class Lookbook::EntityCollection

def add(to_add = nil)
  Array(to_add).each do |entity|
    unless find_by_path(entity.path)
      @entities.push(entity)
    end
  end
  clear_cache
end

def clear_cache
  @_cache = {}
end

def each(&block)
  if block
    entities.sort.each { |entity| yield entity }
  else
    to_enum(:each)
  end
end

def find_by_id(id)
  id = Utils.id(id)
  entities.find { |entity| entity.id == id }
end

def find_by_path(path)
  entities.find { |entity| entity.path.to_s == path.to_s }
end

def flat_map(...)
  entities.map(...).map(&:to_a).flatten
end

def initialize(entities = nil)
  @_cache = {}
  @entities = []
  add(entities)
end

def next(entity)
  index = entities.find_index { |i| i.path == entity.path }
  entities[index + 1] unless index.nil?
end

def previous(entity)
  index = entities.find_index { |i| i.path == entity.path }
  entities[index - 1] if !index.nil? && index > 0
end