feat: [closes #383] Random number generator seeding

api/post-day-results.js

@@ -15,6 +15,7 @@ const {
   getRoomData,
   getRoomName,
 } = require('../api-etc/utils')
+const { random } = require('../src/common/utils')
 
 const client = getRedisClient()
 
@@ -30,7 +31,7 @@ const applyPositionsToMarket = (valueAdjustments, positions) => {
     (acc, itemName) => {
       const itemPositionChange = positions[itemName]
 
-      const variance = Math.random() * 0.2
+      const variance = random() * 0.2
 
       const MAX = 1.5
       const MIN = 0.5
@@ -43,7 +44,7 @@ const applyPositionsToMarket = (valueAdjustments, positions) => {
         // If item value is at a range boundary but was not changed in this
         // operation, randomize it to introduce some variability to the market.
         if (acc[itemName] === MAX || acc[itemName] === MIN) {
-          acc[itemName] = Math.random() + MIN
+          acc[itemName] = random() + MIN
         }
       }
 

package.json

@@ -45,6 +45,7 @@
     "@testing-library/jest-dom": "^5.14.1",
     "@testing-library/react": "^12.0.0",
     "@testing-library/user-event": "^13.2.1",
+    "@types/react": "^17.0.2",
     "@typescript-eslint/eslint-plugin": "^2.23.0",
     "@typescript-eslint/parser": "^2.23.0",
     "bittorrent-tracker": "^9.19.0",
@@ -122,6 +123,7 @@
     "react-use": "^17.4.0",
     "react-zoom-pan-pinch": "^1.6.1",
     "redis": "^3.0.2",
+    "seedrandom": "^3.0.5",
     "shifty": "^2.15.2",
     "source-map-explorer": "^2.3.1",
     "stream": "npm:stream-browserify@^3.0.0",

src/common/services/randomNumber.js

@@ -0,0 +1,40 @@
+import seedrandom from 'seedrandom'
+import window from 'global/window'
+
+export class RandomNumberService {
+  /**
+   * @type {Function?}
+   */
+  seededRandom = null
+
+  constructor() {
+    // The availability of window.location needs to be checked before accessing
+    // its .search property. This code runs in both a browser and Node.js
+    // context, and window.location is not defined in Node.js environments.
+    const initialSeed = new URLSearchParams(window.location?.search).get('seed')
+
+    if (initialSeed) {
+      this.seedRandomNumber(initialSeed)
+    }
+  }
+
+  /**
+   * @param {string} seed
+   */
+  seedRandomNumber(seed) {
+    this.seededRandom = seedrandom(seed)
+  }
+
+  /**
+   * @returns {number}
+   */
+  generateRandomNumber() {
+    return this.seededRandom ? this.seededRandom() : Math.random()
+  }
+
+  unseedRandomNumber() {
+    this.seededRandom = null
+  }
+}
+
+export const randomNumberService = new RandomNumberService()

src/common/utils.js

@@ -1,5 +1,12 @@
+/** @typedef {import("../index").farmhand.priceEvent} farmhand.priceEvent */
 import { itemsMap } from '../data/maps'
 
+import { randomNumberService } from './services/randomNumber'
+
+export const random = () => {
+  return randomNumberService.generateRandomNumber()
+}
+
 /**
  * @param {farmhand.priceEvent} [priceCrashes]
  * @param {farmhand.priceEvent} [priceSurges]
@@ -13,7 +20,7 @@ export const generateValueAdjustments = (priceCrashes = {}, priceSurges = {}) =>
       } else if (priceSurges[key]) {
         acc[key] = 1.5
       } else {
-        acc[key] = Math.random() + 0.5
+        acc[key] = random() + 0.5
       }
     }
 

src/components/CowPen/CowPen.js

@@ -13,9 +13,10 @@ import { pixel } from '../../img'
 import { getCowDisplayName, getCowImage } from '../../utils'
 
 import './CowPen.sass'
+import { random } from '../../common/utils'
 
 // Only moves the cow within the middle 80% of the pen
-const randomPosition = () => 10 + Math.random() * 80
+const randomPosition = () => 10 + random() * 80
 
