const asyncHandler = require('express-async-handler');
const Category = require('../models/Category');
const PromptGroup = require('../models/PromptGroup');

// @desc    获取所有分类
// @route   GET /api/categories
// @access  Private
const getCategories = asyncHandler(async (req, res) => {
  const categories = await Category.find({}).sort({ name: 1 });
  res.json(categories);
});

// @desc    通过ID获取分类
// @route   GET /api/categories/:id
// @access  Private
const getCategoryById = asyncHandler(async (req, res) => {
  const category = await Category.findById(req.params.id);

  if (category) {
    res.json(category);
  } else {
    res.status(404);
    throw new Error('分类未找到');
  }
});

// @desc    创建分类
// @route   POST /api/categories
// @access  Private
const createCategory = asyncHandler(async (req, res) => {
  const { name, color } = req.body;

  // 检查是否分类名称已存在
  const categoryExists = await Category.findOne({ name });

  if (categoryExists) {
    res.status(400);
    throw new Error('分类名称已存在');
  }

  const category = await Category.create({
    name,
    color: color || '#007AFF',
  });

  if (category) {
    res.status(201).json(category);
  } else {
    res.status(400);
    throw new Error('无效的分类数据');
  }
});

// @desc    更新分类
// @route   PUT /api/categories/:id
// @access  Private
const updateCategory = asyncHandler(async (req, res) => {
  const { name, color } = req.body;

  const category = await Category.findById(req.params.id);

  if (category) {
    // 如果更改了名称，检查新名称是否已存在
    if (name && name !== category.name) {
      const categoryExists = await Category.findOne({ name });

      if (categoryExists) {
        res.status(400);
        throw new Error('分类名称已存在');
      }
    }

    category.name = name || category.name;
    category.color = color || category.color;

    const updatedCategory = await category.save();
    res.json(updatedCategory);
  } else {
    res.status(404);
    throw new Error('分类未找到');
  }
});

// @desc    删除分类
// @route   DELETE /api/categories/:id
// @access  Private
const deleteCategory = asyncHandler(async (req, res) => {
  const category = await Category.findById(req.params.id);

  if (!category) {
    res.status(404);
    throw new Error('分类未找到');
  }

  // 检查是否有提示词组使用该分类
  const groupsUsingCategory = await PromptGroup.countDocuments({ category: req.params.id });

  if (groupsUsingCategory > 0) {
    res.status(400);
    throw new Error(`无法删除分类，有 ${groupsUsingCategory} 个提示词组正在使用它`);
  }

  await category.deleteOne();
  res.json({ message: '分类已删除' });
});

module.exports = {
  getCategories,
  getCategoryById,
  createCategory,
  updateCategory,
  deleteCategory,
};