import React, { useMemo, useState, useEffect } from 'react';
import { Transaction, TransactionType, ExpenseCategory, IncomeCategory, BillReminder } from '../types';
import EditTransactionModal from './EditTransactionModal';
import CalendarView from './CalendarView';
import BillReminders, { getDaysRemaining } from './BillReminders';

interface LedgerPageProps {
  transactions: Transaction[];
  onUpdateTransaction: (t: Transaction) => Promise<void>;
  onDeleteTransaction: (id: string) => Promise<void>;
  budgets: Record<string, number>;
  setBudgets: (val: Record<string, number>) => void;
  reminders: BillReminder[];
  onAddReminder: (r: BillReminder) => void;
  onUpdateReminder: (r: BillReminder) => void;
  onDeleteReminder: (id: string) => void;
  onToggleReminder: (id: string) => void;
}

const CARD_THEMES = [
  { id: 'dark-indigo', class: 'from-gray-900 via-indigo-950 to-black', themeColor: 'bg-indigo-600', name: '暗夜霓虹' },
  { id: 'sunset', class: 'from-orange-500 via-rose-600 to-pink-700', themeColor: 'bg-rose-600', name: '落日熔金' },
  { id: 'emerald', class: 'from-emerald-600 via-teal-700 to-cyan-900', themeColor: 'bg-emerald-600', name: '薄荷森林' },
  { id: 'royal', class: 'from-blue-700 via-indigo-800 to-indigo-950', themeColor: 'bg-blue-700', name: '皇家礼赞' },
  { id: 'rose', class: 'from-rose-500 via-pink-600 to-purple-800', themeColor: 'bg-purple-600', name: '浪漫巴黎' },
];

const getLocalDateString = (date = new Date()) => {
    const offset = date.getTimezoneOffset();
    const localDate = new Date(date.getTime() - (offset * 60 * 1000));
    return localDate.toISOString().split('T')[0];
};

const LedgerPage: React.FC<LedgerPageProps> = ({ 
  transactions, onUpdateTransaction, onDeleteTransaction, budgets, reminders, 
  onAddReminder, onUpdateReminder, onDeleteReminder, onToggleReminder 
}) => {
  const [editingTransaction, setEditingTransaction] = useState<Transaction | null>(null);
  const [subTab, setSubTab] = useState<'details' | 'calendar' | 'bills'>('details');
  const [selectedMonth, setSelectedMonth] = useState(getLocalDateString().slice(0, 7)); 
  const [themeIndex, setThemeIndex] = useState(() => Number(localStorage.getItem('cui_card_theme')) || 0);

  useEffect(() => {
    localStorage.setItem('cui_card_theme', themeIndex.toString());
  }, [themeIndex]);

  const currentTheme = CARD_THEMES[themeIndex];

  // Monthly stats for the top cards
  const monthlyTransactions = useMemo(() => transactions.filter(t => t.date.startsWith(selectedMonth)), [transactions, selectedMonth]);
  const currentMonthExpense = useMemo(() => monthlyTransactions.filter(t => t.type === TransactionType.EXPENSE).reduce((sum, t) => sum + t.amount, 0), [monthlyTransactions]);
  const currentMonthIncome = useMemo(() => monthlyTransactions.filter(t => t.type === TransactionType.INCOME).reduce((sum, t) => sum + t.amount, 0), [monthlyTransactions]);
  const todayExpense = useMemo(() => transactions.filter(t => t.date === getLocalDateString() && t.type === TransactionType.EXPENSE).reduce((sum, t) => sum + t.amount, 0), [transactions]);
  const currentMonthBalance = currentMonthIncome - currentMonthExpense;

  const cycleTheme = () => setThemeIndex((prev) => (prev + 1) % CARD_THEMES.length);

  const getIcon = (t: Transaction) => {
      if (t.type === TransactionType.INCOME) return '💰';
      switch (t.category) {
          case ExpenseCategory.FOOD: return '🍔';
          case ExpenseCategory.SHOPPING: return '🛍️';
          case ExpenseCategory.TRANSPORT: return '🚗';
          case ExpenseCategory.HOUSING: return '🏠';
          case ExpenseCategory.ENTERTAINMENT: return '🎬';
          case ExpenseCategory.MEDICAL: return '💊';
          case ExpenseCategory.SOCIAL: return '🤝';
          case ExpenseCategory.EDUCATION: return '📚';
          case ExpenseCategory.FINANCE: return '🏦';
          case ExpenseCategory.CHILD: return '👶';
          case ExpenseCategory.PET: return '🐱';
          case ExpenseCategory.CAR: return '🚘';
          case ExpenseCategory.BEAUTY: return '💄';
          case ExpenseCategory.BUSINESS: return '💼';
          case ExpenseCategory.MISC: return '🧺';
          default: return '🧾';
      }
  };

