import { useState, useEffect, useMemo } from 'react';
import { useRouter } from 'next/router';
import { isLoggedIn, getRecords, getStats, createRecord, updateRecord, deleteRecord } from '../lib/api';
import AppShell from '../components/AppShell';
import { Icon } from '../components/icons';
import RecordModal from '../components/RecordModal';
import SwipeableItem from '../components/SwipeableItem';
import EmptyState from '../components/EmptyState';
import { useToast } from '../components/ToastProvider';
import { useConfirm } from '../components/ConfirmProvider';
import { useCategories } from '../hooks/useCategories';
import { getMonthStr, formatMoney, formatMonth, parseDateTime } from '../lib/utils';

export default function Home() {
  const router = useRouter();
  const { showToast } = useToast();
  const { confirm } = useConfirm();
  const [currentMonth, setCurrentMonth] = useState(new Date());
  const [typeFilter, setTypeFilter] = useState('all');
  const [records, setRecords] = useState([]);
  const [stats, setStats] = useState({ income: 0, expense: 0, balance: 0 });
  const [modalOpen, setModalOpen] = useState(false);
  const [editingRecord, setEditingRecord] = useState(null);
  const [loading, setLoading] = useState(true);
  const [submitting, setSubmitting] = useState(false);
  const [deleting, setDeleting] = useState(false);
  const [formError, setFormError] = useState('');
  const { categories, error: categoriesError } = useCategories();

  // 显示分类加载错误
  useEffect(() => {
    if (categoriesError) {
      showToast('分类加载失败', { tone: 'error' });
    }
  }, [categoriesError]);
  const [formData, setFormData] = useState({
    type: 'expense',
    amount: '',
    category: '',
    date: new Date().toISOString().split('T')[0],
    time: new Date().toTimeString().slice(0, 5),
    note: '',
  });

  useEffect(() => {
    if (!isLoggedIn()) {
      router.push('/login');
      return;
    }
    loadData();
  }, [router, currentMonth, typeFilter]);


  const resetForm = () => ({
    type: 'expense',
    amount: '',
    category: '',
    date: new Date().toISOString().split('T')[0],
    time: new Date().toTimeString().slice(0, 5),
    note: '',
  });

  // Memoized category lookup map for O(1) icon retrieval
  const categoryIconMap = useMemo(() => {
    const icons = {};
    for (const type of ['expense', 'income']) {
      for (const cat of categories[type] || []) {
        icons[`${type}:${cat.name}`] = cat.icon;
      }
    }
    return icons;
  }, [categories]);

  const loadData = async () => {
    setLoading(true);
    try {
      const [recordsData, statsData] = await Promise.all([
        getRecords(getMonthStr(currentMonth), typeFilter),
        getStats(getMonthStr(currentMonth)),
      ]);
      setRecords(recordsData);
      setStats(statsData);
    } catch (err) {
      console.error(err);
      showToast(err.message, { tone: 'error' });
    } finally {
      setLoading(false);
    }
  };

  const prevMonth = () => {
    const newDate = new Date(currentMonth);
    newDate.setMonth(newDate.getMonth() - 1);
    setCurrentMonth(newDate);
  };

  const nextMonth = () => {
    const newDate = new Date(currentMonth);
    newDate.setMonth(newDate.getMonth() + 1);
    setCurrentMonth(newDate);
  };

  const handleCardClick = (type) => {
    setTypeFilter(type === typeFilter ? 'all' : type);
  };

  const openAddModal = () => {
    setEditingRecord(null);
    setFormData(resetForm());
    setFormError('');
    setModalOpen(true);
  };

  const openEditModal = (record) => {
    const { datePart, timePart } = parseDateTime(record.date);
    setEditingRecord(record);
    setFormData({
      type: record.type,
      amount: record.amount.toString(),
      category: record.category,
      date: datePart,
      time: timePart,
      note: record.note || '',
    });
    setFormError('');
    setModalOpen(true);
  };

  const closeModal = () => {
    if (submitting || deleting) return;
    setModalOpen(false);
    setEditingRecord(null);
    setFormError('');
  };

  const handleSubmit = async (e) => {
    e.preventDefault();
    if (!formData.amount || !formData.category || !formData.date) {
      setFormError('请填写完整信息');
      return;
    }

