package graviton

//import "io"
//import "math"

import "golang.org/x/xerrors"

// we only have a keyhash and need to get both the key,value
func (t *Tree) GetKeyValue(keyhash [HASHSIZE]byte) (int, []byte, []byte, error) {
	return t.root.GetKeyValue(t.store, keyhash, 256, 0)
}

func (in *inner) GetKeyValue(store *Store, keyhash [HASHSIZE]byte, valid_bit_count, used_bit_count int) (int, []byte, []byte, error) {
	if err := in.load_partial(store); err != nil { // if inner node is loaded partially, load it fully now
		return used_bit_count, nil, nil, err
	}

	if used_bit_count > valid_bit_count || valid_bit_count <= 0 {
		return used_bit_count, nil, nil, xerrors.Errorf("%w: right dead end at %d. keyhash %x", ErrNotFound, in.bit, keyhash)
	}

	if isBitSet(keyhash[:], uint(in.bit)) {
		if in.right == nil {
			return used_bit_count, nil, nil, xerrors.Errorf("%w: right dead end at %d. keyhash %x", ErrNotFound, in.bit, keyhash)
		}
		switch in.right.(type) { // draw left  branch
		case *inner:
			return in.right.(*inner).GetKeyValue(store, keyhash, valid_bit_count, used_bit_count+1)
		case *leaf:
			return in.right.(*leaf).GetKeyValue(store, keyhash, valid_bit_count, used_bit_count+1)
		default:
			panic("unknown node type")
		}

	}
	if in.left == nil {
		return used_bit_count, nil, nil, xerrors.Errorf("%w: left dead end at %d. keyhash %x", ErrNotFound, in.bit, keyhash)
	}
	switch in.left.(type) { // draw left  branch
	case *inner:
		return in.left.(*inner).GetKeyValue(store, keyhash, valid_bit_count, used_bit_count+1)
	case *leaf:
		return in.left.(*leaf).GetKeyValue(store, keyhash, valid_bit_count, used_bit_count+1)
	default:
		panic("unknown node type")
	}
}

// should we return a copy
func (l *leaf) GetKeyValue(store *Store, keyhash [HASHSIZE]byte, valid_bit_count, used_bit_count int) (int, []byte, []byte, error) {
	if l.loaded_partial { // if leaf is loaded partially, load it fully now
		if err := l.loadfullleaffromstore(store); err != nil {
			return used_bit_count, nil, nil, err
		}
	}

	if l.keyhash == keyhash {
		return used_bit_count, l.key, l.value, nil
	}

	return used_bit_count, nil, nil, xerrors.Errorf("%w: collision, keyhash %x not found", ErrNotFound, keyhash)
}