'use strict';

const createBufferReader = require("../../buffer-reader");
const createBitParser = require("../../../bit-parser");
const parsePrimaryVolumeDescriptor = require("./primary-volume");
const parseEscapeSequences = require("../../parse/escape-sequences");

/* Supplementary volume flags: (ref http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-119.pdf)
 *   Bit      Description
 *   0        If set, the Escape Sequences field specifies at least one escape sequence not registered according to ISO 2375.
 *   1 - 7    Reserved
 */

let parseVolumeFlags = createBitParser([
    "hasNonISO2375EscapeSequences",
    null,
    null,
    null,
    null,
    null,
    null,
    null
]);

module.exports = function parseSupplementaryVolumeDescriptor(data) {
    let bufferReader = createBufferReader(data);

    let escapeSequences = data.slice(81, 113);
    let encodings = parseEscapeSequences(escapeSequences);

    /* The format of a primary and supplementary volume descriptor are mostly the same - the only real difference is that a supplementary volume descriptor will also have a volumeFlags and escapeSequences field. We can therefore just parse this volume descriptor like a primary volume descriptor, and then merge in the additional fields. */

    return Object.assign(parsePrimaryVolumeDescriptor(data, encodings[0]), {
        volumeFlags: parseVolumeFlags(bufferReader.int8(0)),
        escapeSequences: escapeSequences,
        encodings: encodings
    });
};