import type { MenuRecord } from '@/types/auth';
import type { MenuProps } from 'antd';
import type { RouteObject } from 'react-router';
import { lazy, Suspense } from 'react';
import { Spin } from 'antd';
import Icon from '@/components/Icon';

type AntMenuItem = NonNullable<MenuProps['items']>[number];

// ── Component loader using Vite glob import ─────────────────────

const pages = import.meta.glob('@/pages/**/index.{tsx,jsx}');

function loadComponent(componentPath: string) {
  if (!componentPath) return null;
  const tsxKey = `/src/pages/${componentPath}.tsx`;
  const jsxKey = `/src/pages/${componentPath}.jsx`;
  const loader = (pages as Record<string, unknown>)[tsxKey] ?? (pages as Record<string, unknown>)[jsxKey];
  if (!loader) return null;
  return lazy(loader as () => Promise<{ default: React.ComponentType }>);
}

// ── Icon helper ─────────────────────────────────────────────────

function getIcon(iconName?: string): React.ReactNode {
  if (!iconName) return undefined;
  return <Icon icon={iconName} />;
}

// ── Menu UI items (for sidebar) ─────────────────────────────────

export function menusToMenuItems(menus: MenuRecord[]): AntMenuItem[] {
  return menus
    .filter((m) => m.type !== 3 && m.status === 0 && m.visible)
    .sort((a, b) => a.sort - b.sort)
    .map((menu): AntMenuItem => {
      const children = menu.children?.length
        ? menusToMenuItems(menu.children)
        : undefined;
      if (children?.length) {
        return {
          key: menu.path,
          icon: getIcon(menu.icon),
          label: menu.name,
          children,
        };
      }
      return {
        key: menu.path,
        icon: getIcon(menu.icon),
        label: menu.name,
      };
    });
}

// ── Menu → Route conversion ─────────────────────────────────────

/**
 * Flatten all type=2 menu items to a flat list.
 * This avoids the double-path nesting bug where directory routes
 * add their path prefix to children that already have full paths.
 *
 * Equivalent to Vue's flatMultiLevelRoutes(), but more aggressive:
 * we flatten ALL levels instead of just collapsing depth > 2.
 */
function flatMenus(menus: MenuRecord[]): MenuRecord[] {
  const result: MenuRecord[] = [];
  function walk(items: MenuRecord[]) {
    for (const m of items) {
      if (m.visible === false) {
        m.canTo = true;
      }
      if (m.type === 2 && m.component) {
        result.push(m);
      }
      if (m.children?.length) walk(m.children);
    }
  }
  walk(menus);
  return result;
}

function menuToRoute(menu: MenuRecord): RouteObject | null {
  // Skip external links
  if (menu.path.startsWith('http://') || menu.path.startsWith('https://')) {
    return null;
  }

  const routePath = menu.path.startsWith('/')
    ? menu.path.slice(1)
    : menu.path;

  const LazyComponent = loadComponent(menu.component);
  if (!LazyComponent) return null;

  return {
    id: `menu-${menu.id}`,
    path: routePath,
    element: (
      <Suspense
        fallback={
          <div style={{ display: 'flex', justifyContent: 'center', alignItems: 'center', height: '100vh' }}>
            <Spin size="large" />
          </div>
        }
      >
        <LazyComponent />
      </Suspense>
    ),
  };
}

/**
 * 将菜单数据转换为路由配置
 * 1. 仅转换 type=2 且 status=0 的菜单项
 * 2. 路径前缀 '/' 会被移除（因为路由是相对于父路径的）
 * 3. 使用 Suspense 包裹组件，显示全屏加载状态
 * 4. 外部链接（http:// 或 https://）会被忽略，不生成路由
 * 5. 组件路径通过 Vite 的 glob 导入动态加载
 */
export function menusToRoutes(menus: MenuRecord[]): RouteObject[] {
  return flatMenus(menus)
    .filter((m) => m.status === 0)
    .sort((a, b) => a.sort - b.sort)
    .map((menu) => menuToRoute(menu))
    .filter((r): r is RouteObject => r !== null);
}

// ── Open keys & breadcrumbs ─────────────────────────────────────

export function findOpenKeys(
  path: string,
  menus: MenuRecord[],
  parents: string[] = [],
): string[] {
  for (const menu of menus) {
    if (menu.path === path) return parents;
    if (menu.children?.length) {
      const found = findOpenKeys(path, menu.children, [
        ...parents,
        menu.path,
      ]);
      if (found.length) return found;
    }
  }
  return [];
}

export function findBreadcrumb(
  path: string,
  menus: MenuRecord[],
  trail: { title: string }[] = [],
): { title: string }[] {
  for (const menu of menus) {
    if (menu.path === path) return [...trail, { title: menu.name }];
    if (menu.children?.length) {
      const found = findBreadcrumb(path, menu.children, [
        ...trail,
        { title: menu.name },
      ]);
      if (found.length > trail.length + 1) return found;
    }
  }
  return trail;
}

export function findActiveMenuMeta(
  path: string,
  menus: MenuRecord[],
): string | null {
  for (const menu of menus) {
    if (menu.path === path) return menu.activeMenu ?? null;
    if (menu.children?.length) {
      const found = findActiveMenuMeta(path, menu.children);
      if (found) return found;
    }
  }
  return null;
}