mas: handle 3pids from mas

userapi/storage/shared/storage.go

@@ -353,6 +353,41 @@ func (d *Database) SaveThreePIDAssociation(
 	})
 }
 
+// BulkSaveThreePIDAssociation recreates 3PIDs for a user.
+// If the third-party identifier is already part of an association, returns Err3PIDInUse.
+// Returns an error if there was a problem talking to the database.
+func (d *Database) BulkSaveThreePIDAssociation(ctx context.Context, threePIDs []authtypes.ThreePID, localpart string, serverName spec.ServerName) (err error) {
+	return d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error {
+		oldThreePIDs, err := d.ThreePIDs.SelectThreePIDsForLocalpart(ctx, localpart, serverName)
+		if err != nil {
+			return err
+		}
+		for _, t := range oldThreePIDs {
+			if err := d.ThreePIDs.DeleteThreePID(ctx, txn, t.Address, t.Medium); err != nil {
+				return err
+			}
+		}
+		for _, t := range threePIDs {
+			// if 3PID is associated with another user, return Err3PIDInUse
+			user, _, err := d.ThreePIDs.SelectLocalpartForThreePID(
+				ctx, txn, t.Address, t.Medium,
+			)
+			if err != nil {
+				return err
+			}
+
+			if len(user) > 0 && user != localpart {
+				return Err3PIDInUse
+			}
+
+			if err = d.ThreePIDs.InsertThreePID(ctx, txn, t.Address, t.Medium, localpart, serverName); err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+}
+
 // RemoveThreePIDAssociation removes the association involving a given third-party
 // identifier.
 // If no association exists involving this third-party identifier, returns nothing.