import { useState, useEffect } from 'react';
import { useRouter } from 'next/router';
import { isLoggedIn, getRecurringBills, createRecurringBill, updateRecurringBill, deleteRecurringBill, applyRecurringBill } from '../lib/api';
import { DEFAULT_CATEGORIES } from '../lib/categories';
import AppShell from '../components/AppShell';
import { Icon } from '../components/icons';
import { useToast } from '../components/ToastProvider';
import { useConfirm } from '../components/ConfirmProvider';

export default function Recurring() {
  const router = useRouter();
  const { showToast } = useToast();
  const { confirm } = useConfirm();
  const [bills, setBills] = useState([]);
  const [modalOpen, setModalOpen] = useState(false);
  const [editingBill, setEditingBill] = useState(null);
  const [loading, setLoading] = useState(true);
  const [submitting, setSubmitting] = useState(false);
  const [deleting, setDeleting] = useState(false);
  const [applyingId, setApplyingId] = useState(null);
  const [formError, setFormError] = useState('');
  const [formData, setFormData] = useState({
    type: 'expense',
    amount: '',
    category: '',
    day: '1',
    note: '',
    is_active: true,
  });

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

  const loadBills = async () => {
    setLoading(true);
    try {
      const data = await getRecurringBills();
      setBills(data);
    } catch (err) {
      console.error(err);
      showToast(err.message, { tone: 'error' });
    } finally {
      setLoading(false);
    }
  };

  const openAddModal = () => {
    setEditingBill(null);
    setFormData({
      type: 'expense',
      amount: '',
      category: '',
      day: '1',
      note: '',
      is_active: true,
    });
    setFormError('');
    setModalOpen(true);
  };

  const openEditModal = (bill) => {
    setEditingBill(bill);
    setFormData({
      type: bill.type,
      amount: bill.amount.toString(),
      category: bill.category,
      day: bill.day.toString(),
      note: bill.note || '',
      is_active: !!bill.is_active,
    });
    setFormError('');
    setModalOpen(true);
  };

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

  const handleSubmit = async (e) => {
    e.preventDefault();
    if (!formData.amount || !formData.category || !formData.day) {
      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,
        day: parseInt(formData.day),
        note: formData.note,
        is_active: formData.is_active ? 1 : 0,
      };

      if (editingBill) {
        await updateRecurringBill(editingBill.id, data);
        showToast('周期账单已更新', { tone: 'success' });
      } else {
        await createRecurringBill(data);
        showToast('周期账单已创建', { tone: 'success' });
      }
      closeModal();
      await loadBills();
    } catch (err) {
      setFormError(err.message);
      showToast(err.message, { tone: 'error' });
    } finally {
      setSubmitting(false);
    }
  };

  const handleDelete = async () => {
    if (!editingBill) return;
    const shouldDelete = await confirm({
      title: '删除这条周期账单？',
      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 deleteRecurringBill(editingBill.id);
      closeModal();
      showToast('周期账单已删除', { tone: 'success' });
      await loadBills();
    } catch (err) {
      setFormError(err.message);
      showToast(err.message, { tone: 'error' });
    } finally {
      setDeleting(false);
    }
  };

  const handleApply = async (id) => {
    setApplyingId(id);
    try {
      await applyRecurringBill(id);
      showToast('已添加到账目', { tone: 'success' });
    } catch (err) {
      showToast(err.message, { tone: 'error' });
    } finally {
      setApplyingId(null);
    }
  };

  const handleToggleActive = async (bill, event) => {
    event.stopPropagation();
    try {
      await updateRecurringBill(bill.id, {
        ...bill,
        is_active: bill.is_active ? 0 : 1,
      });
      showToast(bill.is_active ? '已停用周期账单' : '已启用周期账单', { tone: 'success' });
      await loadBills();
    } catch (err) {
      showToast(err.message, { tone: 'error' });
    }
  };

  const days = Array.from({ length: 28 }, (_, index) => index + 1);

  const actions = (
    <button type="button" className="icon-button" aria-label="设置" onClick={() => router.push('/settings')}>
      <Icon name="settings" size={18} />
    </button>
  );

