import React, { useState, useEffect, useRef } from 'react';
import { NavLink, useLocation } from 'react-router-dom';
import { useTranslation } from 'react-i18next';
import { useAuth } from '@/lib/auth';
import { useTenant } from '@/lib/tenant';
import {
    BarChart2, TrendingUp, Users, BookOpen, Mic, Building2, Activity,
    Lightbulb, Database, Megaphone, LogOut, LayoutTemplate, MessageSquare,
    Bot, Menu, X, CreditCard
} from 'lucide-react';
import RoleGuard from '@/components/RoleGuard';
import LanguageSwitcher from '@/components/LanguageSwitcher';
import AdminChat, { type AdminChatPage } from '@/components/AdminChat';

interface MainLayoutProps {
    children: React.ReactNode;
    isSuperAdmin: boolean;
    orgs: any[];
}

function useAdminChatPage(): AdminChatPage | null {
    const { pathname } = useLocation();
    if (pathname === '/billing') return null; // billing has its own inline chat
    if (pathname.startsWith('/settings')) return 'settings';
    if (pathname.startsWith('/whatsapp-templates')) return 'templates';
    if (pathname.startsWith('/ai-setup') || pathname.startsWith('/kb')) return 'agent';
    if (pathname.startsWith('/clients/new') || pathname.startsWith('/onboarding')) return 'onboarding';
    return 'general';
}

export default function MainLayout({ children, isSuperAdmin, orgs }: MainLayoutProps) {
    const { t } = useTranslation();
    const { logout, user, token } = useAuth();
    const { selectedOrgId, setSelectedOrgId, currentOrg } = useTenant();
    const [sidebarOpen, setSidebarOpen] = useState(false);
    const [unreadCount, setUnreadCount] = useState(0);
    const chatPage = useAdminChatPage();
    const { pathname } = useLocation();
    const esRef = useRef<EventSource | null>(null);

    const isCrmActive = !!currentOrg?.isCrmActive;
    const isEdTechActive = !!currentOrg?.isEdTechActive;

    // Reset unread count when user is on the conversations page
    useEffect(() => {
        if (pathname.startsWith('/conversations') || pathname.startsWith('/crm')) {
            setUnreadCount(0);
        }
    }, [pathname]);

    // SSE — track new inbound messages for the notification badge
    useEffect(() => {
        if (!selectedOrgId || !token) return;
        const apiBase = import.meta.env.VITE_API_URL || '';
        const es = new EventSource(`${apiBase}/v1/organizations/${selectedOrgId}/stream?token=${encodeURIComponent(token)}`);
        esRef.current = es;
        es.addEventListener('message', (event) => {
            try {
                const payload = JSON.parse(event.data);
                if (payload.type === 'new-message') {
                    // Only increment if not currently viewing conversations
                    const isViewingConversations = window.location.pathname.startsWith('/conversations') || window.location.pathname.startsWith('/crm');
                    if (!isViewingConversations) {
                        setUnreadCount(n => n + 1);
                    }
                }
            } catch { /* ignore */ }
        });
        es.onerror = () => es.close();
        return () => { es.close(); esRef.current = null; };
    }, [selectedOrgId, token]);

    const navItems = [
        { to: '/',                  label: t('nav.home'),          icon: <BarChart2 className="w-4 h-4" />,                        end: true },
        { to: '/analytics',         label: t('common.analytics'),  icon: <TrendingUp className="w-4 h-4 text-amber-500" /> },
        { to: '/conversations',     label: t('nav.conversations'), icon: <MessageSquare className="w-4 h-4 text-sky-400" /> },
        // CRM items
        { to: '/contacts',          label: t('common.clients'),    icon: <Users className="w-4 h-4 text-blue-400" />,              show: isCrmActive },
        { to: '/campaign-history',  label: t('nav.campaigns'),     icon: <Megaphone className="w-4 h-4 text-amber-500" />,         show: isCrmActive },
        { to: '/whatsapp-templates',label: t('nav.templates'),     icon: <LayoutTemplate className="w-4 h-4 text-indigo-400" />,   show: isCrmActive },
        // EdTech items
        { to: '/content',           label: t('nav.content'),       icon: <BookOpen className="w-4 h-4" />,                         show: isEdTechActive },
        { to: '/live-feed',         label: t('nav.moderation'),    icon: <Mic className="w-4 h-4 text-emerald-500" />,             show: isEdTechActive },
        { to: '/users',             label: t('nav.users'),         icon: <Users className="w-4 h-4" />,                            show: isEdTechActive },
        // Shared — accessible to all org members
        { to: '/kb',                label: t('nav.kb'),            icon: <Database className="w-4 h-4 text-violet-400" /> },
        { to: '/ai-setup',          label: t('nav.ai_setup'),      icon: <Bot className="w-4 h-4 text-pink-400" /> },
        // Super admin only
        { to: '/clients',           label: t('nav.b2b'),           icon: <Building2 className="w-4 h-4 text-indigo-400" />,        show: isSuperAdmin },
        { to: '/training',          label: t('nav.training'),      icon: <Activity className="w-4 h-4 text-purple-400" />,         show: isSuperAdmin },
        // Always last
        { to: '/billing',           label: t('nav.billing'),        icon: <CreditCard className="w-4 h-4 text-emerald-400" /> },
        { to: '/settings',          label: t('common.settings'),   icon: <Lightbulb className="w-4 h-4" /> },
    ].filter(item => item.show !== false);

    const linkClass = ({ isActive }: { isActive: boolean }) =>
        `flex items-center gap-3 px-3 py-2.5 rounded-xl text-sm font-medium transition-all ${
            isActive
                ? 'bg-white/15 text-white'
                : 'text-slate-400 hover:text-white hover:bg-white/10'
        }`;

    const avatarInitial = (user?.name?.trim()?.[0] ?? user?.email?.[0] ?? 'U').toUpperCase();
    const displayName = user?.name || user?.email || '—';
    const displayRole = (user?.role ?? '').toLowerCase().replace(/_/g, ' ');

    const sidebarInner = (
        <>
            {/* Logo / org name */}
            <div className="text-xl font-bold mb-8 flex items-center gap-3 shrink-0">
                {currentOrg?.brandingData?.logoUrl ? (
                    <img src={currentOrg.brandingData.logoUrl} className="h-8 w-8 object-contain rounded" alt="Logo" />
                ) : (
                    <span className="text-2xl">🎓</span>
                )}
                <span className="truncate text-base">{currentOrg?.name || 'Admin'}</span>
            </div>

