import express from "express";
import { protectVendor } from "../middleware/vendorAuthMiddleware.js";
import { protectCrypto } from "../middleware/apiAuthMiddleware.js";
import Order from "../models/Order.model.js";
import Wallet from "../models/Wallet.model.js"; 

import crypto from "crypto";
import { setupWallet } from "../utils/litecoin/index.js";
import { returnCryptoPrices } from "../controllers/cryptoController.js";
import Store from "../models/Store.model.js";
import { sendTelegramMessage } from "../utils/telegramUtils.js"
import Product from "../models/Product.model.js";
import mongoose from "mongoose";
import { decreaseStockOnOrder, restoreStockOnCancel } from "../controllers/stock.controller.js";

const router = express.Router();

/**
 * 📌 Get Orders for Vendor
 * @route   GET /api/orders
 * @access  Private (Vendors only)
 */
router.get("/", protectVendor, async (req, res) => {
  try {
    // Extract query params for filtering and navigation
    const { status, page = 1, limit = 25, before, after, storeId } = req.query;

    // Initialize query object
    let query = {};
    
    // Use storeId from query parameter if provided, otherwise use the one from user object
    query.storeId = storeId || req.user.storeId;
    
    // If for some reason there's no storeId in user object and none provided in query
    if (!query.storeId) {
      return res.status(400).json({ error: "No store ID found. Please specify a storeId parameter." });
    }
    // Filter by order status if provided
    if (status) {
      query.status = status;
    }

    // Add orderId filters for navigation
    if (before) {
      query.orderId = { $lt: before };
    } else if (after) {
      query.orderId = { $gt: after };
    }

    // Count total orders for pagination
    const totalOrders = await Order.countDocuments(query);

    // Fetch orders with pagination and sorting
    const orders = await Order.find(query)
      .sort({ orderId: -1 }) // Always sort by newest first
      .limit(parseInt(limit))
      .skip((parseInt(page) - 1) * parseInt(limit));

    res.json({
      orders,
      page: parseInt(page),
      totalPages: Math.ceil(totalOrders / limit),
      totalOrders,
    });
  } catch (error) {
    console.error("Error fetching orders:", error);
    res.status(500).json({ error: "Failed to retrieve orders" });
  }
});

router.get("/stats", protectVendor, async (req, res) => {
  try {
    const vendorId = req.user._id;

    const totalOrders = await Order.countDocuments({ vendorId });
    const pendingOrders = await Order.countDocuments({
      vendorId,
      status: { $in: ["unpaid", "confirming"] },
    });
    const ongoingOrders = await Order.countDocuments({
      vendorId,
      status: { $in: ["paid", "shipped"] },
    });
    const cancelledOrders = await Order.countDocuments({
      vendorId,
      status: "cancelled",
    });
    const completedOrders = await Order.countDocuments({
      vendorId,
      status: "completed",
    });

    res.json({ totalOrders, pendingOrders, ongoingOrders, cancelledOrders, completedOrders });
  } catch (error) {
    console.error("Error fetching order stats:", error);
    res.status(500).json({ error: "Failed to retrieve order statistics" });
  }
});

/**
 * 📌 Get Vendor's Best Selling Products
 * @route   GET /api/orders/top-products
 * @access  Private (Vendors only)
 * @returns Most sold products for the logged-in vendor
 */
router.get("/top-products", protectVendor, async (req, res) => {
  try {
    const vendorId = req.user._id;
    
    // Find the vendor's store
    const store = await Store.findOne({ vendorId });
    if (!store) {
      return res.status(404).json({ message: "Store not found for this vendor" });
    }
    
    // Aggregate orders to find the vendor's best-selling products
    const topProducts = await Order.aggregate([
      // Match only orders for this vendor
      { $match: { vendorId: new mongoose.Types.ObjectId(vendorId) } },
      // Unwind the products array
      { $unwind: "$products" },
      // Group by product ID and count occurrences
      {
        $group: {
          _id: "$products.productId",
          count: { $sum: 1 },
          revenue: { $sum: "$products.price" }
        }
      },
      // Sort by count in descending order
      { $sort: { count: -1 } },
      // Limit to top 10 products
      { $limit: 10 }
    ]);
    
    // Get the actual product details
    const productIds = topProducts.map(item => item._id);
    const products = await Product.find({ 
      _id: { $in: productIds },
      storeId: store._id
    }).select('name price image');
    
