/* Copyright 2010-2019 Will Scullin <scullin@scullinsteel.com>
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation.  No representations are made about the suitability of this
 * software for any purpose.  It is provided "as is" without express or
 * implied warranty.
 */

import { base64_decode, base64_encode } from '../base64';
import { bytify, debug, toHex } from '../util';

//    var DO = [0x0,0x7,0xE,0x6,0xD,0x5,0xC,0x4,
//              0xB,0x3,0xA,0x2,0x9,0x1,0x8,0xF];
export var _DO = [
    0x0,0xD,0xB,0x9,0x7,0x5,0x3,0x1,
    0xE,0xC,0xA,0x8,0x6,0x4,0x2,0xF
];

//    var PO = [0x0,0x8,0x1,0x9,0x2,0xa,0x3,0xb,
//              0x4,0xc,0x5,0xd,0x6,0xe,0x7,0xf];
export var _PO = [
    0x0,0x2,0x4,0x6,0x8,0xa,0xc,0xe,
    0x1,0x3,0x5,0x7,0x9,0xb,0xd,0xf
];

// var D13O = [
//     0x0, 0xa, 0x7, 0x4, 0x1, 0xb, 0x8, 0x5, 0x2, 0xc, 0x9, 0x6, 0x3
// ];

export var _D13O = [
    0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa, 0xb, 0xc
];

var _trans53 = [
    0xab, 0xad, 0xae, 0xaf, 0xb5, 0xb6, 0xb7, 0xba,
    0xbb, 0xbd, 0xbe, 0xbf, 0xd6, 0xd7, 0xda, 0xdb,
    0xdd, 0xde, 0xdf, 0xea, 0xeb, 0xed, 0xee, 0xef,
    0xf5, 0xf6, 0xf7, 0xfa, 0xfb, 0xfd, 0xfe, 0xff
];

var _trans62 = [
    0x96, 0x97, 0x9a, 0x9b, 0x9d, 0x9e, 0x9f, 0xa6,
    0xa7, 0xab, 0xac, 0xad, 0xae, 0xaf, 0xb2, 0xb3,
    0xb4, 0xb5, 0xb6, 0xb7, 0xb9, 0xba, 0xbb, 0xbc,
    0xbd, 0xbe, 0xbf, 0xcb, 0xcd, 0xce, 0xcf, 0xd3,
    0xd6, 0xd7, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde,
    0xdf, 0xe5, 0xe6, 0xe7, 0xe9, 0xea, 0xeb, 0xec,
    0xed, 0xee, 0xef, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6,
    0xf7, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
];

export var detrans62 = [
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
    0x00, 0x00, 0x02, 0x03, 0x00, 0x04, 0x05, 0x06,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x07, 0x08,
    0x00, 0x00, 0x00, 0x09, 0x0A, 0x0B, 0x0C, 0x0D,
    0x00, 0x00, 0x0E, 0x0F, 0x10, 0x11, 0x12, 0x13,
    0x00, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x1B, 0x00, 0x1C, 0x1D, 0x1E,
    0x00, 0x00, 0x00, 0x1F, 0x00, 0x00, 0x20, 0x21,
    0x00, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x29, 0x2A, 0x2B,
    0x00, 0x2C, 0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32,
    0x00, 0x00, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38,
    0x00, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F
];

/**
 * From Beneath Apple DOS
 */

export function fourXfour(val) {
    var xx = val & 0xaa;
    var yy = val & 0x55;

    xx >>= 1;
    xx |= 0xaa;
    yy |= 0xaa;

    return [xx, yy];
}

export function defourXfour(xx, yy) {
    return ((xx << 1) | 0x01) & yy;
}

export function explodeSector16(volume, track, sector, data) {
    var checksum;

    var buf = [], idx;

    var gap;

