added a migration method for deprecated log entries (#890)

imixs-workflow-core/src/main/java/org/imixs/workflow/WorkflowKernel.java

@@ -1045,10 +1045,10 @@ private ItemCollection createVersion(ItemCollection sourceItemCollection) throws
     private ItemCollection logEvent(int taskID, int eventID, int targetTaskID, final ItemCollection workitem) {
         ItemCollection documentResult = workitem;
 
-        List<String> existingLogEntries = (List<String>) workitem.getItemValue(EVENTLOG);
-
         // Migration check for deprecated log entries.
-        migrateOldEventLogFormat(workitem);
+        migrateDeprecatedEventLogFormat(workitem);
+
+        List<String> existingLogEntries = (List<String>) workitem.getItemValue(EVENTLOG);
 
         // Create new log entry...
         StringBuilder logEntry = new StringBuilder();
@@ -1092,7 +1092,7 @@ private ItemCollection logEvent(int taskID, int eventID, int targetTaskID, final
      * @param workitem - the workitem to be migrated
      */
     @SuppressWarnings("unchecked")
-    private void migrateOldEventLogFormat(ItemCollection workitem) {
+    private void migrateDeprecatedEventLogFormat(ItemCollection workitem) {
         if (workitem.hasItem("$eventlogdeprecated")) {
             // already migrated
             return;
@@ -1113,7 +1113,57 @@ private void migrateOldEventLogFormat(ItemCollection workitem) {
                 && parts[2].contains(".")) {
             // backup old format
             workitem.setItemValue("$eventlogdeprecated", logEntries);
+
+            // Create new list with migrated entries
+            List<String> migratedEntries = new ArrayList<>();
+            for (String oldEntry : logEntries) {
+                String migratedEntry = migrateDeprecatedLogEntry(oldEntry);
+                migratedEntries.add(migratedEntry);
+            }
+            // Update eventlog with migrated entries
+            workitem.replaceItemValue(EVENTLOG, migratedEntries);
+        }
+    }
+
+    /**
+     * Converts a single log entry from old to new format
+     * Old: timestamp|model-version|1000.10|1000|comment
+     * New:
+     * timestamp+timezone|model-version|sourcetask|eventid|targettask|actor|comment
+     */
+    private String migrateDeprecatedLogEntry(String oldEntry) {
+        String[] parts = oldEntry.split("\\|");
+        StringBuilder newEntry = new StringBuilder();
+
+        // Convert timestamp to timezone format
+        try {
+            LocalDateTime oldDateTime = LocalDateTime.parse(parts[0]);
+            ZonedDateTime zonedDateTime = oldDateTime.atZone(ZoneId.systemDefault());
+            newEntry.append(zonedDateTime.format(DateTimeFormatter.ISO_OFFSET_DATE_TIME));
+        } catch (Exception e) {
+            // If parsing fails, keep original timestamp
+            newEntry.append(parts[0]);
         }
+
+        newEntry.append("|")
+                .append(parts[1]) // model-version
+                .append("|");
+
+        // Split task.event into separate fields
+        String[] taskEvent = parts[2].split("\\.");
+        newEntry.append(taskEvent[0]) // sourcetask
+                .append("|")
+                .append(taskEvent[1]) // eventid
+                .append("|")
+                .append(parts[3]) // targettask
+                .append("||"); // empty actor field
+
+        // Append comment if exists
+        if (parts.length > 4 && !parts[4].isEmpty()) {
+            newEntry.append(parts[4]);
+        }
+
+        return newEntry.toString();
     }
 
     /**

imixs-workflow-core/src/test/java/org/imixs/workflow/kernel/TestWorkflowKernelBasic.java

@@ -9,6 +9,7 @@
 import java.time.LocalDateTime;
 import java.time.ZonedDateTime;
 import java.time.format.DateTimeParseException;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -473,6 +474,75 @@ public void testActivityLog() {
         assertEquals("comment", parts[6]); // comment
     }
 
+    /**
+     * This test verifies the migration of old eventlog entries into the new format
+     * 
+     * @See Issue 890
+     */
+    @Test
+    public void testEventLogMigration() {
+        ItemCollection workitem = new ItemCollection();
+        workitem.model("1.0.0")
+                .task(1000);
+        workitem.replaceItemValue("txtTitel", "Hello");
+
+        // Create old format log entries
+        List<String> oldLogEntries = new ArrayList<>();
+        oldLogEntries.add("2024-08-27T12:04:20.469|1.0.0|1000.10|1000|");
+        oldLogEntries.add("2024-08-27T12:05:30.127|1.0.0|1000.20|1100|comment");
+        workitem.replaceItemValue("$eventlog", oldLogEntries);
+
+        // Add a new log entry which should trigger the migration
+        try {
+            workitem.replaceItemValue("$editor", "john");
+            workitem.event(10);
+            workitem = workflowEngine.getWorkflowKernel().process(workitem);
+        } catch (Exception e) {
+            fail();
+            e.printStackTrace();
+        }
+
+        // Test if old entries were backed up
+        assertTrue(workitem.hasItem("$eventlogdeprecated"));
+        List oldBackupLog = workitem.getItemValue("$eventlogdeprecated");
+        assertEquals(2, oldBackupLog.size());
+        assertEquals(oldLogEntries.get(0), oldBackupLog.get(0));
+        assertEquals(oldLogEntries.get(1), oldBackupLog.get(1));
+
+        // Verify the new eventlog format
+        List newLog = workitem.getItemValue("$eventlog");
+        // We expect all entries to be in new format
+        assertNotNull(newLog);
+
+        // Test new log entry format
+        String logEntry = (String) newLog.get(0);
+        String[] parts = logEntry.split("\\|", -1);
+        assertEquals(7, parts.length);
+
+        try {
+            ZonedDateTime.parse(parts[0]);
+            assertTrue(true);
+        } catch (DateTimeParseException e) {
+            fail("Invalid timestamp format: " + parts[0]);
+        }
+
+        // Test if a second migration attempt has no effect
+        int currentSize = newLog.size();
+        try {
+            workitem.event(10);
+            workitem = workflowEngine.getWorkflowKernel().process(workitem);
+        } catch (Exception e) {
+            fail();
+            e.printStackTrace();
+        }
+        List finalLog = workitem.getItemValue("$eventlog");
+        assertEquals(currentSize + 1, finalLog.size());
+
+        // Test if backup remained unchanged
+        List finalBackupLog = workitem.getItemValue("$eventlogdeprecated");
+        assertEquals(oldBackupLog, finalBackupLog);
+    }
+
     /**
      * test generated UUID
      *