<?php

/*
 * This file is part of SwiftMailer.
 * (c) 2004-2009 Chris Corbyn
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

/**
 * Handles Base 64 Transfer Encoding in Swift Mailer.
 *
 * @author     Chris Corbyn
 */
class Swift_Mime_ContentEncoder_Base64ContentEncoder extends Swift_Encoder_Base64Encoder implements Swift_Mime_ContentEncoder
{
    /**
     * Encode stream $in to stream $out.
     *
     * @param Swift_OutputByteStream $os
     * @param Swift_InputByteStream  $is
     * @param int                    $firstLineOffset
     * @param int                    $maxLineLength,  optional, 0 indicates the default of 76 bytes
     */
    public function encodeByteStream(Swift_OutputByteStream $os, Swift_InputByteStream $is, $firstLineOffset = 0, $maxLineLength = 0)
    {
        if (0 >= $maxLineLength || 76 < $maxLineLength) {
            $maxLineLength = 76;
        }

        $remainder = 0;

        while (false !== $bytes = $os->read(8190)) {
            $encoded = base64_encode($bytes);
            $encodedTransformed = '';
            $thisMaxLineLength = $maxLineLength - $remainder - $firstLineOffset;

            while ($thisMaxLineLength < strlen($encoded)) {
                $encodedTransformed .= substr($encoded, 0, $thisMaxLineLength)."\r\n";
                $firstLineOffset = 0;
                $encoded = substr($encoded, $thisMaxLineLength);
                $thisMaxLineLength = $maxLineLength;
                $remainder = 0;
            }

            if (0 < $remainingLength = strlen($encoded)) {
                $remainder += $remainingLength;
                $encodedTransformed .= $encoded;
                $encoded = null;
            }

            $is->write($encodedTransformed);
        }
    }

    /**
     * Get the name of this encoding scheme.
     * Returns the string 'base64'.
     *
     * @return string
     */
    public function getName()
    {
        return 'base64';
    }
}
