaid);
   if (isUSD) {
     var curTime = new Date().getTime();
     tickerJob.getTicker(curTime, function(err, docs) {
@@ -123,6 +149,7 @@ var getPaymentHistory = function(paymentsArr) {
 
 module.exports = {
   calculateLineTotals: calculateLineTotals,
+  calculateDiscountTotals: calculateDiscountTotals,
   getActivePayment: getActivePayment,
   getTotalPaid: getTotalPaid,
   getAmountDue: getAmountDue,

lib/payments.js

@@ -207,7 +207,7 @@ function createNewPaymentWithTransaction(invoiceId, transaction, cb) {
         var tickerData = docs.rows[0].value;
         var rate = new BigNumber(tickerData.vwap);
         var totalPaid = new BigNumber(invoicesLib.getTotalPaid(invoice, paymentsArr));
-        var remainingBalance = new BigNumber(invoice.balance_due).minus(totalPaid);
+        var remainingBalance = new BigNumber(invoice.invoice_total).minus(totalPaid);
         var isUSD = invoice.currency.toUpperCase() === 'USD';
         if (isUSD) {
           var actualPaid = helper.roundToDecimal(rate.times(transaction.amount).valueOf(), 2);

lib/validate.js

@@ -42,14 +42,16 @@ var invoice = function(invoice, cb) {
       minimumPrice = 0.00000001;
       break;
   }
+  var billionCeiling = 999999999999;
+
   // Line Items
-  if(invoice.line_items && invoice.line_items.length > 0) {
+  var balanceDue = 0;
+  if (invoice.line_items && invoice.line_items.length > 0) {
     invoice.line_items.forEach(function(item) {
       if (!item.amount || !item.quantity || !item.description) {
         errorMessages.push('invalid line_items: ' + JSON.stringify(item));
       }
       else {
-        var billionCeiling = 999999999999;
         // Amount
         item.amount = parseFloat(item.amount);
         if (typeof item.amount !== 'number' || item.amount < minimumPrice) {
@@ -76,13 +78,61 @@ var invoice = function(invoice, cb) {
         if (typeof item.description !== 'string') {
           errorMessages.push('line_item description must be a string:' + JSON.stringify(item));
         }
+        balanceDue += item.amount * item.quantity;
       }
     });
   }
   else {
     errorMessages.push('line_items must contain at least one entry');
   }
 
+  // Discounts
+  var totalDiscounts = 0;
+  if (invoice.discounts && invoice.discounts.length > 0) {
+    invoice.discounts.forEach(function(item) {
+      if (item.amount && item.percentage) {
+        errorMessages.push('invalid discounts: ' + JSON.stringify(item));
+      }
+      else if (item.amount && !item.description || item.percentage && !item.description) {
+        errorMessages.push('invalid discounts must have description: ' + JSON.stringify(item));
+      }
+      else {
+        // Amount
+        item.amount = parseFloat(item.amount);
+        if (item.amount === 0 || item.amount) {
+          totalDiscounts += item.amount;
+          if (typeof item.amount !== 'number' || item.amount < minimumPrice) {
+            errorMessages.push('discount amount must be >= ' + minimumPrice + ': ' + JSON.stringify(item));
+          }
+          if (helper.decimalPlaces(item.amount) > 8) {
+            errorMessages.push('discount amount must only have 0-8 decimal digits: ' + JSON.stringify(item));
+          }
+          if (item.amount > billionCeiling) {
+            errorMessages.push('discount amount is too large: ' + JSON.stringify(item));
+          }
+        }
+        // Percentage
+        item.percentage = parseFloat(item.percentage);
+        if (item.percentage === 0 || item.percentage) {
+          totalDiscounts += balanceDue * (item.percentage/100);
+          if (typeof item.percentage !== 'number' || item.percentage < minimumPrice) {
+            errorMessages.push('discount percentage must be >= ' + minimumPrice + ': ' + JSON.stringify(item));
+          }
+          if (helper.decimalPlaces(item.percentage) > 8) {
+            errorMessages.push('discount percentage must only have 0-8 decimal digits: ' + JSON.stringify(item));
+          }
+          if (item.percentage > billionCeiling) {
+            errorMessages.push('discount percentage is too large: ' + JSON.stringify(item));
+          }
+        }
+      }
+    });
+  }
+
+  if (totalDiscounts >= balanceDue) {
+    errorMessages.push('discount cannot be greater than or equal to the total balance due');
+  }
+
   // Minimum Confirmations
   invoice.min_confirmations = parseFloat(invoice.min_confirmations);
   if (typeof invoice.min_confirmations !== 'number' || !isInteger(invoice.min_confirmations)) {

public/css/styles.css

@@ -136,6 +136,10 @@ a:hover, a:active {
   color: #41a323;
 }
 
+.info, .discount, .blue {
+  color: #024FB1;
+}
+
 .gray {
   color: #999;
 }

public/js/reloadinvoice.js

@@ -146,8 +146,8 @@ var reloadInvoice = function(queryUrl, expiration, isExpired, isPaid, isVoid) {
     isPaid = invoice.is_paid;
     isVoid = invoice.is_void;
     isExpired = invoice.is_expired;
-    var newAmountPaid = invoice.total_paid;
-    var newAmountDue = invoice.remaining_balance;
+    var newAmountPaid = invoice.amount_paid;
+    var newAmountDue = invoice.balance_due;
     paymentHistory = invoice.payment_history;
 
