[DeckSync] Address auto-sync review: disconnect, backfill and modal conflicts

- Fail the run when the connection drops while a sync is running, and clear
  the active conflict, so the queue is not sent on a dead client and a
  re-login as another account never receives this profile's uploads.
- Backfill last_modified from upload_time in the 37 -> 38 migration and drop
  the "last_modified is null" arm from the sync-check query, so rows that
  predate the column stop reporting as changed on every poll.
- Skip conflicts during auto runs and report how many were skipped, instead
  of opening the modal conflict dialog from a timer or a file-watcher event.

cockatrice/src/interface/deck_sync/deck_sync_manager.cpp

@@ -109,6 +109,14 @@ DeckSyncManager::DeckSyncManager(AbstractClient *_client, ColorIdentityProvider
             if (status == StatusDisconnected) {
                 offline = true;
                 debounceTimer->stop();
+                // A run cannot survive the session it was started on: the in-flight
+                // command comes back RespNotConnected, the remaining queue would be
+                // sent on a dead client, and a re-login as another account would
+                // receive this profile's uploads and deletes.
+                if (syncing) {
+                    activeConflict = ActiveConflict();
+                    failSync(tr("Disconnected."));
+                }
             }
         },
         Qt::UniqueConnection);
@@ -201,7 +209,7 @@ void DeckSyncManager::onDebounceTimeout()
         return;
     }
     if (canAutoRun()) {
-        syncNow();
+        startSync(true);
     }
 }
 
@@ -233,10 +241,16 @@ bool DeckSyncManager::isSyncing() const
 }
 
 void DeckSyncManager::syncNow()
+{
+    startSync(false);
+}
+
+void DeckSyncManager::startSync(bool _autoRun)
 {
     if (syncing) {
         return;
     }
+    autoRun = _autoRun;
     const DeckSyncProfile runProfile = buildProfile();
     if (client == nullptr || !runProfile.isValid() || deckPath.isEmpty()) {
         emit syncFinished(SyncSummary{}, tr("Not connected to a server."));
@@ -253,6 +267,7 @@ void DeckSyncManager::syncNow()
     downloadedCount = 0;
     unchangedCount = 0;
     skippedCount = 0;
+    conflictCount = 0;
     pendingUploads.clear();
     pendingDownloads.clear();
     pendingDeletes.clear();
@@ -746,6 +761,16 @@ void DeckSyncManager::queueConflict(const QString &relativePath,
 void DeckSyncManager::handleConflictDownload(const QString &relativePath, const QString &serverDeckString)
 {
     const ConflictDownload ctx = pendingConflicts.take(relativePath);
+    if (autoRun) {
+        // An auto run has no user in front of it: opening the modal conflict
+        // dialog from a timer or a file-watcher event would pop up mid-game.
+        // Leave the path untouched so the next manual sync classifies it again
+        // and asks.
+        ++conflictCount;
+        ++skippedCount;
+        processNext();
+        return;
+    }
     if (sessionDefault == DeckSyncConflictKeepMine) {
         applyUpload(relativePath, ctx.serverPath, ctx.deckId, ctx.guid);
         processNext();
@@ -1245,6 +1270,9 @@ void DeckSyncManager::finishSync()
                            .arg(summary.downloaded)
                            .arg(summary.unchanged)
                            .arg(summary.skipped));
+    if (conflictCount > 0) {
+        emit statusMessage(tr("%1 conflicting decks skipped. Press Sync now to resolve them.").arg(conflictCount));
+    }
     emit syncFinished(summary, QString());
 }
 

cockatrice/src/interface/deck_sync/deck_sync_manager.h

@@ -159,6 +159,7 @@ private:
         qint64 lastModifiedSecs = 0;
     };
 
+    void startSync(bool autoRun);
     void failSync(const QString &error);
     void finishSync();
     [[nodiscard]] SyncSummary currentSummary() const;
@@ -240,6 +241,8 @@ private:
     int downloadedCount = 0;
     int unchangedCount = 0;
     int skippedCount = 0;
+    int conflictCount = 0;
+    bool autoRun = false;
 };
 
 #endif // DECK_SYNC_MANAGER_H

servatrice/migrations/servatrice_0040_to_0041.sql

@@ -16,6 +16,12 @@ ALTER TABLE `cockatrice_decklist_files`
   ADD COLUMN `last_modified` datetime NULL AFTER `hash`,
   ADD COLUMN `deleted` tinyint(1) NOT NULL DEFAULT 0 AFTER `last_modified`;
 
+-- Rows created before this migration only get a last_modified when a client
+-- re-uploads them, so every sync check would keep reporting them as changed.
+-- Backfill from the upload time once, here, instead of carrying a
+-- "last_modified is null" branch in the poll query forever.
+UPDATE `cockatrice_decklist_files` SET `last_modified` = `upload_time` WHERE `last_modified` IS NULL;
+
 CREATE TABLE IF NOT EXISTS `cockatrice_deck_versions` (
   `id` int(7) unsigned zerofill NOT NULL auto_increment,
   `deck_id` int(7) unsigned zerofill NOT NULL,

servatrice/src/serversocketinterface.cpp

@@ -904,10 +904,11 @@ bool AbstractServerSocketInterface::syncCheckHelper(int userId, qint64 sinceSecs
     // their files linger as tombstones, so walking the live folder tree would
     // miss deletes pointing at nonexistent folders. The client only checks
     // changed_files_size(), so folder paths are not reconstructed here.
+    // last_modified is backfilled by the 37 -> 38 migration, so a plain range
+    // check is enough.
     QSqlQuery *query = sqlInterface->prepareQuery("select id, guid, hash, last_modified, deleted from "
                                                   "{prefix}_decklist_files where id_user = :id_user "
-                                                  "and (last_modified is null or last_modified >= "
-                                                  "FROM_UNIXTIME(:since))");
+                                                  "and last_modified >= FROM_UNIXTIME(:since)");
     query->bindValue(":id_user", userId);
     query->bindValue(":since", sinceSecs);
     if (!sqlInterface->execSqlQuery(query)) {