  return (
    <AppShell title="周期账单" subtitle="管理固定收入与支出节奏" actions={actions} compactHeader>
      {loading ? (
        <div className="card loading-state">加载中...</div>
      ) : bills.length === 0 ? (
        <div className="card empty-state empty-state--card">
          <div className="empty-state__icon"><Icon name="repeat" size={24} /></div>
          <p>暂无周期性账单</p>
          <p className="sub">点击右下角新增定期收入或支出。</p>
        </div>
      ) : (
        <section className="card section-card">
          <div className="section-heading section-heading--compact">
            <div>
              <p className="eyebrow">账单列表</p>
              <h2>{bills.length} 条周期账单</h2>
            </div>
          </div>
          <div className="bills-list">
            {bills.map((bill) => {
              const categories = DEFAULT_CATEGORIES[bill.type];
              const cat = categories.find((item) => item.name === bill.category) || { icon: '📝' };
              return (
                <button
                  key={bill.id}
                  type="button"
                  className={`bill-item ${bill.is_active ? '' : 'inactive'}`}
                  onClick={() => openEditModal(bill)}
                >
                  <div className="bill-left">
                    <div className="bill-icon">{cat.icon}</div>
                    <div className="bill-info">
                      <div className="bill-row">
                        <div className="bill-category">{bill.category}</div>
                        <span className={`status-chip ${bill.is_active ? 'status-chip--success' : ''}`}>
                          {bill.is_active ? '启用中' : '已停用'}
                        </span>
                      </div>
                      <div className="bill-day">每月 {bill.day} 日</div>
                      {bill.note && <div className="bill-note">{bill.note}</div>}
                    </div>
                  </div>
                  <div className="bill-right">
                    <div className={`bill-amount ${bill.type}`}>
                      {bill.type === 'income' ? '+' : '-'}{bill.amount.toFixed(2)}
                    </div>
                    <div className="bill-actions">
                      <button
                        type="button"
                        className="btn btn-secondary btn-inline btn-small"
                        onClick={(e) => {
                          e.stopPropagation();
                          handleApply(bill.id);
                        }}
                        disabled={applyingId === bill.id}
                      >
                        {applyingId === bill.id ? '应用中...' : '应用'}
                      </button>
                      <button
                        type="button"
                        className="btn btn-ghost btn-inline btn-small"
                        onClick={(event) => handleToggleActive(bill, event)}
                      >
                        {bill.is_active ? '停用' : '启用'}
                      </button>
                    </div>
                  </div>
                </button>
              );
            })}
          </div>
        </section>
      )}

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

      {modalOpen && (
        <div className="modal-overlay" onClick={closeModal}>
          <div className="modal" onClick={(e) => e.stopPropagation()}>
            <div className="modal-header">
              <div>
                <p className="eyebrow">{editingBill ? '编辑账单' : '新增账单'}</p>
                <h2>{editingBill ? '更新周期账单' : '创建周期账单'}</h2>
              </div>
              <button type="button" className="icon-button icon-button--ghost" aria-label="关闭弹窗" onClick={closeModal}>
                <Icon name="close" size={18} />
              </button>
            </div>
            {formError && <div className="error-msg">{formError}</div>}
            <form onSubmit={handleSubmit}>
              <div className="type-switch">
                <button
                  type="button"
                  className={`type-btn expense ${formData.type === 'expense' ? 'active' : ''}`}
                  onClick={() => setFormData({ ...formData, type: 'expense', category: '' })}
                  disabled={submitting || deleting}
                >
                  支出
                </button>
                <button
                  type="button"
                  className={`type-btn income ${formData.type === 'income' ? 'active' : ''}`}
                  onClick={() => setFormData({ ...formData, type: 'income', category: '' })}
                  disabled={submitting || deleting}
                >
                  收入
                </button>
              </div>
              <div className="form-group">
                <label htmlFor="bill-amount">金额</label>
                <input
                  id="bill-amount"
                  type="number"
                  className="amount-input"
                  value={formData.amount}
                  onChange={(e) => setFormData({ ...formData, amount: e.target.value })}
                  placeholder="0.00"
                  step="0.01"
                  required
                  disabled={submitting || deleting}
                />
              </div>
              <div className="form-group">
                <label>分类</label>
                <div className="category-grid">
                  {DEFAULT_CATEGORIES[formData.type].map((cat) => (
                    <button
                      key={cat.name}
                      type="button"
                      className={`category-btn ${formData.category === cat.name ? 'active' : ''}`}
                      onClick={() => setFormData({ ...formData, category: cat.name })}
                      disabled={submitting || deleting}
                    >
                      <span className="icon">{cat.icon}</span>
                      <span>{cat.name}</span>
                    </button>
                  ))}
                </div>
              </div>
              <div className="form-group">
                <label htmlFor="bill-day">日期（每月几号）</label>
                <select id="bill-day" value={formData.day} onChange={(e) => setFormData({ ...formData, day: e.target.value })} disabled={submitting || deleting}>
                  {days.map((day) => (
                    <option key={day} value={day}>{day} 日</option>
                  ))}
                </select>
              </div>
              <div className="form-group">
                <label htmlFor="bill-note">备注（可选）</label>
                <input
                  id="bill-note"
                  type="text"
                  value={formData.note}
                  onChange={(e) => setFormData({ ...formData, note: e.target.value })}
                  placeholder="添加备注..."
                  disabled={submitting || deleting}
                />
              </div>
              {editingBill && (
                <div className="form-group form-group--inline">
                  <label className="checkbox-label">
                    <input
                      type="checkbox"
                      checked={formData.is_active}
                      onChange={(e) => setFormData({ ...formData, is_active: e.target.checked })}
                      disabled={submitting || deleting}
                    />
                    启用此账单
                  </label>
                </div>
              )}
              <div className="modal-actions">
                <button type="submit" className="btn btn-primary" disabled={submitting || deleting}>
                  {submitting ? (
                    <span className="button-content">
                      <Icon name="spinner" size={16} className="is-spinning" />
                      保存中...
                    </span>
                  ) : '保存'}
                </button>
                {editingBill && (
                  <button type="button" className="btn btn-danger" onClick={handleDelete} disabled={submitting || deleting}>
                    {deleting ? '删除中...' : '删除'}
                  </button>
                )}
              </div>
            </form>
          </div>
        </div>
      )}
    </AppShell>
  );
}