const functions = require('firebase-functions');
const gcs = require('@google-cloud/storage')({keyFilename:'xxxxx.json'})
const spawn = require('child-process-promise').spawn
const admin = require('firebase-admin')

admin.initializeApp(functions.config().firebase)

exports.generateThumbnail = functions.storage.object().onChange(event => {
  const object = event.data
  const filePath = object.name
  const fileName = filePath.split('/').pop()

  const fileBucket = object.bucket
  const bucket = gcs.bucket(fileBucket)
  const tmpFilePath = '/tmp/${fileName}'

  const ref = admin.database().ref()
  const file = bucket.file(filePath)
  const thumbFilePath = filePath.replace(/(\/)?([^\/]*)$/,'$1thumb_$2')

  if(fileName.startsWith('thumb_')){
    console.log("already a thumb")
    return
  }

  if(!object.contentType.startsWith('image/')){
    console.log("thsi sis not an image")
    return
  }

  if(object.resouceState == 'not_exists'){
    console.log("thsi is a deletion event ")
    return
  }

  return bucket.file(filePath).download({destination:tmpFilePath})
    .then(() => {
      console.log("file downloaded to thmp path",tmpFilePath)
      return spawn('convert',[tmpFilePath,'-thumbnail','300x300>',tmpFilePath])
    })
    .then(() => {
      console.log("thumbail created")
      //const thumbFilePath = filePath.replace(/(\/)?([^\/]*)$/,'$1thumb_$2')
      return bucket.upload(tmpFilePath,{
        destination:thumbFilePath
      })
   }).then(() => {
      const thumbFile = bucket.file(thumbFilePath)
      const config = {
        action : 'write',
        expires : '03-09-2400'             
      }
      return Promise.all([
        thumbFile.getSignedUrl(config),
        file.getSignedUrl(config)
      ])
    }).then(results => {
      const thumbResult = results[0]
      const originalResult = results[1]
      const thumbFileUrl = thumbResult[0]
      const fileUrl = originalResult[0]
      return ref.child('posts').push({path:fileUrl, thumbnail:thumbFileUrl})
    })
})