generateZipParts = function(streamInfo, streamedContent, streamingEnded, offset, platform, encodeFileName) {
    var file = streamInfo['file'],
    compression = streamInfo['compression'],
    useCustomEncoding = encodeFileName !== utf8.utf8encode,
    encodedFileName = utils.transformTo("string", encodeFileName(file.name)),
    utfEncodedFileName = utils.transformTo("string", utf8.utf8encode(file.name)),
    comment = file.comment,
    encodedComment = utils.transformTo("string", encodeFileName(comment)),
    utfEncodedComment = utils.transformTo("string", utf8.utf8encode(comment)),
    useUTF8ForFileName = utfEncodedFileName.length !== file.name.length,
    useUTF8ForComment = utfEncodedComment.length !== comment.length,
    dosTime,
    dosDate,
    extraFields = "",
    unicodePathExtraField = "",
    unicodeCommentExtraField = "",
    dir = file.dir,
    date = file.date;


    var dataInfo = {
        crc32 : 0,
        compressedSize : 0,
        uncompressedSize : 0
    };

    // if the content is streamed, the sizes/crc32 are only available AFTER
    // the end of the stream.
    if (!streamedContent || streamingEnded) {
        dataInfo.crc32 = streamInfo['crc32'];
        dataInfo.compressedSize = streamInfo['compressedSize'];
        dataInfo.uncompressedSize = streamInfo['uncompressedSize'];
    }

    var bitflag = 0;
    if (streamedContent) {
        // Bit 3: the sizes/crc32 are set to zero in the local header.
        // The correct values are put in the data descriptor immediately
        // following the compressed data.
        bitflag |= 0x0008;
    }
    if (!useCustomEncoding && (useUTF8ForFileName || useUTF8ForComment)) {
        // Bit 11: Language encoding flag (EFS).
        bitflag |= 0x0800;
    }


    var extFileAttr = 0;
    var versionMadeBy = 0;
    if (dir) {
        // dos or unix, we set the dos dir flag
        extFileAttr |= 0x00010;
    }
    if(platform === "UNIX") {
        versionMadeBy = 0x031E; // UNIX, version 3.0
        extFileAttr |= generateUnixExternalFileAttr(file.unixPermissions, dir);
    } else { // DOS or other, fallback to DOS
        versionMadeBy = 0x0014; // DOS, version 2.0
        extFileAttr |= generateDosExternalFileAttr(file.dosPermissions, dir);
    }

    // date
    // @see http://www.delorie.com/djgpp/doc/rbinter/it/52/13.html
    // @see http://www.delorie.com/djgpp/doc/rbinter/it/65/16.html
    // @see http://www.delorie.com/djgpp/doc/rbinter/it/66/16.html

    dosTime = date.getUTCHours();
    dosTime = dosTime << 6;
    dosTime = dosTime | date.getUTCMinutes();
    dosTime = dosTime << 5;
    dosTime = dosTime | date.getUTCSeconds() / 2;

    dosDate = date.getUTCFullYear() - 1980;
    dosDate = dosDate << 4;
    dosDate = dosDate | (date.getUTCMonth() + 1);
    dosDate = dosDate << 5;
    dosDate = dosDate | date.getUTCDate();

    if (useUTF8ForFileName) {
        // set the unicode path extra field. unzip needs at least one extra
        // field to correctly handle unicode path, so using the path is as good
        // as any other information. This could improve the situation with
        // other archive managers too.
        // This field is usually used without the utf8 flag, with a non
        // unicode path in the header (winrar, winzip). This helps (a bit)
        // with the messy Windows' default compressed folders feature but
        // breaks on p7zip which doesn't seek the unicode path extra field.
        // So for now, UTF-8 everywhere !
        unicodePathExtraField =
            // Version
            decToHex(1, 1) +
            // NameCRC32
            decToHex(crc32(encodedFileName), 4) +
            // UnicodeName
            utfEncodedFileName;

        extraFields +=
            // Info-ZIP Unicode Path Extra Field
            "\x75\x70" +
            // size
            decToHex(unicodePathExtraField.length, 2) +
            // content
            unicodePathExtraField;
    }

    if(useUTF8ForComment) {

        unicodeCommentExtraField =
            // Version
            decToHex(1, 1) +
            // CommentCRC32
            decToHex(crc32(encodedComment), 4) +
            // UnicodeName
            utfEncodedComment;

        extraFields +=
            // Info-ZIP Unicode Path Extra Field
            "\x75\x63" +
            // size
            decToHex(unicodeCommentExtraField.length, 2) +
            // content
            unicodeCommentExtraField;
    }

    var header = "";

    // version needed to extract
    header += "\x0A\x00";
    // general purpose bit flag
    header += decToHex(bitflag, 2);
    // compression method
    header += compression.magic;
    // last mod file time
    header += decToHex(dosTime, 2);
    // last mod file date
    header += decToHex(dosDate, 2);
    // crc-32
    header += decToHex(dataInfo.crc32, 4);
    // compressed size
    header += decToHex(dataInfo.compressedSize, 4);
    // uncompressed size
    header += decToHex(dataInfo.uncompressedSize, 4);
    // file name length
    header += decToHex(encodedFileName.length, 2);
    // extra field length
    header += decToHex(extraFields.length, 2);


    var fileRecord = signature.LOCAL_FILE_HEADER + header + encodedFileName + extraFields;

    var dirRecord = signature.CENTRAL_FILE_HEADER +
        // version made by (00: DOS)
        decToHex(versionMadeBy, 2) +
        // file header (common to file and central directory)
        header +
        // file comment length
        decToHex(encodedComment.length, 2) +
        // disk number start
        "\x00\x00" +
        // internal file attributes TODO
        "\x00\x00" +
        // external file attributes
        decToHex(extFileAttr, 4) +
        // relative offset of local header
        decToHex(offset, 4) +
        // file name
        encodedFileName +
        // extra field
        extraFields +
        // file comment
        encodedComment;

    return {
        fileRecord: fileRecord,
        dirRecord: dirRecord
    };
}
Generate the various parts used in the construction of the final zip file.
@param {Object} streamInfo the hash with informations about the compressed file.
@param {Boolean} streamedContent is the content streamed ?
@param {Boolean} streamingEnded is the stream finished ?
@param {number} offset the current offset from the start of the zip file.
@param {String} platform let's pretend we are this platform (change platform dependents fields)
@param {Function} encodeFileName the function to encode the file name / comment.
@return {Object} the zip parts.