    // Combine the count with product details
    const result = topProducts.map(item => {
      const productDetails = products.find(p => p._id.toString() === item._id.toString());
      return {
        id: item._id,
        name: productDetails?.name || 'Unknown Product',
        price: productDetails?.price || 0,
        image: productDetails?.image || '',
        count: item.count,
        revenue: item.revenue
      };
    });
    
    res.json(result);
  } catch (error) {
    console.error("Error fetching top products:", error);
    res.status(500).json({ error: "Failed to fetch top products data" });
  }
});

router.post("/create", protectCrypto, async (req, res) => {
  try {
    const { vendorId, storeId, products, totalPrice, shippingMethod, telegramChatId, telegramBuyerId, telegramUsername, cryptoCurrency, pgpAddress } = req.body;

    console.log("Create order request:", req.body);

    if (!vendorId || !storeId || !products || !totalPrice || !shippingMethod || !cryptoCurrency || !pgpAddress) {
      console.log("Missing required fields");
      return res.status(400).json({ error: "Missing required fields" });
    }

    /* 
    // TEMPORARILY DISABLED: Stock check disabled to give vendors time to add stock
    // Check stock levels before creating order
    const outOfStockProducts = [];
    for (const item of products) {
      const product = await Product.findOne({ _id: item.productId, storeId });
      
      if (product && product.stockTracking && product.currentStock < item.quantity) {
        outOfStockProducts.push({
          productId: item.productId,
          name: product.name,
          requested: item.quantity,
          available: product.currentStock
        });
      }
    }
    
    // If any products are out of stock, return an error
    if (outOfStockProducts.length > 0) {
      return res.status(400).json({ 
        error: "Some products are out of stock or have insufficient quantity",
        outOfStockProducts
      });
    }
    */

    const cryptoPrices = returnCryptoPrices();
    const cryptoRate = cryptoPrices[cryptoCurrency.toLowerCase()];

    if (!cryptoRate) {
      console.log("Invalid or unsupported cryptocurrency");
      return res.status(400).json({ error: "Invalid or unsupported cryptocurrency" });
    }

    const cryptoTotal = (totalPrice / cryptoRate).toFixed(8);

    const walletName = "order_" + crypto.randomBytes(8).toString("hex");
    const walletData = await setupWallet(walletName);

    if (!walletData || !walletData.address || !walletData.privKey) {
      return res.status(500).json({ error: "Failed to generate payment address" });
    }

    // ✅ Create Order with `cryptoTotal`
    const newOrder = await Order.create({
      vendorId,
      storeId,
      products,
      pgpAddress,
      totalPrice,
      cryptoTotal,
      shippingMethod,
      telegramChatId,
      telegramUsername,
      telegramBuyerId,
      status: "unpaid",
      paymentAddress: walletData.address, 
    });

    // ✅ Link the Wallet to the Order
    const newWallet = await Wallet.create({
      walletName,
      orderId: newOrder._id,
      address: walletData.address,
      encryptedPrivateKey: walletData.privKey,
    });

    // ✅ Update Order with Wallet ID
    newOrder.wallet = newWallet._id;
    await newOrder.save();

    // TEMPORARILY DISABLED: Stock decrease disabled to give vendors time to add stock
    // Decrease stock for ordered products
    // await decreaseStockOnOrder(newOrder);

    res.status(201).json({
      message: "Order created successfully",
      order: newOrder,
      paymentAddress: walletData.address,
      walletName: walletName,
      cryptoTotal,
    });

  } catch (error) {
    console.error("Error creating order:", error);
    res.status(500).json({ error: "Failed to create order", details: error.message });
  }
});

router.put("/:id/status", protectVendor, async (req, res) => {
  try {
    const { id } = req.params;
    const { status } = req.body;

    if (!status || !["acknowledged", "paid", "shipped", "completed", "cancelled"].includes(status)) {
      return res.status(400).json({ message: "Invalid status" });
    }

    // Get storeId from req.user
    const storeId = req.user.storeId;
    if (!storeId) {
      return res.status(400).json({ message: "No store associated with this user" });
    }

    // Find order by ID and storeId
    const order = await Order.findOne({ _id: id, storeId });
    if (!order) {
      return res.status(404).json({ message: "Order not found" });
    }

    const previousStatus = order.status;

