In memory eventsourcing repository

in_memory_repository.js

var util = require('util')
var EventEmitter = require('events').EventEmitter
var _ = require('lodash')
var Aggregate = require('eventsourced-object')

function InMemoryRepository (Model) {
  this.eventCount = 0
  this._Model = Model
}

util.inherits(InMemoryRepository, EventEmitter)

InMemoryRepository.prototype.get = function (item, cb) {
  var agg = this.aggregates && this.aggregates[item.aggregateId]
  if (_.isEmpty(agg) || agg[0].context !== item.context) cb(new Error('Not found'))
  else cb(null, new this._Model(agg))
}

InMemoryRepository.prototype.save = function (agg, cb) {
  if (!this.aggregates) this.aggregates = {}
  var events = Aggregate.drain(agg)
  var first = events[0]
  if (!first) return cb(null, null)

  if (!this.aggregates[first.aggregateId]) this.aggregates[first.aggregateId] = []
  var a = this.aggregates[first.aggregateId]
  var event

  if (((a.length || 0) + 1) !== first.version) return cb(new Error('Conflict'))
  for (var i = 0; i < events.length; i++) {
    events[i].id = ++this.eventCount
    a[a.length] = events[i]
  }
  cb(null, null)

  // Events are triggered after saving the events
  for (var i = 0; i < events.length; i++) this.emit('data', events[i])
}

InMemoryRepository.prototype.events = function (params, cb) {
  if (params.aggregateId) return cb(null, this.aggregates[params.aggregateId])

  var events = _.chain(this.aggregates).values().filter(Boolean).flatten().value()
  if (params.context) cb(null, _.filter(events, {context: params.context}))
  else cb(null, events)
}