From 44c13665c8f436c32d6a9036c585acfff75829fb Mon Sep 17 00:00:00 2001
From: Daniel Cousens <github@dcousens.com>
Date: Tue, 3 Jul 2018 22:33:35 +1000
Subject: [PATCH] payments: add p2data

---
 src/payments/index.js            | 11 ++-----
 src/payments/p2data.js           | 56 ++++++++++++++++++++++++++++++++
 test/integration/transactions.js |  5 ++-
 3 files changed, 60 insertions(+), 12 deletions(-)
 create mode 100644 src/payments/p2data.js

diff --git a/src/payments/index.js b/src/payments/index.js
index 9e869f5..de3bec1 100644
--- a/src/payments/index.js
+++ b/src/payments/index.js
@@ -1,3 +1,4 @@
+const p2data = require('./p2data')
 const p2ms = require('./p2ms')
 const p2pk = require('./p2pk')
 const p2pkh = require('./p2pkh')
@@ -5,15 +6,7 @@ const p2sh = require('./p2sh')
 const p2wpkh = require('./p2wpkh')
 const p2wsh = require('./p2wsh')
 
-module.exports = {
-  p2ms: p2ms,
-  p2pk: p2pk,
-  p2pkh: p2pkh,
-  p2sh: p2sh,
-  p2wpkh: p2wpkh,
-  p2wsh: p2wsh
-}
+module.exports = { p2data, p2ms, p2pk, p2pkh, p2sh, p2wpkh, p2wsh }
 
 // TODO
-// OP_RETURN
 // witness commitment
diff --git a/src/payments/p2data.js b/src/payments/p2data.js
new file mode 100644
index 0000000..c636c80
--- /dev/null
+++ b/src/payments/p2data.js
@@ -0,0 +1,56 @@
+const lazy = require('./lazy')
+const typef = require('typeforce')
+const OPS = require('bitcoin-ops')
+
+const bscript = require('../script')
+const BITCOIN_NETWORK = require('../networks').bitcoin
+
+function stacksEqual (a, b) {
+  if (a.length !== b.length) return false
+
+  return a.every(function (x, i) {
+    return x.equals(b[i])
+  })
+}
+
+// output: OP_RETURN ...
+function p2data (a, opts) {
+  if (
+    !a.data &&
+    !a.output
+  ) throw new TypeError('Not enough data')
+  opts = opts || { validate: true }
+
+  typef({
+    network: typef.maybe(typef.Object),
+    output: typef.maybe(typef.Buffer),
+    data: typef.maybe(typef.arrayOf(typef.Buffer))
+  }, a)
+
+  const network = a.network || BITCOIN_NETWORK
+  const o = { network }
+
+  lazy.prop(o, 'output', function () {
+    if (!a.data) return
+    return bscript.compile([OPS.OP_RETURN].concat(a.data))
+  })
+  lazy.prop(o, 'data', function () {
+    if (!a.output) return
+    return bscript.decompile(a.output).slice(1)
+  })
+
+  // extended validation
+  if (opts.validate) {
+    if (a.output) {
+      const chunks = bscript.decompile(a.output)
+      if (chunks[0] !== OPS.OP_RETURN) throw new TypeError('Output is invalid')
+      if (!chunks.slice(1).every(typef.Buffer)) throw new TypeError('Output is invalid')
+
+      if (a.data && !stacksEqual(a.data, o.data)) throw new TypeError('Data mismatch')
+    }
+  }
+
+  return Object.assign(o, a)
+}
+
+module.exports = p2data
diff --git a/test/integration/transactions.js b/test/integration/transactions.js
index 5bb1342..cec0839 100644
--- a/test/integration/transactions.js
+++ b/test/integration/transactions.js
@@ -91,10 +91,9 @@ describe('bitcoinjs-lib (transactions)', function () {
 
       const txb = new bitcoin.TransactionBuilder(regtest)
       const data = Buffer.from('bitcoinjs-lib', 'utf8')
-      const dataScript = require('../../src/templates/nulldata').output.encode([data])
-
+      const p2data = bitcoin.payments.p2data({ data: [data] })
       txb.addInput(unspent.txId, unspent.vout)
-      txb.addOutput(dataScript, 1000)
+      txb.addOutput(p2data.output, 1000)
       txb.addOutput(regtestUtils.RANDOM_ADDRESS, 1e5)
       txb.sign(0, keyPair)