From 3f23a11f57fa029818ceb81af1572c052f0924b2 Mon Sep 17 00:00:00 2001
From: Garren Smith <garren.smith@gmail.com>
Date: Tue, 3 Apr 2018 13:26:21 +0200
Subject: [PATCH 1/3] feat: add flow annotations

This adds flow annotations to multihashing
---
 .babelrc           |  34 ++++++++++
 .flowconfig        |   9 +++
 package.json       |  36 ++++++++--
 src/blake.js       |  65 ++++++++++++------
 src/index.js       |  53 +++++++++------
 src/sha3.js        |  49 ++++++++------
 src/types.js       |  10 +++
 test/index.spec.js | 161 ++++++++++++++++++++++++++-------------------
 test/node.js       |   4 ++
 9 files changed, 288 insertions(+), 133 deletions(-)
 create mode 100644 .babelrc
 create mode 100644 .flowconfig
 create mode 100644 src/types.js
 create mode 100644 test/node.js

diff --git a/.babelrc b/.babelrc
new file mode 100644
index 0000000..0a4cc4b
--- /dev/null
+++ b/.babelrc
@@ -0,0 +1,34 @@
+{
+  "env": {
+    "development": {
+      "sourceMaps": "inline",
+      "comments": false,
+      "presets": [
+        [
+          "env",
+          {
+            "targets": {
+              "node": "current"
+            }
+          }
+        ],
+        "flow-node"
+      ]
+    },
+    "umd": {
+      "comments": false,
+      "presets": [
+        [
+          "env",
+          {
+            "modules": false,
+            "targets": {
+              "browsers": "last 2 versions"
+            }
+          }
+        ],
+        "flow-node"
+      ]
+    }
+  }
+}
diff --git a/.flowconfig b/.flowconfig
new file mode 100644
index 0000000..57c6722
--- /dev/null
+++ b/.flowconfig
@@ -0,0 +1,9 @@
+[ignore]
+.*/node_modules/documentation/*
+
+[libs]
+
+[include]
+
+[options]
+suppress_comment= \\(.\\|\n\\)*\\@FlowIgnore
diff --git a/package.json b/package.json
index e2c7f82..460c9f9 100644
--- a/package.json
+++ b/package.json
@@ -4,9 +4,10 @@
   "description": "multiple hash functions",
   "main": "src/index.js",
   "scripts": {
-    "lint": "aegir lint",
-    "build": "aegir build",
-    "test": "aegir test -t node -t browser -t webworker",
+    "lint": "lint-staged && npm run type-check",
+    "type-check": "flow check",
+    "build": "npm run build:node && BABEL_ENV=umd aegir build",
+    "test": "npm run build:node && aegir test -t node -t browser -t webworker",
     "test:node": "aegir test -t node",
     "test:browser": "aegir test -t browser",
     "test:webworker": "aegir test -t webworker",
@@ -14,12 +15,27 @@
     "release-minor": "aegir release --type minor -t node -t browser",
     "release-major": "aegir release --type major -t node -t browser",
     "coverage": "aegir coverage",
-    "coverage-publish": "aegir coverage --provider coveralls"
+    "coverage-publish": "aegir coverage --provider coveralls",
+    "build:types": "flow-copy-source --verbose src lib",
+    "build:lib": "babel --out-dir lib src",
+    "build:node": "npm run build:types && npm run build:lib",
+    "start": "flow-copy-source --watch --verbose src lib & babel --watch --out-dir lib src"
+  },
+  "lint-staged": {
+    "*.js": [
+      "prettier --no-semi --write",
+      "git add"
+    ]
   },
   "pre-commit": [
     "lint",
     "test"
   ],
+  "standard": {
+    "ignore": [
+      "dist"
+    ]
+  },
   "repository": {
     "type": "git",
     "url": "git://github.com/multiformats/js-multihashing.git"
@@ -33,6 +49,9 @@
     "url": "https://github.com/multiformats/js-multihashing/issues"
   },
   "dependencies": {
+    "babel-cli": "^6.26.0",
+    "babel-core": "^6.26.0",
+    "babel-loader": "^7.1.4",
     "blakejs": "^1.1.0",
     "js-sha3": "^0.7.0",
     "multihashes": "~0.4.12",
@@ -40,9 +59,16 @@
   },
   "devDependencies": {
     "aegir": "^12.3.0",
+    "babel-preset-flow-node": "^2.0.1",
     "chai": "^4.1.2",
     "dirty-chai": "^2.0.1",
-    "pre-commit": "^1.2.2"
+    "flow-bin": "^0.69.0",
+    "flow-copy-source": "^1.3.0",
+    "lint-staged": "^7.0.2",
+    "pre-commit": "^1.2.2",
+    "prettier": "^1.11.1",
+    "rollup.config.flow": "^1.0.0",
+    "source-map-support": "^0.5.4"
   },
   "homepage": "https://github.com/multiformats/js-multihashing",
   "contributors": [
diff --git a/src/blake.js b/src/blake.js
index 1f7af54..5796e4a 100644
--- a/src/blake.js
+++ b/src/blake.js
@@ -1,56 +1,79 @@
-'use strict'
+// @flow
+"use strict"
 
-const blake = require('blakejs')
-const minB = 0xb201
-const minS = 0xb241
+import * as blake from "blakejs"
+import type { Hash, HashTable, HashBuilder } from "./types"
+import type { Code } from "multihashes/lib/constants"
 
-var blake2b = {
+const minB: Code = 0xb201
+const minS: Code = 0xb241
+
+type BlakeCtx = {
+  b: Uint8Array,
+  h: Uint32Array,
+  t: number,
+  c: number,
+  outlen: number
+}
+type Blake2Hash = Buffer
+type BlakeHasher = {
+  init(size: number, key: ?number): BlakeCtx,
+  update(ctx: BlakeCtx, input: Uint8Array): void,
+  digest(ctx: BlakeCtx): Uint8Array
+}
+
+const blake2b: BlakeHasher = {
   init: blake.blake2bInit,
   update: blake.blake2bUpdate,
   digest: blake.blake2bFinal
 }
 
