<?php
/**
 * BackWPup_Destination_Ftp_Downloader
 *
 * @since   3.5.0
 * @package Inpsyde\BackWPup
 */

/**
 * Class BackWPup_Destination_Ftp_Downloader
 *
 * @since   3.5.0
 * @package Inpsyde\BackWPup
 */
final class BackWPup_Destination_Ftp_Downloader implements BackWPup_Destination_Downloader_Interface {

	/**
	 * @var \BackWpUp_Destination_Downloader_Data
	 */
	private $data;

	/**
	 * @var resource
	 */
	private $source_file_handler;

	/**
	 * @var resource
	 */
	private $local_file_handler;

	/**
	 * @var BackWPup_Destination_Ftp_Connect
	 */
	private $ftp_resource;

	/**
	 * BackWPup_Destination_Ftp_Downloader constructor
	 */
	public function __construct( BackWpUp_Destination_Downloader_Data $data ) {

		$this->data = $data;

		$this->ftp_resource();
	}

	/**
	 * Clean up things
	 */
	public function __destruct() {

		fclose( $this->source_file_handler );
		fclose( $this->local_file_handler );
	}

	/**
	 * @inheritdoc
	 */
	public function download_chunk( $start_byte, $end_byte ) {

		$this->source_file_handler( $start_byte );
		$this->local_file_handler( $start_byte );

		$bytes = (int) stream_copy_to_stream(
			$this->source_file_handler,
			$this->local_file_handler,
			$end_byte - $start_byte + 1,
			0
		);

		if ( $bytes === 0 ) {
			throw new \RuntimeException( __( 'Could not write data to file.', 'backwpup' ) );
		}
	}

	/**
	 * @inheritdoc
	 */
	public function calculate_size() {

		$resource = $this->ftp_resource
			->connect()
			->resource();

		$size = ftp_size( $resource, $this->data->source_file_path() );
		ftp_close( $resource );

		return $size;
	}

	/**
	 * Set the source file handler
	 *
	 * @param int $start_byte
	 */
	private function source_file_handler( $start_byte ) {

		if ( is_resource( $this->source_file_handler ) ) {
			return;
		}

		$ctx = stream_context_create( array( 'ftp' => array( 'resume_pos' => $start_byte ) ) );
		$url = $this->ftp_resource->getURL( $this->data->source_file_path(), false, $ctx );

		$this->source_file_handler = fopen( $url, 'r' );

		if ( ! is_resource( $this->source_file_handler ) ) {
			throw new \RuntimeException( __( 'Cannot open FTP file for download.', 'backwpup' ) );
		}
	}

	/**
	 * Set the local file handler
	 *
	 * @param int $start_byte
	 */
	private function local_file_handler( $start_byte ) {

		if ( is_resource( $this->local_file_handler ) ) {
			return;
		}

		$this->local_file_handler = fopen( $this->data->local_file_path(), $start_byte === 0 ? 'wb' : 'ab' );

		if ( ! is_resource( $this->local_file_handler ) ) {
			throw new \RuntimeException( __( 'File could not be opened for writing.', 'backwpup' ) );
		}
	}

	/**
	 * Set the Ftp resource
	 *
	 * @return void
	 */
	private function ftp_resource() {

		$opts = (object) BackWPup_Option::get_job( $this->data->job_id() );

		$this->ftp_resource = new BackWPup_Destination_Ftp_Connect(
			$opts->ftphost,
			$opts->ftpuser,
			BackWPup_Encryption::decrypt( $opts->ftppass ),
			$opts->ftphostport,
			$opts->ftptimeout,
			$opts->ftpssl,
			$opts->ftppasv
		);
	}
}