Fix overlapping events to only split columns for overlapping event groups

Implemented clustering algorithm in calculate_event_layout that:
- Only creates column splits for events that actually overlap
- Non-overlapping events maintain full width display
- Uses greedy column assignment for overlapping groups
- Preserves proper column indices for each event

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/components/week_view.rs

@@ -1169,59 +1169,88 @@ fn events_overlap(event1: &VEvent, event2: &VEvent) -> bool {
 
 // Calculate layout columns for overlapping events
 fn calculate_event_layout(events: &[VEvent], date: NaiveDate) -> Vec<(usize, usize)> {
-    // Filter events that should appear on this date and sort by start time
+    
+    // Filter and sort events that should appear on this date
     let mut day_events: Vec<_> = events.iter()
-        .filter(|event| {
+        .enumerate()
+        .filter_map(|(idx, event)| {
             let (_, _, _) = calculate_event_position(event, date);
-            // Only include events that would be positioned (non-zero dimensions or all-day)
             let local_start = event.dtstart.with_timezone(&Local);
             let event_date = local_start.date_naive();
-            event_date == date || 
-                (event_date == date - chrono::Duration::days(1) && local_start.hour() >= 20)
+            if event_date == date || 
+                (event_date == date - chrono::Duration::days(1) && local_start.hour() >= 20) {
+                Some((idx, event))
+            } else {
+                None
+            }
         })
         .collect();
     
     // Sort by start time
-    day_events.sort_by_key(|event| event.dtstart.with_timezone(&Local).naive_local());
+    day_events.sort_by_key(|(_, event)| event.dtstart.with_timezone(&Local).naive_local());
     
-    // Calculate layout: (column_index, total_columns)
-    let mut layout = Vec::with_capacity(day_events.len());
-    let mut columns: Vec<Vec<&VEvent>> = Vec::new();
+    // For each event, find all events it overlaps with
+    let mut event_columns = vec![(0, 1); events.len()]; // (column_idx, total_columns)
     
-    for event in &day_events {
-        // Find the first column where this event doesn't overlap with any existing event
-        let mut placed = false;
-        for (col_idx, column) in columns.iter_mut().enumerate() {
-            if !column.iter().any(|existing_event| events_overlap(event, existing_event)) {
-                column.push(event);
-                layout.push((col_idx, 0)); // total_columns will be set later
-                placed = true;
-                break;
+    for i in 0..day_events.len() {
+        let (orig_idx_i, event_i) = day_events[i];
+        
+        // Find all events that overlap with this event
+        let mut overlapping_events = vec![i];
+        for j in 0..day_events.len() {
+            if i != j {
+                let (_, event_j) = day_events[j];
+                if events_overlap(event_i, event_j) {
+                    overlapping_events.push(j);
+                }
             }
         }
         
-        if !placed {
-            // Create new column
-            columns.push(vec![event]);
-            layout.push((columns.len() - 1, 0)); // total_columns will be set later
-        }
-    }
-    
-    // Update total_columns for all events
-    let total_columns = columns.len();
-    for (_, total_cols) in layout.iter_mut() {
-        *total_cols = total_columns;
-    }
-    
-    // Create result mapping original events to their layout
-    let mut result = Vec::with_capacity(events.len());
-    for event in events {
-        if let Some(pos) = day_events.iter().position(|e| e.uid == event.uid) {
-            result.push(layout[pos]);
+        // If this event doesn't overlap with anything, it gets full width
+        if overlapping_events.len() == 1 {
+            event_columns[orig_idx_i] = (0, 1);
         } else {
-            result.push((0, 1)); // Default: single column
+            // This event overlaps - we need to calculate column layout
+            // Sort the overlapping group by start time
+            overlapping_events.sort_by_key(|&idx| day_events[idx].1.dtstart.with_timezone(&Local).naive_local());
+            
+            // Assign columns using a greedy algorithm
+            let mut columns: Vec<Vec<usize>> = Vec::new();
+            
+            for &event_idx in &overlapping_events {
+                let (orig_idx, event) = day_events[event_idx];
+                
+                // Find the first column where this event doesn't overlap with existing events
+                let mut placed = false;
+                for (col_idx, column) in columns.iter_mut().enumerate() {
+                    let can_place = column.iter().all(|&existing_idx| {
+                        let (_, existing_event) = day_events[existing_idx];
+                        !events_overlap(event, existing_event)
+                    });
+                    
+                    if can_place {
+                        column.push(event_idx);
+                        event_columns[orig_idx] = (col_idx, columns.len());
+                        placed = true;
+                        break;
+                    }
+                }
+                
+                if !placed {
+                    // Create new column
+                    columns.push(vec![event_idx]);
+                    event_columns[orig_idx] = (columns.len() - 1, columns.len());
+                }
+            }
+            
+            // Update total_columns for all events in this overlapping group
+            let total_columns = columns.len();
+            for &event_idx in &overlapping_events {
+                let (orig_idx, _) = day_events[event_idx];
+                event_columns[orig_idx].1 = total_columns;
+            }
         }
     }
     
-    result
+    event_columns
 }