-var blake2s = {
+blake2b.init(1, 1)
+
+const blake2s: BlakeHasher = {
   init: blake.blake2sInit,
   update: blake.blake2sUpdate,
   digest: blake.blake2sFinal
 }
 
-class B2Hash {
-  constructor (size, hashFunc) {
+class B2Hash implements Hash {
+  ctx: BlakeCtx | null
+  hf: BlakeHasher
+
+  constructor(size, hashFunc) {
     this.hf = hashFunc
     this.ctx = this.hf.init(size, null)
   }
 
-  update (buf) {
+  update(buf: Buffer): Hash {
     if (this.ctx === null) {
-      throw new Error('blake2 context is null. (already called digest?)')
+      throw new Error("blake2 context is null. (already called digest?)")
     }
     this.hf.update(this.ctx, buf)
     return this
   }
 
-  digest () {
+  digest(): Blake2Hash {
     const ctx = this.ctx
     this.ctx = null
+    if (ctx === null) {
+      throw Error("blake2 context is null. (already called digest?)")
+    }
     return Buffer.from(this.hf.digest(ctx))
   }
 }
 
-function addFuncs (table) {
-  function mkFunc (size, hashFunc) {
-    return () => new B2Hash(size, hashFunc)
+export const addFuncs = (table: HashTable) => {
+  const mkFunc = (size: number, hashFunc: BlakeHasher): HashBuilder => {
+    return (): Hash => new B2Hash(size, hashFunc)
   }
 
-  var i
+  // I don't like using any here but the only way I could get the types to work here.
+  let i
   for (i = 0; i < 64; i++) {
-    table[minB + i] = mkFunc(i + 1, blake2b)
+    table[(minB + i: any)] = mkFunc(i + 1, blake2b)
   }
   for (i = 0; i < 32; i++) {
-    table[minS + i] = mkFunc(i + 1, blake2s)
+    table[(minS + i: any)] = mkFunc(i + 1, blake2s)
   }
 }
-
-module.exports = {
-  addFuncs: addFuncs
-}
diff --git a/src/index.js b/src/index.js
index 1624e61..1baa2c3 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,23 +1,34 @@
-'use strict'
+// @flow
+"use strict"
 
-const multihash = require('multihashes')
-const blake = require('./blake')
-const sha3 = require('./sha3')
-const crypto = require('webcrypto')
+import * as multihash from "multihashes"
+import type { Multihash } from "multihashes"
+import type { Name, Code } from "multihashes/lib/constants"
+import type { HashTable, Hash } from "./types"
+import * as blake from "./blake"
+import * as sha3 from "./sha3"
+import * as crypto from "webcrypto"
 
-const mh = module.exports = Multihashing
+const mh = (module.exports = Multihashing)
 
 mh.Buffer = Buffer // for browser things
 
-function Multihashing (buf, func, length) {
+function Multihashing(
+  buf: Buffer,
+  func: Name | Code,
+  length: number
+): Multihash {
   return multihash.encode(mh.digest(buf, func, length), func, length)
 }
 
 // expose multihash itself, to avoid silly double requires.
 mh.multihash = multihash
 
-mh.digest = function (buf, func, length) {
-  let digest = mh.createHash(func).update(buf).digest()
+mh.digest = function(buf: Buffer, func: Name | Code, length: ?number): Buffer {
+  let digest = mh
+    .createHash(func)
+    .update(buf)
+    .digest()
 
   if (length) {
     digest = digest.slice(0, length)
@@ -26,38 +37,38 @@ mh.digest = function (buf, func, length) {
   return digest
 }
 
-mh.createHash = function (func, length) {
+mh.createHash = function(func: Name | Code): Hash {
   func = multihash.coerceCode(func)
   if (!mh.functions[func]) {
-    throw new Error('multihash function ' + func + ' not yet supported')
+    throw new Error("multihash function " + func + " not yet supported")
   }
 
   return mh.functions[func]()
 }
 
-mh.verify = function (hash, buf) {
+mh.verify = function verify(hash: Multihash, buf: Buffer): boolean {
   const decoded = multihash.decode(hash)
   const encoded = mh(buf, decoded.name, decoded.length)
   return encoded.equals(hash)
 }
 
 mh.functions = {
-  0x11: gsha1,
-  0x12: gsha2256,
-  0x13: gsha2512
+  [0x11]: gsha1,
+  [0x12]: gsha2256,
+  [0x13]: gsha2512
 }
 
 blake.addFuncs(mh.functions)
 sha3.addFuncs(mh.functions)
 
-function gsha1 () {
-  return crypto.createHash('sha1')
+function gsha1(): Hash {
+  return crypto.createHash("sha1")
 }
 
-function gsha2256 () {
-  return crypto.createHash('sha256')
+function gsha2256(): Hash {
+  return crypto.createHash("sha256")
 }
 
-function gsha2512 () {
-  return crypto.createHash('sha512')
+function gsha2512(): Hash {
+  return crypto.createHash("sha512")
 }
diff --git a/src/sha3.js b/src/sha3.js
index b7a9695..7b81b16 100644
--- a/src/sha3.js
+++ b/src/sha3.js
@@ -1,6 +1,8 @@
-'use strict'
+// @flow
+"use strict"
 
-const sha3 = require('js-sha3')
+import * as sha3 from "js-sha3"
+import type { Hash, HashTable } from "./types"
 
 const functions = [
   [0x14, sha3.sha3_512],
@@ -9,44 +11,53 @@ const functions = [
   [0x17, sha3.sha3_224],
   [0x18, sha3.shake128, 256],
   [0x19, sha3.shake256, 512],
-  [0x1A, sha3.keccak224],
-  [0x1B, sha3.keccak256],
-  [0x1C, sha3.keccak384],
-  [0x1D, sha3.keccak512]
+  [0x1a, sha3.keccak224],
+  [0x1b, sha3.keccak256],
+  [0x1c, sha3.keccak384],
+  [0x1d, sha3.keccak512]
 ]
 
