module JSON::LD
  module Flatten
    include Utils

    ##
    # This algorithm creates a JSON object node map holding an indexed representation of the graphs and nodes represented in the passed expanded document. All nodes that are not uniquely identified by an IRI get assigned a (new) blank node identifier. The resulting node map will have a member for every graph in the document whose value is another object with a member for every node represented in the document. The default graph is stored under the @default member, all other graphs are stored under their graph name.
    #
    # @param [Array, Hash] input
    #   Expanded JSON-LD input
    # @param [Hash] graphs A map of graph name to subjects
    # @param [String] graph
    #   The name of the currently active graph that the processor should use when processing.
    # @param [String] name
    #   The name assigned to the current input if it is a bnode
    # @param [Array] list
    #   List to append to, nil for none
    def create_node_map(input,
                        graphs,
                        graph = '@default',
                        name  = nil,
                        list  = nil)
      log_depth do
        log_debug("node_map") {"graph: #{graph}, input: #{input.inspect}, name: #{name}"}
        case input
        when Array
          # If input is an array, process each entry in input recursively by passing item for input, node map, active graph, active subject, active property, and list.
          input.map {|o| create_node_map(o, graphs, graph, nil, list)}
        when Hash
          type = input['@type']
          if value?(input)
            # Rename blanknode @type
            input['@type'] = namer.get_name(type) if type && blank_node?(type)
            list << input if list
          else
            # Input is a node definition

            # spec requires @type to be named first, so assign names early
            Array(type).each {|t| namer.get_name(t) if blank_node?(t)}

            # get name for subject
            if name.nil?
              name ||= input['@id']
              name = namer.get_name(name) if blank_node?(name)
            end

            # add subject reference to list
            list << {'@id' => name} if list

            # create new subject or merge into existing one
            subject = (graphs[graph] ||= {})[name] ||= {'@id' => name}

            input.keys.kw_sort.each do |property|
              objects = input[property]
              case property
              when '@id'
                # Skip
              when '@reverse'
                # handle reverse properties
                referenced_node, reverse_map = {'@id' => name}, objects
                reverse_map.each do |reverse_property, items|
                  items.each do |item|
                    item_name = item['@id']
                    item_name = namer.get_name(item_name) if blank_node?(item_name)
                    create_node_map(item, graphs, graph, item_name)
                    add_value(graphs[graph][item_name],
                              reverse_property,
                              referenced_node,
                              property_is_array: true,
                              allow_duplicate: false)
                  end
                end
              when '@graph'
                graphs[name] ||= {}
                g = graph == '@merged' ? graph : name
                create_node_map(objects, graphs, g)
              when /^@(?!type)/
                # copy non-@type keywords
                if property == '@index' && subject['@index']
                  raise JsonLdError::ConflictingIndexes,
                        "Element already has index #{subject['@index']} dfferent from #{input['@index']}" if
                        subject['@index'] != input['@index']
                  subject['@index'] = input.delete('@index')
                end
                subject[property] = objects
              else
                # if property is a bnode, assign it a new id
                property = namer.get_name(property) if blank_node?(property)

                add_value(subject, property, [], property_is_array: true) if objects.empty?

                objects.each do |o|
                  o = namer.get_name(o) if property == '@type' && blank_node?(o)

                  case
                  when node?(o) || node_reference?(o)
                    id = o['@id']
                    id = namer.get_name(id) if blank_node?(id)

                    # add reference and recurse
                    add_value(subject, property, {'@id' => id}, property_is_array: true, allow_duplicate: false)
                    create_node_map(o, graphs, graph, id)
                  when list?(o)
                    olist = []
                    create_node_map(o['@list'], graphs, graph, name, olist)
                    o = {'@list' => olist}
                    add_value(subject, property, o, property_is_array: true, allow_duplicate: true)
                  else
                    # handle @value
                    create_node_map(o, graphs, graph, name)
                    add_value(subject, property, o, property_is_array: true, allow_duplicate: false)
                  end
                end
              end
            end
          end
        else
          # add non-object to list
          list << input if list
        end
      end
    end
  end
end