require 'set'

module Middleman
  module Sitemap
    module Extensions
      class OnDisk
        attr_accessor :sitemap
        attr_accessor :waiting_for_ready

        def initialize(app, sitemap)
          @sitemap = sitemap
          @app     = app
          @file_paths_on_disk = Set.new

          scoped_self = self
          @waiting_for_ready = true

          @app.before_configuration do
            # Register file change callback
            extensions[:file_watcher].api.changed do |file|
              scoped_self.touch_file(file)
            end

            # Register file delete callback
            extensions[:file_watcher].api.deleted do |file|
              scoped_self.remove_file(file)
            end
          end

          @app.ready do
            scoped_self.waiting_for_ready = false
            # Make sure the sitemap is ready for the first request
            sitemap.ensure_resource_list_updated!
          end
        end

        # Update or add an on-disk file path
        # @param [String] file
        # @return [Boolean]
        def touch_file(file)
          return false if File.directory?(file)

          path = @sitemap.file_to_path(file)
          return false unless path

          ignored = @app.config[:ignored_sitemap_matchers].any? do |_, callback|
            if callback.arity == 1
              callback.call(file)
            else
              callback.call(file, @app)
            end
          end

          @file_paths_on_disk << file unless ignored

          # Rebuild the sitemap any time a file is touched
          # in case one of the other manipulators
          # (like asset_hash) cares about the contents of this file,
          # whether or not it belongs in the sitemap (like a partial)
          @sitemap.rebuild_resource_list!(:touched_file)

          # Force sitemap rebuild so the next request is ready to go.
          # Skip this during build because the builder will control sitemap refresh.
          @sitemap.ensure_resource_list_updated! unless waiting_for_ready || @app.build?
        end

        # Remove a file from the store
        # @param [String] file
        # @return [void]
        def remove_file(file)
          return unless @file_paths_on_disk.delete?(file)

          @sitemap.rebuild_resource_list!(:removed_file)

          # Force sitemap rebuild so the next request is ready to go.
          # Skip this during build because the builder will control sitemap refresh.
          @sitemap.ensure_resource_list_updated! unless waiting_for_ready || @app.build?
        end

        # Update the main sitemap resource list
        # @return [void]
        def manipulate_resource_list(resources)
          resources + @file_paths_on_disk.map do |file|
            ::Middleman::Sitemap::Resource.new(
              @sitemap,
              @sitemap.file_to_path(file),
              File.join(@app.root, file)
            )
          end
        end
      end
    end
  end
end