favgroups: add stricter favgroup naming rules.

Don't allow favgroup names that:

* Start or end with underscores.
* Contain multiple underscores in a row.
* Contain asterisks or non-printable characters.
* Consist of only underscores.
* Consist of only digits (conflicts with `favgroup:1234` syntax).

Add a fix script that fixes favgroups that violate these rules and notifies the user.

script/fixes/129_fix_favgroup_names.rb

@@ -0,0 +1,66 @@
+#!/usr/bin/env ruby
+
+require_relative "base"
+
+with_confirmation do
+  fix = ENV.fetch("FIX", "false").truthy?
+
+  users = User.where.associated(:favorite_groups).distinct
+  users.find_each do |user|
+    changed_favgroups = []
+
+    user.favorite_groups.each do |favgroup|
+      if favgroup.name.match?(/[^[:graph:]]/)
+        favgroup.name.gsub!(/[^[:graph:]]/, "_")
+      end
+
+      if favgroup.name.include?("*")
+        favgroup.name.tr!("*", "?")
+      end
+
+      if favgroup.name.include?("__")
+        favgroup.name.gsub!(/_+/, "_")
+      end
+
+      if favgroup.name.starts_with?("_")
+        favgroup.name.delete_prefix!("_")
+      end
+
+      if favgroup.name.ends_with?("_")
+        favgroup.name.delete_suffix!("_")
+      end
+
+      if favgroup.name.match?(/\A[0-9]+\z/)
+        favgroup.name = "favgroup_#{favgroup.name}"
+      end
+
+      if favgroup.name.blank? || user.favorite_groups.without(favgroup).exists?(name: favgroup.name)
+        favgroup.name = "favgroup_#{favgroup.id}"
+      end
+
+      if favgroup.changed?
+        changed_favgroups << favgroup
+        puts ({ id: favgroup.id, creator: favgroup.creator.name, changes: favgroup.changes }).to_json
+        favgroup.save! if fix
+      end
+    end
+
+    if fix && changed_favgroups.present?
+      Dmail.create_automated(to: user, title: "Your favorite groups have been renamed", disable_email_notifications: true, body: <<~EOS)
+        The following #{"favgroup".pluralize(changed_favgroups.size)} #{changed_favgroups.one? ? "has" : "have"} been renamed:
+
+        #{changed_favgroups.map { |favgroup| "* favgroup ##{favgroup.id}: \"#{favgroup.name_was}\" -> \"#{favgroup.name}\"" }.join("\n")}
+
+        Your #{"favgroup".pluralize(changed_favgroups.size)} had to be renamed because #{changed_favgroups.one? ? "it" : "they"} didn't follow one of our new naming rules:
+
+        * Names can't consist of numbers only.
+        * Names can't start or end with an underscore (_).
+        * Names can't contain multiple underscores in a row (__).
+        * Names can't contain commas or asterisks (*).
+        * Names can't be blank.
+
+        You can change the name to something else by going to your "Favgroups":[/favorite_groups] page and clicking "Edit" to change the name.
+      EOS
+    end
+  end
+end