// Forked from https://github.com/download13/blockies

// The random number is a js implementation of the Xorshift PRNG
const randseed = new Array(4) // Xorshift: [x, y, z, w] 32 bit values

function seedrand(seed: string) {
	randseed.fill(0)

	for (let i = 0; i < seed.length; i++) {
		randseed[i % 4] = (randseed[i % 4] << 5) - randseed[i % 4] + seed.charCodeAt(i)
	}
}

function rand() {
	// based on Java's String.hashCode(), expanded to 4 32bit values
	const t = randseed[0] ^ (randseed[0] << 11)

	randseed[0] = randseed[1]
	randseed[1] = randseed[2]
	randseed[2] = randseed[3]
	randseed[3] = randseed[3] ^ (randseed[3] >> 19) ^ t ^ (t >> 8)

	return (randseed[3] >>> 0) / ((1 << 31) >>> 0)
}

function createColor() {
	//saturation is the whole color spectrum
	const h = Math.floor(rand() * 360)
	//saturation goes from 40 to 100, it avoids greyish colors
	const s = (rand() * 60 + 40).toFixed(1) + '%'
	//lightness can be anything from 0 to 100, but probabilities are a bell curve around 50%
	const l = ((rand() + rand() + rand() + rand()) * 25).toFixed(1) + '%'

	return 'hsl(' + h + ',' + s + ',' + l + ')'
}

export function createImageData(size: number) {
	const width = size // Only support square icons for now
	const height = size

	const dataWidth = Math.ceil(width / 2)
	const mirrorWidth = width - dataWidth

	const data: number[] = []
	for (let y = 0; y < height; y++) {
		let row: number[] = []
		for (let x = 0; x < dataWidth; x++) {
			// this makes foreground and background color to have a 43% (1/2.3) probability
			// spot color has 13% chance
			row[x] = Math.floor(rand() * 2.3)
		}
		const r = row.slice(0, mirrorWidth)
		r.reverse()
		row = row.concat(r)

		for (let i = 0; i < row.length; i++) {
			data.push(row[i])
		}
	}

	return data
}

export function buildOpts(opts: { seed: string; size?: number; scale?: number }) {
	seedrand(opts.seed)

	const newOpts: BlockiesOptions = {
		seed: opts.seed,
		size: opts.size || 8,
		scale: opts.scale || 10,
		color: createColor(),
		bgcolor: createColor(),
		spotcolor: createColor()
	}

	return newOpts
}

export interface BlockiesOptions {
	seed: string
	size: number
	scale: number
	color: string
	bgcolor: string
	spotcolor: string
}