// 任务模块: 设备端偏好 (不落库, 不跨设备)
//   lastProjectId  上次访问的项目 (T-VW-07)
//   viewMode       按项目记忆的视图 list | board (T-VW-03/06)
//   recentIds      自动按最近访问排序的项目 id (最前 = 最近), 上限 10 (T-VW-08)
//   recentOrder    首屏最近项目卡片的手动排序结果, 优先于 recentIds (T-VW-10)
const KEY = 'iboard_task_prefs'

function blank() {
  return { lastProjectId: null, viewMode: {}, recentIds: [], recentOrder: [] }
}

function read() {
  try {
    const raw = localStorage.getItem(KEY)
    if (!raw) return blank()
    const obj = JSON.parse(raw)
    return {
      lastProjectId: obj.lastProjectId ?? null,
      viewMode: obj.viewMode && typeof obj.viewMode === 'object' ? obj.viewMode : {},
      recentIds: Array.isArray(obj.recentIds) ? obj.recentIds : [],
      recentOrder: Array.isArray(obj.recentOrder) ? obj.recentOrder : [],
    }
  } catch {
    return blank()
  }
}

function write(obj) {
  try {
    localStorage.setItem(KEY, JSON.stringify(obj))
  } catch { /* 忽略配额错误 */ }
}

export function getLastProjectId() {
  return read().lastProjectId
}

export function setLastProjectId(id) {
  const cur = read()
  cur.lastProjectId = id ?? null
  write(cur)
}

/** 视图记忆: 无记录返回 null, 由调用方决定默认值 */
export function getViewMode(projectId) {
  if (!projectId) return null
  return read().viewMode[String(projectId)] || null
}

export function setViewMode(projectId, mode) {
  if (!projectId) return
  const cur = read()
  cur.viewMode[String(projectId)] = mode
  write(cur)
}

/** 最近访问记录: 把 id 提到队首, 上限 10 (T-VW-08) */
export function getRecentIds() {
  return read().recentIds
}

export function setRecentIds(id) {
  if (!id) return
  const cur = read()
  cur.recentIds = [id, ...cur.recentIds.filter((x) => x !== id)].slice(0, 10)
  write(cur)
}

/** 首屏卡片手动排序 (T-VW-10): 完整顺序, 排在前面的项目优先展示 */
export function getRecentOrder() {
  return read().recentOrder
}

export function setRecentOrder(ids) {
  const cur = read()
  cur.recentOrder = (Array.isArray(ids) ? ids : []).map(Number).filter(Boolean)
  write(cur)
}

/** 清理已不可见的项目记录 */
export function prunePrefs(visibleIds) {
  const set = new Set((visibleIds || []).map(Number))
  const cur = read()
  let dirty = false
  if (cur.lastProjectId && !set.has(cur.lastProjectId)) { cur.lastProjectId = null; dirty = true }
  for (const k of Object.keys(cur.viewMode)) {
    if (!set.has(Number(k))) { delete cur.viewMode[k]; dirty = true }
  }
  const ri = cur.recentIds.filter((id) => set.has(id))
  const ro = cur.recentOrder.filter((id) => set.has(id))
  if (ri.length !== cur.recentIds.length || ro.length !== cur.recentOrder.length) dirty = true
  if (dirty) {
    cur.recentIds = ri
    cur.recentOrder = ro
    write(cur)
  }
}