-class Hasher {
-  constructor (hashFunc, arg) {
+type HexString = string
+type Sha3Hash = Buffer
+type ShaHasher = (input: string | Buffer, length?: number) => HexString
+
+class ShaHash implements Hash {
+  hf: ShaHasher
+  input: Buffer | null
+  arg: number
+
+  constructor(hashFunc, arg?: number) {
     this.hf = hashFunc
-    this.arg = arg
+    if (arg) {
+      this.arg = arg
+    }
     this.input = null
   }
 
-  update (buf) {
+  update(buf: Buffer): Hash {
     this.input = buf
     return this
   }
 
-  digest () {
+  digest(): Sha3Hash {
+    if (!this.input) {
+      throw Error("Missing an input to hash")
+    }
     const input = this.input
     const arg = this.arg
-    return Buffer.from(this.hf(input, arg), 'hex')
+    return Buffer.from(this.hf(input, arg), "hex")
   }
 }
 
-function addFuncs (table) {
+export const addFuncs = (table: HashTable) => {
   for (const info of functions) {
     const code = info[0]
     const fn = info[1]
 
     if (info.length === 3) {
-      table[code] = () => new Hasher(fn, info[2])
+      table[code] = () => new ShaHash(fn, info[2])
     } else {
-      table[code] = () => new Hasher(fn)
+      table[code] = () => new ShaHash(fn)
     }
   }
 }
-
-module.exports = {
-  addFuncs: addFuncs
-}
diff --git a/src/types.js b/src/types.js
new file mode 100644
index 0000000..e4ea8d0
--- /dev/null
+++ b/src/types.js
@@ -0,0 +1,10 @@
+// @flow
+import type { Code } from "multihashes/lib/constants"
+
+export interface Hash {
+  update(buf: Buffer): Hash;
+  digest(): Buffer;
+}
+
+export type HashBuilder = () => Hash
+export type HashTable = { [Code]: HashBuilder }
diff --git a/test/index.spec.js b/test/index.spec.js
index ef59261..b8bb154 100644
--- a/test/index.spec.js
+++ b/test/index.spec.js
@@ -1,92 +1,119 @@
 /* eslint-env mocha */
-'use strict'
+"use strict"
 
-const chai = require('chai')
-const dirtyChai = require('dirty-chai')
+const chai = require("chai")
+const dirtyChai = require("dirty-chai")
 chai.use(dirtyChai)
 const expect = chai.expect
-const multihashing = require('../src')
+const multihashing = require("../lib")
 
