const mongoose = require('mongoose');

const notificationSchema = new mongoose.Schema(
  {
    user: {
      type: mongoose.Schema.Types.ObjectId,
      ref: 'User',
      required: [true, 'Notification must belong to a user'],
      index: true,
    },
    title: {
      type: String,
      required: [true, 'Notification must have a title'],
      trim: true,
    },
    message: {
      type: String,
      required: [true, 'Notification must have a message'],
    },
    type: {
      type: String,
      enum: [
        'order_created',
        'order_confirmed',
        'order_shipped',
        'order_delivered',
        'order_cancelled',
        'product_out_of_stock',
        'product_back_in_stock',
        'promo_code',
        'newsletter',
        'review_response',
        'system',
        'general',
      ],
      default: 'general',
    },
    relatedId: {
      type: mongoose.Schema.Types.ObjectId,
      // This can reference different collections based on type (Order, Product, etc.)
    },
    relatedModel: {
      type: String,
      enum: ['Order', 'Product', 'PromoCode', 'Review', null],
    },
    isRead: {
      type: Boolean,
      default: false,
      index: true,
    },
    readAt: {
      type: Date,
    },
    priority: {
      type: String,
      enum: ['low', 'medium', 'high'],
      default: 'medium',
    },
    metadata: {
      type: mongoose.Schema.Types.Mixed,
      // Additional data specific to notification type
    },
  },
  {
    timestamps: true,
    toJSON: { virtuals: true },
    toObject: { virtuals: true },
  },
);

// Indexes for better query performance
notificationSchema.index({ user: 1, createdAt: -1 });
notificationSchema.index({ user: 1, isRead: 1 });

// Middleware to update readAt when isRead changes to true
notificationSchema.pre('save', function (next) {
  if (this.isModified('isRead') && this.isRead && !this.readAt) {
    this.readAt = new Date();
  }
  next();
});

const Notification = mongoose.model('Notification', notificationSchema);

module.exports = Notification;