            {/* Super-admin org selector */}
            <RoleGuard requireSuperAdmin>
                <div className="mb-6 shrink-0">
                    <label className="block text-[10px] uppercase font-bold text-slate-500 tracking-wider mb-2">
                        Multi-Tenant
                    </label>
                    <select
                        value={selectedOrgId || ''}
                        onChange={e => setSelectedOrgId(e.target.value)}
                        className="w-full bg-slate-800 text-slate-200 text-xs px-3 py-2.5 rounded-xl outline-none focus:ring-1 focus:ring-slate-600 appearance-none cursor-pointer"
                    >
                        <option value="">Sélectionner une école...</option>
                        {orgs.map(o => (
                            <option key={o.id} value={o.id}>{o.name}</option>
                        ))}
                    </select>
                </div>
            </RoleGuard>

            {/* Nav — scrollable so it never overflows */}
            <nav className="space-y-0.5 flex-1 overflow-y-auto min-h-0 -mx-1 px-1">
                {navItems.map(n => {
                    const showBadge = n.to === '/conversations' && unreadCount > 0;
                    return (
                        <NavLink
                            key={n.to}
                            to={n.to}
                            end={n.end}
                            className={linkClass}
                            onClick={() => { setSidebarOpen(false); if (n.to === '/conversations') setUnreadCount(0); }}
                        >
                            {n.icon}
                            <span className="truncate flex-1">{n.label}</span>
                            {showBadge && (
                                <span className="ml-auto bg-red-500 text-white text-[10px] font-bold rounded-full min-w-[18px] h-[18px] flex items-center justify-center px-1 shrink-0">
                                    {unreadCount > 99 ? '99+' : unreadCount}
                                </span>
                            )}
                        </NavLink>
                    );
                })}
            </nav>

            {/* Footer */}
            <div className="pt-4 mt-4 border-t border-slate-800 shrink-0">
                <div className="mb-4">
                    <label className="block text-[10px] uppercase font-bold text-slate-500 tracking-wider mb-2">
                        Interface
                    </label>
                    <LanguageSwitcher />
                </div>

                <div className="flex items-center gap-3 px-1 mb-3">
                    <div className="w-8 h-8 rounded-full bg-indigo-500 flex items-center justify-center font-bold text-xs shrink-0">
                        {avatarInitial}
                    </div>
                    <div className="flex-1 min-w-0">
                        <p className="text-sm font-bold truncate">{displayName}</p>
                        <p className="text-[10px] text-slate-500 truncate capitalize">{displayRole}</p>
                    </div>
                </div>

                <button
                    onClick={logout}
                    className="w-full flex items-center gap-3 px-3 py-2 text-xs text-slate-500 hover:text-white transition group rounded-xl hover:bg-white/5"
                >
                    <LogOut className="w-3.5 h-3.5 group-hover:text-red-400 transition" />
                    {t('common.logout')}
                </button>
            </div>
        </>
    );

    return (
        <div className="min-h-screen bg-gray-50 flex">

            {/* ── Desktop sidebar (always visible ≥ lg) ── */}
            <aside className="hidden lg:flex w-64 bg-slate-900 text-white p-5 flex-col shrink-0 h-screen sticky top-0">
                {sidebarInner}
            </aside>

            {/* ── Mobile: backdrop overlay ── */}
            {sidebarOpen && (
                <div
                    className="fixed inset-0 bg-black/50 backdrop-blur-sm z-30 lg:hidden"
                    onClick={() => setSidebarOpen(false)}
                />
            )}

            {/* ── Mobile: sliding sidebar ── */}
            <aside
                className={`fixed top-0 left-0 h-full w-64 bg-slate-900 text-white p-5 flex flex-col z-40 transition-transform duration-200 ease-in-out lg:hidden ${
                    sidebarOpen ? 'translate-x-0' : '-translate-x-full'
                }`}
            >
                <button
                    onClick={() => setSidebarOpen(false)}
                    className="absolute top-4 right-4 text-slate-400 hover:text-white transition"
                    aria-label="Fermer le menu"
                >
                    <X className="w-5 h-5" />
                </button>
                {sidebarInner}
            </aside>

            {/* ── Main content area ── */}
            <div className="flex-1 flex flex-col min-w-0">

                {/* Mobile top bar */}
                <header className="lg:hidden flex items-center gap-3 px-4 py-3 bg-slate-900 text-white sticky top-0 z-20 shrink-0">
                    <button
                        onClick={() => setSidebarOpen(true)}
                        className="text-slate-400 hover:text-white transition"
                        aria-label="Ouvrir le menu"
                    >
                        <Menu className="w-5 h-5" />
                    </button>
                    <span className="font-bold text-sm truncate">{currentOrg?.name || 'Admin'}</span>
                </header>

                <main className="flex-1 overflow-auto">
                    {children}
                </main>
            </div>

            {/* Global AI assistant — hidden on /billing (has its own inline chat) */}
            {chatPage && selectedOrgId && <AdminChat page={chatPage} />}
        </div>
    );
}