4 files changed, 109 insertions, 16 deletions

diff --git a/app/scripts/controllers/transactions.js b/app/scripts/controllers/transactions.js
index f21cb6e00..6f49c9633 100644
--- a/app/scripts/controllers/transactions.js
+++ b/app/scripts/controllers/transactions.js
@@ -1,6 +1,5 @@
 const EventEmitter = require('events')
 const extend = require('xtend')
-const clone = require('clone')
 const ObservableStore = require('obs-store')
 const ethUtil = require('ethereumjs-util')
 const EthQuery = require('ethjs-query')
@@ -8,6 +7,7 @@ const TxProviderUtil = require('../lib/tx-utils')
 const PendingTransactionTracker = require('../lib/pending-tx-tracker')
 const createId = require('../lib/random-id')
 const NonceTracker = require('../lib/nonce-tracker')
+const txStateHistoryHelper = require('../lib/tx-state-history-helper')
 
 module.exports = class TransactionController extends EventEmitter {
   constructor (opts) {
@@ -135,19 +135,17 @@ module.exports = class TransactionController extends EventEmitter {
 
   updateTx (txMeta) {
     // create txMeta snapshot for history
-    const txMetaForHistory = clone(txMeta)
-    // dont include previous history in this snapshot
-    delete txMetaForHistory.history
-    // add snapshot to tx history
-    if (!txMeta.history) txMeta.history = []
-    txMeta.history.push(txMetaForHistory)
-
+    const currentState = txStateHistoryHelper.snapshotFromTxMeta(txMeta)
+    // recover previous tx state obj
+    const previousState = txStateHistoryHelper.replayHistory(txMeta.history)
+    // generate history entry and add to history
+    const entry = txStateHistoryHelper.generateHistoryEntry(previousState, currentState)
+    txMeta.history.push(entry)
+
+    // commit txMeta to state
     const txId = txMeta.id
     const txList = this.getFullTxList()
     const index = txList.findIndex(txData => txData.id === txId)
-    if (!txMeta.history) txMeta.history = []
-    txMeta.history.push(txMetaForHistory)
-
     txList[index] = txMeta
     this._saveTxList(txList)
     this.emit('update')
@@ -155,16 +153,22 @@ module.exports = class TransactionController extends EventEmitter {
 
   // Adds a tx to the txlist
   addTx (txMeta) {
-    const txCount = this.getTxCount()
-    const network = this.getNetwork()
-    const fullTxList = this.getFullTxList()
-    const txHistoryLimit = this.txHistoryLimit
+    // initialize history
+    txMeta.history = []
+    // capture initial snapshot of txMeta for history
+    const snapshot = txStateHistoryHelper.snapshotFromTxMeta(txMeta)
+    txMeta.history.push(snapshot)
 
     // checks if the length of the tx history is
     // longer then desired persistence limit
     // and then if it is removes only confirmed
     // or rejected tx's.
     // not tx's that are pending or unapproved
+    const txCount = this.getTxCount()
+    const network = this.getNetwork()
+    const fullTxList = this.getFullTxList()
+    const txHistoryLimit = this.txHistoryLimit
+
     if (txCount > txHistoryLimit - 1) {
       const index = fullTxList.findIndex((metaTx) => ((metaTx.status === 'confirmed' || metaTx.status === 'rejected') && network === txMeta.metamaskNetworkId))
       fullTxList.splice(index, 1)
@@ -213,7 +217,6 @@ module.exports = class TransactionController extends EventEmitter {
       status: 'unapproved',
       metamaskNetworkId: this.getNetwork(),
       txParams: txParams,
-      history: [],
     }
     // add default tx params
     await this.addTxDefaults(txMeta)
diff --git a/app/scripts/lib/tx-state-history-helper.js b/app/scripts/lib/tx-state-history-helper.js
new file mode 100644
index 000000000..304069d57
--- /dev/null
+++ b/app/scripts/lib/tx-state-history-helper.js
@@ -0,0 +1,37 @@
+const jsonDiffer = require('fast-json-patch')
+const clone = require('clone')
+
+module.exports = {
+  generateHistoryEntry,
+  replayHistory,
+  snapshotFromTxMeta,
+  migrateFromSnapshotsToDiffs,
+}
+
+
+function migrateFromSnapshotsToDiffs(longHistory) {
+  return (
+    longHistory
+    // convert non-initial history entries into diffs
+    .map((entry, index) => {
+      if (index === 0) return entry
+      return generateHistoryEntry(longHistory[index - 1], entry)
+    })
+  )
+}
+
+function generateHistoryEntry(previousState, newState) {
+  return jsonDiffer.compare(previousState, newState)
+}
+
+function replayHistory(shortHistory) {
+  return shortHistory.reduce((val, entry) => jsonDiffer.applyPatch(val, entry).newDocument)
+}
+
+function snapshotFromTxMeta(txMeta) {
+  // create txMeta snapshot for history
+  const snapshot = clone(txMeta)
+  // dont include previous history in this snapshot
+  delete snapshot.history
+  return snapshot
+}
\ No newline at end of file
diff --git a/app/scripts/migrations/018.js b/app/scripts/migrations/018.js
new file mode 100644
index 000000000..d27fe3f46
--- /dev/null
+++ b/app/scripts/migrations/018.js
@@ -0,0 +1,52 @@
+const version = 18
+
+/*
+
+This migration updates "transaction state history" to diffs style
+
+*/
+
+const clone = require('clone')
+const txStateHistoryHelper = require('../lib/tx-state-history-helper')
+
+
+module.exports = {
+  version,
+
+  migrate: function (originalVersionedData) {
+    const versionedData = clone(originalVersionedData)
+    versionedData.meta.version = version
+    try {
+      const state = versionedData.data
+      const newState = transformState(state)
+      versionedData.data = newState
+    } catch (err) {
+      console.warn(`MetaMask Migration #${version}` + err.stack)
+    }
+    return Promise.resolve(versionedData)
+  },
+}
+
+function transformState (state) {
+  const newState = state
+  const transactions = newState.TransactionController.transactions
+  newState.TransactionController.transactions = transactions.map((txMeta) => {
+    // no history: initialize
+    if (!txMeta.history || txMeta.history.length === 0) {
+      const snapshot = txStateHistoryHelper.snapshotFromTxMeta(txMeta)
+      txMeta.history = [snapshot]
+      return txMeta
+    }
+    // has history: migrate
+    const newHistory = (
+      txStateHistoryHelper.migrateFromSnapshotsToDiffs(txMeta.history)
+      // remove empty diffs
+      .filter((entry) => {
+        return !Array.isArray(entry) || entry.length > 0
+      })
+    )
+    txMeta.history = newHistory
+    return txMeta
+  })
+  return newState
+}
diff --git a/app/scripts/migrations/index.js b/app/scripts/migrations/index.js
index f4c87499f..6bfc622f7 100644
--- a/app/scripts/migrations/index.js
+++ b/app/scripts/migrations/index.js
@@ -28,4 +28,5 @@ module.exports = [
   require('./015'),
   require('./016'),
   require('./017'),
+  require('./018'),
 ]