 // TODO: Break this out into its own component file
 export class Cow extends Component {
@@ -155,7 +156,7 @@ export class Cow extends Component {
 
     this.repositionTimeoutId = setTimeout(
       this.repositionTimeoutHandler,
-      Math.random() * this.waitVariance
+      random() * this.waitVariance
     )
   }
 

src/components/Home/SnowBackground.js

@@ -2,8 +2,10 @@ import React from 'react'
 import useWindowSize from 'react-use/lib/useWindowSize'
 import Confetti from 'react-confetti'
 
+import { random } from '../../common/utils'
+
 const randomInt = (min, max) => {
-  return Math.floor(min + Math.random() * (max - min + 1))
+  return Math.floor(min + random() * (max - min + 1))
 }
 
 // Taken from:

src/components/SettingsView/RandomSeedInput.js

@@ -0,0 +1,52 @@
+import React, { useContext, useState } from 'react'
+import { string } from 'prop-types'
+import window from 'global/window'
+import TextField from '@material-ui/core/TextField'
+
+import FarmhandContext from '../Farmhand/Farmhand.context'
+
+import './RandomSeedInput.sass'
+
+export const RandomSeedInput = ({ search = window.location.search }) => {
+  const {
+    handlers: { handleRNGSeedChange },
+  } = useContext(FarmhandContext)
+
+  const [seed, setSeed] = useState(
+    new URLSearchParams(search).get('seed') ?? ''
+  )
+
+  /**
+   * @param {React.SyntheticEvent<HTMLInputElement>} e
+   */
+  const handleChange = e => {
+    setSeed(e.target.value)
+  }
+
+  /**
+   * @param {React.SyntheticEvent<HTMLFormElement>} e
+   */
+  const handleSubmit = e => {
+    e.preventDefault()
+
+    handleRNGSeedChange(seed)
+  }
+
+  return (
+    <form className="RandomSeedInput" onSubmit={handleSubmit}>
+      <TextField
+        value={seed}
+        variant="outlined"
+        label="Random number seed"
+        onChange={handleChange}
+        inputProps={{
+          maxLength: 30,
+        }}
+      />
+    </form>
+  )
+}
+
+RandomSeedInput.propTypes = {
+  search: string,
+}

src/components/SettingsView/RandomSeedInput.sass

@@ -0,0 +1,3 @@
+.RandomSeedInput
+  display: flex
+  justify-content: center

src/components/SettingsView/RandomSeedInput.test.js

@@ -0,0 +1,35 @@
+import React from 'react'
+import { render, screen } from '@testing-library/react'
+import userEvent from '@testing-library/user-event'
+
+import FarmhandContext from '../Farmhand/Farmhand.context'
+
+import { RandomSeedInput } from './RandomSeedInput'
+
+const mockHandleRNGSeedChange = jest.fn()
+
+const MockRandomSeedInput = props => (
+  <FarmhandContext.Provider
+    value={{ handlers: { handleRNGSeedChange: mockHandleRNGSeedChange } }}
+  >
+    <RandomSeedInput {...props} />
+  </FarmhandContext.Provider>
+)
+
+describe('RandomSeedInput', () => {
+  test('gets initial value from query param', () => {
+    render(<MockRandomSeedInput search="?seed=123" />)
+
+    expect(screen.getByDisplayValue('123')).toBeInTheDocument()
+  })
+
+  test('updates query param', () => {
+    render(<MockRandomSeedInput search="?seed=123" />)
+
+    const input = screen.getByDisplayValue('123')
+
+    userEvent.type(input, '[Backspace][Backspace][Backspace]456[Enter]')
+
+    expect(mockHandleRNGSeedChange).toHaveBeenCalledWith('456')
+  })
+})

src/components/SettingsView/SettingsView.js

@@ -16,6 +16,7 @@ import FileReaderInput from 'react-file-reader-input'
 
 import FarmhandContext from '../Farmhand/Farmhand.context'
 
+import { RandomSeedInput } from './RandomSeedInput'
 import './SettingsView.sass'
 
 const SettingsView = ({
@@ -48,6 +49,8 @@ const SettingsView = ({
         </Button>
       </div>
       <Divider />
+      <RandomSeedInput />
+      <Divider />
 
       <FormControl component="fieldset">
         <FormLabel component="legend">Options</FormLabel>