feat: backend service

backend/internal/geo/cascade.go

@@ -0,0 +1,36 @@
+package geo
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"galaxy/backend/internal/postgres/jet/backend/table"
+
+	"github.com/go-jet/jet/v2/postgres"
+	"github.com/google/uuid"
+)
+
+// OnUserDeleted removes every `backend.user_country_counters` row for
+// userID. It is the geo-side leg of the soft-delete cascade documented
+// in `backend/PLAN.md` §5.2 / §5.8 and is invoked from
+// `backend/internal/user.Service.SoftDelete` after the
+// `accounts.deleted_at` write commits.
+//
+// The DELETE is idempotent: re-running on a user with no counters is a
+// successful no-op. Errors from the database are wrapped with the geo
+// prefix so caller logs identify the source.
+func (s *Service) OnUserDeleted(ctx context.Context, userID uuid.UUID) error {
+	if s == nil {
+		return errors.New("geo: nil service")
+	}
+	if userID == uuid.Nil {
+		return errors.New("geo: nil user id")
+	}
+	stmt := table.UserCountryCounters.DELETE().
+		WHERE(table.UserCountryCounters.UserID.EQ(postgres.UUID(userID)))
+	if _, err := stmt.ExecContext(ctx, s.db); err != nil {
+		return fmt.Errorf("geo: delete counters for %s: %w", userID, err)
+	}
+	return nil
+}