// Copyright 2020 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.

/**
 * This application demonstrates how to perform basic operations on files with
 * the Google Cloud Storage API.
 *
 * For more information, see the README.md under /storage and the documentation
 * at https://cloud.google.com/storage/docs.
 */

function main(
  srcBucketName = 'my-bucket',
  srcFilename = 'test2.txt',
  destBucketName = 'my-bucket',
  destFileName = 'test3.txt',
  destinationGenerationMatchPrecondition = 0
) {
  // [START storage_copy_file]
  /**
   * TODO(developer): Uncomment the following lines before running the sample.
   */
  // The ID of the bucket the original file is in
  // const srcBucketName = 'your-source-bucket';

  // The ID of the GCS file to copy
  // const srcFilename = 'your-file-name';

  // The ID of the bucket to copy the file to
  // const destBucketName = 'target-file-bucket';

  // The ID of the GCS file to create
  // const destFileName = 'target-file-name';

  // Imports the Google Cloud client library
  const {Storage} = require('@google-cloud/storage');

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

  async function copyFile() {
    const copyDestination = storage.bucket(destBucketName).file(destFileName);

    // Optional:
    // Set a generation-match precondition to avoid potential race conditions
    // and data corruptions. The request to copy is aborted if the object's
    // generation number does not match your precondition. For a destination
    // object that does not yet exist, set the ifGenerationMatch precondition to 0
    // If the destination object already exists in your bucket, set instead a
    // generation-match precondition using its generation number.
    const copyOptions = {
      preconditionOpts: {
        ifGenerationMatch: destinationGenerationMatchPrecondition,
      },
    };

    // Copies the file to the other bucket
    await storage
      .bucket(srcBucketName)
      .file(srcFilename)
      .copy(copyDestination, copyOptions);

    console.log(
      `gs://${srcBucketName}/${srcFilename} copied to gs://${destBucketName}/${destFileName}`
    );
  }

  copyFile().catch(console.error);
  // [END storage_copy_file]
}
main(...process.argv.slice(2));