// PUT /api/tasks/mirror (desktop) — full-replace of the desktop's current Idle backlog.
// Body: [{ id, listId, title, description? }, ...] (camelCase). An empty array is valid and
// clears the desktop-owned partition. Mirrors PUT /lists. Web-created tasks awaiting pull
// (consumed=false) are never touched here.
export default defineEventHandler(async (event) => {
  const body = await readBody(event);
  if (!Array.isArray(body)) {
    throw createError({ statusCode: 400, statusMessage: "expected an array of tasks" });
  }

  const items: { id: string; listId: string; title: string; description: string | null }[] = [];
  for (let i = 0; i < body.length; i++) {
    const t = body[i];
    if (typeof t?.id !== "string" || !t.id.trim()) {
      throw createError({ statusCode: 400, statusMessage: `item ${i}: id is required` });
    }
    if (typeof t?.listId !== "string" || !t.listId.trim()) {
      throw createError({ statusCode: 400, statusMessage: `item ${i}: listId is required` });
    }
    if (typeof t?.title !== "string" || !t.title.trim()) {
      throw createError({ statusCode: 400, statusMessage: `item ${i}: title is required` });
    }
    items.push({
      id: t.id,
      listId: t.listId,
      title: t.title,
      description: typeof t.description === "string" ? t.description : null,
    });
  }

  const sql = getSql();

  // Every referenced list must exist (lists are full-replaced before tasks are mirrored).
  const listIds = [...new Set(items.map((t) => t.listId))];
  for (const id of listIds) {
    if (!(await listExists(sql, id))) {
      throw createError({ statusCode: 400, statusMessage: `unknown listId: ${id}` });
    }
  }

  await mirrorDesktopTasks(sql, items);
  return { ok: true, count: items.length };
});