package ru.dbotthepony.kstarbound.util

import java.util.Spliterator
import java.util.function.Consumer

class ArraySpliterator<T>(private val source: Array<T>, private val offset: Int = 0, private val size: Int = source.size) : Spliterator<T> {
	init {
		require(offset + size <= source.size) { "Invalid dimensions for spliterator: offset = $offset, size = $size, source has size of ${source.size}" }
	}

	private var index = 0

	override fun tryAdvance(action: Consumer<in T>): Boolean {
		if (index < size) {
			action.accept(source[offset + index++])
			return true
		}

		return false
	}

	override fun trySplit(): Spliterator<T>? {
		if (index + 1 >= size) {
			return null
		}

		val splitSize = size / 2

		if (splitSize == 0) {
			return null
		}

		val pointer = index + offset
		index += splitSize
		return ArraySpliterator(source, pointer, splitSize)
	}

	override fun estimateSize(): Long {
		return (size - index).toLong()
	}

	override fun characteristics(): Int {
		return Spliterator.ORDERED or Spliterator.SIZED
	}
}