Refactor user package (#33423)

and avoid global variables

models/user/user_system.go

@@ -10,9 +10,8 @@ import (
 )
 
 const (
-	GhostUserID        = -1
-	GhostUserName      = "Ghost"
-	GhostUserLowerName = "ghost"
+	GhostUserID   = -1
+	GhostUserName = "Ghost"
 )
 
 // NewGhostUser creates and returns a fake user for someone has deleted their account.
@@ -20,10 +19,14 @@ func NewGhostUser() *User {
 	return &User{
 		ID:        GhostUserID,
 		Name:      GhostUserName,
-		LowerName: GhostUserLowerName,
+		LowerName: strings.ToLower(GhostUserName),
 	}
 }
 
+func IsGhostUserName(name string) bool {
+	return strings.EqualFold(name, GhostUserName)
+}
+
 // IsGhost check if user is fake user for a deleted account
 func (u *User) IsGhost() bool {
 	if u == nil {
@@ -32,20 +35,10 @@ func (u *User) IsGhost() bool {
 	return u.ID == GhostUserID && u.Name == GhostUserName
 }
 
-// NewReplaceUser creates and returns a fake user for external user
-func NewReplaceUser(name string) *User {
-	return &User{
-		ID:        0,
-		Name:      name,
-		LowerName: strings.ToLower(name),
-	}
-}
-
 const (
-	ActionsUserID   = -2
-	ActionsUserName = "gitea-actions"
-	ActionsFullName = "Gitea Actions"
-	ActionsEmail    = "teabot@gitea.io"
+	ActionsUserID    = -2
+	ActionsUserName  = "gitea-actions"
+	ActionsUserEmail = "teabot@gitea.io"
 )
 
 // NewActionsUser creates and returns a fake user for running the actions.
@@ -55,8 +48,8 @@ func NewActionsUser() *User {
 		Name:                    ActionsUserName,
 		LowerName:               ActionsUserName,
 		IsActive:                true,
-		FullName:                ActionsFullName,
-		Email:                   ActionsEmail,
+		FullName:                "Gitea Actions",
+		Email:                   ActionsUserEmail,
 		KeepEmailPrivate:        true,
 		LoginName:               ActionsUserName,
 		Type:                    UserTypeIndividual,