From 2363897a258fdc886b3c55384d125696b6cd57e9 Mon Sep 17 00:00:00 2001
From: Kane York <rikingcoding@gmail.com>
Date: Thu, 20 Aug 2015 18:27:19 -0700
Subject: [PATCH] FEATURE: Arbitrary validations for site settings

---
 config/locales/server.en.yml    | 11 +++++++----
 lib/site_setting_extension.rb   |  6 ++++++
 lib/site_setting_validations.rb | 17 +++++++++++++++++
 3 files changed, 30 insertions(+), 4 deletions(-)
 create mode 100644 lib/site_setting_validations.rb

diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 429fe03dfee..dba03554a76 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -90,6 +90,11 @@ en:
         other: ! '%{count} errors prohibited this %{model} from being saved'
     embed:
       load_from_remote: "There was an error loading that post."
+    site_settings:
+      min_username_length_exists: "You cannot set the minimum username length above the shortest username."
+      min_username_length_range: "You cannot set the minimum above the maximum."
+      max_username_length_exists: "You cannot set the maximum username length below the longest username."
+      max_username_length_range: "You cannot set the maximum above the minimum."
 
   activemodel:
     errors:
@@ -892,14 +897,12 @@ en:
     invite_expiry_days: "How long user invitation keys are valid, in days"
     invite_passthrough_hours: "How long a user can use a previously redeemed invitation key to log in, in hours"
 
-    # TODO: perhaps we need a way of protecting these settings for hosted solution, global settings ...
-
     invite_only: "Public registration is disabled, all new users must be explicitly invited by other members or staff."
 
     login_required: "Require authentication to read content on this site, disallow anonymous access."
 
-    min_username_length: "Minimum username length in characters. WARNING: ANY EXISTING USERS WITH NAMES SHORTER THAN THIS WILL BE UNABLE TO ACCESS THE SITE."
-    max_username_length: "Maximum username length in characters. WARNING: ANY EXISTING USERS WITH NAMES LONGER THAN THIS WILL BE UNABLE TO ACCESS THE SITE."
+    min_username_length: "Minimum username length in characters."
+    max_username_length: "Maximum username length in characters."
 
     reserved_usernames: "Usernames for which signup is not allowed."
 
diff --git a/lib/site_setting_extension.rb b/lib/site_setting_extension.rb
index 228a7e6f395..f4c7c1df20a 100644
--- a/lib/site_setting_extension.rb
+++ b/lib/site_setting_extension.rb
@@ -1,7 +1,9 @@
 require_dependency 'enum'
 require_dependency 'site_settings/db_provider'
+require 'site_setting_validations'
 
 module SiteSettingExtension
+  include SiteSettingValidations
 
   # For plugins, so they can tell if a feature is supported
   def supported_types
@@ -303,6 +305,10 @@ module SiteSettingExtension
       end
     end
 
+    if self.respond_to? "validate_#{name}"
+      send("validate_#{name}", val)
+    end
+
     provider.save(name, val, type)
     current[name] = convert(val, type)
     clear_cache!
diff --git a/lib/site_setting_validations.rb b/lib/site_setting_validations.rb
new file mode 100644
index 00000000000..6ed44df8037
--- /dev/null
+++ b/lib/site_setting_validations.rb
@@ -0,0 +1,17 @@
+
+module SiteSettingValidations
+
+  def validate_error(key)
+    raise Discourse::InvalidParameters.new(I18n.t("errors.site_settings.#{key}"))
+  end
+
+  def validate_min_username_length(new_val)
+    validate_error :min_username_length_range if new_val > SiteSetting.max_username_length
+    validate_error :min_username_length_exists if User.where('length(username) < ?', new_val).exists?
+  end
+
+  def validate_max_username_length(new_val)
+    validate_error :min_username_length_range if new_val < SiteSetting.min_username_length
+    validate_error :max_username_length_exists if User.where('length(username) > ?', new_val).exists?
+  end
+end