feat: add overlap checking and resolution functions for timeline elements

apps/web/src/lib/timeline.ts

@@ -0,0 +1,54 @@
+import { TimelineElement } from "@/types/timeline";
+
+// Helper function to check for element overlaps and prevent invalid timeline states
+export const checkElementOverlaps = (elements: TimelineElement[]): boolean => {
+  // Sort elements by start time
+  const sortedElements = [...elements].sort(
+    (a, b) => a.startTime - b.startTime
+  );
+
+  for (let i = 0; i < sortedElements.length - 1; i++) {
+    const current = sortedElements[i];
+    const next = sortedElements[i + 1];
+
+    const currentEnd =
+      current.startTime +
+      (current.duration - current.trimStart - current.trimEnd);
+
+    // Check if current element overlaps with next element
+    if (currentEnd > next.startTime) return true; // Overlap detected
+  }
+
+  return false; // No overlaps
+};
+
+// Helper function to resolve overlaps by adjusting element positions
+export const resolveElementOverlaps = (
+  elements: TimelineElement[]
+): TimelineElement[] => {
+  // Sort elements by start time
+  const sortedElements = [...elements].sort(
+    (a, b) => a.startTime - b.startTime
+  );
+  const resolvedElements: TimelineElement[] = [];
+
+  for (let i = 0; i < sortedElements.length; i++) {
+    const current = { ...sortedElements[i] };
+
+    if (resolvedElements.length > 0) {
+      const previous = resolvedElements[resolvedElements.length - 1];
+      const previousEnd =
+        previous.startTime +
+        (previous.duration - previous.trimStart - previous.trimEnd);
+
+      // If current element would overlap with previous, push it after previous ends
+      if (current.startTime < previousEnd) {
+        current.startTime = previousEnd;
+      }
+    }
+
+    resolvedElements.push(current);
+  }
+
+  return resolvedElements;
+};