module Ecoportal
  module API
    module Common
      module Content
        module DocHelpers

          # Helper used to build the `body` of an HTTP request
          # @param doc [Page, Hash] hashable object
          # @return [Hash, nil] the `patch` formated `data` ready to include as `body` of a HTTP request
          def get_body(doc, level: "page")
            {}.tap do |body|
              body["#{level}"] = case
                when doc.respond_to?(:as_update)
                  doc.as_update
                when doc.respond_to?(:as_json)
                  Common::Content::HashPatchDiff.patch_diff(doc.as_json)
                when doc.is_a?(Hash)
                  Common::Content::HashPatchDiff.patch_diff(doc)
                else
                  raise "Could not get body for doc: #{doc}"
                end
            end
          end

          # Helper used to **identify** the `id` of the target object
          # @param doc [Page, Hash] hashable object
          # @param exception [Boolean] states if `id` **must** be present
          # @return [Hash, nil] the `patch` formated `data` ready to include as `body` of a HTTP request
          def get_id(doc, exception: true)
            id = nil
            id ||= doc.id if doc.respond_to?(:id)
            id ||= doc["id"] if doc.is_a?(Hash)
            id ||= doc if doc.is_a?(String)
            raise "No ID has been given!" unless id || !exception
            id
          end

          # Helper used to **identify** the `id` s of objects contained in an `Array`
          # @param doc [Array] the source Array
          # @return [Array<String>] the `id` s thereof
          def array_ids(arr)
            return [] if !arr.is_a?(Array) || arr.empty?
            arr.map {|item| get_id(item, exception: false)}
          end

          # Helper used to **identify** in an Array the `position` of an object with certain `id`
          # @param doc [Array] the source Array
          # @return [Integer] the `position` thereof
          def array_id_index(arr, id)
            return unless arr.is_a?(Array)
            arr.index {|item| get_id(item, exception: false) == id}
          end

          # Helper used to **get** in an Array and `object` item with certain `id`
          # @param doc [Array] the source Array
          # @return [Integer] the `object` with that `id`
          def array_id_item(arr, id)
            if idx = array_id_index(arr, id)
              arr[idx]
            end
          end

        end
      end
    end
  end
end