From 2cab96b9afd468fa12ef459362ed5e94df026524 Mon Sep 17 00:00:00 2001
From: Karina Kwiatek <kjk@kjk.dog>
Date: Mon, 3 Jan 2022 22:43:37 +0100
Subject: [PATCH] Implement cursored pagination in Moderation Panel

---
 app/controllers/moderation_controller.rb | 25 +++++++++++++++++++-----
 app/models/report.rb                     | 15 ++++++++++++++
 app/views/moderation/index.haml          |  8 ++++++++
 3 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/app/controllers/moderation_controller.rb b/app/controllers/moderation_controller.rb
index 792fee95..f2ba17a0 100644
--- a/app/controllers/moderation_controller.rb
+++ b/app/controllers/moderation_controller.rb
@@ -3,11 +3,14 @@ class ModerationController < ApplicationController
 
   def index
     @type = params[:type]
-    @reports = if @type == 'all'
-                 Report.where(deleted: false).reverse_order
-               else
-                 Report.where(deleted: false).where('LOWER(type) = ?', "reports::#{@type}").reverse_order
-               end
+    @reports = list_reports(type: @type, last_id: params[:last_id])
+    @reports_last_id = @reports.map(&:id).min
+    @more_data_available = !list_reports(type: @type, last_id: @reports_last_id, size: 1).count.zero?
+
+    respond_to do |format|
+      format.html
+      format.js { render layout: false }
+    end
   end
 
   def priority
@@ -62,4 +65,16 @@ class ModerationController < ApplicationController
 
     render template: 'moderation/priority'
   end
+
+  private
+
+  def list_reports(type:, last_id:, size: nil)
+    cursor_params = { last_id: last_id, size: size }.compact
+
+    if type == 'all'
+      Report.cursored_reports(**cursor_params)
+    else
+      Report.cursored_reports_of_type(type, **cursor_params)
+    end
+  end
 end
diff --git a/app/models/report.rb b/app/models/report.rb
index 9ed86152..b801d322 100644
--- a/app/models/report.rb
+++ b/app/models/report.rb
@@ -13,4 +13,19 @@ class Report < ApplicationRecord
   def votes
     moderation_votes.where(upvote: true).count - moderation_votes.where(upvote: false).count
   end
+
+  class << self
+    include CursorPaginatable
+
+    define_cursor_paginator :cursored_reports, :list_reports
+    define_cursor_paginator :cursored_reports_of_type, :list_reports_of_type
+
+    def list_reports(options = {})
+      self.where(options.merge!(deleted: false)).reverse_order
+    end
+
+    def list_reports_of_type(type, options = {})
+      self.where(options.merge!(deleted: false)).where('LOWER(type) = ?', "reports::#{type}").reverse_order
+    end
+  end
 end
diff --git a/app/views/moderation/index.haml b/app/views/moderation/index.haml
index 0e7b0a7a..a3d90ac1 100644
--- a/app/views/moderation/index.haml
+++ b/app/views/moderation/index.haml
@@ -1,2 +1,10 @@
 - @reports.each do |r|
   = render 'moderation/moderationbox', report: r
+
+- unless @reports.count.zero?
+  = render 'shared/cursored_pagination_dummy', more_data_available: @more_data_available, last_id: @reports_last_id, permitted_params: %i[type]
+
+  - if @more_data_available
+    .d-flex.justify-content-center.justify-content-sm-start
+      %button.btn.btn-light#load-more-btn{ type: :button, data: { last_id: @reports_last_id } }
+        = t 'views.actions.load'