package etl

import "bytes"

type HeapElem struct {
	key     []byte
	timeIdx int
	value   []byte
}

type Heap []HeapElem

func (h Heap) Len() int {
	return len(h)
}

func (h Heap) Less(i, j int) bool {
	if c := bytes.Compare(h[i].key, h[j].key); c != 0 {
		return c < 0
	}
	return h[i].timeIdx < h[j].timeIdx
}

func (h Heap) Swap(i, j int) {
	h[i], h[j] = h[j], h[i]
}

func (h *Heap) Push(x interface{}) {
	// Push and Pop use pointer receivers because they modify the slice's length,
	// not just its contents.
	*h = append(*h, x.(HeapElem))
}

func (h *Heap) Pop() interface{} {
	old := *h
	n := len(old)
	x := old[n-1]
	*h = old[0 : n-1]
	return x
}