Doesn't work yet, but are close

app/controllers/forumthreads_controller.rb

@@ -10,6 +10,7 @@ class ForumthreadsController < ApplicationController
     @threads = Forumthread.filter(current_user, params[:title].try(:slice, 0..255), params[:content].try(:slice, 0..255), params[:reply].try(:slice, 0..255), params[:label], User.find_by(ign: params[:author].to_s.strip) || params[:author], params[:query].try(:slice, 0..255), Forum.find_by(id: params[:forum]))
     .page(params[:page]).per(30)
   end
+
   def show
     if params[:reverse] == "true"
       @replies = @thread.replies.order(id: :desc).page(params[:page])

app/views/forums/edit.html.erb

@@ -25,6 +25,10 @@
       <td><%= f.label :necro_length, "Necropost warning delay (in days)" %></td>
       <td><%= f.number_field :necro_length, placeholder: "Warning Delay (leave blank for no warning)" %></td>
     </tr>
+    <tr>
+      <td><%= f.label :disable_deletion, "Disable deletion of threads for non-staff" %></td>
+      <td><%= f.check_box :disable_deletion %></td>
+    </tr>
   </table>
   <p><%= f.submit "Update Forum", class: "btn blue left" %></p>
 <% end %>

app/views/forums/new.html.erb

@@ -25,6 +25,10 @@
       <td><%= f.label :necro_length, "Necropost warning delay (in days)" %></td>
       <td><%= f.number_field :necro_length, placeholder: "Warning Delay (leave blank for no warning)" %></td>
     </tr>
+    <tr>
+      <td><%= f.label :disable_deletion %></td>
+      <td><%= f.check_box :disable_deletion %></td>
+    </tr>
   </table>
   <%= f.hidden_field :forumgroup_id %>
   <p><%= f.submit "Create Forum", class: "btn blue left" %></p>

app/views/forumthreads/edit.html.erb

@@ -11,6 +11,8 @@
   end
 %>
 
+<% forum = Forum.find(@thread.forum_id) %>
+
 <h1>Edit Thread</h1>
 <%= link_to @thread.forum.group, forumgroup_path(@thread.forum.group) %> → <%= link_to @thread.forum, @thread.forum %> → <%= link_to @thread, @thread %> → Edit thread
 <%= form_for @thread do |f|%>
@@ -37,5 +39,7 @@
   <%= render partial: "md_editor", locals: {name: "forumthread[content]", content: @thread.content} %>
   <p><%= f.submit "Update Thread", class: "btn blue left" %></p>
 <% end %>
-<%= button_to "Delete Thread", @thread, :method => "delete", data: {confirm: "Delete thread & comments forever?"}, class: "btn red right" %>
+<% if mod? || !forum.disable_deletion %>
+  <%= button_to "Delete Thread", @thread, :method => "delete", data: {confirm: "Delete thread & comments forever?"}, class: "btn red right" %>
+<% end %>
 <div class="clear"></div>

db/migrate/20190224093907_disable_deletion_forums.rb

@@ -0,0 +1,5 @@
+class DisableDeletionForums < ActiveRecord::Migration
+  def change
+    add_column :forums, :disable_deletion, :boolean
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20190222152638) do
+ActiveRecord::Schema.define(version: 20190224093907) do
 
   create_table "badges", force: :cascade do |t|
     t.string  "name",   limit: 191
@@ -46,12 +46,13 @@ ActiveRecord::Schema.define(version: 20190222152638) do
   end
 
   create_table "forums", force: :cascade do |t|
-    t.string  "name",          limit: 255
-    t.integer "position",      limit: 4
-    t.integer "role_read_id",  limit: 4
-    t.integer "role_write_id", limit: 4
-    t.integer "forumgroup_id", limit: 4
-    t.integer "necro_length",  limit: 4
+    t.string  "name",             limit: 255
+    t.integer "position",         limit: 4
+    t.integer "role_read_id",     limit: 4
+    t.integer "role_write_id",    limit: 4
+    t.integer "forumgroup_id",    limit: 4
+    t.integer "necro_length",     limit: 4
+    t.boolean "disable_deletion",                 default: false
   end
 
   create_table "forumthreads", force: :cascade do |t|
@@ -156,7 +157,6 @@ ActiveRecord::Schema.define(version: 20190222152638) do
   add_index "users", ["email"], name: "index_users_on_email", unique: true, using: :btree
   add_index "users", ["ign"], name: "index_users_on_ign", unique: true, using: :btree
   add_index "users", ["name"], name: "index_users_on_name", unique: true, using: :btree
-  add_index "users", ["discord"], name: "index_users_on_discord", unique: true, using: :btree
   add_index "users", ["twitter"], name: "index_users_on_twitter", unique: true, using: :btree
   add_index "users", ["uuid"], name: "index_users_on_uuid", unique: true, using: :btree
   add_index "users", ["youtube"], name: "index_users_on_youtube", unique: true, using: :btree

db/seeds.rb

@@ -32,7 +32,7 @@ deleted_user = User.create!(
   password_confirmation: userpw,
   role: Role.get(:disabled),
   badge: Badge.get(:none),
-  discord: "echo123",
+  discord: "echo123#9804",
   last_ip: "0.0.0.0",
   confirmed: true,
   last_seen: Time.utc(0).to_datetime,