AIRegulation-DocAnalysis/frontend/src/components/layout/KeepAliveViewport.tsx

import { useEffect, useState } from 'react';

import { appTabs, type AppTabConfig } from '../../router/tabs';

interface KeepAliveViewportProps {
  activeTab: AppTabConfig;
}

export function KeepAliveViewport({ activeTab }: KeepAliveViewportProps) {
  const [mountedTabIds, setMountedTabIds] = useState<string[]>([activeTab.id]);

  useEffect(() => {
    const timerId = window.setTimeout(() => {
      setMountedTabIds((prev) => (prev.includes(activeTab.id) ? prev : [...prev, activeTab.id]));
    }, 0);
    return () => window.clearTimeout(timerId);
  }, [activeTab.id]);

  return (
    <div className="flex min-h-0 flex-1">
      {appTabs.map((tab) => {
        const shouldRender = tab.keepAlive ? mountedTabIds.includes(tab.id) : tab.id === activeTab.id;
        if (!shouldRender) {
          return null;
        }

        const TabComponent = tab.component;
        const isActive = tab.id === activeTab.id;

        return (
          <div
            key={tab.id}
            aria-hidden={!isActive}
            className={[
              'min-h-0 flex-1',
              isActive ? 'flex' : 'hidden',
            ].join(' ')}
          >
            <TabComponent />
          </div>
        );
      })}
    </div>
  );
}