Add validation of string site settings with regex, and min and max lengths

lib/validators/string_setting_validator.rb

@@ -0,0 +1,38 @@
+class StringSettingValidator
+  def initialize(opts={})
+    @opts = opts
+    @regex = Regexp.new(opts[:regex]) if opts[:regex]
+  end
+
+  def valid_value?(val)
+    return true if !val.present?
+
+    if (@opts[:min] and @opts[:min].to_i > val.length) || (@opts[:max] and @opts[:max].to_i < val.length)
+      @length_fail = true
+      return false
+    end
+
+    if @regex and !(val =~ @regex)
+      @regex_fail = true
+      return false
+    end
+
+    true
+  end
+
+  def error_message
+    if @regex_fail
+      I18n.t('site_settings.errors.regex_mismatch')
+    elsif @length_fail
+      if @opts[:min] && @opts[:max]
+        I18n.t('site_settings.errors.invalid_string_min_max', {min: @opts[:min], max: @opts[:max]})
+      elsif @opts[:min]
+        I18n.t('site_settings.errors.invalid_string_min', {min: @opts[:min]})
+      else
+        I18n.t('site_settings.errors.invalid_string_max', {max: @opts[:max]})
+      end
+    else
+      I18n.t('site_settings.errors.invalid_string')
+    end
+  end
+end