 const tests = {
-  sha1: [
-    ['beep boop', '11147c8357577f51d4f0a8d393aa1aaafb28863d9421']
-  ],
-  'sha2-256': [
-    ['beep boop', '122090ea688e275d580567325032492b597bc77221c62493e76330b85ddda191ef7c']
-  ],
-  'sha2-512': [
-    ['beep boop', '134014f301f31be243f34c5668937883771fa381002f1aaa5f31b3f78e500b66ff2f4f8ea5e3c9f5a61bd073e2452c480484b02e030fb239315a2577f7ae156af177']
-  ],
-  'blake2b-512': [
-    ['beep boop', 'c0e402400eac6255ba822373a0948122b8d295008419a8ab27842ee0d70eca39855621463c03ec75ac3610aacfdff89fa989d8d61fc00450148f289eb5b12ad1a954f659']
-  ],
-  'blake2b-160': [
-    ['beep boop', '94e40214fe303247293e54e0a7ea48f9408ca68b36b08442']
-  ],
-  'blake2s-256': [
-    ['beep boop', 'e0e402204542eaca484e4311def8af74b546edd7fceb49eeb3cdcfd8a4a72ed0dc81d4c0']
-  ],
-  'blake2s-40': [
-    ['beep boop', 'c5e402059ada01bb57']
-  ],
-  'sha3-512': [
-    ['beep bop', '144038122bf54c0e1eeff013e9b8c735af7c08ff8a7bb2b55b5abe9d97f9653e19f388cd9719ffb4ab8ccb9330a1fd27929b0a9ee6d7b8b9884c6f787f11088219bc']
-  ],
-  'sha3-384': [
-    ['beep bop', '15302f0456d702d4cafa23c091f8da2dc878b1536fd592c47c2d239f5de67f0a306f36e0197dbbf1c5409292aa92e326b16e']
-  ],
-  'sha3-256': [
-    ['beep bop', '16204de761fac0b163270f59056e1c5d1038348fcb960c03610bde24565473600dfe']
-  ],
-  'sha3-224': [
-    ['beep bop', '171cda7cce25c2f6248dc88a2fdfca56bb97bf39b100089cacfdf68b7b50']
-  ],
-  'shake-128': [
-    ['beep boop', '18205fe422311f770743c2e0d86bcca092111cbce85487212829739c3c3723776e5a']
-  ],
-  'shake-256': [
-    ['beep boop', '194059feb5565e4f924baef74708649fed376d63948a862322ed763ecf093b63b38b0955908c099c63dda73ee469c31b1456cec95e325bd868d0ce0c0135f5a54411']
-  ],
-  'keccak-224': [
-    ['beep bop', '1a1c45f2663794752c0a2292985b476a6aec407cfd78ad6f14f56d7060d9']
-  ],
-  'keccak-256': [
-    ['beep bop', '1b209e7c2fee63c4065cbaa989bd2655a288f877aa788484fb0640d125417796b5e9']
-  ],
-  'keccak-384': [
-    ['beep bop', '1c305a1da4b6e329884e88b66d82961d6518d9cec66eae6ff6900344a30a742a044b6eb584ab6e8a1c609e04f2f235f5cab3']
-  ],
-  'keccak-512': [
-    ['beep bop', '1d403c22f68c98a6c8ea9fa7819721fba90f905d3c29390d4a94fefc4f8348ed04829a7521b44af4aeea707b32fe63e28322666ae26a59feb3493fafa11873383f6c']
+  sha1: [["beep boop", "11147c8357577f51d4f0a8d393aa1aaafb28863d9421"]],
+  "sha2-256": [
+    [
+      "beep boop",
+      "122090ea688e275d580567325032492b597bc77221c62493e76330b85ddda191ef7c"
+    ]
+  ],
+  "sha2-512": [
+    [
+      "beep boop",
+      "134014f301f31be243f34c5668937883771fa381002f1aaa5f31b3f78e500b66ff2f4f8ea5e3c9f5a61bd073e2452c480484b02e030fb239315a2577f7ae156af177"
+    ]
+  ],
+  "blake2b-512": [
+    [
+      "beep boop",
+      "c0e402400eac6255ba822373a0948122b8d295008419a8ab27842ee0d70eca39855621463c03ec75ac3610aacfdff89fa989d8d61fc00450148f289eb5b12ad1a954f659"
+    ]
+  ],
+  "blake2b-160": [
+    ["beep boop", "94e40214fe303247293e54e0a7ea48f9408ca68b36b08442"]
+  ],
+  "blake2s-256": [
+    [
+      "beep boop",
+      "e0e402204542eaca484e4311def8af74b546edd7fceb49eeb3cdcfd8a4a72ed0dc81d4c0"
+    ]
+  ],
+  "blake2s-40": [["beep boop", "c5e402059ada01bb57"]],
+  "sha3-512": [
+    [
+      "beep bop",
+      "144038122bf54c0e1eeff013e9b8c735af7c08ff8a7bb2b55b5abe9d97f9653e19f388cd9719ffb4ab8ccb9330a1fd27929b0a9ee6d7b8b9884c6f787f11088219bc"
+    ]
+  ],
+  "sha3-384": [
+    [
+      "beep bop",
+      "15302f0456d702d4cafa23c091f8da2dc878b1536fd592c47c2d239f5de67f0a306f36e0197dbbf1c5409292aa92e326b16e"
+    ]
+  ],
+  "sha3-256": [
+    [
+      "beep bop",
+      "16204de761fac0b163270f59056e1c5d1038348fcb960c03610bde24565473600dfe"
+    ]
+  ],
+  "sha3-224": [
+    ["beep bop", "171cda7cce25c2f6248dc88a2fdfca56bb97bf39b100089cacfdf68b7b50"]
+  ],
+  "shake-128": [
+    [
+      "beep boop",
+      "18205fe422311f770743c2e0d86bcca092111cbce85487212829739c3c3723776e5a"
+    ]
+  ],
+  "shake-256": [
+    [
+      "beep boop",
+      "194059feb5565e4f924baef74708649fed376d63948a862322ed763ecf093b63b38b0955908c099c63dda73ee469c31b1456cec95e325bd868d0ce0c0135f5a54411"
+    ]
+  ],
+  "keccak-224": [
+    ["beep bop", "1a1c45f2663794752c0a2292985b476a6aec407cfd78ad6f14f56d7060d9"]
+  ],
+  "keccak-256": [
+    [
+      "beep bop",
+      "1b209e7c2fee63c4065cbaa989bd2655a288f877aa788484fb0640d125417796b5e9"
+    ]
+  ],
+  "keccak-384": [
+    [
+      "beep bop",
+      "1c305a1da4b6e329884e88b66d82961d6518d9cec66eae6ff6900344a30a742a044b6eb584ab6e8a1c609e04f2f235f5cab3"
+    ]
+  ],
+  "keccak-512": [
+    [
+      "beep bop",
+      "1d403c22f68c98a6c8ea9fa7819721fba90f905d3c29390d4a94fefc4f8348ed04829a7521b44af4aeea707b32fe63e28322666ae26a59feb3493fafa11873383f6c"
+    ]
   ]
 }
 
-describe('multihashing', () => {
+describe("multihashing", () => {
   for (const algo in tests) {
     it(algo, () => {
       for (const test of tests[algo]) {
         const input = Buffer.from(test[0])
-        const output = Buffer.from(test[1], 'hex')
+        const output = Buffer.from(test[1], "hex")
         expect(multihashing(input, algo)).to.be.eql(output)
         expect(multihashing.verify(output, input)).to.be.eql(true)
       }
     })
   }
 
-  it('cuts the length', () => {
-    const buf = Buffer.from('beep boop')
-
-    expect(
-      multihashing(buf, 'sha2-256', 10)
-    ).to.be.eql(
-      Buffer.from('120a90ea688e275d58056732', 'hex')
+  it("cuts the length", () => {
+    const buf = Buffer.from("beep boop")
+    expect(multihashing(buf, "sha2-256", 10)).to.be.eql(
+      Buffer.from("120a90ea688e275d58056732", "hex")
     )
   })
 
-  it('throws on non implemented func', () => {
-    expect(
-      () => multihashing(Buffer.from('beep boop'), 'sha3')
-    ).to.throw(
+  it("throws on non implemented func", () => {
+    expect(() => multihashing(Buffer.from("beep boop"), "sha3")).to.throw(
       /Unrecognized hash function named:/
     )
   })
diff --git a/test/node.js b/test/node.js
new file mode 100644
index 0000000..0998241
--- /dev/null
+++ b/test/node.js
@@ -0,0 +1,4 @@
+// TODO: Instead mocha should be passed additional arg
+// `--require source-map-support/register` but as things stand now there is
+// no way to do it without changes to aegir so we do this instead for now.
+require("source-map-support/register")

