require "ox"
require_relative "xml_document"
require_relative "builder/ox"

module Lutaml
  module Model
    module XmlAdapter
      class OxAdapter < XmlDocument
        def self.parse(xml)
          parsed = Ox.parse(xml)
          root = OxElement.new(parsed)
          new(root)
        end

        def to_xml(options = {})
          builder = Builder::Ox.build
          builder_options = { version: options[:version] }

          if options.key?(:encoding)
            builder_options[:encoding] = options[:encoding] unless options[:encoding].nil?
          else
            builder_options[:encoding] = "UTF-8"
          end

          builder.xml.instruct(:xml, builder_options)
          if @root.is_a?(Lutaml::Model::XmlAdapter::OxElement)
            @root.build_xml(builder)
          elsif ordered?(@root, options)
            build_ordered_element(builder, @root, options)
          else
            mapper_class = options[:mapper_class] || @root.class
            options[:xml_attributes] = build_namespace_attributes(mapper_class)
            build_element(builder, @root, options)
          end

          xml_data = builder.xml.to_s
          options[:declaration] ? xml_data : xml_data.sub(/\A<\?xml[^>]*\?>\n?/, "")
        end

        private

        def build_ordered_element(builder, element, options = {})
          mapper_class = options[:mapper_class] || element.class
          xml_mapping = mapper_class.mappings_for(:xml)
          return xml unless xml_mapping

          attributes = build_attributes(element, xml_mapping).compact

          tag_name = options[:tag_name] || xml_mapping.root_element
          builder.create_and_add_element(tag_name,
                                         attributes: attributes) do |el|
            index_hash = {}
            content = []

            element.element_order.each do |name|
              index_hash[name] ||= -1
              curr_index = index_hash[name] += 1

              element_rule = xml_mapping.find_by_name(name)
              next if element_rule.nil?

              attribute_def = attribute_definition_for(element, element_rule,
                                                       mapper_class: mapper_class)
              value = attribute_value_for(element, element_rule)

              next if element_rule == xml_mapping.content_mapping && element_rule.cdata && name == "text"

              if element_rule == xml_mapping.content_mapping
                text = element.send(xml_mapping.content_mapping.to)
                text = text[curr_index] if text.is_a?(Array)

                next el.add_text(el, text, cdata: element_rule.cdata) if element.mixed?

                content << text
              elsif !value.nil? || element_rule.render_nil?
                value = value[curr_index] if attribute_def.collection?

                add_to_xml(
                  el,
                  element,
                  nil,
                  value,
                  options.merge(
                    attribute: attribute_def,
                    rule: element_rule,
                  ),
                )
              end
            end

            el.add_text(el, content.join)
          end
        end
      end

      class OxElement < XmlElement
        def initialize(node, root_node: nil)
          case node
          when String
            super("text", {}, [], node, parent_document: root_node)
          when Ox::Comment
            super("comment", {}, [], node.value, parent_document: root_node)
          when Ox::CData
            super("#cdata-section", {}, [], node.value, parent_document: root_node)
          else
            namespace_attributes(node.attributes).each do |(name, value)|
              if root_node
                root_node.add_namespace(XmlNamespace.new(value, name))
              else
                add_namespace(XmlNamespace.new(value, name))
              end
            end

            attributes = node.attributes.each_with_object({}) do |(name, value), hash|
              next if attribute_is_namespace?(name)

              namespace_prefix = name.to_s.split(":").first
              if (n = name.to_s.split(":")).length > 1
                namespace = (root_node || self).namespaces[namespace_prefix]&.uri
                namespace ||= XML_NAMESPACE_URI
                prefix = n.first
              end

              hash[name.to_s] = XmlAttribute.new(
                name.to_s,
                value,
                namespace: namespace,
                namespace_prefix: prefix,
              )
            end

            super(
              node,
              attributes,
              parse_children(node, root_node: root_node || self),
              node.text,
              parent_document: root_node,
            )
          end
        end

        def to_xml
          return text if text?

          build_xml.xml.to_s
        end

        def build_xml(builder = nil)
          builder ||= Builder::Ox.build
          attrs = build_attributes(self)

          if text?
            builder.add_text(builder, text)
          else
            builder.create_and_add_element(name, attributes: attrs) do |el|
              children.each { |child| child.build_xml(el) }
            end
          end

          builder
        end

        def namespace_attributes(attributes)
          attributes.select { |attr| attribute_is_namespace?(attr) }
        end

        def text?
          # false
          children.empty? && text&.length&.positive?
        end

        def build_attributes(node)
          attrs = node.attributes.transform_values(&:value)

          node.own_namespaces.each_value do |namespace|
            attrs[namespace.attr_name] = namespace.uri
          end

          attrs
        end

        def nodes
          children
        end

        private

        def parse_children(node, root_node: nil)
          node.nodes.map do |child|
            OxElement.new(child, root_node: root_node)
          end
        end
      end
    end
  end
end