class RESTFramework::BaseFilter
  def initialize(controller:)
    @controller = controller
  end

  def get_filtered_data(data)
    raise NotImplementedError
  end
end


# A simple filtering backend that supports filtering a recordset based on fields defined on the
# controller class.
class RESTFramework::ModelFilter < RESTFramework::BaseFilter
  # Filter params for keys allowed by the current action's filterset_fields/fields config.
  def _get_filter_params
    fields = @controller.send(:get_filterset_fields)
    return @controller.request.query_parameters.select { |p, _|
      fields.include?(p)
    }.to_h.symbolize_keys  # convert from HashWithIndifferentAccess to Hash w/keys
  end

  # Filter data according to the request query parameters.
  def get_filtered_data(data)
    filter_params = self._get_filter_params
    unless filter_params.blank?
      return data.where(**filter_params)
    end

    return data
  end
end


# A filter backend which handles ordering of the recordset.
class RESTFramework::ModelOrderingFilter < RESTFramework::BaseFilter
  # Convert ordering string to an ordering configuration.
  def _get_ordering
    return nil if @controller.class.ordering_query_param.blank?
    ordering_fields = @controller.send(:get_ordering_fields)
    order_string = @controller.params[@controller.class.ordering_query_param]

    unless order_string.blank?
      ordering = {}
      order_string.split(',').each do |field|
        if field[0] == '-'
          column = field[1..-1]
          direction = :desc
        else
          column = field
          direction = :asc
        end
        if column.in?(ordering_fields)
          ordering[column.to_sym] = direction
        end
      end
      return ordering
    end

    return nil
  end

  # Order data according to the request query parameters.
  def get_filtered_data(data)
    ordering = self._get_ordering
    reorder = !@controller.send(:ordering_no_reorder)

    if ordering && !ordering.empty?
      return data.send(reorder ? :reorder : :order, _get_ordering)
    end

    return data
  end
end


# Multi-field text searching on models.
class RESTFramework::ModelSearchFilter < RESTFramework::BaseFilter
  # Filter data according to the request query parameters.
  def get_filtered_data(data)
    fields = @controller.send(:get_search_fields)
    search = @controller.request.query_parameters[@controller.send(:search_query_param)]

    # Ensure we use array conditions to prevent SQL injection.
    unless search.blank?
      return data.where(fields.map { |f|
        "CAST(#{f} AS text) #{@controller.send(:search_ilike) ? "ILIKE" : "LIKE"} ?"
      }.join(' OR '), *(["%#{search}%"] * fields.length))
    end

    return data
  end
end