<?php

namespace Aws\S3;

use Aws\Exception\MultipartUploadException;
use Aws\Result;
use Aws\S3\Exception\S3Exception;
use GuzzleHttp\Promise\PromisorInterface;
use InvalidArgumentException;
use function GuzzleHttp\Promise\coroutine;

/**
 * Copies objects from one S3 location to another, utilizing a multipart copy
 * when appropriate.
 */
class ObjectCopier implements PromisorInterface {
	const DEFAULT_MULTIPART_THRESHOLD = MultipartUploader::PART_MAX_SIZE;
	private static $defaults = [
		'before_lookup' => null,
		'before_upload' => null,
		'concurrency'   => 5,
		'mup_threshold' => self::DEFAULT_MULTIPART_THRESHOLD,
		'params'        => [],
		'part_size'     => null,
		'version_id'    => null,
	];
	private $client;
	private $source;
	private $destination;
	private $acl;
	private $options;

	/**
	 * @param S3ClientInterface $client The S3 Client used to execute
	 *                                          the copy command(s).
	 * @param array $source The object to copy, specified as
	 *                                          an array with a 'Bucket' and
	 *                                          'Key' keys. Provide a
	 *                                          'VersionID' key to copy a
	 *                                          specified version of an object.
	 * @param array $destination The bucket and key to which to
	 *                                          copy the $source, specified as
	 *                                          an array with a 'Bucket' and
	 *                                          'Key' keys.
	 * @param string $acl ACL to apply to the copy
	 *                                          (default: private).
	 * @param array $options Options used to configure the
	 *                                          copy process. Options passed in
	 *                                          through 'params' are added to
	 *                                          the sub commands.
	 *
	 * @throws InvalidArgumentException
	 */
	public function __construct(
		S3ClientInterface $client,
		array $source,
		array $destination,
		$acl = 'private',
		array $options = []
	) {
		$this->validateLocation( $source );
		$this->validateLocation( $destination );

		$this->client      = $client;
		$this->source      = $source;
		$this->destination = $destination;
		$this->acl         = $acl;
		$this->options     = $options + self::$defaults;
	}

	private function validateLocation( array $location ) {
		if ( empty( $location['Bucket'] ) || empty( $location['Key'] ) ) {
			throw new InvalidArgumentException( 'Locations provided to an'
			                                    . ' Aws\S3\ObjectCopier must have a non-empty Bucket and Key' );
		}
	}

	/**
	 * Perform the configured copy synchronously. Returns the result of the
	 * CompleteMultipartUpload or CopyObject operation.
	 *
	 * @return Result
	 *
	 * @throws S3Exception
	 * @throws MultipartUploadException
	 */
	public function copy() {
		return $this->promise()->wait();
	}

	/**
	 * Perform the configured copy asynchronously. Returns a promise that is
	 * fulfilled with the result of the CompleteMultipartUpload or CopyObject
	 * operation or rejected with an exception.
	 */
	public function promise() {
		return coroutine( function () {
			$headObjectCommand = $this->client->getCommand(
				'HeadObject',
				$this->options['params'] + $this->source
			);
			if ( is_callable( $this->options['before_lookup'] ) ) {
				$this->options['before_lookup']( $headObjectCommand );
			}
			$objectStats = ( yield $this->client->executeAsync(
				$headObjectCommand
			) );

			if ( $objectStats['ContentLength'] > $this->options['mup_threshold'] ) {
				$mup = new MultipartCopy(
					$this->client,
					$this->getSourcePath(),
					[ 'source_metadata' => $objectStats, 'acl' => $this->acl ]
					+ $this->destination
					+ $this->options
				);

				yield $mup->promise();
			} else {
				$defaults = [
					'ACL'               => $this->acl,
					'MetadataDirective' => 'COPY',
					'CopySource'        => $this->getSourcePath(),
				];

				$params = array_diff_key( $this->options, self::$defaults )
				          + $this->destination + $defaults + $this->options['params'];

				yield $this->client->executeAsync(
					$this->client->getCommand( 'CopyObject', $params )
				);
			}
		} );
	}

	private function getSourcePath() {
		$sourcePath = "/{$this->source['Bucket']}/"
		              . rawurlencode( $this->source['Key'] );
		if ( isset( $this->source['VersionId'] ) ) {
			$sourcePath .= "?versionId={$this->source['VersionId']}";
		}

		return $sourcePath;
	}
}
