Move AddCollabrator and CreateRepositoryByExample to service layer (#32419)

- [x] Move `CreateRepositoryByExample` to service layer
- [x] Move `AddCollabrator` to service layer
- [x] Add a new parameter for `AddCollabrator` so that changing mode
immediately after that will become unnecessary.

services/repository/collaboration.go

@@ -9,11 +9,60 @@ import (
 
 	"code.gitea.io/gitea/models"
 	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/perm"
 	access_model "code.gitea.io/gitea/models/perm/access"
 	repo_model "code.gitea.io/gitea/models/repo"
 	user_model "code.gitea.io/gitea/models/user"
+
+	"xorm.io/builder"
 )
 
+func AddOrUpdateCollaborator(ctx context.Context, repo *repo_model.Repository, u *user_model.User, mode perm.AccessMode) error {
+	// only allow valid access modes, read, write and admin
+	if mode < perm.AccessModeRead || mode > perm.AccessModeAdmin {
+		return perm.ErrInvalidAccessMode
+	}
+
+	if err := repo.LoadOwner(ctx); err != nil {
+		return err
+	}
+
+	if user_model.IsUserBlockedBy(ctx, u, repo.OwnerID) || user_model.IsUserBlockedBy(ctx, repo.Owner, u.ID) {
+		return user_model.ErrBlockedUser
+	}
+
+	return db.WithTx(ctx, func(ctx context.Context) error {
+		collaboration, has, err := db.Get[repo_model.Collaboration](ctx, builder.Eq{
+			"repo_id": repo.ID,
+			"user_id": u.ID,
+		})
+		if err != nil {
+			return err
+		} else if has {
+			if collaboration.Mode == mode {
+				return nil
+			}
+			if _, err = db.GetEngine(ctx).
+				Where("repo_id=?", repo.ID).
+				And("user_id=?", u.ID).
+				Cols("mode").
+				Update(&repo_model.Collaboration{
+					Mode: mode,
+				}); err != nil {
+				return err
+			}
+		} else if err = db.Insert(ctx, &repo_model.Collaboration{
+			RepoID: repo.ID,
+			UserID: u.ID,
+			Mode:   mode,
+		}); err != nil {
+			return err
+		}
+
+		return access_model.RecalculateUserAccess(ctx, repo, u.ID)
+	})
+}
+
 // DeleteCollaboration removes collaboration relation between the user and repository.
 func DeleteCollaboration(ctx context.Context, repo *repo_model.Repository, collaborator *user_model.User) (err error) {
 	collaboration := &repo_model.Collaboration{