<?php
/**
 * Dropbox Files Downloader
 *
 * @package Inpsyde\BackWPup
 */

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

	const OPTION_ROOT = 'dropboxroot';
	const OPTION_TOKEN = 'dropboxtoken';

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

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

	/**
	 * @var BackWPup_Destination_Dropbox_API
	 */
	private $dropbox_api;

	/**
	 * BackWPup_Destination_Dropbox_Downloader constructor
	 *
	 * @param \BackWpUp_Destination_Downloader_Data $data
	 *
	 * @throws \BackWPup_Destination_Dropbox_API_Exception
	 */
	public function __construct( BackWpUp_Destination_Downloader_Data $data ) {

		$this->data = $data;

		$this->dropbox_api();
	}

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

		fclose( $this->local_file_handler );
	}

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

		$this->local_file_handler( $start_byte );

		try {
			$data = $this->dropbox_api->download(
				array( 'path' => $this->data->source_file_path() ),
				$start_byte,
				$end_byte
			);

			$bytes = (int) fwrite( $this->local_file_handler, $data );
			if ( $bytes === 0 ) {
				throw new \RuntimeException( __( 'Could not write data to file.', 'backwpup' ) );
			}
		} catch ( \Exception $e ) {
			BackWPup_Admin::message( 'Dropbox: ' . $e->getMessage() );
		}
	}

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

		$metadata = $this->dropbox_api->filesGetMetadata( array( 'path' => $this->data->source_file_path() ) );

		return $metadata['size'];
	}

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

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

		// Open file; write mode if $start_byte is 0, else append
		$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 dropbox api instance
	 *
	 * @return $this
	 * @throws \BackWPup_Destination_Dropbox_API_Exception
	 */
	private function dropbox_api() {

		$this->dropbox_api = new \BackWPup_Destination_Dropbox_API(
			\BackWPup_Option::get( $this->data->job_id(), self::OPTION_ROOT )
		);

		$this->dropbox_api->setOAuthTokens( \BackWPup_Option::get( $this->data->job_id(), self::OPTION_TOKEN ) );
	}
}