  // Grouped transactions for "Details" - Filtered by selectedMonth
  const allGroupedTransactions = useMemo(() => {
    const grouped = monthlyTransactions.reduce((acc, t) => {
        if (!acc[t.date]) acc[t.date] = [];
        acc[t.date].push(t);
        return acc;
    }, {} as Record<string, Transaction[]>);
    
    return Object.entries(grouped).sort((a, b) => new Date(b[0]).getTime() - new Date(a[0]).getTime());
  }, [monthlyTransactions]);

  return (
      <div className="h-full flex flex-col bg-gray-50 overflow-y-auto no-scrollbar pb-24 md:pb-4 relative font-sans text-gray-900 antialiased">
          <div className="px-5 pt-8 pb-4">
             <div className="flex justify-between items-center mb-8">
                 <div>
                    <h1 className="text-2xl font-black text-gray-800 tracking-tight">我的账本</h1>
                    <p className="text-[10px] text-gray-400 font-bold uppercase tracking-widest">Financial Ledger</p>
                 </div>
                 <input 
                    type="month" 
                    value={selectedMonth} 
                    onChange={e => setSelectedMonth(e.target.value)}
                    className="bg-gray-100 rounded-lg px-3 py-1.5 text-sm font-bold text-gray-600 outline-none border-none shadow-sm focus:ring-1 focus:ring-indigo-300 transition-all"
                />
             </div>

             <div className="grid grid-cols-2 gap-4">
                 <div className={`col-span-2 bg-gradient-to-br ${currentTheme.class} rounded-[2.5rem] p-8 text-white shadow-2xl shadow-indigo-200/40 relative overflow-hidden group transition-all duration-700`}>
                     <button 
                        onClick={cycleTheme} 
                        className="absolute bottom-4 right-5 p-1 bg-white/10 rounded-full hover:bg-white/20 transition-all z-20 opacity-40 backdrop-blur-sm border border-white/5"
                     >
                        <svg className="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor"><path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M4 4v5h.582m15.356 2A8.001 8.001 0 004.582 9m0 0H9m11 11v-5h-.581m0 0a8.003 8.003 0 01-15.357-2m15.357 2H15" /></svg>
                     </button>
                     
                     <div className="relative z-10 pointer-events-none">
                        <div className="flex justify-between items-start gap-4">
                            <div className="flex-1 min-w-0">
                                <div className="text-white/80 text-sm font-black mb-2 flex items-center gap-2 uppercase tracking-widest"><span className="w-1.5 h-1.5 bg-white/60 rounded-full"></span>本月总支出</div>
                                <div className="text-3xl sm:text-4xl font-black tracking-tighter font-mono whitespace-nowrap overflow-hidden">-¥{currentMonthExpense.toFixed(0)}</div>
                            </div>
                            <div className="text-right shrink-0">
                                <div className="text-white/50 text-xs font-black mb-1.5 uppercase tracking-widest">今日支出</div>
                                <div className="text-xl sm:text-2xl font-black font-mono text-white/90">-¥{todayExpense.toFixed(0)}</div>
                            </div>
                        </div>
                         <div className="mt-10 flex gap-8 pt-6 border-t border-white/10">
                             <div className="shrink-0">
                                 <div className="text-xs text-white/60 font-black uppercase tracking-widest mb-1">本月总收入</div>
                                 <div className="font-mono font-black text-xl sm:text-2xl text-white/90">+¥{currentMonthIncome.toFixed(0)}</div>
                             </div>
                             <div className="shrink-0">
                                 <div className="text-xs text-white/60 font-black uppercase tracking-widest mb-1">本月结余</div>
                                 <div className="font-mono font-black text-xl sm:text-2xl text-white/90">
                                    {currentMonthBalance < 0 ? '-' : ''}¥{Math.abs(currentMonthBalance).toFixed(0)}
                                 </div>
                             </div>
                         </div>
                     </div>
                     <div className="absolute -right-16 -top-24 w-80 h-80 bg-white/5 rounded-full blur-[90px]"></div>
                 </div>
             </div>
          </div>

          <div className="px-5 mb-4">
              <div className="bg-gray-100/50 p-1 rounded-2xl flex font-bold text-[13px] text-gray-400 border border-gray-200">
                  <button onClick={() => setSubTab('details')} className={`flex-1 py-2.5 rounded-xl transition-all duration-300 ${subTab === 'details' ? `${currentTheme.themeColor} text-white shadow-lg` : 'hover:text-gray-600'}`}>明细</button>
                  <button onClick={() => setSubTab('calendar')} className={`flex-1 py-2.5 rounded-xl transition-all duration-300 ${subTab === 'calendar' ? `${currentTheme.themeColor} text-white shadow-lg` : 'hover:text-gray-600'}`}>开销日历</button>
                  <button onClick={() => setSubTab('bills')} className={`flex-1 py-2.5 rounded-xl transition-all duration-300 relative ${subTab === 'bills' ? `${currentTheme.themeColor} text-white shadow-lg` : 'hover:text-gray-600'}`}>待办 {reminders.some(r => !r.isCompleted && getDaysRemaining(r) <= 1) && <span className={`absolute top-3 right-4 w-1.5 h-1.5 rounded-full animate-pulse ${subTab === 'bills' ? 'bg-white' : 'bg-rose-500'}`}></span>}</button>
              </div>
          </div>

