[verified] redesign trash with deadline groups

frontend/src/lib/task-utils.ts

@@ -85,6 +85,27 @@ export function groupTaskTree<T extends MinimalTask>(tasks: T[]) {
   }))
 }
 
+export type TrashTaskGroup<T extends MinimalTask> = {
+  key: 'overdue' | 'upcoming' | 'undated'
+  label: '已过期' | '未来截止' | '无截止日期'
+  nodes: Array<{ task: T; subtasks: T[] }>
+}
+
+export function groupTrashTaskTree<T extends MinimalTask>(tasks: T[], now = new Date()): TrashTaskGroup<T>[] {
+  const nodes = groupTaskTree(tasks)
+  const groups: TrashTaskGroup<T>[] = [
+    { key: 'overdue', label: '已过期', nodes: [] },
+    { key: 'upcoming', label: '未来截止', nodes: [] },
+    { key: 'undated', label: '无截止日期', nodes: [] },
+  ]
+  for (const node of nodes) {
+    const due = node.task.due_at ? Date.parse(node.task.due_at) : Number.NaN
+    const key = Number.isFinite(due) ? (due < now.valueOf() ? 'overdue' : 'upcoming') : 'undated'
+    groups.find((group) => group.key === key)!.nodes.push(node)
+  }
+  return groups.filter((group) => group.nodes.length)
+}
+
 export function classifyTaskForToday(
   task: Pick<MinimalTask, 'completed' | 'due_at'>,
   start: Date,