const Category = require('../models/categoryModel');

// Get all categories (optionally filter by parent to get root categories or subcategories)
exports.getAllCategories = async (req, res) => {
  try {
    const { parentId } = req.query;

    // Build filter - if parentId is 'root' or null, get root categories
    let filter = {};
    if (parentId === 'root' || parentId === 'null') {
      filter.parent = null;
    } else if (parentId) {
      filter.parent = parentId;
    }

    const categories = await Category.find(filter)
      .populate('parent', 'nameAr nameEn slug')
      .lean();
    res.status(200).json({
      status: 'success',
      results: categories.length,
      data: {
        categories,
      },
    });
  } catch (err) {
    res.status(500).json({
      status: 'fail',
      message: err.message,
    });
  }
};

// Get single category with parent and children
exports.getCategory = async (req, res) => {
  try {
    const category = await Category.findById(req.params.id)
      .populate('parent', 'nameAr nameEn slug')
      .populate('children', 'nameAr nameEn slug level')
      .lean();
    if (!category) {
      return res.status(404).json({
        status: 'fail',
        message: 'No category found with that ID',
      });
    }
    res.status(200).json({
      status: 'success',
      data: { category },
    });
  } catch (err) {
    res.status(400).json({
      status: 'fail',
      message: err.message,
    });
  }
};

// Create a new category
exports.createCategory = async (req, res) => {
  try {
    const lastCategory = await Category.findOne().sort({ id: -1 });
    const autoId = lastCategory ? lastCategory.id + 1 : 1;

    const newCategory = await Category.create({
      // eslint-disable-next-line node/no-unsupported-features/es-syntax
      ...req.body,
      id: req.body.id || autoId,
    });

    res.status(201).json({
      status: 'success',
      data: { category: newCategory },
    });
  } catch (err) {
    res.status(400).json({
      status: 'fail',
      message: err.message,
    });
  }
};

// Update a category
exports.updateCategory = async (req, res) => {
  try {
    const updatedCategory = await Category.findByIdAndUpdate(
      req.params.id,
      req.body,
      { new: true, runValidators: true },
    );
    if (!updatedCategory) {
      return res.status(404).json({
        status: 'fail',
        message: 'No category found with that ID',
      });
    }
    res.status(200).json({
      status: 'success',
      data: { category: updatedCategory },
    });
  } catch (err) {
    res.status(400).json({
      status: 'fail',
      message: err.message,
    });
  }
};

// Delete a category
exports.deleteCategory = async (req, res) => {
  try {
    // First check if category has children
    const childrenCount = await Category.countDocuments({
      parent: req.params.id,
    });
    if (childrenCount > 0) {
      return res.status(400).json({
        status: 'fail',
        message:
          'Cannot delete category with subcategories. Delete subcategories first.',
      });
    }

    const category = await Category.findByIdAndDelete(req.params.id);
    if (!category) {
      return res.status(404).json({
        status: 'fail',
        message: 'No category found with that ID',
      });
    }
    res.status(204).json({
      status: 'success',
      data: null,
    });
  } catch (err) {
    res.status(400).json({
      status: 'fail',
      message: err.message,
    });
  }
};

// Get all subcategories of a specific category
exports.getSubcategories = async (req, res) => {
  try {
    const subcategories = await Category.find({ parent: req.params.id }).lean();
    res.status(200).json({
      status: 'success',
      results: subcategories.length,
      data: {
        subcategories,
      },
    });
  } catch (err) {
    res.status(400).json({
      status: 'fail',
      message: err.message,
    });
  }
};

// Get full category tree (hierarchical structure)
exports.getCategoryTree = async (req, res) => {
  try {
    // Fetch all categories once to build tree in memory
    const allCategories = await Category.find().lean();

    const categoryMap = {};
    allCategories.forEach((cat) => {
      categoryMap[cat._id.toString()] = { ...cat, children: [] };
    });

    const tree = [];
    allCategories.forEach((cat) => {
      const catObj = categoryMap[cat._id.toString()];
      if (cat.parent) {
        const parentId = cat.parent.toString();
        if (categoryMap[parentId]) {
          categoryMap[parentId].children.push(catObj);
        }
      } else {
        tree.push(catObj);
      }
    });

    res.status(200).json({
      status: 'success',
      results: tree.length,
      data: {
        categories: tree,
      },
    });
  } catch (err) {
    res.status(500).json({
      status: 'fail',
      message: err.message,
    });
  }
};