Firebase Cloud Functions: Storage Thumbnails

storage-thumbnails.js

'use strict'

const functions = require('firebase-functions')
const mkdirp = require('mkdirp-promise')
const gcs = require('@google-cloud/storage')({
    keyFilename: '***********************************-c3d9469093.json'
})
const admin = require('firebase-admin')
const spawn = require('child-process-promise').spawn
const path = require('path')
const os = require('os')
const fs = require('fs')

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

const THUMB_1200_WIDTH = 1200
const THUMB_600_HEIGHT = 600

const THUMB_600_WIDTH = 600
const THUMB_400_HEIGHT = 400

const THUMB_200_WIDTH = 200
const THUMB_200_HEIGHT = 200

const THUMB_LARGE_PREFIX = 'thumb_large_'
const THUMB_SMALL_PREFIX = 'thumb_small_'
const THUMB_ICON_PREFIX = 'thumb_icon_'

exports.storageThumbnails2 = functions.storage.object()
    .onChange((event) => {
    
        const filePath = event.data.name
        const contentType = event.data.contentType
        
        const fileDir = path.dirname(filePath)
        const fileName = path.basename(filePath)
        
        const thumbLargePath = path.normalize(path.join(fileDir, `${THUMB_LARGE_PREFIX}${fileName}`))
        const thumbSmallPath = path.normalize(path.join(fileDir, `${THUMB_SMALL_PREFIX}${fileName}`))
        const thumbIconPath = path.normalize(path.join(fileDir, `${THUMB_ICON_PREFIX}${fileName}`))
        
        const tempLocalFile = path.join(os.tmpdir(), filePath)
        const tempLocalDir = path.dirname(tempLocalFile)

        const tempLocalThumbLarge = path.join(os.tmpdir(), thumbLargePath)
        const tempLocalThumbSmall = path.join(os.tmpdir(), thumbSmallPath)
        const tempLocalThumbIcon = path.join(os.tmpdir(), thumbIconPath)

        // Exit if this is a move or deletion event.
        if (event.data.resourceState === 'not_exists') {
            console.log('This is a deletion event.')
            return null
        }

        // Exit if this is triggered on a file that is not an image.
        if (!contentType.startsWith('image/')) {
            console.log('This is not an image.')
            return null
        }

        // Exit if the image is already a thumbnail.
        if (
            fileName.startsWith(THUMB_LARGE_PREFIX) || 
            fileName.startsWith(THUMB_SMALL_PREFIX) || 
            fileName.startsWith(THUMB_ICON_PREFIX)) {
            console.log('Already created!')
            return null
        }

        // Cloud Storage files.
        const bucket = gcs.bucket(event.data.bucket)
        const file = bucket.file(filePath)
        const thumbLargeFile = bucket.file(thumbLargePath)
        const thumbSmallFile = bucket.file(thumbSmallPath)
        const thumbIconFile = bucket.file(thumbIconPath)

        const metadata = {
            contentType: contentType
        }

        return mkdirp(tempLocalDir)
            .then(() => file.download({ destination: tempLocalFile }))
            // Large thumb
            .then(() => { console.log('The file has been downloaded to', tempLocalFile)
                return spawn(
                    `convert`, [
                        `-define`, 
                        `jpeg:size=${THUMB_1200_WIDTH}x${THUMB_600_HEIGHT}>`, 
                        tempLocalFile, 
                        `-thumbnail`, 
                        `${THUMB_1200_WIDTH}x${THUMB_600_HEIGHT}>^`, 
                        `-gravity`, 
                        `center`, 
                        `-extent`, 
                        `${THUMB_1200_WIDTH}x${THUMB_600_HEIGHT}>`, 
                        tempLocalThumbLarge
                    ]
                )
            })
            .then(() => { console.log('Thumbnail created at', tempLocalThumbLarge)
                // Uploading the Thumbnail.
                return bucket.upload(tempLocalThumbLarge, {
                    destination: thumbLargePath,
                    metadata: metadata
                })
            })
            // Small thumb
            .then(() => { console.log('The file has been downloaded to', tempLocalFile)
                return spawn(
                    `convert`, [
                        `-define`, 
                        `jpeg:size=${THUMB_600_WIDTH}x${THUMB_400_HEIGHT}>`, 
                        tempLocalFile, 
                        `-thumbnail`, 
                        `${THUMB_600_WIDTH}x${THUMB_400_HEIGHT}>^`, 
                        `-gravity`, 
                        `center`, 
                        `-extent`, 
                        `${THUMB_600_WIDTH}x${THUMB_400_HEIGHT}>`, 
                        tempLocalThumbSmall
                    ]
                )
            })
            .then(() => { console.log('Thumbnail created at', tempLocalThumbSmall)
                // Uploading the Thumbnail.
                return bucket.upload(tempLocalThumbSmall, {
                    destination: thumbSmallPath,
                    metadata: metadata
                })
            })
            // Icon thumb
            .then(() => { console.log('The file has been downloaded to', tempLocalFile)
                return spawn(
                    `convert`, [
                        `-define`, 
                        `jpeg:size=${THUMB_200_WIDTH}x${THUMB_200_HEIGHT}>`, 
                        tempLocalFile, 
                        `-thumbnail`, 
                        `${THUMB_200_WIDTH}x${THUMB_200_HEIGHT}>^`, 
                        `-gravity`, 
                        `center`, 
                        `-extent`, 
                        `${THUMB_200_WIDTH}x${THUMB_200_HEIGHT}>`, 
                        tempLocalThumbIcon
                    ]
                )
            })
            .then(() => { console.log('Thumbnail created at', tempLocalThumbIcon)
                // Uploading the Thumbnail.
                return bucket.upload(tempLocalThumbIcon, {
                    destination: thumbIconPath,
                    metadata: metadata
                })
            })
            // Finish upload
            .then(() => {

                console.log('Thumbnails uploaded to Storage')
                // Once the image has been uploaded delete the local files to free up disk space.
                fs.unlinkSync(tempLocalFile)
                fs.unlinkSync(tempLocalThumbLarge)
                fs.unlinkSync(tempLocalThumbSmall)
                fs.unlinkSync(tempLocalThumbIcon)

                // Get the Signed URLs for the thumbnail and original image.
                const config = {
                    action: 'read',
                    expires: '03-01-2500',
                }
                return Promise.all([
                    thumbLargeFile.getSignedUrl(config),
                    thumbSmallFile.getSignedUrl(config),
                    thumbIconFile.getSignedUrl(config),
                    file.getSignedUrl(config)
                ])

            })
            .then((results) => {

                console.log('Got Signed URLs.')
                const thumbLargeResult = results[0]
                const thumbSmallResult = results[1]
                const thumbIconResult = results[2]
                const originalResult = results[3]

                const thumbLargeFileUrl = thumbLargeResult[0]
                const thumbSmallFileUrl = thumbSmallResult[0]
                const thumbIconFileUrl = thumbIconResult[0]
                const fileUrl = originalResult[0]

                // Add the URLs to the Database
                return admin.database().ref('images').push({
                    oryginal: {
                        name: fileName,
                        url: fileUrl
                    },
                    large: {
                        name: `${THUMB_LARGE_PREFIX}${fileName}`,
                        url: thumbLargeFileUrl
                    },
                    small: {
                        name: `${THUMB_SMALL_PREFIX}${fileName}`,
                        url: thumbSmallFileUrl
                    },
                    icon: {
                        name: `${THUMB_ICON_PREFIX}${fileName}`,
                        url: thumbIconFileUrl
                    }
                })

            })
            .then(() => console.log('Thumbnail URLs saved to database.'))
})