<?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.
 */

/**
 * Provides a mechanism for storing data using two keys.
 *
 * @author Chris Corbyn
 */
interface Swift_KeyCache
{
    /** Mode for replacing existing cached data */
    const MODE_WRITE = 1;

    /** Mode for appending data to the end of existing cached data */
    const MODE_APPEND = 2;

    /**
     * Set a string into the cache under $itemKey for the namespace $nsKey.
     *
     * @see MODE_WRITE, MODE_APPEND
     *
     * @param string $nsKey
     * @param string $itemKey
     * @param string $string
     * @param int    $mode
     */
    public function setString($nsKey, $itemKey, $string, $mode);

    /**
     * Set a ByteStream into the cache under $itemKey for the namespace $nsKey.
     *
     * @see MODE_WRITE, MODE_APPEND
     *
     * @param string $nsKey
     * @param string $itemKey
     * @param int    $mode
     */
    public function importFromByteStream($nsKey, $itemKey, Swift_OutputByteStream $os, $mode);

    /**
     * Provides a ByteStream which when written to, writes data to $itemKey.
     *
     * NOTE: The stream will always write in append mode.
     * If the optional third parameter is passed all writes will go through $is.
     *
     * @param string                $nsKey
     * @param string                $itemKey
     * @param Swift_InputByteStream $is      optional input stream
     *
     * @return Swift_InputByteStream
     */
    public function getInputByteStream($nsKey, $itemKey, Swift_InputByteStream $is = null);

    /**
     * Get data back out of the cache as a string.
     *
     * @param string $nsKey
     * @param string $itemKey
     *
     * @return string
     */
    public function getString($nsKey, $itemKey);

    /**
     * Get data back out of the cache as a ByteStream.
     *
     * @param string                $nsKey
     * @param string                $itemKey
     * @param Swift_InputByteStream $is      stream to write the data to
     */
    public function exportToByteStream($nsKey, $itemKey, Swift_InputByteStream $is);

    /**
     * Check if the given $itemKey exists in the namespace $nsKey.
     *
     * @param string $nsKey
     * @param string $itemKey
     *
     * @return bool
     */
    public function hasKey($nsKey, $itemKey);

    /**
     * Clear data for $itemKey in the namespace $nsKey if it exists.
     *
     * @param string $nsKey
     * @param string $itemKey
     */
    public function clearKey($nsKey, $itemKey);

    /**
     * Clear all data in the namespace $nsKey if it exists.
     *
     * @param string $nsKey
     */
    public function clearAll($nsKey);
}