Generate Minesweeper for Discord

discord-minesweeper.js

// https://gist.github.com/frzi/5c397d396db3b94c281d57e803227db8

const MINE = -1

function generateSpaces(width = 9, height = 9, mines = 15) {
	const totalSpaces = width * height
	mines = Math.min(totalSpaces - 1, Math.abs(mines))
	
	let spaces = new Array(totalSpaces).fill(0)
	let openSpaces = spaces.map((_, index) => index)
	
	// Generate the mines.
	while (mines > 0 && openSpaces.length) {
		const randomIndex = Math.floor(Math.random() * openSpaces.length)
		const space = openSpaces.splice(randomIndex, 1)
		
		spaces[space] = MINE
		
		mines--
	}
	
	// Utils.
	const indexToXY = index => [index % width, Math.floor(index / height)]
	const xyToIndex = ([x, y]) => y * width + x
	
	// Generate the numbers.
	const kernel = [
		[-1, -1], [0, -1], [1, -1],
		[-1,  0],          [1,  0],
		[-1,  1], [0,  1], [1,  1],	
	]
	
	function trace(index) {
		if (spaces[index] == -1) {
			return
		}
		
		let mineCount = 0
		
		for (const [offsetX, offsetY] of kernel) {
			let [x, y] = indexToXY(index)
			x += offsetX
			y += offsetY
			
			if (x < 0 || x >= width || y < 0 || y >= height) {
				continue
			}
			
			const offsetIndex = xyToIndex([x, y])
			if (spaces[offsetIndex] == MINE) {
				mineCount++
			}
		}
		
		spaces[index] = mineCount
	}
	
	spaces.forEach((_, index) => trace(index))
	
	return spaces
}

function createDiscordString(spaces, width = 9) {
	const nonMineIndices = spaces.map((space, index) => space != MINE ? index : null).filter(p => p !== null)
	const openSpaceIndices = spaces.map((space, index) => space == 0 ? index : null).filter(p => p !== null)
	
	// Find a random index to reveal.
	const revealIndex = (() => {
		if (openSpaceIndices.length > 0) {
			return openSpaceIndices[Math.floor(Math.random() * openSpaceIndices.length)]
		}
		else {
			return nonMineIndices[Math.floor(Math.random() * nonMineIndices.length)]
		}
	})()
	
	const emojis = [
		'white_large_square', 'one', 'two', 'three',
		'four', 'five', 'six', 'seven', 'eight',
	]
	emojis[MINE] = 'boom'
	
	let revealed = false
	let string = ''
	let parsedOpenSpaces = 0
	
	for (let a = 0; a < spaces.length; a++) {
		const emoji = emojis[spaces[a]]
		
		parsedOpenSpaces += spaces[a] == 0
		
		if (a == revealIndex) {
			string += `:${emoji}:`
		}
		else {
			string += `||:${emoji}:||`
		}
		
		if ((a + 1) % width == 0) {
			string += '\n'
		}
	}
	
	return string
}

function generate() {
	const field = generateSpaces(iwidth.value, iheight.value, imines.value)
	const string = createDiscordString(field, iwidth.value) 
	pre.textContent = string
	warning.style.display = string.length > 2000 ? 'block' : 'none'
}

iwidth.oninput = iheight.oninput = imines.oninput = generate

generate()