1 files changed, 133 insertions, 0 deletions
diff --git a/lib/helpers/contact-importer/contact-importer.js b/lib/helpers/contact-importer/contact-importer.js
new file mode 100644
index 0000000..017fa69
--- /dev/null
+++ b/lib/helpers/contact-importer/contact-importer.js
@@ -0,0 +1,133 @@
+/* eslint dot-notation: 'off' */
+'use strict';
+
+var Bottleneck = require('bottleneck');
+var EventEmitter = require('events').EventEmitter;
+var chunk = require('lodash.chunk');
+var debug = require('debug')('sendgrid');
+var util = require('util');
+var queue = require('async.queue');
+var ensureAsync = require('async.ensureasync');
+
+var ContactImporter = module.exports = function(sg, options) {
+  options = options || {};
+  var self = this;
+  this.sg = sg;
+  this.pendingItems = [];
+
+  // Number of items to send per batch.
+  this.batchSize = options.batchSize || 1500;
+
+  // Max number of requests per rate limit period.
+  this.rateLimitLimit = options.rateLimitLimit || 3;
+
+  // Length of rate limit period (miliseconds).
+  this.rateLimitPeriod = options.rateLimitPeriod || 2000;
+
+  // Create a throttler that will process no more than `rateLimitLimit` requests every `rateLimitPeriod` ms.
+  this.throttle = new Bottleneck(1, this.rateLimitPeriod / this.rateLimitLimit);
+
+  // Create a queue that wil be used to send batches to the throttler.
+  this.queue = queue(ensureAsync(this._worker));
+
+  // When the last batch is removed from the queue, add any incomplete batches.
+  this.queue.empty = function() {
+    if (self.pendingItems.length) {
+      debug('adding %s items from deferrd queue for processing', self.pendingItems.length);
+      var batch = self.pendingItems.splice(0);
+      self.queue.push({
+        data: batch,
+        owner: self,
+      }, function(error, result) {
+        self._notify(error, JSON.parse(result.body), batch);
+      });
+    }
+  };
+
+  // Emit an event when the queue is drained.
+  this.queue.drain = function() {
+    self.emit('drain');
+  };
+};
+util.inherits(ContactImporter, EventEmitter);
+
+/**
+ *  Add a new contact, or an array of contact, to the end of the queue.
+ *
+ * @param {Array|Object} data A contact or array of contacts.
+ */
+ContactImporter.prototype.push = function(data) {
+  var self = this;
+  data = Array.isArray(data) ? data : [data];
+
+  // Add the new items onto the pending items.
+  var itemsToProcess = this.pendingItems.concat(data);
+
+  // Chunk the pending items into batches and add onto the queue
+  var batches = chunk(itemsToProcess, this.batchSize);
+  debug('generated batches %s from %s items', batches.length, data.length);
+
+  batches.forEach(function(batch) {
+    // If this batch is full or the queue is empty queue it for processing.
+    if (batch.length === self.batchSize || !self.queue.length()) {
+      self.queue.push({
+        data: batch,
+        owner: self,
+      }, function(error, result) {
+        self._notify(error, JSON.parse(result.body), batch);
+      });
+    }
+    // Otherwise, it store it for later.
+    else {
+      debug('the last batch with only %s item is deferred (partial batch)', batch.length);
+      self.pendingItems = batch;
+    }
+  });
+
+  debug('batches in queue: %s', this.queue.length());
+  debug('items in deferred queue: %s', this.pendingItems.length);
+};
+
+/**
+ * Send a batch of contacts to Sendgrid.
+ *
+ * @param {Object} task Task to be processed (data in 'data' property)
+ * @param {Function} callback Callback function.
+ */
+ContactImporter.prototype._worker = function(task, callback) {
+  var context = task.owner;
+  debug('processing batch (%s items)', task.data.length);
+  context.throttle.submit(context._sendBatch, context, task.data, callback);
+};
+
+ContactImporter.prototype._sendBatch = function(context, data, callback) {
+  debug('sending batch (%s items)', data.length);
+
+  var request = context.sg.emptyRequest();
+  request.method = 'POST';
+  request.path = '/v3/contactdb/recipients';
+  request.body = data;
+
+  context.sg.API(request)
+    .then(function(response) {
+      debug('got response: %o', response);
+      return callback(null, response);
+    })
+    .catch(function(error) {
+      debug('got error, %o', error);
+      return callback(error);
+    });
+};
+
+/**
+ * Emit the result of processing a batch.
+ *
+ * @param {Object} error
+ * @param {Object} result
+ */
+ContactImporter.prototype._notify = function(error, result, batch) {
+  if (error) {
+    return this.emit('error', result, batch);
+  }
+  return this.emit('success', result, batch);
+};