export function* range(
	start: number,
	end: number,
	step = 1,
): Generator<number> {
	for (let i = start; i < end; i += step) yield i
}

export type List<T> = IteratorObject<T> | T[]

export function count(): <T>(previous: T, current: T) => number {
	let count = 1
	let first = false
	return () => {
		if (first) {
			count++
			first = false
		}
		return count++
	}
}

export function sum(previous: number, current: number) {
	return previous + current
}

export function mean(): (mean: number, value: number) => number {
	let count = 0
	let total = 0
	let first = true
	return (mean: number, value: number) => {
		if (first) {
			total = mean
			first = false
		}
		count++
		total += value
		return total / count
	}
}

export function stdDeviation(list: List<number>): number {
	let count = 0
	const meanValue = list.reduce(mean())
	const deviation = list.reduce((dev, value) => {
		count++
		return dev + (value - meanValue) ** 2
	}, 0)
	return Math.sqrt(deviation / (count - 1))
}

export function min(min: number, value: number): number {
	return value < min ? value : min
}

export function max(max: number, value: number): number {
	return value > max ? value : max
}

export function makeBins(count: number, array: number[]): number[] {
	const bins: number[] = new Array(count + 1).fill(0)
	const minValue = array.reduce(min)
	const maxValue = array.reduce(max)
	const size = (maxValue - minValue) / count

	array.forEach((value) => {
		for (const step of range(0, count + 1)) {
			if (
				value >= minValue + step * size && value < minValue + (step + 1) * size
			) {
				bins[step]++
				break
			}
		}
	})

	return bins
}