// app/admin/page.tsx

"use client";

import { CalendarRange, ClipboardCheck, Loader2, Lock, Unlock, Users as UsersIcon } from 'lucide-react';
import React, { useEffect, useRef, useState } from 'react';
import { verifyLogin } from '../actions/admin';
import { OfflineBadge } from '../components/ui/OfflineBadge';
import { AppUser } from './adminTypes';
import { AttendanceTab } from './AttendanceTab';
import { ReportTab } from './ReportTab';
import { SetupTab } from './SetupTab';
import { useAdminState } from './useAdminState';

export default function Admin() {
    const [currentUser, setCurrentUser] = useState<AppUser | null>(null);
    const [isCheckingSession, setIsCheckingSession] = useState(true);

    const usernameRef = useRef<HTMLInputElement>(null);
    const pinRef = useRef<HTMLInputElement>(null);

    const [isLoading, setIsLoading] = useState(false);
    const [loginError, setLoginError] = useState(false);

    const [activeTab, setActiveTab] = useState<'setup' | 'today' | 'report'>('report');
    const adminState = useAdminState();

    useEffect(() => {
        const savedSession = localStorage.getItem('kullaberg_admin_session');
        if (savedSession) {
            const user = JSON.parse(savedSession) as AppUser;
            setCurrentUser(user);
            if (user.role === 'Viewer') setActiveTab('report');
            else if (user.role === 'Staff') setActiveTab('today');
            else setActiveTab('today');
        }
        setIsCheckingSession(false);
    }, []);

    const handleLogin = async (e: React.SyntheticEvent<HTMLFormElement>) => {
        e.preventDefault();
        setLoginError(false);

        const usernameVal = usernameRef.current?.value || '';
        const pinVal = pinRef.current?.value || '';

        if (!usernameVal || !pinVal) {
            setLoginError(true);
            return;
        }

        setIsLoading(true);

        const result = await verifyLogin(usernameVal, pinVal);
        if (result.success && result.user) {
            const user = result.user as AppUser;
            setCurrentUser(user);
            localStorage.setItem('kullaberg_admin_session', JSON.stringify(user));
            if (user.role === 'Viewer') setActiveTab('report');
            else if (user.role === 'Staff') setActiveTab('today');
            else setActiveTab(adminState.periods.length > 0 ? 'today' : 'setup');
        } else {
            if (pinRef.current) pinRef.current.value = '';
            setLoginError(true);
        }
        setIsLoading(false);
    };

    const handleLogout = () => {
        setCurrentUser(null);
        localStorage.removeItem('kullaberg_admin_session');
    };

    if (isCheckingSession) return <div className="flex justify-center py-20"><Loader2 className="animate-spin text-slate-teal" size={40} /></div>;

    if (!currentUser) {
        return (
            <div className="flex flex-col items-center justify-center py-20 animate-fade-in px-4">
                <div className="bg-eggshell border-2 border-slate-teal/20 p-6 md:p-8 rounded-2xl shadow-sm w-full max-w-sm text-center">
                    <div className="bg-slate-teal/10 w-16 h-16 rounded-full flex items-center justify-center mx-auto mb-4">
                        <Lock size={32} className="text-slate-teal" />
                    </div>
                    <h2 className="text-2xl font-black text-ebony uppercase mb-6 tracking-widest">Admin Login</h2>

                    <form onSubmit={handleLogin} className="space-y-3 text-left">
                        <div className="relative">
                            <input
                                id="username"
                                name="username"
                                autoComplete="username"
                                type="text"
                                ref={usernameRef}
                                placeholder="Användarnamn"
                                className="w-full bg-white border border-slate-teal/20 text-center text-ebony font-bold p-3 rounded-xl focus:outline-none focus:border-slate-teal"
                                onChange={() => setLoginError(false)}
                            />
                        </div>

                        <div className="relative">
                            <input
                                id="pin"
                                name="pin"
                                autoComplete="current-password"
                                type="password"
                                ref={pinRef}
                                placeholder="•••••"
                                className={`w-full bg-white border text-center text-2xl text-ebony font-mono p-3 rounded-xl focus:outline-none ${loginError ? 'border-emergency/50 bg-emergency/5' : 'border-slate-teal/20 focus:border-slate-teal'}`}
                                onChange={() => setLoginError(false)}
                            />
                        </div>