    // TEMPORARILY DISABLED: Stock restoration disabled to give vendors time to add stock
    // Handle stock changes based on status transitions
    /*
    if (status === "cancelled" && previousStatus !== "cancelled") {
      // Restore stock quantities if order is cancelled
      await restoreStockOnCancel(order);
    }
    */

    const store = await Store.findById(order.storeId);
    if (!store) return res.status(404).json({ message: "Store not found" });

    order.status = status;
    await order.save();

    if (store.telegramToken && order.telegramChatId) {
      let message = '';
      
      switch (status) {
        case 'acknowledged':
          message = `✅ Your order ${order.orderId} has been acknowledged.`;
          break;
        case 'paid':
          message = `💰 Your order ${order.orderId} has been marked as paid.`;
          break;
        case 'shipped':
          message = `🚚 Your order ${order.orderId} has been shipped!`;
          break;
        case 'completed':
          message = `🎉 Your order ${order.orderId} has been completed.`;
          break;
        case 'cancelled':
          message = `❌ Your order ${order.orderId} has been cancelled.`;
          break;
      }

      if (message) {
        const sent = await sendTelegramMessage(store.telegramToken, order.telegramChatId, message);
        if (!sent) {
          console.error(`Failed to notify user ${order.telegramChatId} about status update to ${status}.`);
        }
      }
    }

    return res.status(200).json({ message: "Order status updated successfully" });
  } catch (error) {
    console.error("❌ Error updating order status:", error);
    return res.status(500).json({ error: "Failed to update order status", details: error.message });
  }
});

router.get("/:id", protectVendor, async (req, res) => {
  if (!req.params.id) return res.status(400).json({ message: "Missing order ID" });
  
  try {
    // Get storeId from req.user
    const storeId = req.user.storeId;
    if (!storeId) {
      return res.status(400).json({ message: "No store associated with this user" });
    }
    
    // Find order by ID and storeId
    const order = await Order.findOne({ _id: req.params.id, storeId: storeId });
    
    if(!order) return res.status(404).json({ message: "Order not found for this store" });
    
    return res.status(200).json(order);
  } catch (error) {
    console.error("Error fetching order:", error);
    res.status(500).json({ error: "Failed to retrieve order" });
  }
})

/**
 * Mark Multiple Orders as Shipped
 * @route   POST /api/orders/mark-shipped
 * @access  Private (Vendors only)
 */
router.post("/mark-shipped", protectVendor, async (req, res) => {
  try {
    const { orderIds } = req.body;

    if (!Array.isArray(orderIds) || orderIds.length === 0) {
      return res.status(400).json({ error: "Order IDs array is required" });
    }

    // Get storeId from req.user
    const storeId = req.user.storeId;
    if (!storeId) {
      return res.status(400).json({ error: "No store associated with this user" });
    }

    const updatedOrders = [];
    const failedOrders = [];

    // Get store for notifications
    const store = await Store.findById(storeId);
    if (!store) {
      return res.status(404).json({ error: "Store not found" });
    }

    for (const orderId of orderIds) {
      try {
        // Find and update order using storeId instead of vendorId
        const order = await Order.findOne({ _id: orderId, storeId: storeId });
        
        if (!order) {
          failedOrders.push({ orderId, reason: "Order not found or not associated with this store" });
          continue;
        }

        if (order.status !== "paid") {
          failedOrders.push({ orderId, reason: "Order must be in paid status to be marked as shipped" });
          continue;
        }

        order.status = "shipped";
        await order.save();
        updatedOrders.push(order);

        // Send notification if possible
        if (store.telegramToken && order.telegramChatId) {
          const message = `🚚 Your order ${order.orderId} has been marked as shipped!`;
          const sent = await sendTelegramMessage(store.telegramToken, order.telegramChatId, message);
          
          if (!sent) {
            console.error(`Failed to notify user ${order.telegramChatId} about shipping update.`);
          }
        }
      } catch (error) {
        console.error(`Error updating order ${orderId}:`, error);
        failedOrders.push({ orderId, reason: "Internal server error" });
      }
    }

    return res.json({
      message: "Orders processed",
      success: {
        count: updatedOrders.length,
        orders: updatedOrders.map(o => ({
          id: o._id,
          orderId: o.orderId,
          status: o.status
        }))
      },
      failed: {
        count: failedOrders.length,
        orders: failedOrders
      }
    });

  } catch (error) {
    console.error("Error marking orders as shipped:", error);
    return res.status(500).json({ 
      error: "Failed to mark orders as shipped",
      details: error.message 
    });
  }
});

