From f3fde8605b695216ad5442ac6a008d2753ab52b1 Mon Sep 17 00:00:00 2001
From: Benjamin Fleischer <github@benjaminfleischer.com>
Date: Thu, 29 Jun 2017 00:25:17 -0500
Subject: [PATCH] WIP: Document Serializer... assumes more Rails

---
 lib/ams/document_serializer.rb | 142 +++++++++++++++++++++++++++++++++
 lib/ams/serializer.rb          |   1 +
 2 files changed, 143 insertions(+)
 create mode 100644 lib/ams/document_serializer.rb

diff --git a/lib/ams/document_serializer.rb b/lib/ams/document_serializer.rb
new file mode 100644
index 00000000..18fc1c33
--- /dev/null
+++ b/lib/ams/document_serializer.rb
@@ -0,0 +1,142 @@
+# frozen_string_literal: true
+
+module AMS
+  class DocumentSerializer
+    # @abstract
+    attr_reader :resource, :resource_serializer, :resource_params, :link_builder
+
+    # @param resource [ActiveRecord::Base] The object to serialize
+    # @param resource_serializer [AMS::Serializer] Serializer for the object
+    #   Often is "#{controller_name.singularize.classify}Serializer"
+    # @param resource_params [ActionController::Parameters] permitted parameters
+    # @param link_builder [#url_for] builds a link from controller(resource_type), action, id, and params
+    def initialize(resource, resource_serializer, resource_params, link_builder)
+      @resource = resource
+      @resource_serializer = resource_serializer
+      @resource_params = resource_params
+      @link_builder = link_builder
+    end
+
+    def resource_type
+      serializer.type
+    end
+
+    def to_json
+      JSON.dump(as_json) # calling to_json converts & in links to \u0026, which we don't want or need
+    end
+
+    def self.permit_params(params, resource_serializer)
+      permitted_params = permitted_action_params(resource_serializer)
+      resource_params = params.permit(*permitted_params)
+      filter = resource_params[:filter] && resource_params[:filter].any? ? resource_params[:filter].symbolize_keys : nil
+      resource_params[:filter] = filter
+      resource_params.permit(*permitted_params)
+    end
+  end
+
+  class ShowDocumentSerializer < DocumentSerializer
+    def self.permitted_action_params(resource_serializer)
+      [:id, *resource_serializer.show_params]
+    end
+
+    def as_json
+      {
+        "data": data,
+        "links": top_level_self_link
+      }
+    end
+
+    def data
+      serializer.as_json
+    end
+
+    def serializer
+      @_serializer ||= resource_serializer.new(resource, link_builder: link_builder)
+    end
+
+    def top_level_self_link
+      resource_id = serializer.id
+      {
+        "self": link_builder.url_for(controller: resource_type, action: :show, id: resource_id)
+      }
+    end
+  end
+
+  class IndexDocumentSerializer < DocumentSerializer
+    alias paginated_resource resource
+
+    def self.permitted_action_params(resource_serializer)
+      resource_serializer.index_params
+    end
+
+    def as_json
+      {
+        "data": data,
+        "meta": top_level_meta,
+        "links": top_level_links
+      }
+    end
+
+    def data
+      resource.map do |record|
+        serializer(record).as_json
+      end
+    end
+
+    def serializer(record = nil)
+      @_serializer ||= resource_serializer.new(record || resource.first, link_builder: link_builder)
+      @_serializer.object = record if record
+      @_serializer
+    end
+
+    def top_level_meta
+      {
+        "total_pages": paginated_resource.total_pages,
+        "current_page": paginated_resource.current_page
+      }
+    end
+
+    def top_level_links
+      pagination_links
+    end
+
+    def pagination_links
+      {
+        "self": location_url,
+        "first": first_page_url,
+        "prev": prev_page_url,
+        "next": next_page_url,
+        "last": last_page_url
+      }
+    end
+
+    def location_url
+      url_for_page
+    end
+
+    def first_page_url
+      url_for_page(1)
+    end
+
+    def prev_page_url
+      return nil if paginated_resource.first_page?
+      url_for_page(paginated_resource.prev_page)
+    end
+
+    def next_page_url
+      return nil if paginated_resource.last_page? || paginated_resource.out_of_range?
+      url_for_page(paginated_resource.next_page)
+    end
+
+    def last_page_url
+      url_for_page(paginated_resource.total_pages)
+    end
+
+    def url_for_page(number = nil)
+      params = resource_params.dup
+      params[:page] = paginated_resource.page_params
+      params[:page][:number] = number if number
+      link_builder.url_for(controller: resource_type, action: :index, params: params)
+    end
+  end
+end
diff --git a/lib/ams/serializer.rb b/lib/ams/serializer.rb
index 46d645ea..f5813d05 100644
--- a/lib/ams/serializer.rb
+++ b/lib/ams/serializer.rb
@@ -249,6 +249,7 @@ module AMS
     self._query_params = []
 
     attr_reader :object, :link_builder
+    attr_writer :object # useful for re-using the serializer when serializing a collection
 
     # @param object [Object] the model whose data is used in serialization
     def initialize(object, link_builder: :no_links)