package iskra

import "git.smesh.lol/iskradb/lattice"

// WalkPath returns the node path from root to key in the given branch.
// Delegates to iskradb's WalkPath which tracks intermediate nodes.
func (t *Tree) WalkPath(branch lattice.Branch, key lattice.Key) []uint32 {
	return t.db.WalkPath(branch, key)
}

// TreeDistance returns the hop count between two keys within a branch
// via their lowest common ancestor. Returns -1 if either key is not found.
func (t *Tree) TreeDistance(branch lattice.Branch, keyA, keyB lattice.Key) int {
	if keyA == keyB {
		return 0
	}

	pathA := t.WalkPath(branch, keyA)
	pathB := t.WalkPath(branch, keyB)
	if pathA == nil || pathB == nil {
		return -1
	}

	lcaDepth := 0
	minLen := len(pathA)
	if len(pathB) < minLen {
		minLen = len(pathB)
	}
	for i := 0; i < minLen; i++ {
		if pathA[i] != pathB[i] {
			break
		}
		lcaDepth = i
	}

	return (len(pathA) - 1 - lcaDepth) + (len(pathB) - 1 - lcaDepth)
}