From 3aa135fdb4d2f36c2759005b003591f1a9478889 Mon Sep 17 00:00:00 2001
From: Beaudan <beau@loki.network>
Date: Wed, 14 Nov 2018 13:09:33 +1100
Subject: [PATCH] Grabbing last hash from server response. only requesting
 messages after the lasthash. Keeping track of lasthash for array of nodes
 (currently hardcoded for one)

---
 js/modules/loki_message_api.js | 37 +++++++++++++++++++++++++---------
 libloki/proof-of-work.js       |  2 +-
 package.json                   |  1 +
 preload.js                     |  2 +-
 4 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/js/modules/loki_message_api.js b/js/modules/loki_message_api.js
index 0caaf8130..af835e3cd 100644
--- a/js/modules/loki_message_api.js
+++ b/js/modules/loki_message_api.js
@@ -36,15 +36,20 @@ function getPoWNonce(timestamp, ttl, pubKey, data) {
 
 class LokiServer {
 
-  constructor({ url }) {
-    if (!is.string(url)) {
-      throw new Error('WebAPI.initialize: Invalid server url');
-    }
-    this.url = url;
+  constructor({ urls }) {
+    this.nodes = [];
+    urls.forEach(url => {
+      if (!is.string(url)) {
+        throw new Error('WebAPI.initialize: Invalid server url');
+      }
+      this.nodes.push({ url });
+    });
   }
 
   async sendMessage(pubKey, data, ttl) {
     const data64 = dcodeIO.ByteBuffer.wrap(data).toString('base64');
+    // Hardcoded to use a single node/server for now
+    const currentNode = this.nodes[0];
 
     const timestamp = Math.floor(Date.now() / 1000);
     // Nonce is returned as a base64 string to include in header
@@ -58,7 +63,7 @@ class LokiServer {
     }
 
     const options = {
-      url: `${this.url}/store`,
+      url: `${currentNode.url}/store`,
       type: 'POST',
       responseType: undefined,
       timeout: undefined,
@@ -107,8 +112,11 @@ class LokiServer {
   }
 
   async retrieveMessages(pubKey) {
+    // Hardcoded to use a single node/server for now
+    const currentNode = this.nodes[0];
+
     const options = {
-      url: `${this.url}/retrieve`,
+      url: `${currentNode.url}/retrieve`,
       type: 'GET',
       responseType: 'json',
       timeout: undefined,
@@ -116,11 +124,17 @@ class LokiServer {
 
     log.info(options.type, options.url);
 
+    const headers = {
+      'X-Loki-recipient': pubKey,
+    };
+
+    if (currentNode.lastHash) {
+      headers['X-Loki-last-hash'] = currentNode.lastHash;
+    }
+
     const fetchOptions = {
       method: options.type,
-      headers: {
-        'X-Loki-recipient': pubKey,
-      },
+      headers,
       timeout: options.timeout,
     };
 
@@ -146,6 +160,9 @@ class LokiServer {
 
     if (response.status >= 0 && response.status < 400) {
       log.info(options.type, options.url, response.status, 'Success');
+      if (result.lastHash) {
+        currentNode.lastHash = result.lastHash;
+      }
       return result;
     }
     log.error(options.type, options.url, response.status, 'Error');
diff --git a/libloki/proof-of-work.js b/libloki/proof-of-work.js
index e9bdafb1f..3adab32b2 100644
--- a/libloki/proof-of-work.js
+++ b/libloki/proof-of-work.js
@@ -1,6 +1,6 @@
 const hash = require('js-sha512');
 const bb = require('bytebuffer');
-const BigInteger = require('jsbn').BigInteger;
+const { BigInteger } = require('jsbn');
 
 const NONCE_LEN = 8;
 // Modify this value for difficulty scaling
diff --git a/package.json b/package.json
index de82011e0..67c188093 100644
--- a/package.json
+++ b/package.json
@@ -71,6 +71,7 @@
     "intl-tel-input": "^12.1.15",
     "jquery": "^3.3.1",
     "js-sha512": "^0.8.0",
+    "jsbn": "^1.1.0",
     "linkify-it": "^2.0.3",
     "lodash": "^4.17.4",
     "mkdirp": "^0.5.1",
diff --git a/preload.js b/preload.js
index d2383891f..abf376e3e 100644
--- a/preload.js
+++ b/preload.js
@@ -204,7 +204,7 @@ window.WebAPI = initializeWebAPI({
 const { LokiServer } = require('./js/modules/loki_message_api');
 
 window.LokiAPI = new LokiServer({
-  url: config.serverUrl,
+  urls: [config.serverUrl],
 });
 
 window.mnemonic = require('./libloki/mnemonic');