default has_no_front_page to true for new wikis

also fixup old ones

test plan:
* export a course with a wiki page set as the front page
* create a new course
* import the exported package
* should be set as the front page

closes #CNVS-14601

Change-Id: Icb660f2c84ab9a9c208d0fc092cf348d69edcab7
Reviewed-on: https://gerrit.instructure.com/52245
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
Product-Review: Jeremy Stanley <jeremy@instructure.com>
Tested-by: Jenkins
QA-Review: Jahnavi Yetukuri <jyetukuri@instructure.com>

app/controllers/application_controller.rb

@@ -1144,7 +1144,6 @@ class ApplicationController < ActionController::Base
   # the page title.
   def get_wiki_page
     @wiki = @context.wiki
-    @wiki.check_has_front_page
 
     @page_name = params[:wiki_page_id] || params[:id] || (params[:wiki_page] && params[:wiki_page][:title])
     if(params[:format] && !['json', 'html'].include?(params[:format]))

app/controllers/courses_controller.rb

@@ -1492,7 +1492,6 @@ class CoursesController < ApplicationController
 
       # make sure the wiki front page exists
       if @course_home_view == 'wiki'
-        @context.wiki.check_has_front_page
         @course_home_view = 'feed' if @context.wiki.front_page.nil?
       end
 

app/controllers/wiki_pages_api_controller.rb

@@ -485,7 +485,6 @@ class WikiPagesApiController < ApplicationController
   
   def get_wiki_page
     @wiki = @context.wiki
-    @wiki.check_has_front_page
 
     # attempt to find an existing page
     url = params[:url]

app/models/importers/course_content_importer.rb

@@ -137,7 +137,6 @@ module Importers
       end
 
       # be very explicit about draft state courses, but be liberal toward legacy courses
-      course.wiki.check_has_front_page
       if course.wiki.has_no_front_page
         if migration.for_course_copy? && (source = migration.source_course || Course.where(id: migration.migration_settings[:source_course_id]).first)
           mig_id = CC::CCHelper.create_key(source.wiki.front_page)

app/models/wiki.rb

@@ -42,7 +42,7 @@ class Wiki < ActiveRecord::Base
   DEFAULT_FRONT_PAGE_URL = 'front-page'
 
   def set_has_no_front_page_default
-    if self.has_no_front_page.nil? && self.id && context
+    if self.has_no_front_page.nil?
       self.has_no_front_page = true
     end
   end
@@ -72,15 +72,6 @@ class Wiki < ActiveRecord::Base
     end
   end
 
-  def check_has_front_page
-    return unless self.has_no_front_page.nil?
-
-    url = DEFAULT_FRONT_PAGE_URL
-    self.has_no_front_page = !self.wiki_pages.not_deleted.where(:url => url).exists?
-    self.front_page_url = url unless self.has_no_front_page
-    self.save
-  end
-
   def front_page
     url = self.get_front_page_url
     return nil if url.nil?
@@ -129,7 +120,7 @@ class Wiki < ActiveRecord::Base
 
   def context
     shard.activate do
-      @context ||= Course.where(wiki_id: self).first || Group.where(wiki_id: self).first
+      @context ||= self.id && (Course.where(wiki_id: self).first || Group.where(wiki_id: self).first)
     end
   end
 

db/migrate/20150415152143_set_wiki_has_no_front_page.rb

@@ -0,0 +1,11 @@
+class SetWikiHasNoFrontPage < ActiveRecord::Migration
+  tag :postdeploy
+
+  def up
+    DataFixup::SetWikiHasNoFrontPage.send_later_if_production_enqueue_args(:run,
+      :priority => Delayed::LOWER_PRIORITY)
+  end
+
+  def down
+  end
+end

lib/data_fixup/set_wiki_has_no_front_page.rb

@@ -0,0 +1,9 @@
+module DataFixup::SetWikiHasNoFrontPage
+  def self.run
+    while Wiki.where(:has_no_front_page => nil, :front_page_url => nil).
+      where("NOT EXISTS (SELECT 1 FROM wiki_pages WHERE id=wiki_pages.wiki_id AND wiki_pages.url = ?)",
+            Wiki::DEFAULT_FRONT_PAGE_URL).
+      limit(1000).update_all(:has_no_front_page => true) > 0
+    end
+  end
+end

spec/models/content_migration/course_copy_wiki_spec.rb

@@ -50,14 +50,23 @@ describe ContentMigration do
 
     context "wiki front page" do
       it "should copy wiki front page setting if there is no front page" do
-        page = @copy_from.wiki.wiki_pages.create!(:title => "stuff and stuff")
-        @copy_from.wiki.set_front_page_url!(page.url)
+        fake_front_page = @copy_from.wiki.wiki_pages.create!(:title => "Front Page")
+        real_front_page = @copy_from.wiki.wiki_pages.create!(:title => "actual front page")
+        @copy_from.wiki.set_front_page_url!(real_front_page.url)
 
-        @copy_to.wiki.unset_front_page!
         run_course_copy
 
-        new_page = @copy_to.wiki.wiki_pages.where(migration_id: mig_id(page)).first
-        expect(@copy_to.wiki.front_page).to eq new_page
+        new_front_page = @copy_to.wiki.wiki_pages.where(migration_id: mig_id(real_front_page)).first
+        expect(@copy_to.wiki.front_page).to eq new_front_page
+      end
+
+      it "should not set 'Front Page' as the front page" do
+        fake_front_page = @copy_from.wiki.wiki_pages.create!(:title => "Front Page")
+
+        run_course_copy
+
+        @copy_to.reload
+        expect(@copy_to.wiki.front_page).to be_nil
       end
 
       it "should not overwrite current front page" do