From fe4c5539989ddda58231df94237fb68572a6bb0a Mon Sep 17 00:00:00 2001
From: Garren Smith <garren.smith@gmail.com>
Date: Thu, 5 Apr 2018 17:01:33 +0200
Subject: [PATCH 2/3] improvements on the types based on review

---
 src/blake.js | 12 ++++++------
 src/index.js |  3 ++-
 src/sha3.js  | 12 +++++++-----
 src/types.js | 17 ++++++++++++++---
 4 files changed, 29 insertions(+), 15 deletions(-)

diff --git a/src/blake.js b/src/blake.js
index 5796e4a..deff167 100644
--- a/src/blake.js
+++ b/src/blake.js
@@ -1,8 +1,6 @@
 // @flow
-"use strict"
-
 import * as blake from "blakejs"
-import type { Hash, HashTable, HashBuilder } from "./types"
+import type { Hash, HashUpdate, HashTable, HashBuilder } from "./types"
 import type { Code } from "multihashes/lib/constants"
 
 const minB: Code = 0xb201
@@ -28,8 +26,6 @@ const blake2b: BlakeHasher = {
   digest: blake.blake2bFinal
 }
 
-blake2b.init(1, 1)
-
 const blake2s: BlakeHasher = {
   init: blake.blake2sInit,
   update: blake.blake2sUpdate,
@@ -45,6 +41,10 @@ class B2Hash implements Hash {
     this.ctx = this.hf.init(size, null)
   }
 
+  static new(size, hashFunc): HashUpdate {
+    return new B2Hash(size, hashFunc)
+  }
+
   update(buf: Buffer): Hash {
     if (this.ctx === null) {
       throw new Error("blake2 context is null. (already called digest?)")
@@ -65,7 +65,7 @@ class B2Hash implements Hash {
 
 export const addFuncs = (table: HashTable) => {
   const mkFunc = (size: number, hashFunc: BlakeHasher): HashBuilder => {
-    return (): Hash => new B2Hash(size, hashFunc)
+    return (): HashUpdate => B2Hash.new(size, hashFunc)
   }
 
   // I don't like using any here but the only way I could get the types to work here.
diff --git a/src/index.js b/src/index.js
index 1baa2c3..b10db90 100644
--- a/src/index.js
+++ b/src/index.js
@@ -9,7 +9,8 @@ import * as blake from "./blake"
 import * as sha3 from "./sha3"
 import * as crypto from "webcrypto"
 
-const mh = (module.exports = Multihashing)
+const mh = Multihashing
+export default mh
 
 mh.Buffer = Buffer // for browser things
 
diff --git a/src/sha3.js b/src/sha3.js
index 7b81b16..0772d2f 100644
--- a/src/sha3.js
+++ b/src/sha3.js
@@ -1,8 +1,6 @@
 // @flow
-"use strict"
-
 import * as sha3 from "js-sha3"
-import type { Hash, HashTable } from "./types"
+import type { Hash, HashTable, HashUpdate } from "./types"
 
 const functions = [
   [0x14, sha3.sha3_512],
@@ -34,6 +32,10 @@ class ShaHash implements Hash {
     this.input = null
   }
 
+  static new(hashFunc, arg?: number): HashUpdate {
+    return new ShaHash(hashFunc, arg)
+  }
+
   update(buf: Buffer): Hash {
     this.input = buf
     return this
@@ -55,9 +57,9 @@ export const addFuncs = (table: HashTable) => {
     const fn = info[1]
 
     if (info.length === 3) {
-      table[code] = () => new ShaHash(fn, info[2])
+      table[code] = () => ShaHash.new(fn, info[2])
     } else {
-      table[code] = () => new ShaHash(fn)
+      table[code] = () => ShaHash.new(fn)
     }
   }
 }
diff --git a/src/types.js b/src/types.js
index e4ea8d0..9dcd4cb 100644
--- a/src/types.js
+++ b/src/types.js
@@ -1,10 +1,21 @@
 // @flow
 import type { Code } from "multihashes/lib/constants"
 
-export interface Hash {
-  update(buf: Buffer): Hash;
+// We break up the Hash Class into Hash and HashUpdate
+// this is a really nice use of types to avoid the user
+// calling digest on the hash class before doing an update
+// and adding an input. This works by only returning an interface
+// that supports update. Once update is called a full hash interface with
+// the digest function exposed is available.
+// This will only work for a code also using flow.
+
+export interface Hash extends HashUpdate {
   digest(): Buffer;
 }
 
-export type HashBuilder = () => Hash
+export interface HashUpdate {
+  update(buf: Buffer): Hash;
+}
+
+export type HashBuilder = () => HashUpdate
 export type HashTable = { [Code]: HashBuilder }

From e6f7f0e8ec3677f7fa28e62be7a050de71f8148c Mon Sep 17 00:00:00 2001
From: Garren Smith <garren.smith@gmail.com>
Date: Fri, 6 Apr 2018 10:11:40 +0200
Subject: [PATCH 3/3] remove prettier and use standardjs for linting

---
 package.json       |  11 +----
 src/blake.js       |  18 ++++----
 src/index.js       |  43 +++++++++---------
 src/sha3.js        |  16 +++----
 src/types.js       |  12 +++--
 test/index.spec.js | 111 ++++++++++++++++++++++-----------------------
 test/node.js       |   2 +-
 7 files changed, 104 insertions(+), 109 deletions(-)

