require 'fiona7/builder/widget_builder'
require 'fiona7/builder/widget_updater'

require 'set'
require 'tsort'

module Fiona7
  module Builder
    class BatchWidgetWriter

      class WidgetGraph
        include TSort

        def initialize(nodes)
          @nodes = nodes
          @dependencies = {}

          @nodes.each do |node|
            @dependencies[node] = node.dependencies.map do |id|
              node = @nodes.find {|n| n.id.to_sym == id.to_sym }
            end.compact
          end
        end

        def tsort_each_node(&block)
          @nodes.each(&block)
        end

        def tsort_each_child(node, &block)
          if !@dependencies[node]
            raise Scrivito::ScrivitoError, "Broken widget dependency graph"
          end
          @dependencies[node].each(&block)
        end
      end

      class WidgetNode
        attr_reader :id, :values, :builder

        def initialize(id, values, builder)
          @id, @values, @builder = id, values, builder
        end

        def dependencies
          Set.new.tap do |dependencies|
            values.each do |_, value|
              if value.kind_of?(Hash) && (list = value[:list] || value["list"])
                dependencies.merge(list.map {|c| c[:widget] || c['widget']})
              end
            end
          end
        end

        def eql?(other)
          id.eql?(other.id)
        end

        def hash
          id.hash
        end
      end

      
      def initialize(obj, id_map, widget_pool, path_map)
        @obj, @id_map, @widget_pool, @path_map = obj, id_map, widget_pool, path_map
        @pool_changed = false
      end

      def write
        widget_nodes = @widget_pool.map do |widget_id, values|
          obj_id = @id_map[widget_id]

          if values.nil?
            # TODO: this widget can be GC-ed
            @pool_changed = true
            @path_map.delete(widget_id)
            next
          end

          if obj_id
            builder = WidgetUpdater.new(@obj, widget_id, values.merge(_id: obj_id), @path_map)
          else
            builder = WidgetBuilder.new(@obj, widget_id, values, @path_map)
            @pool_changed = true
          end

          WidgetNode.new(widget_id, values, builder)
        end.compact

        widget_graph = WidgetGraph.new(widget_nodes)

        widget_graph.tsort.each do |widget_node|
          widget_node.builder.build
          @path_map[widget_node.id] = widget_node.builder.path
        end
      end

      def pool_changed?
        !!@pool_changed
      end

      def path_map
        @path_map
      end
    end
  end
end