fix(GODT-3123): Trigger bad event on empty EventID on existing accounts

See `checkIrrecoverableEventID` for more details.

internal/user/user_check.go

@@ -0,0 +1,68 @@
+// Copyright (c) 2023 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package user
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/ProtonMail/proton-bridge/v3/internal/events"
+	"github.com/ProtonMail/proton-bridge/v3/internal/services/imapservice"
+)
+
+func checkIrrecoverableEventID(
+	ctx context.Context,
+	lastEventID,
+	userID,
+	syncConfigDir string,
+	publisher events.EventPublisher,
+) error {
+	// If we detect that the event ID stored in the vault got reset, the user is not a new account and
+	// we have started or finished syncing: this is an irrecoverable state and we should produce a bad event.
+	if lastEventID != "" {
+		return nil
+	}
+
+	syncConfigPath := imapservice.GetSyncConfigPath(syncConfigDir, userID)
+
+	syncState, err := imapservice.NewSyncState(syncConfigPath)
+	if err != nil {
+		return fmt.Errorf("failed to read imap sync state: %w", err)
+	}
+
+	syncStatus, err := syncState.GetSyncStatus(ctx)
+	if err != nil {
+		return fmt.Errorf("failed to imap sync status: %w", err)
+	}
+
+	if syncStatus.IsComplete() || syncStatus.InProgress() {
+		publisher.PublishEvent(ctx, newEmptyEventIDBadEvent(userID))
+	}
+
+	return nil
+}
+
+func newEmptyEventIDBadEvent(userID string) events.UserBadEvent {
+	return events.UserBadEvent{
+		UserID:     userID,
+		OldEventID: "",
+		NewEventID: "",
+		EventInfo:  "EventID missing from vault",
+		Error:      fmt.Errorf("eventID in vault is empty, when it shouldn't be"),
+	}
+}