     // Update Status Banner

routes/invoices.js

@@ -72,7 +72,7 @@ var invoices = function(app) {
           res.status(200).write('Invoice ' + invoiceId + ' is already void.');
           res.end();
         }
-        else if (Number(invoice.total_paid) > 0) {
+        else if (Number(invoice.amount_paid) > 0) {
           res.status(400).write('Invoice ' + invoiceId + ' has payments, cannot be void.');
           res.end();
         }

routes/utils/invoices.js

@@ -21,18 +21,18 @@ var findInvoiceAndPaymentHistory = function(invoiceId, cb) {
 
     var isUSD = invoice.currency.toUpperCase() === 'USD';
     invoicesLib.calculateLineTotals(invoice);
-    invoice.total_paid = invoicesLib.getTotalPaid(invoice, paymentsArr);
-    invoice.balance_due = isUSD ? helper.roundToDecimal(invoice.balance_due, 2) : Number(invoice.balance_due);
-    invoice.remaining_balance = invoicesLib.getAmountDue(invoice.balance_due, invoice.total_paid, invoice.currency);
+    invoicesLib.calculateDiscountTotals(invoice);
+    invoice.amount_paid = invoicesLib.getTotalPaid(invoice, paymentsArr);
+    invoice.balance_due = invoicesLib.getAmountDue(invoice.invoice_total, invoice.amount_paid, invoice.currency);
     invoice.is_expired = false;
     invoice.is_void = invoice.is_void ? invoice.is_void : false;
     invoice.expiration = invoice.expiration ? invoice.expiration : null;
     invoice.text = invoice.text ? invoice.text : null;
 
     var invoiceExpired = validate.invoiceExpired(invoice);
-    invoice.is_expired = invoiceExpired && invoice.remaining_balance > 0;
+    invoice.is_expired = invoiceExpired && invoice.balance_due > 0;
     invoice.expiration_time = null;
-    if (invoice.expiration && !invoiceExpired && invoice.remaining_balance > 0) {
+    if (invoice.expiration && !invoiceExpired && invoice.balance_due > 0) {
       invoice.expiration_time = helper.getExpirationCountDown(invoice.expiration);
     }
 
@@ -55,8 +55,8 @@ var findInvoiceAndPaymentHistory = function(invoiceId, cb) {
       return payment.created;
     });
 
-    invoice.is_paid = !hasPending && invoice.remaining_balance <= 0;
-    invoice.is_overpaid = !hasPending && invoice.remaining_balance < 0;
+    invoice.is_paid = !hasPending && invoice.balance_due <= 0;
+    invoice.is_overpaid = !hasPending && invoice.balance_due < 0;
 
     delete invoice.webhooks;
     delete invoice.metadata;

tests/invoicehelpertests.js

@@ -37,6 +37,55 @@ describe('invoicehelper', function() {
   });
 });
 
+describe('invoicehelper', function() {
+  describe('#calculateDiscountTotals', function() {
+    it('should calculate discount totals given percentage or amount', function() {
+      var invoiceBTC = {
+        currency: 'BTC',
+        line_items: [
+          { quantity: 2, amount: 0.5 },
+          { quantity: 9, amount: 1 }
+        ],
+        discounts: [
+          { amount: 2.5 },
+          { percentage: 55 },
+          { percentage: 25.643 },
+          { percentage: 1 },
+          { percentage: 0.5 }
+        ]
+      };
+      invoiceHelper.calculateDiscountTotals(invoiceBTC);
+      assert.equal('2.5', invoiceBTC.discounts[0].amount.toString());
+      assert.equal('5.5', invoiceBTC.discounts[1].amount.toString());
+      assert.equal('2.5643', invoiceBTC.discounts[2].amount.toString());
+      assert.equal('0.1', invoiceBTC.discounts[3].amount.toString());
+      assert.equal('0.05', invoiceBTC.discounts[4].amount.toString());
+
+      var invoiceUSD = {
+        currency: 'USD',
+        line_items: [
+          { quantity: 3, amount: 50.13 },
+          { quantity: 4, amount: 100.64 }
+        ],
+        discounts: [
+          { amount: 10.45 },
+          { percentage: 55 },
+          { percentage: 25.643 },
+          { percentage: 1 },
+          { percentage: 0.5 }
+        ]
+      };
+      invoiceHelper.calculateDiscountTotals(invoiceUSD);
+      assert.equal('10.45', invoiceUSD.discounts[0].amount.toString());
+      assert.equal('304.12', invoiceUSD.discounts[1].amount.toString());
+      assert.equal('141.79', invoiceUSD.discounts[2].amount.toString());
+      assert.equal('5.53', invoiceUSD.discounts[3].amount.toString());
+      assert.equal('2.76', invoiceUSD.discounts[4].amount.toString());
+
+    });
+  });
+});
+
 describe('invoicehelper', function() {
   describe('#getActivePayment', function() {
     it('should return payment with latest creation date', function() {

