refactor: improve reorder logic

apps/client/src/features/rundown/rundown.utils.ts

@@ -164,7 +164,85 @@ export function canDrop(targetType?: SupportedEntry, targetParent?: EntryId | nu
   return targetType == 'block';
 }
 
-export function getNextId(entryId: EntryId, sortableData: EntryId[]): MaybeString {
+/**
+ * Calculates destinations for an entry moving one position up in the rundown
+ * - Handles noops
+ * - Handles moving in and out of blocks
+ * TODO: handle moving blocks
+ */
+export function moveUp(entryId: EntryId, sortableData: EntryId[], entries: RundownEntries) {
+  const previousEntryId = getPreviousId(entryId, sortableData);
+
+  // the user is moving up at the top of the list
+  if (!previousEntryId) {
+    return { destinationId: null, order: 'before', isBlock: false };
+  }
+
+  if (previousEntryId.startsWith('end-')) {
+    const entry = entries[entryId];
+    if (isOntimeBlock(entry)) {
+      // if we are moving a block, we cannot insert it
+      return { destinationId: previousEntryId.replace('end-', ''), order: 'before', isBlock: false };
+    }
+    // insert in the block ID will add to the end of the block events
+    return { destinationId: previousEntryId.replace('end-', ''), order: 'insert', isBlock: true };
+  }
+
+  // @ts-expect-error -- we safeguard the entry not having a parent property
+  return { destinationId: previousEntryId, order: 'before', isBlock: Boolean(entries[previousEntryId]?.parent) };
+}
+
+/**
+ * Calculates destinations for an entry moving one position down in the rundown
+ * - Handles noops
+ * - Handles moving in and out of blocks
+ * TODO: handle moving blocks
+ */
+export function moveDown(entryId: EntryId, sortableData: EntryId[], entries: RundownEntries) {
+  const nextEntryId = getNextId(entryId, sortableData);
+
+  // the user is moving down at the end of the list
+  if (!nextEntryId) {
+    return { destinationId: null, order: 'after', isBlock: false };
+  }
+
+  if (nextEntryId.startsWith('end-')) {
+    // move outside the block
+    return { destinationId: nextEntryId.replace('end-', ''), order: 'after', isBlock: false };
+  }
+
+  /**
+   * If the next entry is a block
+   * - 1. blocks need to skip over it
+   * - 2. if the block has children, we insert before the first child
+   * - 3. if the block is empty, we insert into the block
+   */
+  if (isOntimeBlock(entries[nextEntryId])) {
+    const entry = entries[entryId];
+
+    if (isOntimeBlock(entry)) {
+      // 1. if we are moving a block, we cannot insert it
+      return { destinationId: nextEntryId, order: 'after', isBlock: false };
+    }
+
+    const firstBlockChild = entries[nextEntryId].events.at(0);
+    if (firstBlockChild) {
+      // 2. add before the first child of the block
+      return { destinationId: firstBlockChild, order: 'before', isBlock: true };
+    } else {
+      // 3. or insert into an empty block
+      return { destinationId: nextEntryId, order: 'insert', isBlock: true };
+    }
+  }
+
+  return { destinationId: nextEntryId, order: 'after', isBlock: Boolean(entries[nextEntryId]?.parent) };
+}
+
+/**
+ * Utility function gets the ID if the next entry in the list
+ * returns null if none is found
+ */
+function getNextId(entryId: EntryId, sortableData: EntryId[]): EntryId | null {
   const currentIndex = sortableData.indexOf(entryId);
   if (currentIndex === -1 || currentIndex === sortableData.length - 1) {
     // No next ID if not found or at the end
@@ -173,7 +251,11 @@ export function getNextId(entryId: EntryId, sortableData: EntryId[]): MaybeStrin
   return sortableData[currentIndex + 1];
 }
 
-export function getPreviousId(entryId: EntryId, sortableData: EntryId[]): MaybeString {
+/**
+ * Utility function gets the ID if the previous entry in the list
+ * returns null if none is found
+ */
+function getPreviousId(entryId: EntryId, sortableData: EntryId[]): EntryId | null {
   const currentIndex = sortableData.indexOf(entryId);
   if (currentIndex < 1) {
     // No previous ID found or at the beginning