module Scrivito

module AttributeContent
  extend ActiveSupport::Concern

  def respond_to?(method_id, include_private=false)
    if has_custom_attribute?(method_id)
      true
    else
      super
    end
  end

  def method_missing(method_name, *args)
    if has_custom_attribute?(method_name)
      read_attribute(method_name.to_s)
    else
      super
    end
  end

  def referenced_widgets
    data_from_cms.all_custom_attributes.
      select { |attr| type_of_attribute(attr) == "widget" }.
      map { |attr| read_attribute(attr) }.
      flatten
  end

  def contained_widgets
    referenced = referenced_widgets
    referenced + referenced.map { |w| w.contained_widgets }.flatten
  end

  def read_attribute(attribute_name)
    @attribute_cache.fetch(attribute_name) do
      (raw_value, attribute_type) = data_from_cms.value_and_type_of(attribute_name)
      @attribute_cache[attribute_name] =
        prepare_attribute_value(raw_value, attribute_type, attribute_name)
    end
  end

  def has_custom_attribute?(name)
    name = name.to_s
    name != 'blob' && data_from_cms.has_custom_attribute?(name)
  end
  alias_method :has_attribute?, :has_custom_attribute?

  # @return [String]
  def type_of_attribute(field_name)
    data_from_cms.type_of(field_name.to_s)
  end

  # Returns the value of an internal or external attribute specified by its name.
  # Passing an invalid key will not raise an error, but return +nil+.
  # @api public
  def [](key)
    key = key.to_s

    if key == '_obj_class'
      obj_class
    else
      has_attribute?(key) ? read_attribute(key) : nil
    end
  end

  # Hook method to control which widget classes should be available for this page.
  # Override it to allow only certain classes or none.
  # Must return either +NilClass+, or +Array+.
  #
  # If +nil+ is returned (default), then all widget classes will be available for this page.
  #
  # If +Array+ is returned, then it should include desired class names.
  # Each class name must be either a +String+ or a +Symbol+.
  # Only this class names will be available for this page.
  # Order of the class names will be preserved.
  #
  # @param [String] field_name Name of the widget field.
  # @return [nil, Array<Symbol, String>]
  # @api public
  def valid_widget_classes_for(field_name)
  end

  def modification_for_attribute(attribute_name, revision=Workspace.current.base_revision)
    return Modification::UNMODIFIED unless revision

    if new?(revision)
      Modification::NEW
    elsif deleted?(revision)
      Modification::DELETED
    else
      cms_data_in_revision = cms_data_for_revision(revision)

      if cms_data_in_revision
        other_value = cms_data_in_revision.value_without_default_of(attribute_name.to_s)
        if data_from_cms.value_without_default_of(attribute_name.to_s) == other_value
          Modification::UNMODIFIED
        else
          Modification::EDITED
        end
      else # I am deleted in both revisions!
        Modification::UNMODIFIED
      end
    end
  end

  def update_data(data)
    self.data_from_cms = data
    @attribute_cache = {}
  end

  # Returns the obj class name of this object.
  # @api public
  # @return [String]
  def obj_class_name
    data_from_cms.value_of('_obj_class')
  end

  # Returns the obj class of this object.
  # @api public
  # @return [ObjClass]
  def obj_class
    if obj_class_data = CmsBackend.instance.find_obj_class_data_by_name(revision, obj_class_name)
      ObjClass.new(obj_class_data, revision.workspace)
    end
  end

  private

  attr_writer :data_from_cms

  def data_from_cms
    if @data_from_cms.respond_to?(:call)
      @data_from_cms = @data_from_cms.call
    else
      @data_from_cms
    end
  end

  def prepare_attribute_value(attribute_value, attribute_type, attribute_name)
    case attribute_type
    when "html"
      StringTagging.tag_as_html(attribute_value)
    when "date"
      DateAttribute.parse(attribute_value) if attribute_value
    when "linklist"
      build_links(attribute_value)
    when "link"
      build_link(attribute_value)
    when "reference"
      BasicObj.find([attribute_value]).first
    when "referencelist"
      BasicObj.find(attribute_value).compact
    when "widget"
      build_widgets(attribute_value, attribute_name)
    else
      attribute_value
    end
  end

  def build_links(link_definitions)
    if link_definitions.present?
      link_definitions = link_definitions.map(&:with_indifferent_access)

      object_ids = link_definitions.map { |link_data| link_data[:destination] }.compact.uniq
      objects = object_ids.empty? ? [] : BasicObj.find(object_ids)
      link_definitions.each_with_object([]) do |link_data, links|
        obj = objects.detect { |o| o && o.id == link_data[:destination] }
        link = Link.new(link_data.merge(obj: obj))
        links << link if link.resolved?
      end
    else
      []
    end
  end

  def build_link(attribute_value)
    return unless attribute_value

    if attribute_value['destination']
      build_internal_link(attribute_value)
    else
      build_external_link(attribute_value)
    end
  end

  def build_internal_link(attribute_value)
    properties = {
      obj: BasicObj.find(attribute_value['destination']),
      title: attribute_value['title'],
      query: attribute_value['query'],
      fragment: attribute_value['fragment'],
      target: attribute_value['target'],
    }

    Link.new(properties)
  rescue ResourceNotFound
  end

  def build_external_link(attribute_value)
    properties = {
      url: attribute_value['url'],
      title: attribute_value['title'],
      target: attribute_value['target'],
    }

    Link.new(properties)
  end

  def build_widgets(widget_data, attribute_name)
    widget_data.map do |widget_id|
      widget = widget_from_pool(widget_id)

      unless widget
        raise ScrivitoError, "Widget with ID #{widget_id} not found!"
      end

      widget.container = self
      widget.container_field_name = attribute_name

      widget
    end
  end

  module ClassMethods
    # Instantiate an Obj or Widget instance from obj_data.
    # If a subclass of Obj or Widget with the same name as the property +_obj_class+ exists,
    # the instantiated Obj or Widget will be an instance of that subclass.
    def instantiate(obj_data)
      obj_class = obj_data.value_of('_obj_class')

      instance = type_computer.compute_type(obj_class).allocate
      instance.update_data(obj_data)

      instance
    end

    def with_default_obj_class(attributes)
      return attributes if attributes[:_obj_class] || attributes["_obj_class"]
      return attributes if type_computer.special_class?(self)
      attributes.merge("_obj_class" => self.to_s)
    end

    def descendants
      type_computer = TypeComputer.new(self, nil)
      CmsRestApi.get("workspaces/#{Workspace.current.id}/obj_classes")['results']
          .map { |obj_class_spec| obj_class_spec['name'] }
          .sort
          .map { |obj_class_name| type_computer.compute_type(obj_class_name) }
          .compact
    end
  end
end

end