Add emoji hash function (#343)

* add emojis

* add func

* add tests

packages/status-js/src/utils/public-key-to-color-hash.ts

@@ -7,6 +7,9 @@ export type ColorHash = number[][]
 const COLOR_HASH_COLORS_COUNT = 32
 const COLOR_HASH_SEGMENT_MAX_LENGTH = 5
 
+/**
+ * @see https://github.com/status-im/specs/pull/166 for specs
+ */
 export function publicKeyToColorHash(publicKey: string): ColorHash {
   const compressedPublicKey = compressPublicKey(publicKey)
 
@@ -34,7 +37,7 @@ export function hexToColorHash(
   return colorHash
 }
 
-function numberToIndices(number: bigint, base: bigint): bigint[] {
+export function numberToIndices(number: bigint, base: bigint): bigint[] {
   const indices: bigint[] = []
   let nextNumber = number
 

packages/status-js/src/utils/public-key-to-emoji-hash.test.ts

@@ -0,0 +1,41 @@
+import { expect, test } from 'vitest'
+
+import { publicKeyToEmojiHash } from './public-key-to-emoji-hash'
+
+test('should return emoji hash from public key', () => {
+  expect(
+    publicKeyToEmojiHash(
+      '0x04e25da6994ea2dc4ac70727e07eca153ae92bf7609db7befb7ebdceaad348f4fc55bbe90abf9501176301db5aa103fc0eb3bc3750272a26c424a10887db2a7ea8'
+    )
+  ).toEqual('👦🏽🦹🏻👶🏿🛁🌁🙌🏻🙇🏽‍♂️🙌🏾🤥🐛👩🏽‍🔧🔧⚙️🧒🏽')
+  expect(
+    publicKeyToEmojiHash(
+      '0x0400000000000000000000000000000000000000000000000000000000000000014218F20AE6C646B363DB68605822FB14264CA8D2587FDD6FBC750D587E76A7EE'
+    )
+  ).toEqual('😀😀😀😀😀😀😀😀😀😀😀😀😀😀')
+  expect(
+    publicKeyToEmojiHash(
+      '0x04000000000000000000000000000000000000000010000000000000000000000033600332D373318ECC2F212A30A5750D2EAC827B6A32B33D326CCF369B12B1BE'
+    )
+  ).toEqual('😀😀😀😀😀😀😀😀😀😀😀😀😀😃')
+  expect(
+    publicKeyToEmojiHash(
+      '0x040000000000000000000000000000000000000000200000000000000000000000353050BFE33B724E60A0C600FBA565A9B62217B1BD35BF9848F2AB847C598B30'
+    )
+  ).toEqual('😀😀😀😀😀😀😀😀😀😀😀😀😀😄')
+})
+
+test('should throw for invalid public keys', () => {
+  expect(() => publicKeyToEmojiHash('abc')).toThrow()
+  expect(() => publicKeyToEmojiHash('0x01')).toThrow()
+  expect(() =>
+    publicKeyToEmojiHash(
+      '0x01e25da6994ea2dc4ac70727e07eca153ae92bf7609db7befb7ebdceaad348f4fc55bbe90abf9501176301db5aa103fc0eb3bc3750272a26c424a10887db2a7ea8'
+    )
+  ).toThrow()
+  expect(() =>
+    publicKeyToEmojiHash(
+      '0x04425da6994ea2dc4ac70727e07eca153ae92bf7609db7befb7ebdceaad348f4fc55bbe90abf9501176301db5aa103fc0eb3bc3750272a26c424a10887db2a7ea8'
+    )
+  ).toThrow()
+})

packages/status-js/src/utils/public-key-to-emoji-hash.ts

@@ -0,0 +1,55 @@
+import { emojis } from '../consts/emojis'
+import { compressPublicKey } from './compress-public-key'
+import { numberToIndices } from './public-key-to-color-hash'
+
+const MIN_EMOJI_HASH_EMOJIS_COUNT = 2757
+const EMOJI_HASH_LENGTH = 14
+
+/**
+ * @see https://github.com/status-im/specs/pull/166 for specs
+ */
+export function publicKeyToEmojiHash(publicKey: string): string {
+  if (emojis.length < MIN_EMOJI_HASH_EMOJIS_COUNT) {
+    throw new Error('Not enough emojis')
+  }
+
+  const compressedPublicKeyHex = compressPublicKey(publicKey)
+
+  const emojiHashHex = compressedPublicKeyHex.slice(3, 43)
+  const emojiHash = hexToEmojiHash(
+    emojiHashHex,
+    MIN_EMOJI_HASH_EMOJIS_COUNT,
+    EMOJI_HASH_LENGTH
+  )
+
+  return emojiHash
+}
+
+export function hexToEmojiHash(
+  hex: string,
+  emojisCount: number,
+  hashLength: number
+): string {
+  const emojiIndices = numberToIndices(BigInt(`0x${hex}`), BigInt(emojisCount))
+  const emojiHash = emojiIndicesToEmojiHash(emojiIndices, hashLength)
+
+  return emojiHash
+}
+
+function emojiIndicesToEmojiHash(emojiIndices: bigint[], hashLength: number) {
+  let emojiHash = ''
+
+  if (emojiIndices.length < hashLength) {
+    let fillerIndices = hashLength - emojiIndices.length
+
+    while (fillerIndices--) {
+      emojiIndices.unshift(BigInt(0))
+    }
+  }
+
+  for (const i of emojiIndices) {
+    emojiHash += emojis[Number(i)]
+  }
+
+  return emojiHash
+}