package defrag

// Defrag performs an in-place sort of blocks.
// If an error occurs during processing, it will be returned. The slice may have been partially sorted.
func Defrag(blocks []byte) error {
	lastPulled := len(blocks)
	lastPushed := -1
	for block := 0; block < len(blocks); block++ {
		if blocks[block] != '.' {
			continue
		}
		if lastPulled <= block {
			break
		}
		for swap := lastPulled - 1; swap > lastPushed; swap-- {
			if blocks[swap] == '.' {
				continue
			}
			blocks[block], blocks[swap] = blocks[swap], blocks[block]
			lastPulled = swap
			lastPushed = block
			break
		}
	}
	return nil
}