class Lookbook::PageCollection

def self.entity(file_path)
  File.basename(file_path).match?(%r{\[(.*?\w+)\]}) ? PageSectionEntity.new(file_path) : PageEntity.new(file_path)
end

def self.file_paths(directories)
  directories.flat_map do |dir|
    PathUtils.normalize_paths(Dir["#{dir}/**/*.html.*", "#{dir}/**/*.md.*"].sort)
  end
end

def load(page_paths, changes = nil)
  file_paths = PageCollection.file_paths(page_paths)
  reload_all(file_paths) # TODO: Fix incremental reloading
  # changes.present? ? reload_changed(file_paths, changes) : reload_all(file_paths)
end

def pages_from_paths(file_paths)
  entities = file_paths.map { |path| PageCollection.entity(path) }
  pages, sections = entities.partition { |page| page.type == :page }
  page_dict = pages.index_by(&:lookup_path)
  sections.each do |section|
    parent = page_dict[section.lookup_path]
    section.parent = parent
    parent.add_section(section)
  end
  pages
end

def reload_all(file_paths)
  clear_all
  add(pages_from_paths(file_paths))
end

def reload_changed(file_paths, changes)
  modified = Array(changes[:modified])
  removed = Array(changes[:removed]) + modified
  added = Array(changes[:added]) + modified
  remove_by_file_path(removed)
  add(pages_from_paths(added))
end

def remove_by_file_path(paths)
  paths = Array(paths).map(&:to_s)
  @entities.reject! { |page| page.file_path.to_s.in?(paths) }
  clear_cache
end