    /*
        * Gap 1/3 (40/0x28 bytes)
        */

    if (sector === 0) // Gap 1
        gap = 0x80;
    else { // Gap 3
        gap = track === 0 ? 0x28 : 0x26;
    }

    for (idx = 0; idx < gap; idx++) {
        buf.push(0xff);
    }

    /*
        * Address Field
        */

    checksum  = volume ^ track ^ sector;
    buf = buf.concat([0xd5, 0xaa, 0x96]); // Address Prolog D5 AA 96
    buf = buf.concat(fourXfour(volume));
    buf = buf.concat(fourXfour(track));
    buf = buf.concat(fourXfour(sector));
    buf = buf.concat(fourXfour(checksum));
    buf = buf.concat([0xde, 0xaa, 0xeb]); // Epilog DE AA EB

    /*
        * Gap 2 (5 bytes)
        */

    for (idx = 0; idx < 0x05; idx++) {
        buf.push(0xff);
    }

    /*
        * Data Field
        */

    buf = buf.concat([0xd5, 0xaa, 0xad]); // Data Prolog D5 AA AD

    var nibbles = [];
    var ptr2 = 0;
    var ptr6 = 0x56;
    var idx2, idx6;

    for (idx = 0; idx < 0x156; idx++) {
        nibbles[idx] = 0;
    }

    idx2 = 0x55;
    for (idx6 = 0x101; idx6 >= 0; idx6--) {
        var val6 = data[idx6 % 0x100];
        var val2 = nibbles[ptr2 + idx2];

        val2 = (val2 << 1) | (val6 & 1);
        val6 >>= 1;
        val2 = (val2 << 1) | (val6 & 1);
        val6 >>= 1;

        nibbles[ptr6 + idx6] = val6;
        nibbles[ptr2 + idx2] = val2;

        if (--idx2 < 0)
            idx2 = 0x55;
    }

    var last = 0;
    for (idx = 0; idx < 0x156; idx++) {
        var val = nibbles[idx];
        buf.push(_trans62[last ^ val]);
        last = val;
    }
    buf.push(_trans62[last]);

    buf = buf.concat([0xde, 0xaa, 0xf2]); // Epilog DE AA F2

    /*
        * Gap 3
        */

    buf.push(0xff);

    return buf;
}

export function explodeSector13(volume, track, sector, data) {
    var checksum;

    var buf = [], idx;

    var gap;

    /*
        * Gap 1/3 (40/0x28 bytes)
        */

    if (sector === 0) // Gap 1
        gap = 0x80;
    else { // Gap 3
        gap = track === 0 ? 0x28 : 0x26;
    }

    for (idx = 0; idx < gap; idx++) {
        buf.push(0xff);
    }

    /*
        * Address Field
        */

    checksum  = volume ^ track ^ sector;
    buf = buf.concat([0xd5, 0xaa, 0xb5]); // Address Prolog D5 AA B5
    buf = buf.concat(fourXfour(volume));
    buf = buf.concat(fourXfour(track));
    buf = buf.concat(fourXfour(sector));
    buf = buf.concat(fourXfour(checksum));
    buf = buf.concat([0xde, 0xaa, 0xeb]); // Epilog DE AA EB

    /*
        * Gap 2 (5 bytes)
        */

    for (idx = 0; idx < 0x05; idx++) {
        buf.push(0xff);
    }

    /*
        * Data Field
        */

    buf = buf.concat([0xd5, 0xaa, 0xad]); // Data Prolog D5 AA AD

    var nibbles = [];

    var jdx = 0;
    for (idx = 0x32; idx >= 0; idx--) {
        var a5 = data[jdx] >> 3;
        var a3 = data[jdx] & 0x07;
        jdx++;
        var b5 = data[jdx] >> 3;
        var b3 = data[jdx] & 0x07;
        jdx++;
        var c5 = data[jdx] >> 3;
        var c3 = data[jdx] & 0x07;
        jdx++;
        var d5 = data[jdx] >> 3;
        var d3 = data[jdx] & 0x07;
        jdx++;
        var e5 = data[jdx] >> 3;
        var e3 = data[jdx] & 0x07;
        jdx++;
        nibbles[idx + 0x00] = a5;
        nibbles[idx + 0x33] = b5;
        nibbles[idx + 0x66] = c5;
        nibbles[idx + 0x99] = d5;
        nibbles[idx + 0xcc] = e5;
        nibbles[idx + 0x100] = a3 << 2 | (d3 & 0x4) >> 1 | (e3 & 0x4) >> 2;
        nibbles[idx + 0x133] = b3 << 2 | (d3 & 0x2)      | (e3 & 0x2) >> 1;
        nibbles[idx + 0x166] = c3 << 2 | (d3 & 0x1) << 1 | (e3 & 0x1);
    }
    nibbles[0xff] = data[jdx] >> 3;
    nibbles[0x199] = data[jdx] & 0x07;

