Add comment threads REST API

Previewers can fetch comment threads with comments for an
entry's draft revision. This provides the data for rendering
comment badges on content elements in the entry preview.

REDMINE-21261

Author: tf

app/controllers/pageflow/review/comment_threads_controller.rb

@@ -0,0 +1,16 @@
+module Pageflow
+  module Review
+    # @api private
+    class CommentThreadsController < Pageflow::ApplicationController
+      respond_to :json
+      before_action :authenticate_user!
+
+      def index
+        entry = DraftEntry.find(params[:entry_id])
+        authorize!(:read, entry.to_model)
+
+        @comment_threads = entry.comment_threads.includes(:comments)
+      end
+    end
+  end
+end

app/models/pageflow/comment.rb

@@ -0,0 +1,15 @@
+module Pageflow
+  # @api private
+  class Comment < ApplicationRecord
+    include NestedRevisionComponent
+
+    belongs_to :comment_thread
+    belongs_to :creator, class_name: 'User'
+
+    validates :body, presence: true
+
+    def entry_for_auto_generated_perma_id
+      comment_thread.revision.entry
+    end
+  end
+end

app/models/pageflow/comment_thread.rb

@@ -0,0 +1,13 @@
+module Pageflow
+  # @api private
+  class CommentThread < ApplicationRecord
+    include RevisionComponent
+
+    belongs_to :creator, class_name: 'User'
+    has_many :comments, dependent: :destroy
+
+    nested_revision_components :comments
+
+    validates :subject_type, :subject_id, presence: true
+  end
+end

app/models/pageflow/entry_at_revision.rb

@@ -38,6 +38,7 @@ def initialize(entry, revision, theme: nil)
              :author, :publisher, :keywords,
              :published_at,
              :noindex?,
+             :comment_threads,
              :configuration,
              :structured_data_type_name,
              to: :revision)

app/models/pageflow/revision.rb

@@ -27,6 +27,8 @@ class Revision < ApplicationRecord # rubocop:todo Style/Documentation
     has_many :chapters, -> { order(CHAPTER_ORDER) }, through: :storylines
     has_many :pages, -> { reorder(PAGE_ORDER) }, through: :storylines
 
+    has_many :comment_threads, dependent: :destroy
+
     has_many :file_usages, dependent: :destroy
 
     has_many :image_files, -> { extending WithFileUsageExtension },

app/views/pageflow/review/comment_threads/_comment_thread.json.jbuilder

@@ -0,0 +1,15 @@
+json.key_format!(camelize: :lower)
+
+json.call(comment_thread,
+          :id,
+          :perma_id,
+          :subject_type,
+          :subject_id,
+          :creator_id,
+          :resolved_at,
+          :created_at,
+          :updated_at)
+
+json.comments(comment_thread.comments) do |comment|
+  json.partial!('pageflow/review/comments/comment', comment:)
+end

app/views/pageflow/review/comment_threads/index.json.jbuilder

@@ -0,0 +1,10 @@
+json.key_format!(camelize: :lower)
+
+json.current_user do
+  json.id current_user.id
+  json.name current_user.full_name
+end
+
+json.comment_threads(@comment_threads) do |comment_thread|
+  json.partial!('pageflow/review/comment_threads/comment_thread', comment_thread:)
+end

app/views/pageflow/review/comments/_comment.json.jbuilder

@@ -0,0 +1,11 @@
+json.key_format!(camelize: :lower)
+
+json.call(comment,
+          :id,
+          :perma_id,
+          :creator_id,
+          :body,
+          :created_at,
+          :updated_at)
+
+json.creator_name comment.creator.full_name

config/routes.rb

@@ -77,6 +77,12 @@
       resource :oembed, only: [:show]
     end
 
+    namespace :review do
+      resources :entries, only: [] do
+        resources :comment_threads, only: [:index]
+      end
+    end
+
     root to: redirect('/admin')
   end
 

db/migrate/20260323000000_create_comment_threads_and_comments.rb

@@ -0,0 +1,30 @@
+class CreateCommentThreadsAndComments < ActiveRecord::Migration[6.0]
+  def change
+    create_table :pageflow_comment_threads do |t|
+      t.integer :revision_id, null: false
+      t.integer :perma_id
+      t.string :subject_type, null: false
+      t.integer :subject_id, null: false
+      t.integer :creator_id, null: false
+      t.datetime :resolved_at
+      t.integer :resolved_by_id
+      t.timestamps
+    end
+
+    add_index :pageflow_comment_threads, :revision_id
+    add_index :pageflow_comment_threads, :creator_id
+    add_index :pageflow_comment_threads, [:revision_id, :subject_type, :subject_id],
+              name: 'index_comment_threads_on_revision_and_subject'
+
+    create_table :pageflow_comments do |t|
+      t.integer :comment_thread_id, null: false
+      t.integer :perma_id
+      t.integer :creator_id, null: false
+      t.text :body, null: false
+      t.timestamps
+    end
+
+    add_index :pageflow_comments, :comment_thread_id
+    add_index :pageflow_comments, :creator_id
+  end
+end