1 files changed, 104 insertions, 0 deletions
diff --git a/app/scripts/lib/account-tracker.js b/app/scripts/lib/account-tracker.js
new file mode 100644
index 000000000..cdc21282d
--- /dev/null
+++ b/app/scripts/lib/account-tracker.js
@@ -0,0 +1,104 @@
+/* Account Tracker
+ *
+ * This module is responsible for tracking any number of accounts
+ * and caching their current balances & transaction counts.
+ *
+ * It also tracks transaction hashes, and checks their inclusion status
+ * on each new block.
+ */
+
+const async = require('async')
+const EthQuery = require('eth-query')
+const ObservableStore = require('obs-store')
+const EventEmitter = require('events').EventEmitter
+function noop () {}
+
+
+class AccountTracker extends EventEmitter {
+
+  constructor (opts = {}) {
+    super()
+
+    const initState = {
+      accounts: {},
+      currentBlockGasLimit: '',
+    }
+    this.store = new ObservableStore(initState)
+
+    this._provider = opts.provider
+    this._query = new EthQuery(this._provider)
+    this._blockTracker = opts.blockTracker
+    // subscribe to latest block
+    this._blockTracker.on('block', this._updateForBlock.bind(this))
+    // blockTracker.currentBlock may be null
+    this._currentBlockNumber = this._blockTracker.currentBlock
+  }
+
+  //
+  // public
+  //
+
+  addAccount (address) {
+    const accounts = this.store.getState().accounts
+    accounts[address] = {}
+    this.store.updateState({ accounts })
+    if (!this._currentBlockNumber) return
+    this._updateAccount(address)
+  }
+
+  removeAccount (address) {
+    const accounts = this.store.getState().accounts
+    delete accounts[address]
+    this.store.updateState({ accounts })
+  }
+
+  //
+  // private
+  //
+
+  _updateForBlock (block) {
+    this._currentBlockNumber = block.number
+    const currentBlockGasLimit = block.gasLimit
+
+    this.store.updateState({ currentBlockGasLimit })
+
+    async.parallel([
+      this._updateAccounts.bind(this),
+    ], (err) => {
+      if (err) return console.error(err)
+      this.emit('block', this.store.getState())
+    })
+  }
+
+  _updateAccounts (cb = noop) {
+    const accounts = this.store.getState().accounts
+    const addresses = Object.keys(accounts)
+    async.each(addresses, this._updateAccount.bind(this), cb)
+  }
+
+  _updateAccount (address, cb = noop) {
+    this._getAccount(address, (err, result) => {
+      if (err) return cb(err)
+      result.address = address
+      const accounts = this.store.getState().accounts
+      // only populate if the entry is still present
+      if (accounts[address]) {
+        accounts[address] = result
+        this.store.updateState({ accounts })
+      }
+      cb(null, result)
+    })
+  }
+
+  _getAccount (address, cb = noop) {
+    const query = this._query
+    async.parallel({
+      balance: query.getBalance.bind(query, address),
+      nonce: query.getTransactionCount.bind(query, address),
+      code: query.getCode.bind(query, address),
+    }, cb)
+  }
+
+}
+
+module.exports = AccountTracker