/**
 * 驾驶舱导航状态管理
 * 核心逻辑：
 * - 菜单进入：清空导航栈
 * - 页面跳转 push：当前页面状态入栈
 * - 返回 go(-1)：出栈，恢复前一个页面状态
 * - 返回按钮：栈长度 > 0 时显示
 */

const STACK_KEY = 'cockpit_nav_stack';
const STATE_PREFIX = 'cockpit_nav_state_';

/**
 * 获取导航栈
 * @returns {Array<{ path: string, state: object }>}
 */
export function getNavStack() {
  try {
    const raw = sessionStorage.getItem(STACK_KEY);
    if (!raw) return [];
    return JSON.parse(raw);
  } catch (e) {
    return [];
  }
}

/**
 * 获取导航栈长度
 * @returns {number}
 */
export function getNavStackLength() {
  return getNavStack().length;
}

/**
 * 页面跳转时调用：将当前页面状态入栈
 * @param {string} fromPath - 来源页面路径
 * @param {object} state - 来源页面的业务状态（如 dateData）
 */
export function pushNavigation(fromPath, state = {}) {
  if (!fromPath) return;
  try {
    const stack = getNavStack();
    stack.push({
      path: fromPath,
      state,
      timestamp: Date.now()
    });
    sessionStorage.setItem(STACK_KEY, JSON.stringify(stack));
    console.log('[navigation] push', fromPath, 'stack length:', stack.length);
  } catch (e) {
    console.warn('[navigation] push failed', e);
  }
}

/**
 * 返回时调用：出栈，返回前一个页面信息
 * @returns {{ path: string, state: object } | null}
 */
export function popNavigation() {
  try {
    const stack = getNavStack();
    if (stack.length === 0) return null;
    const prev = stack.pop();
    sessionStorage.setItem(STACK_KEY, JSON.stringify(stack));
    console.log('[navigation] pop', prev.path, 'stack length:', stack.length);
    return prev;
  } catch (e) {
    console.warn('[navigation] pop failed', e);
    return null;
  }
}

/**
 * 清空导航栈和所有页面状态
 */
export function clearNavigation() {
  try {
    // 清空栈
    sessionStorage.removeItem(STACK_KEY);
    // 清空所有页面状态
    Object.keys(sessionStorage)
      .filter(k => k.startsWith(STATE_PREFIX))
      .forEach(k => sessionStorage.removeItem(k));
    console.log('[navigation] cleared');
    // 通知所有监听器
    window.dispatchEvent(new Event('navigation-cleared'));
  } catch (e) {
    console.warn('[navigation] clear failed', e);
  }
}

/**
 * 获取指定页面的状态
 * @param {string} path - 页面路径
 * @returns {object | null}
 */
export function getNavigationState(path) {
  if (!path) return null;
  try {
    const key = STATE_PREFIX + path;
    const raw = sessionStorage.getItem(key);
    if (!raw) return null;
    return JSON.parse(raw);
  } catch (e) {
    return null;
  }
}

/**
 * 消费（读取并删除）指定页面的状态
 * @param {string} path - 页面路径
 * @returns {object | null}
 */
export function consumeNavigationState(path) {
  if (!path) return null;
  try {
    const key = STATE_PREFIX + path;
    const raw = sessionStorage.getItem(key);
    if (!raw) return null;
    sessionStorage.removeItem(key);
    return JSON.parse(raw);
  } catch (e) {
    try {
      sessionStorage.removeItem(STATE_PREFIX + path);
    } catch (e2) { /* ignore */ }
    return null;
  }
}

/**
 * 保存指定页面的状态
 * @param {string} path - 页面路径
 * @param {object} state - 业务状态
 */
export function saveNavigationState(path, state) {
  if (!path) return;
  try {
    const key = STATE_PREFIX + path;
    sessionStorage.setItem(key, JSON.stringify(state));
  } catch (e) {
    console.warn('[navigation] save state failed', e);
  }
}

// ============ 兼容旧 API（后续可逐步移除）===========

/**
 * @deprecated 使用 pushNavigation 代替
 */
export function saveNavigationReturnState(scope, state) {
  console.warn('[navigation] saveNavigationReturnState 已废弃，请使用 pushNavigation + saveNavigationState');
}

/**
 * @deprecated 使用 consumeNavigationState 代替
 */
export function consumeNavigationReturnState(scope) {
  console.warn('[navigation] consumeNavigationReturnState 已废弃，请使用 popNavigation + consumeNavigationState');
  return null;
}

/**
 * @deprecated
 */
export function getNavScope(moduleName) {
  console.warn('[navigation] getNavScope 已废弃，请直接使用路径作为 key');
  return `nav:${moduleName}`;
}