views/invoice.ejs

@@ -72,9 +72,27 @@
       </div>
     <% }); %>
 
+    <% discounts.forEach(function(item){ %>
+      <div class="row line-item thin-underline discount">
+        <% if (item.amount && !item.percentage) { %>
+          <div class="col-xs-12 col-sm-9"><%= item.description %></div>
+          <div class="col-xs-4 visible-xs mobile-lbl-text">Discount</div>
+          <div class="col-xs-8 col-sm-3 right">(<%= item.amount %> <%= currency.toUpperCase() %>)</div>
+        <% } else if (item.amount && item.percentage) { %>
+          <div class="col-xs-12 col-sm-6"><%= item.description %></div>
+          <div class="col-xs-4 visible-xs mobile-lbl-text">Percentage</div>
+          <div class="col-xs-8 col-sm-3 right"><%= item.percentage %> % off</div>
+          <div class="col-xs-4 visible-xs mobile-lbl-text">Discount</div>
+          <div class="col-xs-8 col-sm-3 right">
+            (<%= item.amount %> <%= currency.toUpperCase() %>)
+          </div>
+        <% } %>
+      </div>
+    <% }); %>
+
     <div class="row">
       <div class="col-xs-12 col-sm-4">
-        <form id="pay-button" style="<% if (remaining_balance <= 0 || is_paid || is_void || is_expired) { %>display: none;<% } %>" method="POST" action="/pay/<%= _id %>">
+        <form id="pay-button" style="<% if (balance_due <= 0 || is_paid || is_void || is_expired) { %>display: none;<% } %>" method="POST" action="/pay/<%= _id %>">
           <button type="submit" class="btn btn-lg btn-default btn-wide">
             Pay Now
           </button>
@@ -83,15 +101,15 @@
       <div class="col-xs-12 col-sm-8 spacer-5 right dark-gray">
         <span class="visible-xs float-left medium-text">Total</span><!-- phone -->
         <span class="hidden-xs float-left">Invoice Total</span>
-        <span class="visible-xs medium-text"><%= balance_due %> <%= currency.toUpperCase() %></span>
-        <span class="hidden-xs"><%= balance_due %> <%= currency.toUpperCase() %></span>
+        <span class="visible-xs medium-text"><%= invoice_total %> <%= currency.toUpperCase() %></span>
+        <span class="hidden-xs"><%= invoice_total %> <%= currency.toUpperCase() %></span>
       </div>
     </div>
 
     <div class="row visible-xs medium-text">
       <div class="col-xs-12 right gray">
           <span class="float-left dark-gray">Paid</span><!-- phone -->
-          <span class="amount-paid-text green"><%= total_paid %></span>
+          <span class="amount-paid-text green"><%= amount_paid %></span>
           <span class="green"> <%= currency.toUpperCase() %></span>
       </div>
     </div>
@@ -100,15 +118,15 @@
       <div class="col-sm-4"></div>
       <div class="col-sm-8 right gray">
           <span class="float-left dark-gray">Amount Paid</span>
-          <span class="amount-paid-text green"><%= total_paid %></span>
+          <span class="amount-paid-text green"><%= amount_paid %></span>
           <span class="green"> <%= currency.toUpperCase() %></span>
       </div>
     </div>
 
     <div class="row visible-xs medium-text">
       <div class="col-xs-12 right gray">
           <span class="float-left dark-gray">Due</span><!-- phone -->
-          <span class="amount-due-text red"><%= remaining_balance %></span>
+          <span class="amount-due-text red"><%= balance_due %></span>
           <span class="red"> <%= currency.toUpperCase() %></span>
       </div>
     </div>
@@ -117,7 +135,7 @@
       <div class="col-sm-4"></div>
       <div class="col-sm-8 right gray">
           <span class="float-left dark-gray">Balance Due</span>
-          <span class="amount-due-text red"><%= remaining_balance %></span>
+          <span class="amount-due-text red"><%= balance_due %></span>
           <span class="red"> <%= currency.toUpperCase() %></span>
       </div>
     </div>