diff --git a/package.json b/package.json
index 460c9f9..11ed80f 100644
--- a/package.json
+++ b/package.json
@@ -4,7 +4,7 @@
   "description": "multiple hash functions",
   "main": "src/index.js",
   "scripts": {
-    "lint": "lint-staged && npm run type-check",
+    "lint": "npm run type-check && aegir lint",
     "type-check": "flow check",
     "build": "npm run build:node && BABEL_ENV=umd aegir build",
     "test": "npm run build:node && aegir test -t node -t browser -t webworker",
@@ -21,12 +21,6 @@
     "build:node": "npm run build:types && npm run build:lib",
     "start": "flow-copy-source --watch --verbose src lib & babel --watch --out-dir lib src"
   },
-  "lint-staged": {
-    "*.js": [
-      "prettier --no-semi --write",
-      "git add"
-    ]
-  },
   "pre-commit": [
     "lint",
     "test"
@@ -58,7 +52,7 @@
     "webcrypto": "~0.1.1"
   },
   "devDependencies": {
-    "aegir": "^12.3.0",
+    "aegir": "git+https://github.com/ipfs/aegir.git#flow",
     "babel-preset-flow-node": "^2.0.1",
     "chai": "^4.1.2",
     "dirty-chai": "^2.0.1",
@@ -66,7 +60,6 @@
     "flow-copy-source": "^1.3.0",
     "lint-staged": "^7.0.2",
     "pre-commit": "^1.2.2",
-    "prettier": "^1.11.1",
     "rollup.config.flow": "^1.0.0",
     "source-map-support": "^0.5.4"
   },
diff --git a/src/blake.js b/src/blake.js
index deff167..55603de 100644
--- a/src/blake.js
+++ b/src/blake.js
@@ -1,7 +1,7 @@
 // @flow
-import * as blake from "blakejs"
-import type { Hash, HashUpdate, HashTable, HashBuilder } from "./types"
-import type { Code } from "multihashes/lib/constants"
+import * as blake from 'blakejs'
+import type { Hash, HashUpdate, HashTable, HashBuilder } from './types'
+import type { Code } from 'multihashes/lib/constants'
 
 const minB: Code = 0xb201
 const minS: Code = 0xb241
@@ -36,28 +36,28 @@ class B2Hash implements Hash {
   ctx: BlakeCtx | null
   hf: BlakeHasher
 
-  constructor(size, hashFunc) {
+  constructor (size, hashFunc) {
     this.hf = hashFunc
     this.ctx = this.hf.init(size, null)
   }
 
-  static new(size, hashFunc): HashUpdate {
+  static new (size, hashFunc): HashUpdate {
     return new B2Hash(size, hashFunc)
   }
 
-  update(buf: Buffer): Hash {
+  update (buf: Buffer): Hash {
     if (this.ctx === null) {
-      throw new Error("blake2 context is null. (already called digest?)")
+      throw new Error('blake2 context is null. (already called digest?)')
     }
     this.hf.update(this.ctx, buf)
     return this
   }
 
-  digest(): Blake2Hash {
+  digest (): Blake2Hash {
     const ctx = this.ctx
     this.ctx = null
     if (ctx === null) {
-      throw Error("blake2 context is null. (already called digest?)")
+      throw Error('blake2 context is null. (already called digest?)')
     }
     return Buffer.from(this.hf.digest(ctx))
   }
diff --git a/src/index.js b/src/index.js
index b10db90..5b564d8 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,20 +1,19 @@
 // @flow
-"use strict"
 
-import * as multihash from "multihashes"
-import type { Multihash } from "multihashes"
-import type { Name, Code } from "multihashes/lib/constants"
-import type { HashTable, Hash } from "./types"
-import * as blake from "./blake"
-import * as sha3 from "./sha3"
-import * as crypto from "webcrypto"
+import * as multihash from 'multihashes'
+import type { Multihash } from 'multihashes'
+import type { Name, Code } from 'multihashes/lib/constants'
+import type { HashUpdate, HashTable } from './types'
+import * as blake from './blake'
+import * as sha3 from './sha3'
+import * as crypto from 'webcrypto'
 
 const mh = Multihashing
 export default mh
 
 mh.Buffer = Buffer // for browser things
 
-function Multihashing(
+function Multihashing (
   buf: Buffer,
   func: Name | Code,
   length: number
@@ -25,7 +24,7 @@ function Multihashing(
 // expose multihash itself, to avoid silly double requires.
 mh.multihash = multihash
 
-mh.digest = function(buf: Buffer, func: Name | Code, length: ?number): Buffer {
+mh.digest = function (buf: Buffer, func: Name | Code, length: ?number): Buffer {
   let digest = mh
     .createHash(func)
     .update(buf)
@@ -38,38 +37,40 @@ mh.digest = function(buf: Buffer, func: Name | Code, length: ?number): Buffer {
   return digest
 }
 
-mh.createHash = function(func: Name | Code): Hash {
+mh.createHash = function (func: Name | Code): HashUpdate {
   func = multihash.coerceCode(func)
   if (!mh.functions[func]) {
-    throw new Error("multihash function " + func + " not yet supported")
+    throw new Error('multihash function ' + func + ' not yet supported')
   }
 
   return mh.functions[func]()
 }
 
-mh.verify = function verify(hash: Multihash, buf: Buffer): boolean {
+mh.verify = function verify (hash: Multihash, buf: Buffer): boolean {
   const decoded = multihash.decode(hash)
   const encoded = mh(buf, decoded.name, decoded.length)
   return encoded.equals(hash)
 }
 
-mh.functions = {
+/* eslint-disable no-useless-computed-key */
+mh.functions = ({
   [0x11]: gsha1,
   [0x12]: gsha2256,
   [0x13]: gsha2512
-}
+}: HashTable)
+/* eslint-enable no-useless-computed-key */
 
 blake.addFuncs(mh.functions)
 sha3.addFuncs(mh.functions)
 
-function gsha1(): Hash {
-  return crypto.createHash("sha1")
+function gsha1 (): HashUpdate {
+  return crypto.createHash('sha1')
 }
 
-function gsha2256(): Hash {
-  return crypto.createHash("sha256")
+function gsha2256 (): HashUpdate {
+  return crypto.createHash('sha256')
 }
 