/**
 * Update Order Tracking Number
 * @route   PUT /api/orders/:id/tracking
 * @access  Private (Vendors only)
 */
router.put("/:id/tracking", protectVendor, async (req, res) => {
  const { id } = req.params;
  const { trackingNumber } = req.body;

  if (!id) return res.status(400).json({ error: "Missing order ID" });
  if (!trackingNumber) return res.status(400).json({ error: "Missing tracking number" });

  try {
    // Get storeId from req.user
    const storeId = req.user.storeId;
    if (!storeId) {
      return res.status(400).json({ error: "No store associated with this user" });
    }

    // Use storeId for lookup instead of vendorId
    const order = await Order.findOne({ _id: id, storeId: storeId });
    if (!order) return res.status(404).json({ error: "Order not found for this store" });

    // Only allow tracking updates for paid or shipped orders
    if (order.status !== "paid" && order.status !== "shipped") {
      return res.status(400).json({ error: "Can only add tracking to paid or shipped orders" });
    }

    // Get store details for notification
    const store = await Store.findById(order.storeId);
    if (!store) return res.status(404).json({ error: "Store not found" });

    // Update the order with tracking number
    order.trackingNumber = trackingNumber;
    await order.save();

    // Send tracking notification
    if (store.telegramToken && order.telegramChatId) {
      const message = `📦 Tracking added for order ${order.orderId}\!`;
      const sent = await sendTelegramMessage(store.telegramToken, order.telegramChatId, message);
      
      if (!sent) {
        console.error(`Failed to notify user ${order.telegramChatId} about tracking update.`);
      }
    }

    return res.json({ 
      message: "Tracking number updated successfully",
      order: {
        id: order._id,
        orderId: order.orderId,
        status: order.status,
        trackingNumber: order.trackingNumber
      }
    });
  } catch (error) {
    console.error("Error updating tracking number:", error);
    return res.status(500).json({ 
      error: "Failed to update tracking number", 
      details: error.message 
    });
  }
});

/**
 * Delete Order
 * @route   DELETE /api/orders/:id
 * @access  Private (Vendors only)
 */
router.delete("/:id", protectVendor, async (req, res) => {
  try {
    const { id } = req.params;
    
    // Get storeId from req.user
    const storeId = req.user.storeId;
    if (!storeId) {
      return res.status(400).json({ message: "No store associated with this user" });
    }
    
    // Find order by ID and storeId
    const order = await Order.findOne({ _id: id, storeId: storeId });
    
    if (!order) {
      return res.status(404).json({ message: "Order not found for this store" });
    }

    // Delete associated wallet if exists
    if (order.wallet) {
      await Wallet.findByIdAndDelete(order.wallet);
    }

    // Delete the order
    await Order.findByIdAndDelete(id);

    res.status(200).json({ message: "Order deleted successfully" });
  } catch (error) {
    console.error("Error deleting order:", error);
    res.status(500).json({ error: "Failed to delete order" });
  }
});

/**
 * 📌 Get Adjacent Orders (for navigation)
 * @route   GET /api/orders/adjacent/:orderId
 * @access  Private (Vendors only)
 * @description Returns the immediately previous and next orders by orderId
 */
router.get("/adjacent/:orderId", protectVendor, async (req, res) => {
  try {
    const { orderId } = req.params;
    const numericOrderId = parseInt(orderId);
    
    if (isNaN(numericOrderId)) {
      return res.status(400).json({ error: "Invalid order ID format" });
    }
    
    // Get the store ID from user or query parameter
    const storeId = req.query.storeId || req.user.storeId;
    if (!storeId) {
      return res.status(400).json({ error: "No store ID found. Please specify a storeId parameter." });
    }
    
    // Find the next newer order (higher orderId)
    const newerOrder = await Order.findOne({
      storeId,
      orderId: { $gt: numericOrderId }
    })
    .sort({ orderId: 1 }) // Ascending to get the immediately next one
    .select('_id orderId')
    .lean();
    
    // Find the next older order (lower orderId)
    const olderOrder = await Order.findOne({
      storeId,
      orderId: { $lt: numericOrderId }
    })
    .sort({ orderId: -1 }) // Descending to get the immediately previous one
    .select('_id orderId')
    .lean();
    
    res.json({
      current: { orderId: numericOrderId },
      newer: newerOrder || null,
      older: olderOrder || null
    });
    
  } catch (error) {
    console.error("Error fetching adjacent orders:", error);
    res.status(500).json({ error: "Failed to retrieve adjacent orders" });
  }
});

export default router;