import Result from './result'
import fetch from 'node-fetch'

type Status = 'succeeded'|'failed'

export interface ResultData {
  // Size of the PDF in bytes.
  size: number
  // Width of the PDF in pixel.
  width: number
  // Height of the PDF in pixel.
  height: number
  // Expiration time of the CDN URL.
  expiresAt: Date|null
  // Runtime in milliseconds.
  runtime: number
  // URL to the PDF.
  url: string
}

export default class Conversion extends Result {
  private cachedBuffer: Buffer|null = null

  constructor(public initializedAt: Date, public finishedAt: Date, public status: Status, public error: string|null, public result: ResultData) {
    super()
  }

  async buffer() {
    if (this.cachedBuffer) {
      return this.cachedBuffer
    }

    if (!this.result) {
      throw new Error('PDF does not exist.')
    }

    const response = await fetch(this.result.url)

    if (response.status !== 200) {
      throw new Error('PDF could not be downloaded from the CDN.')
    }

    return this.cachedBuffer = await response.buffer()
  }
}