-function gsha2512(): Hash {
-  return crypto.createHash("sha512")
+function gsha2512 (): HashUpdate {
+  return crypto.createHash('sha512')
 }
diff --git a/src/sha3.js b/src/sha3.js
index 0772d2f..2d673cb 100644
--- a/src/sha3.js
+++ b/src/sha3.js
@@ -1,6 +1,6 @@
 // @flow
-import * as sha3 from "js-sha3"
-import type { Hash, HashTable, HashUpdate } from "./types"
+import * as sha3 from 'js-sha3'
+import type { Hash, HashTable, HashUpdate } from './types'
 
 const functions = [
   [0x14, sha3.sha3_512],
@@ -24,7 +24,7 @@ class ShaHash implements Hash {
   input: Buffer | null
   arg: number
 
-  constructor(hashFunc, arg?: number) {
+  constructor (hashFunc, arg?: number) {
     this.hf = hashFunc
     if (arg) {
       this.arg = arg
@@ -32,22 +32,22 @@ class ShaHash implements Hash {
     this.input = null
   }
 
-  static new(hashFunc, arg?: number): HashUpdate {
+  static new (hashFunc, arg?: number): HashUpdate {
     return new ShaHash(hashFunc, arg)
   }
 
-  update(buf: Buffer): Hash {
+  update (buf: Buffer): Hash {
     this.input = buf
     return this
   }
 
-  digest(): Sha3Hash {
+  digest (): Sha3Hash {
     if (!this.input) {
-      throw Error("Missing an input to hash")
+      throw Error('Missing an input to hash')
     }
     const input = this.input
     const arg = this.arg
-    return Buffer.from(this.hf(input, arg), "hex")
+    return Buffer.from(this.hf(input, arg), 'hex')
   }
 }
 
diff --git a/src/types.js b/src/types.js
index 9dcd4cb..973bd99 100644
--- a/src/types.js
+++ b/src/types.js
@@ -1,5 +1,5 @@
 // @flow
-import type { Code } from "multihashes/lib/constants"
+import type { Code } from 'multihashes/lib/constants'
 
 // We break up the Hash Class into Hash and HashUpdate
 // this is a really nice use of types to avoid the user
@@ -9,13 +9,15 @@ import type { Code } from "multihashes/lib/constants"
 // the digest function exposed is available.
 // This will only work for a code also using flow.
 
-export interface Hash extends HashUpdate {
-  digest(): Buffer;
-}
-
+/* eslint-disable no-use-before-define */
 export interface HashUpdate {
   update(buf: Buffer): Hash;
 }
 
+export interface Hash extends HashUpdate {
+  digest(): Buffer;
+}
+/* eslint-enable no-use-before-define */
+
 export type HashBuilder = () => HashUpdate
 export type HashTable = { [Code]: HashBuilder }
diff --git a/test/index.spec.js b/test/index.spec.js
index b8bb154..5737474 100644
--- a/test/index.spec.js
+++ b/test/index.spec.js
@@ -1,119 +1,118 @@
 /* eslint-env mocha */
-"use strict"
 
-const chai = require("chai")
-const dirtyChai = require("dirty-chai")
+const chai = require('chai')
+const dirtyChai = require('dirty-chai')
 chai.use(dirtyChai)
 const expect = chai.expect
-const multihashing = require("../lib")
+const multihashing = require('../lib')
 
