import { getEventObject } from './helpers'
import Manager from './manager'
import { Event, TracktorConfig, UserConfig } from './interfaces'

export default class EventBuffer {
  private manager: Manager
  private queue: Array<Event> = []
  private timerId: number | NodeJS.Timer

  constructor(config?: TracktorConfig) {
    this.manager = new Manager(config)
  }

  public push(name: string, version: number, payload: object, userConfig: UserConfig) {
    const failureEventDescription = `[${name}.${version}]`
    const {
      request_max_size,
      event_max_count,
      event_max_size,
      emit_frequency,
    } = this.manager.config

    if (Object.keys(payload).length === 0) {
      return this.manager.sendFailureEvent(
        `${failureEventDescription} No event data passed.`,
        userConfig
      )
    }

    const event = getEventObject(name, version, payload)
    const eventLength = JSON.stringify(event).length

    if (eventLength > event_max_size) {
      return this.manager.sendFailureEvent(
        `${failureEventDescription} Pushed event exceeds allowed event size.`,
        userConfig
      )
    }

    if (eventLength >= request_max_size - JSON.stringify(this.queue).length) {
      this.flush(userConfig)
    }

    this.queue.push(event)

    if (this.queue.length == event_max_count) {
      this.flush(userConfig)
    }

    // If we reach the emit frequency, initiate a flush
    if (!this.timerId && this.queue.length > 0) {
      this.timerId = setTimeout(() => {
        this.flush(userConfig)
        this.timerId = null
      }, emit_frequency)
    }
  }

  public flush(userConfig: UserConfig) {
    if (this.queue.length > 0) {
      const events: Array<Event> = this.queue.splice(0, this.manager.config.event_max_count)
      this.manager.send({ events }, userConfig)
    }
  }
}