import React, { useState, useEffect, useRef } from 'react';
import { Link, useLocation } from 'react-router-dom';
// We keep heroicons for fallback, but nav uses custom SVGs from /public/icons
import { PowerIcon, HomeIcon, AcademicCapIcon, BookOpenIcon, HandThumbUpIcon, WrenchScrewdriverIcon, ChatBubbleLeftRightIcon, Cog6ToothIcon } from '@heroicons/react/24/outline';
import HitokotoBar from './HitokotoBar';
import { api } from '../services/api';

interface User {
  name: string;
  email: string;
  role: string;
}

const Layout: React.FC<{ children: React.ReactNode }> = ({ children }) => {
  const location = useLocation();
  const [viewMode, setViewMode] = useState<'admin' | 'student' | 'auto'>(() => {
    try {
      const saved = localStorage.getItem('viewMode') as any;
      return saved === 'admin' || saved === 'student' ? saved : 'auto';
    } catch { return 'auto'; }
  });
  const [isTransitioning] = useState(false);
  const userData = localStorage.getItem('user');
  const user: User | null = userData ? JSON.parse(userData) : null;
  const [unreadCount, setUnreadCount] = useState<number>(0);

  // Lightweight online presence: send heartbeat periodically
  useEffect(() => {
    let timer: any;
    const sendHeartbeat = async () => {
      try {
        if (!user?.email) return;
        const token = localStorage.getItem('token') || '';
        const base = (((api.defaults as any)?.baseURL as string) || '').replace(/\/$/, '');
        await fetch(`${base}/api/auth/online/heartbeat`, {
          method: 'POST',
          headers: {
            'Authorization': `Bearer ${token}`,
            'Content-Type': 'application/json',
            'user-role': user.role || 'visitor',
            'user-info': userData || ''
          },
          body: JSON.stringify({ email: user.email, path: location.pathname })
        });
      } catch {}
    };
    sendHeartbeat();
    timer = setInterval(sendHeartbeat, 60000);
    return () => { if (timer) clearInterval(timer); };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [user?.email]);

  // Send a heartbeat on route changes for fresher session tracking
  useEffect(() => {
    const run = async () => {
      try {
        if (!user?.email) return;
        const token = localStorage.getItem('token') || '';
        const base = (((api.defaults as any)?.baseURL as string) || '').replace(/\/$/, '');
        await fetch(`${base}/api/auth/online/heartbeat`, {
          method: 'POST',
          headers: {
            'Authorization': `Bearer ${token}`,
            'Content-Type': 'application/json',
            'user-role': user.role || 'visitor',
            'user-info': userData || ''
          },
          body: JSON.stringify({ email: user.email, path: location.pathname })
        });
      } catch {}
    };
    run();
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [location.pathname]);

  // React to external view mode changes (from Manage toggle)
  useEffect(() => {
    const handler = (e: any) => {
      const mode = e?.detail;
      if (mode === 'admin' || mode === 'student') {
        setViewMode(mode);
      }
    };
    window.addEventListener('view-mode-change', handler as any);
    return () => window.removeEventListener('view-mode-change', handler as any);
  }, []);

  // Admin unread message badge (non-invasive)
  useEffect(() => {
    let timer: any;
    const run = async () => {
      try {
        if (user?.role !== 'admin') return;
        const token = localStorage.getItem('token') || '';
        const base = (((api.defaults as any)?.baseURL as string) || '').replace(/\/$/, '');
        const resp = await fetch(`${base}/api/messages/unread-count`, {
          headers: {
            'Authorization': `Bearer ${token}`,
            'user-role': 'admin',
            'user-info': userData || ''
          }
        });
        if (resp.ok) {
          const data = await resp.json();
          if (typeof data?.count === 'number') setUnreadCount(data.count);
        }
      } catch {}
    };
    run();
    if (user?.role === 'admin') {
      timer = setInterval(run, 60000);
    }
    return () => { if (timer) clearInterval(timer); };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [user?.role]);

  // Admin unread message badge (non-invasive)
  useEffect(() => {
    let timer: any;
    const run = async () => {
      try {
        if (user?.role !== 'admin') return;
        const token = localStorage.getItem('token') || '';
        const base = (((api.defaults as any)?.baseURL as string) || '').replace(/\/$/, '');
        const resp = await fetch(`${base}/api/messages/unread-count`, {
          headers: {
            'Authorization': `Bearer ${token}`,
            'user-role': 'admin',
            'user-info': userData || ''
          }
        });
        if (resp.ok) {
          const data = await resp.json();
          if (typeof data?.count === 'number') setUnreadCount(data.count);
        }
      } catch {}
    };
    run();
    if (user?.role === 'admin') {
      timer = setInterval(run, 60000);
    }
    return () => { if (timer) clearInterval(timer); };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [user?.role]);

  const handleLogout = () => {
    try {
    localStorage.removeItem('token');
    localStorage.removeItem('user');
    } catch {}
    window.location.href = '/login';
  };

