Pseudocode, heavily influenced by Golang

reranking-pseudo.go

func RankReposition(newPosition int, siblings List) {
	// No siblings, we take the middle spot
	if len(siblings) == 0 {
		return midWay // 2^63?
	}

	// Want to be the first one? Take the lowest rank and stand before it
	if newPosition == 0 {
		result = siblings.first.rank - windowSize
		if result < 0 {
			return -1 // we need respreading
		}
		return result
	}

	// To be the last one, take the last rank, and stand after it.
	if newPosition >= len(siblings) {
		result = siblings.last.rank + windowSize
		if result > maxSize {
			return -1 // we need respreading
		}
		return result
	}

	// To be at position i, stay in the middle of i-1 and i.
	availableWindowSize = siblings[newPosition].rank - siblings[newPosition-1].rank
	if availableWindowSize < 2 {
		return -1 // we need respreading
	}

	return siblings[newPosition].rank + (availableWindowSize / 2)
}