<?php
/**
 * Folder Downloader.
 */

/**
 * Class BackWPup_Destination_Folder_Downloader.
 *
 * @since   3.6.0
 */
final class BackWPup_Destination_Folder_Downloader implements BackWPup_Destination_Downloader_Interface
{
    public const OPTION_BACKUP_DIR = 'backupdir';

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

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

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

    /**
     * BackWPup_Destination_Folder_Downloader constructor.
     */
    public function __construct(BackWpUp_Destination_Downloader_Data $data)
    {
        $this->data = $data;

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

    /**
     * Clean up things.
     */
    public function __destruct()
    {
        fclose($this->local_file_handler);
        fclose($this->source_file_handler);
    }

    /**
     * {@inheritdoc}
     */
    public function download_chunk($start_byte, $end_byte)
    {
        if (ftell($this->source_file_handler) !== $start_byte) {
            fseek($this->source_file_handler, $start_byte);
        }

        $data = fread($this->source_file_handler, $end_byte - $start_byte + 1);
        if (!$data) {
            throw new Exception(__('Could not read data from source file.', 'backwpup'));
        }

        $bytes = (int) fwrite($this->local_file_handler, $data);
        if ($bytes === 0) {
            throw new Exception(__('Could not write data into target file.', 'backwpup'));
        }
    }

    /**
     * {@inheritdoc}
     */
    public function calculate_size()
    {
        return filesize($this->source_backup_file());
    }

    /**
     * Retrieve the file handler for the source file.
     */
    private function source_file_handler()
    {
        if (is_resource($this->source_file_handler)) {
            return;
        }

        $file = $this->source_backup_file();

        $this->source_file_handler = @fopen($file, 'rb');
        if (!is_resource($this->source_file_handler)) {
            throw new \RuntimeException(__('File could not be opened for reading.', 'backwpup'));
        }
    }

    /**
     * @return string
     */
    private function backup_dir()
    {
        $backup_dir = esc_attr(BackWPup_Option::get($this->data->job_id(), self::OPTION_BACKUP_DIR));
        $backup_dir = trailingslashit(BackWPup_File::get_absolute_path($backup_dir));

        return (string) $backup_dir;
    }

    /**
     * @return string
     */
    private function source_backup_file()
    {
        return (string) realpath(
            BackWPup_Sanitize_Path::sanitize_path(
                $this->backup_dir() . basename($this->data->source_file_path())
            )
        );
    }

    /**
     * Retrieve the file handler for the local file.
     */
    private function local_file_handler()
    {
        if (is_resource($this->local_file_handler)) {
            return;
        }

        try {
            $this->local_file_handler = @fopen($this->data->local_file_path(), 'wb');
        } catch (\RuntimeException $exc) {
            throw new \RuntimeException(__('File could not be opened for writing.', 'backwpup'));
        } catch (\LogicException $exc) {
            throw new \RuntimeException(sprintf(
            // translators: $1 is the path of the local file where the backup will be stored
                __('%s is a directory not a file.', 'backwpup'),
                $this->data->local_file_path()
            ));
        }
    }
}