class Eco::Data::Locations::NodeLevel
  module Parsing
    include Eco::Data::Locations::NodeLevel::Cleaner
    include Eco::Data::Locations::Convert

    attr_writer :node_class

    def node_class
      @node_class ||= Eco::Data::Locations::NodeLevel
    end

    # It evaluates as an opposite to `NodePlain`
    # @note there are only two accepted input csv formats.
    #   The expected header of `NodePlain` is predictable,
    #   but the header of `NodeLevel` is not.
    # @param [CSV::Table]
    # @return [Boolean] whether or not it's worthy trying to parse with `NodeLevel`.
    def csv_matches_format?(csv)
      return false unless csv.is_a?(::CSV::Table)
      !Eco::Data::Locations::NodePlain.csv_matches_format?(csv)
    end

    # @note
    #   1. It ensures basic data integrity when builing the nodes in the first screening
    #   2. It then delegates the tidy up to a cleaner function (see `tidy_nodes`)
    # @param `csv` [CSV::Table]
    # @return [Array<NodeLevel>]
    def nodes_from_csv(csv)
      raise ArgumentError, "Expecting CSV::Table. Given: #{csv.class}" unless csv.is_a?(::CSV::Table)

      prev_level = nil
      prev_node  = nil
      prev_nodes = empty_level_tracker_hash(11)

      # Convert to Eco::CSV::Table for a fresh start
      csv = Eco::CSV.parse(csv.to_csv).nil_blank_cells.add_index_column(:row_num)

      nodes = csv.each_with_object([]) do |row, out|
        row_num, *values = row.fields
        node = node_class.new(row_num, *values)
        prev_node ||= node

        # If node is nested in prev_node or is a sibling thereof
        if prev_node.raw_level <= node.raw_level
          # Make sure parent is among upper level tags
          node.set_high_levels(prev_node)
        else
          if parent_node = prev_nodes[node.raw_level - 1]
            node.set_high_levels(parent_node)
          elsif node.raw_level == 1
            # It is expected not to have parent (as it's top level tag)
          else
            raise "Node '#{node.raw_tag}' (#{node.row_num} row) doesn't have parent"
          end
        end
        out << node
        prev_nodes[node.raw_level] = node
        prev_node = node
      end
      tidy_nodes(nodes)
    end
  end
end