const Order = require('../models/Order');
const ErrorResponse = require('../utils/errorResponse');
const { sendEmail } = require('../utils/sendEmail');

// Mock payment gateway client (replace with actual payment gateway SDK)
const paymentGateway = {
  // Mock function to process refund
  refund: async (paymentId, amount) => {
    // In a real implementation, this would call the actual payment gateway API
    console.log(`Processing refund of ${amount} for payment ${paymentId}`);
    
    // Simulate API call delay
    await new Promise(resolve => setTimeout(resolve, 1000));
    
    return {
      id: `ref_${Date.now()}`,
      amount,
      status: 'processed',
      timestamp: new Date().toISOString()
    };
  },
  
  // Add other payment gateway methods as needed
};

/**
 * Process a refund for an order
 * @param {Object} params - Refund parameters
 * @param {string} params.orderId - The order ID
 * @param {number} params.amount - Amount to refund
 * @param {string} params.reason - Reason for refund
 * @returns {Promise<Object>} Refund details
 */
const refundPayment = async ({ orderId, amount, reason }) => {
  try {
    // In a real implementation, you would:
    // 1. Get the payment ID from the order
    // 2. Call the payment gateway to process the refund
    // 3. Update the order with refund details
    
    // For now, we'll just log and return a mock response
    console.log(`Processing refund for order ${orderId}: ${amount} (${reason})`);
    
    const refund = await paymentGateway.refund(`pay_${orderId}`, amount);
    
    // Update order with refund details
    await Order.findByIdAndUpdate(orderId, {
      $set: {
        'payment.status': 'refunded',
        'refund': {
          amount: refund.amount,
          status: refund.status,
          reference: refund.id,
          processedAt: new Date(),
          reason: reason
        },
        updatedAt: new Date()
      },
      $push: {
        'payment.history': {
          type: 'refund',
          amount: refund.amount,
          status: refund.status,
          reference: refund.id,
          notes: reason,
          createdAt: new Date()
        }
      }
    });
    
    return refund;
  } catch (error) {
    console.error('Error processing refund:', error);
    throw new ErrorResponse(`Failed to process refund: ${error.message}`, 500);
  }
};

/**
 * Process a payment for an order
 * @param {Object} params - Payment parameters
 * @param {string} params.orderId - The order ID
 * @param {number} params.amount - Amount to charge
 * @param {Object} params.paymentMethod - Payment method details
 * @returns {Promise<Object>} Payment details
 */
const processPayment = async ({ orderId, amount, paymentMethod }) => {
  try {
    // In a real implementation, you would integrate with a payment gateway here
    // This is a mock implementation
    
    // For COD, we don't need to process a payment, just return success
    if (paymentMethod.type === 'cod') {
      return {
        id: `cod_${Date.now()}`,
        amount,
        currency: 'INR',
        status: 'pending',
        method: 'cod',
        timestamp: new Date().toISOString()
      };
    }
    
    // For online payments, generate a mock payment ID
    const paymentId = `pay_${Date.now()}`;
    
    // Simulate payment processing
    const payment = {
      id: paymentId,
      amount,
      currency: 'INR',
      status: 'captured',
      method: paymentMethod.type,
      timestamp: new Date().toISOString()
    };
    
    // For non-COD payments, we would update the order status
    // But we'll let the order controller handle the order update
    // to avoid duplicate order ID issues
    await Order.findByIdAndUpdate(orderId, {
      $set: {
        'payment.status': 'paid',
        'payment.details': payment,
        updatedAt: new Date()
      },
      $push: {
        'payment.history': {
          type: 'payment',
          amount: payment.amount,
          status: payment.status,
          reference: payment.id,
          method: payment.method,
          createdAt: new Date()
        }
      }
    });
    
    return payment;
  } catch (error) {
    console.error('Error processing payment:', error);
    throw new Error(`Payment processing failed: ${error.message}`);
  }
};

/**
 * Verify a payment status
 * @param {string} paymentId - The payment ID to verify
 * @returns {Promise<Object>} Payment status
 */
const verifyPayment = async (paymentId) => {
  try {
    // In a real implementation, you would:
    // 1. Call the payment gateway to verify the payment status
    
    // For now, we'll just return a mock response
    console.log(`Verifying payment status for ${paymentId}`);
    
    await new Promise(resolve => setTimeout(resolve, 800));
    
    return {
      id: paymentId,
      status: 'captured',
      amount: 1000, // Example amount
      currency: 'INR',
      captured: true,
      createdAt: new Date().toISOString()
    };
  } catch (error) {
    console.error('Error verifying payment:', error);
    throw new ErrorResponse(`Payment verification failed: ${error.message}`, 500);
  }
};

module.exports = {
  refundPayment,
  processPayment,
  verifyPayment
};
