const Product = require('../models/Product');
const Category = require('../models/Category');
const Brand = require('../models/Brand');
const { successResponse, errorResponse } = require('../utils/apiResponse');

// @desc    Get all products with filtering, search, sorting & pagination
// @route   GET /api/products
// @access  Public
const getProducts = async (req, res, next) => {
  try {
    const page = parseInt(req.query.page) || 1;
    const limit = parseInt(req.query.limit) || 12;
    const skip = (page - 1) * limit;

    const query = { isActive: true };

    // Search query
    if (req.query.search) {
      const searchRegex = new RegExp(req.query.search, 'i');
      query.$or = [
        { name: searchRegex },
        { description: searchRegex },
        { tags: searchRegex },
        { sku: searchRegex }
      ];
    }

    // Category filter
    if (req.query.category) {
      const cat = await Category.findOne({ slug: req.query.category });
      if (cat) query.category = cat._id;
    }

    // Brand filter
    if (req.query.brand) {
      const brand = await Brand.findOne({ slug: req.query.brand });
      if (brand) query.brand = brand._id;
    }

    // Price range filter
    if (req.query.minPrice || req.query.maxPrice) {
      query.price = {};
      if (req.query.minPrice) query.price.$gte = Number(req.query.minPrice);
      if (req.query.maxPrice) query.price.$lte = Number(req.query.maxPrice);
    }

    // Guitar specific filters
    if (req.query.guitarType) {
      query['specs.guitarType'] = req.query.guitarType;
    }
    if (req.query.bodyShape) {
      query['specs.bodyShape'] = req.query.bodyShape;
    }
    if (req.query.handOrientation) {
      query['specs.handOrientation'] = req.query.handOrientation;
    }
    if (req.query.numberOfStrings) {
      query['specs.numberOfStrings'] = Number(req.query.numberOfStrings);
    }
    if (req.query.isFeatured) {
      query.isFeatured = true;
    }
    if (req.query.isNewArrival) {
      query.isNewArrival = true;
    }
    if (req.query.isBestSeller) {
      query.isBestSeller = true;
    }

    // Sorting
    let sortOption = { createdAt: -1 };
    if (req.query.sort === 'price_asc') sortOption = { price: 1 };
    if (req.query.sort === 'price_desc') sortOption = { price: -1 };
    if (req.query.sort === 'rating') sortOption = { rating: -1 };
    if (req.query.sort === 'bestselling') sortOption = { salesCount: -1 };

    const total = await Product.countDocuments(query);
    const products = await Product.find(query)
      .populate('category', 'name slug')
      .populate('brand', 'name slug logo')
      .sort(sortOption)
      .skip(skip)
      .limit(limit);

    return successResponse(res, 'Products retrieved successfully', {
      products,
      pagination: {
        total,
        page,
        pages: Math.ceil(total / limit),
        limit
      }
    });
  } catch (error) {
    next(error);
  }
};

// @desc    Guitar Finder Recommendation Tool
// @route   POST /api/products/guitar-finder
// @access  Public
const getGuitarRecommendations = async (req, res, next) => {
  try {
    const { skillLevel, acousticElectric, musicStyle, maxBudget, handOrientation } = req.body;

    const query = { isActive: true };

    if (acousticElectric && acousticElectric !== 'Any') {
      query['specs.guitarType'] = acousticElectric;
    }

    if (maxBudget) {
      query.price = { $lte: Number(maxBudget) };
    }

    if (handOrientation) {
      query['specs.handOrientation'] = handOrientation;
    }

    const recommendations = await Product.find(query)
      .populate('category', 'name slug')
      .populate('brand', 'name slug logo')
      .sort({ rating: -1, salesCount: -1 })
      .limit(6);

    return successResponse(res, 'Guitar recommendations generated', recommendations);
  } catch (error) {
    next(error);
  }
};

// @desc    Get single product by slug
// @route   GET /api/products/:slug
// @access  Public
const getProductBySlug = async (req, res, next) => {
  try {
    const product = await Product.findOne({ slug: req.params.slug })
      .populate('category', 'name slug')
      .populate('brand', 'name slug logo description');

    if (!product) {
      return errorResponse(res, 'Product not found', [], 404);
    }

    // Related products (same category)
    const relatedProducts = await Product.find({
      category: product.category._id,
      _id: { $ne: product._id },
      isActive: true
    })
      .limit(4)
      .select('name slug price salePrice images rating brand');

    return successResponse(res, 'Product retrieved successfully', {
      product,
      relatedProducts
    });
  } catch (error) {
    next(error);
  }
};

// @desc    Compare products by array of IDs
// @route   POST /api/products/compare
// @access  Public
const compareProducts = async (req, res, next) => {
  try {
    const { productIds } = req.body;
    if (!productIds || !Array.isArray(productIds)) {
      return errorResponse(res, 'Please provide an array of product IDs', [], 400);
    }

    const products = await Product.find({ _id: { $in: productIds } })
      .populate('brand', 'name logo')
      .populate('category', 'name');

    return successResponse(res, 'Comparison data retrieved', products);
  } catch (error) {
    next(error);
  }
};

// @desc    Create new product (Admin)
// @route   POST /api/products
// @access  Private/Admin
const createProduct = async (req, res, next) => {
  try {
    const product = new Product(req.body);
    const createdProduct = await product.save();
    return successResponse(res, 'Product created successfully', createdProduct, 201);
  } catch (error) {
    next(error);
  }
};

// @desc    Update product (Admin)
// @route   PUT /api/products/:id
// @access  Private/Admin
const updateProduct = async (req, res, next) => {
  try {
    const product = await Product.findByIdAndUpdate(req.params.id, req.body, { new: true, runValidators: true });
    if (!product) {
      return errorResponse(res, 'Product not found', [], 404);
    }
    return successResponse(res, 'Product updated successfully', product);
  } catch (error) {
    next(error);
  }
};

// @desc    Delete product (Admin)
// @route   DELETE /api/products/:id
// @access  Private/Admin
const deleteProduct = async (req, res, next) => {
  try {
    const product = await Product.findByIdAndDelete(req.params.id);
    if (!product) {
      return errorResponse(res, 'Product not found', [], 404);
    }
    return successResponse(res, 'Product deleted successfully');
  } catch (error) {
    next(error);
  }
};

module.exports = {
  getProducts,
  getGuitarRecommendations,
  getProductBySlug,
  compareProducts,
  createProduct,
  updateProduct,
  deleteProduct
};