    setSubmitting(true);
    setFormError('');
    try {
      const data = {
        type: formData.type,
        amount: parseFloat(formData.amount),
        category: formData.category,
        date: `${formData.date} ${formData.time || '00:00'}`,
        note: formData.note,
      };

      if (editingRecord) {
        const updated = { ...editingRecord, ...data, amount: parseFloat(data.amount) };
        await updateRecord(editingRecord.id, data);
        setRecords(prev => prev.map(r => r.id === editingRecord.id ? updated : r));
        showToast('记录已更新', { tone: 'success' });
      } else {
        const newRecord = await createRecord(data);
        setRecords(prev => [...prev, newRecord]);
        showToast('记录已添加', { tone: 'success' });
      }
      closeModal();
    } catch (err) {
      setFormError(err.message);
      showToast(err.message, { tone: 'error' });
    } finally {
      setSubmitting(false);
    }
  };

  const handleDelete = async () => {
    if (!editingRecord) return;
    const shouldDelete = await confirm({
      title: '删除这条记录？',
      description: '删除后将无法恢复，请确认是否继续。',
      confirmText: '删除',
    });
    if (!shouldDelete) return;

    setDeleting(true);
    try {
      await deleteRecord(editingRecord.id);
      setRecords(prev => prev.filter(r => r.id !== editingRecord.id));
      closeModal();
      showToast('记录已删除', { tone: 'success' });
    } catch (err) {
      setFormError(err.message);
      showToast(err.message, { tone: 'error' });
    } finally {
      setDeleting(false);
    }
  };

  const handleQuickDelete = async (record) => {
    const shouldDelete = await confirm({
      title: '删除这条记录？',
      description: `${record.category} ${record.type === 'income' ? '+' : '-'}${formatMoney(record.amount)}`,
      confirmText: '删除',
    });
    if (!shouldDelete) return;

    try {
      await deleteRecord(record.id);
      setRecords(prev => prev.filter(r => r.id !== record.id));
      showToast('记录已删除', { tone: 'success' });
    } catch (err) {
      showToast(err.message, { tone: 'error' });
    }
  };

  const groupedRecords = useMemo(() => {
    return records.reduce((groups, record) => {
      const date = getDatePart(record.date);
      if (!groups[date]) groups[date] = [];
      groups[date].push(record);
      return groups;
    }, {});
  }, [records]);

  const sortedDates = useMemo(
    () => Object.keys(groupedRecords).sort((a, b) => b.localeCompare(a)),
    [groupedRecords]
  );

  const getDayExpense = (date) => {
    const dayRecords = groupedRecords[date] || [];
    return dayRecords
      .filter((record) => record.type === 'expense')
      .reduce((sum, record) => sum + record.amount, 0);
  };

  const homeHeaderContent = (
    <div className="header-center-container">
      <div className="header-left-actions">
        <button type="button" className="icon-button" aria-label="搜索记录" onClick={() => router.push('/search')}>
          <Icon name="search" size={18} />
        </button>
      </div>
      <div className="month-switcher-container">
        <button type="button" className="icon-button" aria-label="上个月" onClick={prevMonth}>
          <Icon name="chevronLeft" size={18} />
        </button>
        <span className="month-switcher__label">{formatMonth(currentMonth)}</span>
        <button type="button" className="icon-button" aria-label="下个月" onClick={nextMonth}>
          <Icon name="chevronRight" size={18} />
        </button>
      </div>
      <div className="header-right-actions">
        <button type="button" className="icon-button" aria-label="设置" onClick={() => router.push('/settings')}>
          <Icon name="settings" size={18} />
        </button>
      </div>
    </div>
  );

  const modalHeaderContent = (
    <div className="header-center-container">
      <div className="header-left-actions">
        <button type="button" className="icon-button" aria-label="关闭" onClick={closeModal}>
          <Icon name="chevronLeft" size={18} />
        </button>
      </div>
      <div className="modal-title-container">
        <span className="modal-title">{editingRecord ? '编辑记录' : '新增记录'}</span>
      </div>
      <div className="header-right-actions"></div>
    </div>
  );

