Permit dots in usernames with conditions (#6844)

* Permit dots in usernames with conditions

- Dot cannot be the start or end of username
- a.lice and al.ice are considered the same during sign-up

* Fix regex mixin flags

1 files changed, 4 insertions, 2 deletions

diff --git a/app/models/account.rb b/app/models/account.rb
index c1347fe65..14269860f 100644
--- a/app/models/account.rb
+++ b/app/models/account.rb
@@ -47,7 +47,8 @@
 #
 
 class Account < ApplicationRecord
-  MENTION_RE = /(?<=^|[^\/[:word:]])@(([a-z0-9_]+)(?:@[a-z0-9\.\-]+[a-z0-9]+)?)/i
+  USERNAME_RE = /[a-z0-9_]+([a-z0-9_\.]+[a-z0-9_]+)?/i
+  MENTION_RE  = /(?<=^|[^\/[:word:]])@((#{USERNAME_RE}?)(?:@[a-z0-9\.\-]+[a-z0-9]+)?)/i
 
   include AccountAvatar
   include AccountFinderConcern
@@ -68,7 +69,8 @@ class Account < ApplicationRecord
   validates :username, uniqueness: { scope: :domain, case_sensitive: true }, if: -> { !local? && will_save_change_to_username? }
 
   # Local user validations
-  validates :username, format: { with: /\A[a-z0-9_]+\z/i }, uniqueness: { scope: :domain, case_sensitive: false }, length: { maximum: 30 }, if: -> { local? && will_save_change_to_username? }
+  validates :username, format: { with: /\A#{USERNAME_RE}\z/i }, length: { maximum: 30 }, if: -> { local? && will_save_change_to_username? }
+  validates_with UniqueUsernameValidator, if: -> { local? && will_save_change_to_username? }
   validates_with UnreservedUsernameValidator, if: -> { local? && will_save_change_to_username? }
   validates :display_name, length: { maximum: 30 }, if: -> { local? && will_save_change_to_display_name? }
   validates :note, length: { maximum: 160 }, if: -> { local? && will_save_change_to_note? }