From 61303c013e07fe37ed7e0f0590ed2f7cff4977a6 Mon Sep 17 00:00:00 2001
From: Gal Buki <jkl@torus.ch>
Date: Mon, 20 Jun 2022 07:58:23 +0300
Subject: [PATCH] add function to create safe data (op_false op_return) scripts

---
 functions/create-safedata-script.js      | 19 ++++++++++++
 functions/index.js                       |  1 +
 test/functions/create-safedata-script.js | 39 ++++++++++++++++++++++++
 test/index.js                            |  1 +
 4 files changed, 60 insertions(+)
 create mode 100644 functions/create-safedata-script.js
 create mode 100644 test/functions/create-safedata-script.js

diff --git a/functions/create-safedata-script.js b/functions/create-safedata-script.js
new file mode 100644
index 0000000..5973b48
--- /dev/null
+++ b/functions/create-safedata-script.js
@@ -0,0 +1,19 @@
+const BufferWriter = require('../classes/buffer-writer')
+const writePushData = require('./write-push-data')
+
+function createSafeDataScript (data = []) {
+  const writer = new BufferWriter()
+  writer.write([0]) // OP_FALSE
+  writer.write([106]) // OP_RETURN
+
+  try {
+    const datas = Array.isArray(data) ? data : [data];
+    datas.forEach(data => writePushData(writer, new Buffer.from(data)))
+  } catch (err) {
+    throw new Error('invalid data ', err)
+  }
+
+  return writer.toBuffer()
+}
+
+module.exports = createSafeDataScript
diff --git a/functions/index.js b/functions/index.js
index 5b3ad1b..cae4c1e 100644
--- a/functions/index.js
+++ b/functions/index.js
@@ -6,6 +6,7 @@ module.exports = {
   calculateTxid: require('./calculate-txid'),
   createP2PKHLockScript: require('./create-p2pkh-lock-script'),
   createP2PKHUnlockScript: require('./create-p2pkh-unlock-script'),
+  createSafeDataScript: require('./create-safedata-script'),
   decodeAddress: require('./decode-address'),
   decodeASM: require('./decode-asm'),
   decodeBase58Check: require('./decode-base58-check'),
diff --git a/test/functions/create-safedata-script.js b/test/functions/create-safedata-script.js
new file mode 100644
index 0000000..b5b054d
--- /dev/null
+++ b/test/functions/create-safedata-script.js
@@ -0,0 +1,39 @@
+const { describe, it } = require('mocha')
+const { expect } = require('chai')
+const nimble = require('../env/nimble')
+const { createSafeDataScript } = nimble.functions
+const bsv = require('bsv')
+
+describe('safe data script', () => {
+  it('script with no values', () => {
+    const data = []
+    const emptyString = ''
+    const bsvScript = bsv.Script.buildSafeDataOut(data).toBuffer()
+    const bsvScript2 = bsv.Script.buildSafeDataOut(emptyString).toBuffer()
+    const nimbleScript = createSafeDataScript(data)
+    const nimbleScript2 = createSafeDataScript(emptyString)
+    const nimbleScript3 = createSafeDataScript()
+    expect(Array.from(bsvScript)).to.deep.equal(Array.from(nimbleScript))
+    expect(Array.from(bsvScript2)).to.deep.equal(Array.from(nimbleScript2))
+    expect(Array.from(bsvScript)).to.deep.equal(Array.from(nimbleScript3))
+  })
+
+  it('script from single pushdata', () => {
+    const data = 'Nimble 42'
+    const bsvSCript = bsv.Script.buildSafeDataOut(data).toBuffer()
+    const nimbleScript = createSafeDataScript(data)
+    expect(Array.from(bsvSCript)).to.deep.equal(Array.from(nimbleScript))
+  })
+
+  it('script from pushdata array', () => {
+    const data = ['Nimble', '42']
+    const bsvSCript = bsv.Script.buildSafeDataOut(data).toBuffer()
+    const nimbleScript = createSafeDataScript(data)
+    expect(Array.from(bsvSCript)).to.deep.equal(Array.from(nimbleScript))
+  })
+
+  it('throws if not valid data', () => {
+    const data = {}
+    expect(() => createSafeDataScript(data)).to.throw('invalid data')
+  })
+})
diff --git a/test/index.js b/test/index.js
index 79014ce..edd292b 100644
--- a/test/index.js
+++ b/test/index.js
@@ -19,6 +19,7 @@ describe('functions', () => {
   require('./functions/calculate-txid')
   require('./functions/create-p2pkh-lock-script')
   require('./functions/create-p2pkh-unlock-script')
+  require('./functions/create-safedata-script')
   require('./functions/decode-address')
   require('./functions/decode-asm')
   require('./functions/decode-base64')