Consolidate account scopes for `LOWER` (index using) username/domain queries (#30451)

app/models/account.rb

@@ -142,6 +142,8 @@ class Account < ApplicationRecord
   scope :not_excluded_by_account, ->(account) { where.not(id: account.excluded_from_timeline_account_ids) }
   scope :not_domain_blocked_by_account, ->(account) { where(arel_table[:domain].eq(nil).or(arel_table[:domain].not_in(account.excluded_from_timeline_domains))) }
   scope :dormant, -> { joins(:account_stat).merge(AccountStat.without_recent_activity) }
+  scope :with_username, ->(value) { where arel_table[:username].lower.eq(value.to_s.downcase) }
+  scope :with_domain, ->(value) { where arel_table[:domain].lower.eq(value&.to_s&.downcase) }
 
   after_update_commit :trigger_update_webhooks
 

app/models/account_suggestions/setting_source.rb

@@ -3,7 +3,7 @@
 class AccountSuggestions::SettingSource < AccountSuggestions::Source
   def get(account, limit: DEFAULT_LIMIT)
     if setting_enabled?
-      base_account_scope(account).where(setting_to_where_condition).limit(limit).pluck(:id).zip([key].cycle)
+      base_account_scope(account).merge(setting_to_where_condition).limit(limit).pluck(:id).zip([key].cycle)
     else
       []
     end
@@ -25,11 +25,9 @@ class AccountSuggestions::SettingSource < AccountSuggestions::Source
 
   def setting_to_where_condition
     usernames_and_domains.map do |(username, domain)|
-      Arel::Nodes::Grouping.new(
-        Account.arel_table[:username].lower.eq(username.downcase).and(
-          Account.arel_table[:domain].lower.eq(domain&.downcase)
-        )
-      )
+      Account
+        .with_username(username)
+        .with_domain(domain)
     end.reduce(:or)
   end
 

app/models/concerns/account/finder_concern.rb

@@ -25,42 +25,11 @@ module Account::FinderConcern
     end
 
     def find_remote(username, domain)
-      AccountFinder.new(username, domain).account
-    end
-  end
-
-  class AccountFinder
-    attr_reader :username, :domain
-
-    def initialize(username, domain)
-      @username = username
-      @domain = domain
-    end
-
-    def account
-      scoped_accounts.order(id: :asc).take
-    end
-
-    private
-
-    def scoped_accounts
-      Account.unscoped.tap do |scope|
-        scope.merge! with_usernames
-        scope.merge! matching_username
-        scope.merge! matching_domain
-      end
-    end
-
-    def with_usernames
-      Account.where.not(Account.arel_table[:username].lower.eq '')
-    end
-
-    def matching_username
-      Account.where(Account.arel_table[:username].lower.eq username.to_s.downcase)
-    end
-
-    def matching_domain
-      Account.where(Account.arel_table[:domain].lower.eq(domain.nil? ? nil : domain.to_s.downcase))
+      Account
+        .with_username(username)
+        .with_domain(domain)
+        .order(id: :asc)
+        .take
     end
   end
 end

app/models/concerns/user/ldap_authenticable.rb

@@ -22,7 +22,7 @@ module User::LdapAuthenticable
         safe_username = safe_username.gsub(keys, replacement)
       end
 
-      resource = joins(:account).merge(Account.where(Account.arel_table[:username].lower.eq safe_username.downcase)).take
+      resource = joins(:account).merge(Account.with_username(safe_username)).take
 
       if resource.blank?
         resource = new(

app/services/report_service.rb

@@ -81,7 +81,7 @@ class ReportService < BaseService
 
     # If the account making reports is remote, it is likely anonymized so we have to relax the requirements for attaching statuses.
     domain = @source_account.domain.to_s.downcase
-    has_followers = @target_account.followers.where(Account.arel_table[:domain].lower.eq(domain)).exists?
+    has_followers = @target_account.followers.with_domain(domain).exists?
     visibility = has_followers ? %i(public unlisted private) : %i(public unlisted)
     scope = @target_account.statuses.with_discarded
     scope.merge!(scope.where(visibility: visibility).or(scope.where('EXISTS (SELECT 1 FROM mentions m JOIN accounts a ON m.account_id = a.id WHERE lower(a.domain) = ?)', domain)))

app/validators/unique_username_validator.rb

@@ -6,10 +6,7 @@ class UniqueUsernameValidator < ActiveModel::Validator
   def validate(account)
     return if account.username.blank?
 
-    normalized_username = account.username.downcase
-    normalized_domain = account.domain&.downcase
-
-    scope = Account.where(Account.arel_table[:username].lower.eq normalized_username).where(Account.arel_table[:domain].lower.eq normalized_domain)
+    scope = Account.with_username(account.username).with_domain(account.domain)
     scope = scope.where.not(id: account.id) if account.persisted?
 
     account.errors.add(:username, :taken) if scope.exists?