# frozen_string_literal: true

module Cocina
  module Models
    module Mapping
      module FromMods
        # Maps titles
        class TitleBuilder
          # @param [Nokogiri::XML::Element] title_info_element titleInfo element
          # @param [Cocina::Models::Mapping::ErrorNotifier] notifier
          # @return [Hash] a hash that can be mapped to a cocina model
          def self.build(title_info_element:, notifier:)
            new(title_info_element: title_info_element, notifier: notifier).build
          end

          def initialize(title_info_element:, notifier:)
            @title_info_element = title_info_element
            @notifier = notifier
          end

          def build
            return { valueAt: title_info_element['xlink:href'] } if title_info_element['xlink:href']

            # Find all the child nodes that have text
            return nil if title_info_element.children.empty?

            children = title_info_element.xpath('./*[child::node()[self::text()]]')
            if children.empty?
              notifier.warn('Empty title node')
              return nil
            end

            notifier.warn('Title with type') if children_with_type?(children)

            # If a displayLabel only with no title text element
            # Note: this is an error condition,
            # exceptions documented at: https://github.com/sul-dlss-labs/cocina-descriptive-metadata/blob/master/mods_cocina_mappings/mods_to_cocina_value_dependencies.txt
            return {} if children.map(&:name) == []

            # Is this a basic title or a title with parts
            return simple_value(title_info_element) if simple_title?(children)

            structured_value(children)
          end

          private

          attr_reader :title_info_element, :notifier

          def children_with_type?(children)
            children.any? do |child|
              child.name == 'title' && child[:type].present?
            end
          end

          def simple_title?(children)
            children.size == 1 && children.first.name == 'title'
          end

          # @param [Nokogiri::XML::Element] node the titleInfo node
          def simple_value(node)
            value = node.xpath('./mods:title', mods: Description::DESC_METADATA_NS).text

            { value: clean_title(value, node.name) }
          end

          # @param [Nokogiri::XML::NodeSet] child_nodes the children of the titleInfo
          def structured_value(child_nodes)
            values = child_nodes.map do |node|
              { value: clean_title(node.text, node.name), type: Title::TYPES[node.name] }
            end
            {
              structuredValue: values,
              note: note(child_nodes)
            }.compact
          end

          def clean_title(title, tag)
            if %w[title titleInfo].include?(tag)
              title.delete_suffix(',')
            elsif tag == 'nonSort'
              title.sub(/ +$/, '')
            else
              title
            end
          end

          def note(child_nodes)
            unsortable = child_nodes.select { |node| node.name == 'nonSort' }
            return nil if unsortable.empty?

            count = unsortable.sum do |node|
              last_character = node.text.slice(-1, 1)
              add = ['-', "'", ' '].include?(last_character) ? 0 : 1
              node.text.size + add
            end
            [{
              value: count.to_s,  # cast to String until cocina-models 0.40.0 is used. See https://github.com/sul-dlss/cocina-models/pull/146
              type: 'nonsorting character count'
            }]
          end
        end
      end
    end
  end
end