class Lookbook::EntityTree

def children
  @children ||= nodes.select { _1.depth == 1 }.sort
end

def children_of(parent)
  nodes.select do |node|
    node.depth == parent.depth + 1 &&
      node.lookup_path.start_with?("#{parent.lookup_path}/")
  end
end

def collect_ordered_entities(start_node)
  start_node.children.flat_map do |node|
    child_nodes = collect_ordered_entities(node)
    [node, child_nodes]
  end
end

def initialize(leaf_nodes = [])
  @leaf_nodes = leaf_nodes
  @lookup_path = ""
end

def navigable_nodes
  ordered_nodes.select(&:navigable?)
end

def next(node)
  nodes = navigable_nodes.filter(&:visible?)
  index = nodes.index(node)
  nodes[index + 1] unless node == nodes.last
end

def nodes
  @nodes ||= begin
    node_entities = [@leaf_nodes, *@leaf_nodes.map(&:ancestors)].flatten.uniq
    node_entities.sort_by { _1.lookup_path }
  end
end

def ordered_nodes
  @ordered_nodes ||= collect_ordered_entities(self).flatten
end

def previous(node)
  nodes = navigable_nodes.filter(&:visible?)
  index = nodes.index(node)
  nodes[index - 1] unless node == nodes.first
end

def root? = true

def to_data
  children.map(&:to_h)
end