Merge pull request #7 from ethereumjs/feature/provider-engine

Add provider-engine integration

Author: axic

README.md

@@ -87,6 +87,18 @@ Instance methods:
 * `deriveChild(index)` - derive a node based on a child index
 * `getWallet()` - return a `Wallet` instance as seen above
 
+## Provider Engine
+
+The Wallet can be easily plugged into [provider-engine](https://github.com/metamask/provider-engine) to provide signing:
+
+```js
+const WalletSubprovider = require('ethereumjs-wallet/provider-engine')
+
+<engine>.addProvider(new WalletSubprovider(<wallet instance>))
+```
+
+Note it only supports the basic wallet. With a HD Wallet, call `getWallet()` first.
+
 ### Remarks about `toV3`
 
 The `options` is an optional object hash, where all the serialization parameters can be fine tuned:

provider-engine.js

@@ -0,0 +1,24 @@
+'use strict'
+
+const inherits = require('util').inherits
+const HookedWalletEthTxSubprovider = require('web3-provider-engine/subproviders/hooked-wallet-ethtx')
+
+module.exports = WalletSubprovider
+
+inherits(WalletSubprovider, HookedWalletEthTxSubprovider)
+
+function WalletSubprovider (wallet, opts) {
+  opts.getAccounts = function (cb) {
+    cb(null, [ wallet.getAddressesString() ])
+  }
+
+  opts.getPrivateKey = function (address, cb) {
+    if (address !== wallet.getAddressString()) {
+      return cb('Account not found')
+    }
+
+    cb(null, wallet.getPrivateKey())
+  }
+
+  WalletSubprovider.super_.call(this, opts)
+}