From 5dab189815f2447a8d29d071539ee7906102fd5f Mon Sep 17 00:00:00 2001
From: zadam <zadam.apps@gmail.com>
Date: Tue, 3 May 2022 00:30:09 +0200
Subject: [PATCH] recovery for tree cycle errors, #2831

---
 src/services/consistency_checks.js | 57 +++++++++++++++++++++---------
 1 file changed, 41 insertions(+), 16 deletions(-)

diff --git a/src/services/consistency_checks.js b/src/services/consistency_checks.js
index 267c9fec3..dbf4b4478 100644
--- a/src/services/consistency_checks.js
+++ b/src/services/consistency_checks.js
@@ -56,41 +56,66 @@ class ConsistencyChecks {
             childToParents[childNoteId].push(parentNoteId);
         }
 
+        /** @returns {boolean} true if cycle was found and we should try again */
         const checkTreeCycle = (noteId, path) => {
             if (noteId === 'root') {
-                return;
-            }
-
-            if (!childToParents[noteId] || childToParents[noteId].length === 0) {
-                logError(`No parents found for note ${noteId}`);
-
-                this.unrecoveredConsistencyErrors = true;
-                return;
+                return false;
             }
 
             for (const parentNoteId of childToParents[noteId]) {
                 if (path.includes(parentNoteId)) {
-                    logError(`Tree cycle detected at parent-child relationship: ${parentNoteId} - ${noteId}, whole path: ${path}`);
+                    if (this.autoFix) {
+                        const branch = becca.getBranchFromChildAndParent(noteId, parentNoteId);
+                        branch.markAsDeleted('cycle-autofix');
+                        logFix(`Branch '${branch.branchId}' between child '${noteId}' and parent '${parentNoteId}' has been deleted since it was causing a tree cycle.`);
 
-                    this.unrecoveredConsistencyErrors = true;
+                        return true;
+                    }
+                    else {
+                        logError(`Tree cycle detected at parent-child relationship: ${parentNoteId} - ${noteId}, whole path: ${path}`);
+
+                        this.unrecoveredConsistencyErrors = true;
+                    }
                 } else {
                     const newPath = path.slice();
                     newPath.push(noteId);
 
-                    checkTreeCycle(parentNoteId, newPath);
+                    const retryNeeded = checkTreeCycle(parentNoteId, newPath);
+
+                    if (retryNeeded) {
+                        return true;
+                    }
                 }
             }
+
+            return false;
         };
 
         const noteIds = Object.keys(childToParents);
 
         for (const noteId of noteIds) {
-            checkTreeCycle(noteId, []);
+            const retryNeeded = checkTreeCycle(noteId, []);
+
+            if (retryNeeded) {
+                return true;
+            }
         }
 
-        if (childToParents['root'].length !== 1 || childToParents['root'][0] !== 'none') {
-            logError('Incorrect root parent: ' + JSON.stringify(childToParents['root']));
-            this.unrecoveredConsistencyErrors = true;
+        return false;
+    }
+
+    checkAndRepairTreeCycles() {
+        let treeFixed = false;
+
+        while (this.checkTreeCycles()) {
+            // fixing cycle means deleting branches, we might need to create a new branch to recover the note
+            this.findExistencyIssues();
+
+            treeFixed = true;
+        }
+
+        if (treeFixed) {
+            this.reloadNeeded = true;
         }
     }
 
@@ -646,7 +671,7 @@ class ConsistencyChecks {
         if (!this.unrecoveredConsistencyErrors) {
             // we run this only if basic checks passed since this assumes basic data consistency
 
-            this.checkTreeCycles();
+            this.checkAndRepairTreeCycles();
         }
 
         if (this.reloadNeeded) {