import APIClient from 'App/api_client';

const ALLOWED_404 = "No-file-and-this-is-ok"
const NO_BACKUP_FILE = "No-efs-file"
export const NO_URLS = 'No-urls-provided'


export async function loadFiles(
  urls: string[],
  onData: (data: Uint8Array) => void,
  canSkip: boolean = false,
): Promise<void> {
  if (!urls.length) {
    throw NO_URLS
  }
  try {
    for (let url of urls) {
      await loadFile(url, onData, urls.length > 1 ? url !== urls[0] : canSkip)
    }
    return Promise.resolve()
  } catch (e) {
    return Promise.reject(e)
  }
}

export async function loadFile(
  url: string,
  onData: (data: Uint8Array) => void,
  canSkip: boolean = false,
): Promise<void> {
  return window.fetch(url)
    .then(response => processAPIStreamResponse(response, canSkip))
    .then(data => onData(data))
    .catch(e => {
      if (e === ALLOWED_404) {
        return;
      } else {
        throw e
      }
    })
}

export async function requestEFSDom(sessionId: string) {
  return await requestEFSMobFile(sessionId + "/dom.mob")
}

export async function requestEFSDevtools(sessionId: string) {
  return await requestEFSMobFile(sessionId + "/devtools.mob")
}

async function requestEFSMobFile(filename: string) {
  const api = new APIClient()
  const res = await api.fetch('/unprocessed/' + filename)
  if (res.status >= 400) {
    throw NO_BACKUP_FILE
  }
  return await processAPIStreamResponse(res, false)
}

const processAPIStreamResponse = (response: Response, skippable: boolean) => {
  return new Promise<Blob>((res, rej) => {
    if (response.status === 404 && skippable) {
      return rej(ALLOWED_404)
    }
    if (response.status >= 400) {
      return rej(`Bad file status code ${response.status}. Url: ${response.url}`)
    }
    res(response.blob())
  }).then(async blob => new Uint8Array(await blob.arrayBuffer()))
}