 const tests = {
-  sha1: [["beep boop", "11147c8357577f51d4f0a8d393aa1aaafb28863d9421"]],
-  "sha2-256": [
+  sha1: [['beep boop', '11147c8357577f51d4f0a8d393aa1aaafb28863d9421']],
+  'sha2-256': [
     [
-      "beep boop",
-      "122090ea688e275d580567325032492b597bc77221c62493e76330b85ddda191ef7c"
+      'beep boop',
+      '122090ea688e275d580567325032492b597bc77221c62493e76330b85ddda191ef7c'
     ]
   ],
-  "sha2-512": [
+  'sha2-512': [
     [
-      "beep boop",
-      "134014f301f31be243f34c5668937883771fa381002f1aaa5f31b3f78e500b66ff2f4f8ea5e3c9f5a61bd073e2452c480484b02e030fb239315a2577f7ae156af177"
+      'beep boop',
+      '134014f301f31be243f34c5668937883771fa381002f1aaa5f31b3f78e500b66ff2f4f8ea5e3c9f5a61bd073e2452c480484b02e030fb239315a2577f7ae156af177'
     ]
   ],
-  "blake2b-512": [
+  'blake2b-512': [
     [
-      "beep boop",
-      "c0e402400eac6255ba822373a0948122b8d295008419a8ab27842ee0d70eca39855621463c03ec75ac3610aacfdff89fa989d8d61fc00450148f289eb5b12ad1a954f659"
+      'beep boop',
+      'c0e402400eac6255ba822373a0948122b8d295008419a8ab27842ee0d70eca39855621463c03ec75ac3610aacfdff89fa989d8d61fc00450148f289eb5b12ad1a954f659'
     ]
   ],
-  "blake2b-160": [
-    ["beep boop", "94e40214fe303247293e54e0a7ea48f9408ca68b36b08442"]
+  'blake2b-160': [
+    ['beep boop', '94e40214fe303247293e54e0a7ea48f9408ca68b36b08442']
   ],
-  "blake2s-256": [
+  'blake2s-256': [
     [
-      "beep boop",
-      "e0e402204542eaca484e4311def8af74b546edd7fceb49eeb3cdcfd8a4a72ed0dc81d4c0"
+      'beep boop',
+      'e0e402204542eaca484e4311def8af74b546edd7fceb49eeb3cdcfd8a4a72ed0dc81d4c0'
     ]
   ],
-  "blake2s-40": [["beep boop", "c5e402059ada01bb57"]],
-  "sha3-512": [
+  'blake2s-40': [['beep boop', 'c5e402059ada01bb57']],
+  'sha3-512': [
     [
-      "beep bop",
-      "144038122bf54c0e1eeff013e9b8c735af7c08ff8a7bb2b55b5abe9d97f9653e19f388cd9719ffb4ab8ccb9330a1fd27929b0a9ee6d7b8b9884c6f787f11088219bc"
+      'beep bop',
+      '144038122bf54c0e1eeff013e9b8c735af7c08ff8a7bb2b55b5abe9d97f9653e19f388cd9719ffb4ab8ccb9330a1fd27929b0a9ee6d7b8b9884c6f787f11088219bc'
     ]
   ],
-  "sha3-384": [
+  'sha3-384': [
     [
-      "beep bop",
-      "15302f0456d702d4cafa23c091f8da2dc878b1536fd592c47c2d239f5de67f0a306f36e0197dbbf1c5409292aa92e326b16e"
+      'beep bop',
+      '15302f0456d702d4cafa23c091f8da2dc878b1536fd592c47c2d239f5de67f0a306f36e0197dbbf1c5409292aa92e326b16e'
     ]
   ],
-  "sha3-256": [
+  'sha3-256': [
     [
-      "beep bop",
-      "16204de761fac0b163270f59056e1c5d1038348fcb960c03610bde24565473600dfe"
+      'beep bop',
+      '16204de761fac0b163270f59056e1c5d1038348fcb960c03610bde24565473600dfe'
     ]
   ],
-  "sha3-224": [
-    ["beep bop", "171cda7cce25c2f6248dc88a2fdfca56bb97bf39b100089cacfdf68b7b50"]
+  'sha3-224': [
+    ['beep bop', '171cda7cce25c2f6248dc88a2fdfca56bb97bf39b100089cacfdf68b7b50']
   ],
-  "shake-128": [
+  'shake-128': [
     [
-      "beep boop",
-      "18205fe422311f770743c2e0d86bcca092111cbce85487212829739c3c3723776e5a"
+      'beep boop',
+      '18205fe422311f770743c2e0d86bcca092111cbce85487212829739c3c3723776e5a'
     ]
   ],
-  "shake-256": [
+  'shake-256': [
     [
-      "beep boop",
-      "194059feb5565e4f924baef74708649fed376d63948a862322ed763ecf093b63b38b0955908c099c63dda73ee469c31b1456cec95e325bd868d0ce0c0135f5a54411"
+      'beep boop',
+      '194059feb5565e4f924baef74708649fed376d63948a862322ed763ecf093b63b38b0955908c099c63dda73ee469c31b1456cec95e325bd868d0ce0c0135f5a54411'
     ]
   ],
-  "keccak-224": [
-    ["beep bop", "1a1c45f2663794752c0a2292985b476a6aec407cfd78ad6f14f56d7060d9"]
+  'keccak-224': [
+    ['beep bop', '1a1c45f2663794752c0a2292985b476a6aec407cfd78ad6f14f56d7060d9']
   ],
-  "keccak-256": [
+  'keccak-256': [
     [
-      "beep bop",
-      "1b209e7c2fee63c4065cbaa989bd2655a288f877aa788484fb0640d125417796b5e9"
+      'beep bop',
+      '1b209e7c2fee63c4065cbaa989bd2655a288f877aa788484fb0640d125417796b5e9'
     ]
   ],
-  "keccak-384": [
+  'keccak-384': [
     [
-      "beep bop",
-      "1c305a1da4b6e329884e88b66d82961d6518d9cec66eae6ff6900344a30a742a044b6eb584ab6e8a1c609e04f2f235f5cab3"
+      'beep bop',
+      '1c305a1da4b6e329884e88b66d82961d6518d9cec66eae6ff6900344a30a742a044b6eb584ab6e8a1c609e04f2f235f5cab3'
     ]
   ],
-  "keccak-512": [
+  'keccak-512': [
     [
-      "beep bop",
-      "1d403c22f68c98a6c8ea9fa7819721fba90f905d3c29390d4a94fefc4f8348ed04829a7521b44af4aeea707b32fe63e28322666ae26a59feb3493fafa11873383f6c"
+      'beep bop',
+      '1d403c22f68c98a6c8ea9fa7819721fba90f905d3c29390d4a94fefc4f8348ed04829a7521b44af4aeea707b32fe63e28322666ae26a59feb3493fafa11873383f6c'
     ]
   ]
 }
 
-describe("multihashing", () => {
+describe('multihashing', () => {
   for (const algo in tests) {
     it(algo, () => {
       for (const test of tests[algo]) {
         const input = Buffer.from(test[0])
-        const output = Buffer.from(test[1], "hex")
+        const output = Buffer.from(test[1], 'hex')
         expect(multihashing(input, algo)).to.be.eql(output)
         expect(multihashing.verify(output, input)).to.be.eql(true)
       }
     })
   }
 
-  it("cuts the length", () => {
-    const buf = Buffer.from("beep boop")
-    expect(multihashing(buf, "sha2-256", 10)).to.be.eql(
-      Buffer.from("120a90ea688e275d58056732", "hex")
+  it('cuts the length', () => {
+    const buf = Buffer.from('beep boop')
+    expect(multihashing(buf, 'sha2-256', 10)).to.be.eql(
+      Buffer.from('120a90ea688e275d58056732', 'hex')
     )
   })
 
-  it("throws on non implemented func", () => {
-    expect(() => multihashing(Buffer.from("beep boop"), "sha3")).to.throw(
+  it('throws on non implemented func', () => {
+    expect(() => multihashing(Buffer.from('beep boop'), 'sha3')).to.throw(
       /Unrecognized hash function named:/
     )
   })
diff --git a/test/node.js b/test/node.js
index 0998241..f58bab2 100644
--- a/test/node.js
+++ b/test/node.js
@@ -1,4 +1,4 @@
 // TODO: Instead mocha should be passed additional arg
 // `--require source-map-support/register` but as things stand now there is
 // no way to do it without changes to aegir so we do this instead for now.
-require("source-map-support/register")
+require('source-map-support/register')