const mongoose = require('mongoose');

const orderItemSchema = new mongoose.Schema(
  {
    menuItem: { type: mongoose.Schema.Types.ObjectId, ref: 'MenuItem', required: true },
    menuItemName: { type: String, required: true }, // denormalised snapshot for reporting
    variantId: { type: mongoose.Schema.Types.ObjectId, required: true },
    variantLabel: { type: String, required: true }, // snapshot
    qty: { type: Number, required: true, min: 1 },
    priceAtSale: { type: Number, required: true, min: 0 }, // snapshot — never recalculate from live menu
  },
  { _id: false }
);

const orderSchema = new mongoose.Schema(
  {
    // Client-generated UUID — used as idempotency key during offline sync
    localId: { type: String, required: true, unique: true, index: true },

    orderType: { type: String, enum: ['dine-in', 'takeaway', 'delivery'], required: true },
    items: { type: [orderItemSchema], required: true },
    subtotal: { type: Number, required: true },
    discount: {
      amount: { type: Number, default: 0 },
      reason: { type: String, default: '' },
    },
    netTotal: { type: Number, required: true },
    deliveryFee: { type: Number, default: 0 },
    cashReceived: { type: Number, default: 0 },
    change: { type: Number, default: 0 },
    status: { type: String, enum: ['held', 'completed', 'voided'], default: 'completed' },
    voidedBy: { type: mongoose.Schema.Types.ObjectId, ref: 'User', default: null },
    voidedAt: { type: Date, default: null },
    cashier: { type: mongoose.Schema.Types.ObjectId, ref: 'User', required: true },
    // synced is a client-side-only concept; all server records are considered synced
    createdAt: { type: Date, default: Date.now },
  },
  { timestamps: false } // we manage createdAt manually to preserve offline timestamps
);

orderSchema.index({ createdAt: -1 });
orderSchema.index({ status: 1, createdAt: -1 });

module.exports = mongoose.model('Order', orderSchema);