Add TransactionSigner Interface to makeTransaction functions

.eslintrc

@@ -1,7 +1,7 @@
 {
   "extends": "airbnb",
   "parser": "babel-eslint",
-  "plugins": [],
+  "plugins": ["flowtype"],
   "ecmaFeatures": {
     "jsx": false,
     "modules": true
@@ -31,6 +31,7 @@
     "new-cap": 0,
     "camelcase": 2,
     "semi": [2, "never"],
-    "valid-jsdoc": ["error"]
+    "valid-jsdoc": ["error"],
+    "flowtype/define-flow-type": 1
   }
 }

CHANGELOG.md

@@ -6,6 +6,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- New `TransactionSigner` interface to allow for different signing agents
+  in the `transactions` functions (e.g., makePreorder).
+
 ## [17.2.0]
 
 ### Added

package.json

@@ -86,6 +86,7 @@
     "documentation": "^4.0.0-rc.1",
     "eslint": "^2.10.2",
     "eslint-config-airbnb": "^9.0.1",
+    "eslint-plugin-flowtype": "^2.46.3",
     "eslint-plugin-import": "^1.8.1",
     "eslint-plugin-jsx-a11y": "^1.2.2",
     "eslint-plugin-react": "^5.1.1",

src/operations/index.js

@@ -7,5 +7,6 @@ export {
 export { transactions } from './txbuild'
 
 export * from './utils'
+export * from './signers'
 
 export { safety } from './safety'

src/operations/signers.js

@@ -0,0 +1,53 @@
+/* @flow */
+import bitcoinjs from 'bitcoinjs-lib'
+import { hexStringToECPair } from '../utils'
+
+export interface TransactionSigner {
+  /**
+   * @returns version number of the signer, currently, should always be 1
+   */
+  signerVersion(): number;
+  /**
+   * @returns a string representing the transaction signer's address
+   * (usually Base58 check encoding)
+   */
+  getAddress(): Promise<string>;
+  /**
+   * Signs a transaction input
+   * @param {TransactionBuilder} transaction - the transaction to sign
+   * @param {number} inputIndex - the input on the transaction to sign
+   */
+  signTransaction(transaction: bitcoinjs.TransactionBuilder, inputIndex: number): Promise<void>;
+}
+
+/**
+ * Class representing a transaction signer for pubkeyhash addresses
+ * (a.k.a. single-sig addresses)
+ */
+export class PubkeyHashSigner implements TransactionSigner {
+  ecPair: bitcoinjs.ECPair
+
+  constructor(ecPair: bitcoinjs.ECPair) {
+    this.ecPair = ecPair
+  }
+
+  static fromHexString(keyHex: string) {
+    return new PubkeyHashSigner(hexStringToECPair(keyHex))
+  }
+
+  signerVersion(): number {
+    return 1
+  }
+
+  getAddress(): Promise<string> {
+    return Promise.resolve()
+      .then(() => this.ecPair.getAddress())
+  }
+
+  signTransaction(transaction: bitcoinjs.TransactionBuilder, inputIndex: number) : Promise<void> {
+    return Promise.resolve()
+      .then(() => {
+        transaction.sign(inputIndex, this.ecPair)
+      })
+  }
+}