models/ErrorLog.js

const mongoose = require('mongoose');

const errorLogSchema = new mongoose.Schema(
  {
    timestamp:  { type: Date,   default: Date.now, index: true },
    type:       { type: String, default: 'Error', trim: true },
    message:    { type: String, required: true, trim: true },
    stack:      { type: String, default: '' },
    code:       { type: String, default: 'INTERNAL_SERVER_ERROR', trim: true },
    statusCode: { type: Number, default: 500 },
    request: {
      url:        { type: String, default: '' },
      method:     { type: String, default: '' },
      ip:         { type: String, default: '' },
      userAgent:  { type: String, default: '', maxlength: 300 },
      bodyFields: { type: [String], default: [] },
    },
    userId: { type: String, default: '' },
    env:    { type: String, default: 'development' },
  },
  { versionKey: false }
);

errorLogSchema.index({ timestamp: -1 });
errorLogSchema.index({ code: 1, timestamp: -1 });

module.exports = mongoose.model('ErrorLog', errorLogSchema);