                        {loginError && <p className="text-emergency text-xs font-bold text-center mt-1">Fel namn eller lösenord.</p>}

                        <button type="submit" disabled={isLoading} className="w-full bg-slate-teal text-eggshell font-black uppercase tracking-widest py-3 mt-2 rounded-xl hover:bg-ebony transition-colors disabled:opacity-50">
                            {isLoading ? <Loader2 className="animate-spin mx-auto" /> : 'Logga in'}
                        </button>
                    </form>
                </div>
            </div>
        );
    }

    const availableTabs = [];
    if (currentUser.role === 'Admin') availableTabs.push({ id: 'setup', icon: CalendarRange, label: 'Perioder' });
    if (currentUser.role === 'Admin' || currentUser.role === 'Staff') availableTabs.push({ id: 'today', icon: ClipboardCheck, label: 'Närvaro' });
    availableTabs.push({ id: 'report', icon: UsersIcon, label: 'Rapport' });

    return (
        <div className="space-y-6 animate-fade-in w-full">
            <div className="flex flex-col md:flex-row justify-between md:items-end border-b border-slate-teal/20 pb-3 gap-2">
                <div className="flex flex-col">
                    <div className="flex items-center gap-3">
                        <Unlock className="text-seafoam" size={24} />
                        <h1 className="text-2xl font-black text-slate-teal uppercase tracking-widest">Admin</h1>
                    </div>
                    {adminState.isOffline && <OfflineBadge className="mt-2" />}
                </div>
                <div className="flex items-center gap-3 text-sm md:text-right bg-eggshell md:bg-transparent p-2 md:p-0 rounded-lg">
                    <span className="font-bold text-ebony">Inloggad: {currentUser.name}</span>
                    <span className="text-slate-teal/30">|</span>
                    <button onClick={handleLogout} className="font-bold text-slate-teal hover:text-goldenrod transition-colors">Logga ut</button>
                </div>
            </div>

            {adminState.isLoadingData && (adminState.periods.length === 0 || adminState.scheduleData.length === 0) ? (
                <div className="flex flex-col items-center justify-center py-20 text-slate-teal">
                    <Loader2 size={40} className="animate-spin mb-4" />
                    <p className="font-bold text-sm animate-pulse">Hämtar data...</p>
                </div>
            ) : (
                <>
                    {availableTabs.length > 1 && (
                        <div className="flex gap-2 overflow-x-auto scrollbar-hide">
                            {availableTabs.map(tab => (
                                <button
                                    key={tab.id}
                                    onClick={() => setActiveTab(tab.id as any)}
                                    className={`flex items-center px-4 py-2.5 rounded-lg font-bold text-xs uppercase tracking-widest transition-colors ${activeTab === tab.id ? 'bg-slate-teal text-eggshell' : 'bg-white/60 text-slate-teal hover:bg-slate-teal/10'}`}
                                >
                                    <tab.icon size={16} className="mr-2 hidden md:block shrink-0" /> {tab.label}
                                </button>
                            ))}
                        </div>
                    )}

                    {activeTab === 'setup' && currentUser.role === 'Admin' && <SetupTab {...adminState} />}
                    {activeTab === 'today' && (currentUser.role === 'Admin' || currentUser.role === 'Staff') && (
                        <AttendanceTab
                            periods={adminState.periods}
                            attendance={adminState.attendance}
                            setManualAttendance={adminState.setManualAttendance}
                            bulkSetManualAttendance={adminState.bulkSetManualAttendance}
                            addPendingAttendance={adminState.addPendingAttendance}
                            removeAttendanceEntry={adminState.removeAttendanceEntry}
                            activePeriodId={adminState.activePeriodId}
                            setActivePeriodId={adminState.setActivePeriodId}
                            scheduleData={adminState.scheduleData}
                        />
                    )}
                    {activeTab === 'report' && (
                        <ReportTab
                            periods={adminState.periods}
                            attendance={adminState.attendance}
                            activePeriodId={adminState.activePeriodId}
                            setActivePeriodId={adminState.setActivePeriodId}
                            currentUserRole={currentUser.role}
                            scheduleData={adminState.scheduleData}
                        />
                    )}
                </>
            )}
        </div>
    );
}