          <div className="flex-1 px-5 pb-20 space-y-4">
                {subTab === 'details' && (
                    <div className="space-y-4">
                        {allGroupedTransactions.map(([date, items]) => {
                            const dayIncome = items.filter((t:any) => t.type === TransactionType.INCOME).reduce((s:any,t:any)=>s+t.amount,0);
                            const dayExpense = items.filter((t:any) => t.type === TransactionType.EXPENSE).reduce((s:any,t:any)=>s+t.amount,0);
                            const dObj = new Date(date);
                            const isToday = getLocalDateString() === date;
                            
                            return (
                            <div key={date} className="bg-white rounded-2xl border border-gray-100 shadow-sm overflow-hidden animate-float-in">
                                <div className="bg-gray-50/50 px-4 py-2.5 border-b border-gray-100 flex justify-between items-center text-[11px] font-bold text-gray-500">
                                    <div className="flex items-center gap-2">
                                        <span className={isToday ? 'text-indigo-600' : ''}>
                                            {isToday ? '今天' : `${dObj.getMonth()+1}月${dObj.getDate()}日`}
                                        </span>
                                        <span className="text-gray-300 opacity-50">|</span>
                                        <span className="text-gray-400 uppercase tracking-tighter">
                                            {['周日','周一','周二','周三','周四','周五','周六'][dObj.getDay()]}
                                        </span>
                                    </div>
                                    <div className="flex items-center gap-3">
                                        {dayIncome > 0 && <span className="font-mono text-emerald-500">收 +¥{dayIncome.toFixed(0)}</span>}
                                        {dayExpense > 0 && <span className="font-mono text-red-500">支 -¥{dayExpense.toFixed(0)}</span>}
                                    </div>
                                </div>
                                <div className="divide-y divide-gray-50">
                                    {items.slice().reverse().map((t:any) => (
                                        <div key={t.id} onClick={() => setEditingTransaction(t)} className="flex items-center justify-between py-4 px-4 hover:bg-gray-50 active:bg-gray-100 cursor-pointer transition-colors">
                                            <div className="flex items-center gap-3 overflow-hidden">
                                                <div className="w-10 h-10 rounded-xl flex items-center justify-center text-lg shrink-0 bg-gray-50 border border-gray-100 shadow-inner">{getIcon(t)}</div>
                                                <div className="min-w-0">
                                                    <p className="font-bold text-gray-800 truncate text-[14px] mb-0.5 tracking-tight">{t.item}</p>
                                                    <p className="text-[10px] text-gray-300 font-bold uppercase tracking-wider">{t.category}</p>
                                                </div>
                                            </div>
                                            <div className={`font-black font-mono whitespace-nowrap pl-2 text-[15px] ${t.type === TransactionType.INCOME ? 'text-emerald-500' : 'text-red-500'}`}>
                                                {t.type === TransactionType.INCOME ? '+' : '-'}¥{t.amount.toFixed(0)}
                                            </div>
                                        </div>
                                    ))}
                                </div>
                            </div>
                        )})}
                        {allGroupedTransactions.length === 0 && <div className="text-center text-gray-300 py-12 bg-white rounded-2xl border border-dashed border-gray-200"><div className="w-16 h-16 bg-gray-50 rounded-full flex items-center justify-center mx-auto mb-3 opacity-50 text-2xl">📓</div><p className="text-[11px] font-bold uppercase tracking-widest">本月暂无明细</p></div>}
                    </div>
                )}
                {subTab === 'calendar' && <CalendarView transactions={transactions} reminders={reminders} viewDate={selectedMonth} />}
                {subTab === 'bills' && <BillReminders reminders={reminders.filter(r => r.frequency === 'monthly' || r.targetDate.startsWith(selectedMonth))} onAdd={onAddReminder} onUpdate={onUpdateReminder} onDelete={onDeleteReminder} onToggle={onToggleReminder} />}
          </div>
          {editingTransaction && (
            <EditTransactionModal 
              transaction={editingTransaction} 
              onSave={async (updated) => { 
                try {
                  await onUpdateTransaction(updated); 
                  setEditingTransaction(null); 
                } catch (e) {
                  // Error handled in App.tsx
                }
              }} 
              onDelete={async (id) => { 
                await onDeleteTransaction(id); 
                setEditingTransaction(null); 
              }} 
              onClose={() => setEditingTransaction(null)} 
            />
          )}
      </div>
  );
};

export default LedgerPage;