  return (
    <AppShell headerContent={modalOpen ? modalHeaderContent : homeHeaderContent} compactHeader hideNav={modalOpen}>
      <section className="dashboard-hero card">
        <div className="stats-grid stats-grid--hero">
          <button type="button" className={`stat-card ${typeFilter === 'income' ? 'active' : ''}`} onClick={() => handleCardClick('income')}>
            <span className="label">收入</span>
            <span className="value income">+{formatMoney(stats.income)}</span>
          </button>
          <button type="button" className={`stat-card ${typeFilter === 'expense' ? 'active' : ''}`} onClick={() => handleCardClick('expense')}>
            <span className="label">支出</span>
            <span className="value expense">-{formatMoney(stats.expense)}</span>
          </button>
          <button type="button" className="stat-card stat-card--balance" onClick={() => handleCardClick('all')}>
            <span className="label">结余</span>
            <span className="value">{formatMoney(stats.balance)}</span>
          </button>
        </div>
      </section>

      <section className="card section-card">
        <div className="section-heading section-heading--compact">
          <div>
            <p className="eyebrow">记录列表</p>
            <h2>{typeFilter === 'all' ? '全部记录' : typeFilter === 'income' ? '仅看收入' : '仅看支出'}</h2>
          </div>
          <button type="button" className="btn btn-secondary btn-inline" onClick={openAddModal}>
            <span className="button-content">
              <Icon name="plus" size={16} />
              新增记录
            </span>
          </button>
        </div>

        {loading ? (
          <div className="loading-state">加载中...</div>
        ) : records.length === 0 ? (
          <EmptyState
            icon="info"
            title="暂无记录"
            description={typeFilter === 'all' ? '本月还没有记账，点击下方按钮添加第一笔记录' : '该类型下暂无记录'}
            action
            actionLabel="添加记录"
            onAction={openAddModal}
          />
        ) : (
          <div className="records-list records-list--flush">
            {sortedDates.map((date) => (
              <div key={date} className="date-group">
                <div className="date-label">
                  <span>{new Date(date).toLocaleDateString('zh-CN', { month: 'short', day: 'numeric', weekday: 'short' })}</span>
                  <span className="day-expense">支出 {formatMoney(getDayExpense(date))}</span>
                </div>
                {groupedRecords[date].map((record) => {
                  const icon = categoryIconMap[`${record.type}:${record.category}`] || '📝';
                  return (
                    <SwipeableItem
                      key={record.id}
                      onSwipeLeft={() => openEditModal(record)}
                      renderRightActions={(handleAction) => (
                        <>
                          <button
                            type="button"
                            className="swipeable-action swipeable-action--edit"
                            onClick={() => handleAction(() => openEditModal(record))}
                            aria-label="编辑"
                          >
                            <Icon name="edit" size={20} />
                          </button>
                          <button
                            type="button"
                            className="swipeable-action swipeable-action--delete"
                            onClick={() => handleAction(() => handleQuickDelete(record))}
                            aria-label="删除"
                          >
                            <Icon name="trash" size={20} />
                          </button>
                        </>
                      )}
                    >
                      <button type="button" className="record-item" onClick={() => openEditModal(record)}>
                        <div className="record-left">
                          <div className="record-icon">{icon}</div>
                          <div className="record-info">
                            <div className="record-category">{record.category}</div>
                            {record.note && <div className="record-note">{record.note}</div>}
                          </div>
                        </div>
                        <div className={`record-amount ${record.type}`}>
                          {record.type === 'income' ? '+' : '-'}
                          {formatMoney(record.amount)}
                        </div>
                      </button>
                    </SwipeableItem>
                  );
                })}
              </div>
            ))}
          </div>
        )}
      </section>

      <button type="button" className="fab" aria-label="新增记录" onClick={openAddModal}>
        <Icon name="plus" size={24} />
      </button>

      <RecordModal
        isOpen={modalOpen}
        onClose={closeModal}
        onSubmit={handleSubmit}
        onDelete={handleDelete}
        formData={formData}
        setFormData={setFormData}
        formError={formError}
        submitting={submitting}
        deleting={deleting}
        editingRecord={editingRecord}
        categories={categories}
      />
    </AppShell>
  );
}