const express = require('express');
const router = express.Router();
const { getDb } = require('../db');

// 获取所有分类
router.get('/', (req, res) => {
  const db = getDb();
  const { type } = req.query;
  let sql = 'SELECT * FROM categories';
  const params = [];

  if (type) {
    sql += ' WHERE type = ?';
    params.push(type);
  }

  sql += ' ORDER BY sort_order ASC';
  const categories = db.all(sql, ...params);
  res.json(categories);
});

// 新增分类
router.post('/', (req, res) => {
  const db = getDb();
  const { name, type = 'expense', icon, sort_order = 0 } = req.body;
  if (!name) {
    return res.status(400).json({ error: '分类名称不能为空' });
  }

  try {
    const result = db.run(
      'INSERT INTO categories (name, type, icon, sort_order) VALUES (?, ?, ?, ?)',
      name, type, icon, sort_order
    );
    const category = db.get('SELECT * FROM categories WHERE id = ?', result.lastInsertRowid);
    res.status(201).json(category);
  } catch (err) {
    if (err.message.includes('UNIQUE')) {
      return res.status(400).json({ error: '分类名称已存在' });
    }
    throw err;
  }
});

// 修改分类
router.put('/:id', (req, res) => {
  const db = getDb();
  const { id } = req.params;
  const { name, type, icon, sort_order } = req.body;

  const existing = db.get('SELECT * FROM categories WHERE id = ?', parseInt(id));
  if (!existing) {
    return res.status(404).json({ error: '分类不存在' });
  }

  db.run(
    'UPDATE categories SET name = ?, type = ?, icon = ?, sort_order = ? WHERE id = ?',
    name || existing.name,
    type || existing.type,
    icon !== undefined ? icon : existing.icon,
    sort_order !== undefined ? sort_order : existing.sort_order,
    parseInt(id)
  );

  const updated = db.get('SELECT * FROM categories WHERE id = ?', parseInt(id));
  res.json(updated);
});

// 删除分类
router.delete('/:id', (req, res) => {
  const db = getDb();
  const { id } = req.params;

  const recordCount = db.get(
    'SELECT COUNT(*) as count FROM records WHERE category_id = ?', parseInt(id)
  );

  if (recordCount.count > 0) {
    return res.status(400).json({ error: '该分类下存在记录，无法删除' });
  }

  const result = db.run('DELETE FROM categories WHERE id = ?', parseInt(id));
  if (result.changes === 0) {
    return res.status(404).json({ error: '分类不存在' });
  }

  res.json({ message: '删除成功' });
});

module.exports = router;