const mongoose = require('mongoose');

const inventoryHistorySchema = new mongoose.Schema({
  product: { type: mongoose.Schema.Types.ObjectId, ref: 'Product', required: true },
  sku: { type: String, required: true },
  changeType: { 
    type: String, 
    enum: ['Order Placed', 'Order Cancelled', 'Manual Adjustment', 'Restock', 'Returned Product'], 
    required: true 
  },
  quantityChanged: { type: Number, required: true }, // positive for addition, negative for deduction
  previousStock: { type: Number, required: true },
  newStock: { type: Number, required: true },
  reason: { type: String, default: '' },
  performedBy: { type: mongoose.Schema.Types.ObjectId, ref: 'User', default: null }
}, { timestamps: true });

module.exports = mongoose.model('InventoryHistory', inventoryHistorySchema);