models/Transaction.js

const mongoose = require('mongoose');

const transactionSchema = new mongoose.Schema({
  user_id: { type: mongoose.Schema.Types.ObjectId, ref: 'User' },
  utr: { type: String, unique: true }, 
  amount: { type: Number, required: true },
  tier: { type: String }, // Optional for withdrawals

  asset_id: { type: mongoose.Schema.Types.ObjectId, ref: 'Asset' },
  
  // Status Enum Expanded
  status: { 
    type: String, 
    enum: ['Pending', 'Verified', 'Failed', 'Pending_Withdrawal', 'Withdrawn', 'Rejected_Withdrawal'], 
    default: 'Pending' 
  },
  
  // NEW FIELD
  rejection_reason: { type: String, default: null },
  
  timestamp: { type: Date, default: Date.now }
});

module.exports = mongoose.model('Transaction', transactionSchema);