// Copyright 2016 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

'use strict';

const process = require('process'); // Required to mock environment variables

// [START gae_flex_storage_app]
const {format} = require('util');
const express = require('express');
const Multer = require('multer');

// By default, the client will authenticate using the service account file
// specified by the GOOGLE_APPLICATION_CREDENTIALS environment variable and use
// the project specified by the GOOGLE_CLOUD_PROJECT environment variable. See
// https://github.com/GoogleCloudPlatform/google-cloud-node/blob/master/docs/authentication.md
// These environment variables are set automatically on Google App Engine
const {Storage} = require('@google-cloud/storage');

// Instantiate a storage client
const storage = new Storage();

const app = express();
app.set('view engine', 'pug');

// This middleware is available in Express v4.16.0 onwards
app.use(express.json());

// Multer is required to process file uploads and make them available via
// req.files.
const multer = Multer({
  storage: Multer.memoryStorage(),
  limits: {
    fileSize: 5 * 1024 * 1024, // no larger than 5mb, you can change as needed.
  },
});

// A bucket is a container for objects (files).
const bucket = storage.bucket(process.env.GCLOUD_STORAGE_BUCKET);

// Display a form for uploading files.
app.get('/', (req, res) => {
  res.render('form.pug');
});

// Process the file upload and upload to Google Cloud Storage.
app.post('/upload', multer.single('file'), (req, res, next) => {
  if (!req.file) {
    res.status(400).send('No file uploaded.');
    return;
  }

  // Create a new blob in the bucket and upload the file data.
  const blob = bucket.file(req.file.originalname);
  const blobStream = blob.createWriteStream();

  blobStream.on('error', err => {
    next(err);
  });

  blobStream.on('finish', () => {
    // The public URL can be used to directly access the file via HTTP.
    const publicUrl = format(
      `https://storage.googleapis.com/${bucket.name}/${blob.name}`
    );
    res.status(200).send(publicUrl);
  });

  blobStream.end(req.file.buffer);
});

const PORT = parseInt(process.env.PORT) || 8080;
app.listen(PORT, () => {
  console.log(`App listening on port ${PORT}`);
  console.log('Press Ctrl+C to quit.');
});
// [END gae_flex_storage_app]

module.exports = app;
