<?php

/**

 * File containing the ezcArchiveCentralDirectoryHeader class.

 *

 * @package Archive

 * @version //autogentag//

 * @copyright Copyright (C) 2005-2010 eZ Systems AS. All rights reserved.

 * @license http://ez.no/licenses/new_bsd New BSD License

 * @access private

 */



/**

 * The ezcArchiveCentralDirectoryEndHeader class represents the Zip central directory end header.

 *

 * ezcArchiveCentralDirectoryEndHeader can read the header from an ezcArchiveCharacterFile.

 *

 * The values from the headers are directly accessible via the class properties, and allows

 * reading and writing to specific header values.

 *

 * The entire header can be appended to an ezcArchiveCharacterFile again.

 *

 * The central directory end header is the last header of the ZIP archive. Some algorithms

 * search back to this header in order to find the other headers. The variable comment length

 * makes it tricky.

 *

 * The Central Directory End Header has the following structure:

 *

 * <pre>

 * + ---+---------+------------+------------------------------------+-------------------------------------------------------------------------------+

 * | ID | Offset  | Field size | Property                           |  Description                                                                  |

 * +----+---------+------------+------------------------------------+-------------------------------------------------------------------------------+

 * |    |  0      | 4          | -                                  | Central directory header signature                                            |

 * |    |  4      | 2          | diskNumber                         | nr of this disk                                                               |

 * |    |  6      | 2          | centralDirectoryDisk               | number of the disk with the start of the central directory                    |

 * |    |  8      | 2          | totalCentralDirectoryEntriesOnDisk | total number of entries in the central directory on this disk                 |

 * |    |  10     | 2          | totalCentralDirectoryEntries       | total number of entries in the central directory                              |

 * |    |  12     | 4          | centralDirectorySize               | size of the central directory                                                 |

 * |    |  16     | 4          | centralDirectoryStart              | offset of start of central directory with respect to the starting disk number |

 * | X: |  20     | 2          | commentLength                      | .ZIP file comment length                                                      |

 * |    |  22     | X          | comment                            | .ZIP file comment                                                             |

 * +----+---------+------------+------------------------------------+-------------------------------------------------------------------------------+

 * </pre>

 *

 *

 * The columns of the table are:

 * - ID gives a label to a specific field or row in the table.

 * - Offset describes the start position of a header field.

 * - Field size describes the size of the field in bytes.

 * - Property is the name of the property that will be set by the header field.

 * - Description explains what this field describes.

 *

 *

 * @package Archive

 * @version //autogentag//

 * @access private

 */

class ezcArchiveCentralDirectoryEndHeader

{

    /**

     * Defines the signature of this header.

     */

    const magic = 0x06054b50;



    /**

     * Holds the properties of this class.

     *

     * @var array(string=>mixed)

     */

    private $properties = array();



    /**

     * Creates and initializes a new header.

     *

     * If the ezcArchiveCharacterFile $file is null then the header will be empty.

     * When an ezcArchiveCharacterFile is given, the file position should be directly after the

     * signature of the header. This header will be read from the file and initialized in this class.

     *

     * @param ezcArchiveCharacterFile $file

     */

    public function __construct( ezcArchiveCharacterFile $file = null )

    {

        if ( !is_null( $file ) )

        {

            $this->properties = unpack (

                "vdiskNumber/".

                "vcentralDirectoryDisk/".

                "vtotalCentralDirectoryEntriesOnDisk/".

                "vtotalCentralDirectoryEntries/".

                "VcentralDirectorySize/".

                "VcentralDirectoryStart/".

                "vcommentLength",

                $file->read( 18 ) );



                $this->properties["comment"] = $file->read( $this->properties["commentLength"] );

        }

        else

        {

            $this->properties["diskNumber"] = 0;

            $this->properties["centralDirectoryDisk"] = 0;

            $this->properties["totalCentralDirectoryEntries"] = 0;

            $this->properties["totalCentralDirectoryEntriesOnDisk"] = 0;

            $this->properties["totalCentralDirectorySize"] = 0;

            $this->properties["totalCentralDirectoryStart"] = 0;



            $this->setComment( "" );

        }

    }



    /**

     * Sets the property $name to $value.

     *

     * @throws ezcBasePropertyNotFoundException if the property does not exist.

     * @throws ezcBasePropertyReadOnlyException if the property is read-only

     * @param string $name

     * @param mixed $value

     * @return void

     * @ignore

     */

    public function __set( $name, $value )

    {

        switch ( $name )

        {

            case "diskNumber":

            case "centralDirectoryDisk":

            case "totalCentralDirectoryEntriesOnDisk":

                throw new ezcBasePropertyReadOnlyException( $name );



            case "totalCentralDirectoryEntries":

                $this->setTotalDirectoryEntries( $value );

                break;



            case "centralDirectorySize":

            case "centralDirectoryStart":

                $this->properties[$name] = $value;

                break;



            case "commentLength":

                throw new ezcBasePropertyReadOnlyException( $name );



            case "comment":

                $this->setComment( $value );

                break;



            default:

                throw new ezcBasePropertyNotFoundException( $name );

        }

    }



    /**

     * Returns the value of the property $name.

     *

     * @throws ezcBasePropertyNotFoundException if the property does not exist.

     * @param string $name

     * @return mixed

     * @ignore

     */

    public function __get( $name )

    {

        switch ( $name )

        {

            case "diskNumber":

            case "centralDirectoryDisk":

            case "totalCentralDirectoryEntriesOnDisk":

            case "totalCentralDirectoryEntries":

            case "centralDirectorySize":

            case "centralDirectoryStart":

            case "commentLength":

            case "comment":

                return $this->properties[$name];



            default:

                throw new ezcBasePropertyNotFoundException( $name );

        }

    }



    /**

     * Sets the comment and comment length in the header from the string $comment.

     *

     * @param string $comment

     * @return void

     */

    public function setComment( $comment )

    {

        $this->properties["comment"] = $comment;

        $this->properties["commentLength"] = strlen( $comment );

    }



    /**

     * Sets the total directory entries to the int $numberOfEntries.

     *

     * The properties: diskNumber and centralDirectory will be set to 0.

     * The properties: totalCentralDirectoryEntriesOnDisk and totalCentralDirectoryEntries are set to the $numberOfEntries.

     *

     * @param int $numberOfEntries

     * @return void

     */

    public function setTotalDirectoryEntries( $numberOfEntries )

    {

        $this->properties["diskNumber"] = 0;

        $this->properties["centralDirectoryDisk"] = 0;

        $this->properties["totalCentralDirectoryEntriesOnDisk"] = $numberOfEntries;

        $this->properties["totalCentralDirectoryEntries"] = $numberOfEntries;

    }



    /**

     * Serializes this header and appends it to the given ezcArchiveCharacterFile $archiveFile.

     *

     * @param ezcArchiveCharacterFile $archiveFile

     * @return void

     */

    public function writeEncodedHeader( $archiveFile )

    {

        $enc = pack ( "VvvvvVVv",

            self::magic,

            $this->properties["diskNumber"],

            $this->properties["centralDirectoryDisk"],

            $this->properties["totalCentralDirectoryEntriesOnDisk"],

            $this->properties["totalCentralDirectoryEntries"],

            $this->properties["centralDirectorySize"],

            $this->properties["centralDirectoryStart"],

            $this->properties["commentLength"] );



        $archiveFile->write( $enc . $this->properties["comment"] );

    }



    /**

     * Returns true if the given string $string matches with the current signature.

     *

     * @param string $string

     * @return void

     */

    public static function isSignature( $string )

    {

        return $string == pack( "V", self::magic );

    }

}

?>