Refactors drag and drop logic

Improves drag and drop initialization and handling by extracting methods for clarity.
This enhances code readability and maintainability.

src/managers/DragDropManager.ts

@@ -214,88 +214,111 @@ export class DragDropManager {
     if (event.buttons === 1) {
       const currentPosition: MousePosition = { x: event.clientX, y: event.clientY };
 
-      // Check if we need to start drag (movement threshold)
+      // Try to initialize drag if not started
       if (!this.isDragStarted && this.draggedElement) {
-        const deltaX = Math.abs(currentPosition.x - this.initialMousePosition.x);
-        const deltaY = Math.abs(currentPosition.y - this.initialMousePosition.y);
-        const totalMovement = Math.sqrt(deltaX * deltaX + deltaY * deltaY);
-
-        if (totalMovement >= this.dragThreshold) {
-          // Start drag - emit drag:start event
-          this.isDragStarted = true;
-
-          // Set high z-index on event-group if exists, otherwise on event itself
-          const eventGroup = this.draggedElement.closest<HTMLElement>('swp-event-group');
-          if (eventGroup) {
-            eventGroup.style.zIndex = '9999';
-          } else {
-            this.draggedElement.style.zIndex = '9999';
-          }
-
-          // Detect current column and save as initial source column
-          this.currentColumnBounds = ColumnDetectionUtils.getColumnBounds(currentPosition);
-          this.initialColumnBounds = this.currentColumnBounds;  // Save source column
-
-          // Cast to BaseSwpEventElement and create clone (works for both SwpEventElement and SwpAllDayEventElement)
-          const originalElement = this.draggedElement as BaseSwpEventElement;
-          this.draggedClone = originalElement.createClone();
-
-          const dragStartPayload: DragStartEventPayload = {
-            draggedElement: this.draggedElement,
-            draggedClone: this.draggedClone,
-            mousePosition: this.initialMousePosition,
-            mouseOffset: this.mouseOffset,
-            columnBounds: this.currentColumnBounds
-          };
-          this.eventBus.emit('drag:start', dragStartPayload);
-        } else {
-          // Not enough movement yet - don't start drag
-          return;
+        if (!this.tryInitializeDrag(currentPosition)) {
+          return; // Not enough movement yet
         }
       }
 
-      // Continue with normal drag behavior only if drag has started
+      // Continue drag if started
       if (this.isDragStarted && this.draggedElement && this.draggedClone) {
-        if (!this.draggedElement.hasAttribute("data-allday")) {
-          // Calculate raw position from mouse (no snapping)
-          const column = ColumnDetectionUtils.getColumnBounds(currentPosition);
+        this.continueDrag(currentPosition);
+        this.detectAndEmitColumnChange(currentPosition);
+      }
+    }
+  }
 
-          if (column) {
-            // Calculate raw Y position relative to column (accounting for mouse offset)
-            const columnRect = column.boundingClientRect;
-            const eventTopY = currentPosition.y - columnRect.top - this.mouseOffset.y;
-            this.targetY = Math.max(0, eventTopY); // Store raw Y as target (no snapping)
-            this.targetColumn = column;
+  /**
+   * Try to initialize drag based on movement threshold
+   * Returns true if drag was initialized, false if not enough movement
+   */
+  private tryInitializeDrag(currentPosition: MousePosition): boolean {
+    const deltaX = Math.abs(currentPosition.x - this.initialMousePosition.x);
+    const deltaY = Math.abs(currentPosition.y - this.initialMousePosition.y);
+    const totalMovement = Math.sqrt(deltaX * deltaX + deltaY * deltaY);
 
-            // Start animation loop if not already running
-            if (this.dragAnimationId === null) {
-              this.currentY = parseFloat(this.draggedClone.style.top) || 0;
-              this.animateDrag();
-            }
-          }
+    if (totalMovement < this.dragThreshold) {
+      return false; // Not enough movement
+    }
 
-          // Check for auto-scroll
-          this.checkAutoScroll(currentPosition);
-        }
+    // Start drag
+    this.isDragStarted = true;
 
-        const newColumn = ColumnDetectionUtils.getColumnBounds(currentPosition);
-        if (newColumn == null)
-          return;
+    // Set high z-index on event-group if exists, otherwise on event itself
+    const eventGroup = this.draggedElement!.closest<HTMLElement>('swp-event-group');
+    if (eventGroup) {
+      eventGroup.style.zIndex = '9999';
+    } else {
+      this.draggedElement!.style.zIndex = '9999';
+    }
 
-        if (newColumn?.index !== this.currentColumnBounds?.index) {
-          const previousColumn = this.currentColumnBounds;
-          this.currentColumnBounds = newColumn;
+    // Detect current column and save as initial source column
+    this.currentColumnBounds = ColumnDetectionUtils.getColumnBounds(currentPosition);
+    this.initialColumnBounds = this.currentColumnBounds;
 
-          const dragColumnChangePayload: DragColumnChangeEventPayload = {
-            originalElement: this.draggedElement,
-            draggedClone: this.draggedClone,
-            previousColumn,
-            newColumn,
-            mousePosition: currentPosition
-          };
-          this.eventBus.emit('drag:column-change', dragColumnChangePayload);
+    // Cast to BaseSwpEventElement and create clone
+    const originalElement = this.draggedElement as BaseSwpEventElement;
+    this.draggedClone = originalElement.createClone();
+
+    const dragStartPayload: DragStartEventPayload = {
+      draggedElement: this.draggedElement!,
+      draggedClone: this.draggedClone,
+      mousePosition: this.initialMousePosition,
+      mouseOffset: this.mouseOffset,
+      columnBounds: this.currentColumnBounds
+    };
+    this.eventBus.emit('drag:start', dragStartPayload);
+
+    return true;
+  }
+
+  /**
+   * Continue drag movement - update position and auto-scroll
+   */
+  private continueDrag(currentPosition: MousePosition): void {
+    if (!this.draggedElement!.hasAttribute("data-allday")) {
+      // Calculate raw position from mouse (no snapping)
+      const column = ColumnDetectionUtils.getColumnBounds(currentPosition);
+
+      if (column) {
+        // Calculate raw Y position relative to column (accounting for mouse offset)
+        const columnRect = column.boundingClientRect;
+        const eventTopY = currentPosition.y - columnRect.top - this.mouseOffset.y;
+        this.targetY = Math.max(0, eventTopY);
+        this.targetColumn = column;
+
+        // Start animation loop if not already running
+        if (this.dragAnimationId === null) {
+          this.currentY = parseFloat(this.draggedClone!.style.top) || 0;
+          this.animateDrag();
         }
       }
+
+      // Check for auto-scroll
+      this.checkAutoScroll(currentPosition);
+    }
+  }
+
+  /**
+   * Detect column change and emit event
+   */
+  private detectAndEmitColumnChange(currentPosition: MousePosition): void {
+    const newColumn = ColumnDetectionUtils.getColumnBounds(currentPosition);
+    if (newColumn == null) return;
+
+    if (newColumn.index !== this.currentColumnBounds?.index) {
+      const previousColumn = this.currentColumnBounds;
+      this.currentColumnBounds = newColumn;
+
+      const dragColumnChangePayload: DragColumnChangeEventPayload = {
+        originalElement: this.draggedElement!,
+        draggedClone: this.draggedClone!,
+        previousColumn,
+        newColumn,
+        mousePosition: currentPosition
+      };
+      this.eventBus.emit('drag:column-change', dragColumnChangePayload);
     }
   }