  // heroicons already imported at top

  let navigation = [
    { name: 'Home', href: '/dashboard', icon: HomeIcon },
    { name: 'Tutorial Tasks', href: '/tutorial-tasks', icon: AcademicCapIcon },
    { name: 'Weekly Practice', href: '/weekly-practice', icon: BookOpenIcon },
    { name: 'Votes', href: '/votes', icon: HandThumbUpIcon },
    { name: 'Toolkit', href: '/toolkit', icon: WrenchScrewdriverIcon },
    { name: 'Slides', href: '/slides', icon: BookOpenIcon },
    { name: 'Feedback', href: '/feedback', icon: ChatBubbleLeftRightIcon },
  ];

  // Effective role based on viewMode
  const effectiveRole = (() => {
    if (viewMode === 'auto') return user?.role;
    return viewMode === 'student' ? 'student' : 'admin';
  })();

  // Hide Slides for visitors
  if (!user || effectiveRole === 'visitor') {
    navigation = navigation.filter(item => item.name !== 'Slides');
  }

  // Add Manage link for admin users (always keep in nav)
  if (user?.role === 'admin') {
    navigation.push({ name: 'Manage', href: '/manage', icon: Cog6ToothIcon });
  }

  const iconSrcFor = (name: string): string => {
    switch (name) {
      case 'Home': return '/icons/home.svg';
      case 'Tutorial Tasks': return '/icons/tutorial tasks.svg';
      case 'Weekly Practice': return '/icons/weekly practice.svg';
      case 'Votes': return '/icons/votes.svg';
      case 'Toolkit': return '/icons/toolkit.svg';
      case 'Slides': return '/icons/slides.svg';
      case 'Feedback': return '/icons/feedback.svg';
      case 'Manage': return '/icons/manage.svg';
      default: return '/icons/home.svg';
    }
  };

  return (
    <div className="min-h-[calc(100vh+25vh)] text-ui-text bg-white app-shell" style={{ backgroundImage: 'url(/background/background.png)', backgroundSize: '100% auto', backgroundPosition: 'bottom', backgroundRepeat: 'no-repeat', paddingBottom: '25vh' }}>
      {/* Top Bar */}
      <header className="sticky top-0 z-40 bg-ui-panel/80 backdrop-blur border-b border-ui-border">
        <div className="px-4 sm:px-6 lg:px-8 h-14 flex items-center justify-between">
          <Link to="/dashboard" className="text-[1.6rem] font-bold text-ui-text flex items-center -ml-4 hover:text-ui-text" style={{ fontFamily: 'Lobster, Inter, system-ui, sans-serif' }}>
            <img src="/favicon-512x512.png" alt="logo" className="h-8 w-8 mr-2" />
            TransHub
                </Link>
          <div />
              </div>
      </header>

      {/* Shell: Sidebar + Content */}
      <div className="flex">
        {/* Sidebar */}
        <aside className="hidden md:flex md:flex-col w-60 fixed top-14 left-0 bottom-0 border-r border-ui-border bg-ui-panel/80 backdrop-blur z-30 sidebar-shell">
          <nav className="p-4 space-y-2 flex-1 sidebar-nav">
                {navigation.map((item) => {
                  const isActive = location.pathname === item.href;
                  return (
                    <Link
                      key={item.name}
                      to={item.href}
                  className={`flex items-center px-3 py-2 rounded-lg text-[0.95rem] font-medium transition-colors ${
                    isActive ? 'text-ui-text' : 'text-ui-text/80 hover:text-ui-text'
                      }`}
                    >
                  <img src={iconSrcFor(item.name)} alt="" className="h-6 w-6 mr-3" />
                  <span>{item.name}</span>
                    </Link>
                  );
                })}
          </nav>
          <div className="p-3 border-t border-ui-border mt-auto sidebar-footer">
            {user ? (
              <button onClick={handleLogout} className="w-full flex items-center justify-start px-3 py-2 rounded-md text-sm font-medium text-ui-text/80 hover:bg-ui-panel/60">
                <PowerIcon className="h-4 w-4 mr-2" />
                Log Out
                  </button>
            ) : (
              <Link to="/login" className="w-full flex items-center justify-start px-3 py-2 rounded-md text-sm font-medium text-ui-text/80 hover:bg-ui-panel/60">
                <PowerIcon className="h-4 w-4 mr-2" />
                Log In
              </Link>
            )}
        </div>
        </aside>

                        {/* Main Content */}
        <main className="flex-1 p-4 sm:p-6 lg:p-8 md:ml-60">
                    {!isTransitioning && children}
                  </main>
      </div>
      
      {/* Transition Loading Indicator */}
      {isTransitioning && (
        <div className="fixed top-1/2 left-1/2 transform -translate-x-1/2 -translate-y-1/2 z-50">
          <div className="bg-ui-panel rounded-lg shadow-lg p-4 flex items-center space-x-3 border border-ui-border">
            <div className="animate-spin rounded-full h-6 w-6 border-b-2 border-ui-neonCyan"></div>
            <span className="text-ui-text font-medium">Loading...</span>
          </div>
        </div>
      )}
      {/* <HitokotoBar /> */}
    </div>
  );
};

export default Layout;