    var val;
    var last = 0;
    for (idx = 0x199; idx >= 0x100; idx--) {
        val = nibbles[idx];
        buf.push(_trans53[last ^ val]);
        last = val;
    }
    for (idx = 0x0; idx < 0x100; idx++) {
        val = nibbles[idx];
        buf.push(_trans53[last ^ val]);
        last = val;
    }
    buf.push(_trans53[last]);

    buf = buf.concat([0xde, 0xaa, 0xeb]); // Epilog DE AA EB

    /*
        * Gap 3
        */

    buf.push(0xff);

    return buf;
}

export function readSector(drive, track, sector) {
    var _sector = drive.fmt == 'po' ? _PO[sector] : _DO[sector];
    var val, state = 0;
    var idx = 0;
    var retry = 0;
    var cur = drive.tracks[track];

    function _readNext() {
        var result = cur[idx++];
        if (idx >= cur.length) {
            idx = 0;
            retry++;
        }
        return result;
    }
    function _skipBytes(count) {
        idx += count;
        if (idx >= cur.length) {
            idx %= cur.length;
            retry++;
        }
    }
    var t = 0, s = 0, v = 0, jdx, kdx, checkSum;
    var data = [];
    while (retry < 4) {
        switch (state) {
        case 0:
            val = _readNext();
            state = (val === 0xd5) ? 1 : 0;
            break;
        case 1:
            val = _readNext();
            state = (val === 0xaa) ? 2 : 0;
            break;
        case 2:
            val = _readNext();
            state = (val === 0x96) ? 3 : (val === 0xad ? 4 : 0);
            break;
        case 3: // Address
            v = defourXfour(_readNext(), _readNext()); // Volume
            t = defourXfour(_readNext(), _readNext());
            s = defourXfour(_readNext(), _readNext());
            checkSum = defourXfour(_readNext(), _readNext());
            if (checkSum != (v ^ t ^ s)) {
                debug('Invalid header checksum:', toHex(v), toHex(t), toHex(s), toHex(checkSum));
            }
            _skipBytes(3); // Skip footer
            state = 0;
            break;
        case 4: // Data
            if (s === _sector && t === track) {
                var data2 = [];
                var last = 0;
                for (jdx = 0x55; jdx >= 0; jdx--)  {
                    val = detrans62[_readNext() - 0x80] ^ last;
                    data2[jdx] = val;
                    last = val;
                }
                for (jdx = 0; jdx < 0x100; jdx++) {
                    val = detrans62[_readNext() - 0x80] ^ last;
                    data[jdx] = val;
                    last = val;
                }
                checkSum = detrans62[_readNext() - 0x80] ^ last;
                if (checkSum) {
                    debug('Invalid data checksum:', toHex(v), toHex(t), toHex(s), toHex(checkSum));
                }
                for (kdx = 0, jdx = 0x55; kdx < 0x100; kdx++) {
                    data[kdx] <<= 1;
                    if ((data2[jdx] & 0x01) !== 0) {
                        data[kdx] |= 0x01;
                    }
                    data2[jdx] >>= 1;

                    data[kdx] <<= 1;
                    if ((data2[jdx] & 0x01) !== 0) {
                        data[kdx] |= 0x01;
                    }
                    data2[jdx] >>= 1;

                    if (--jdx < 0) jdx = 0x55;
                }
                return data;
            }
            else
                _skipBytes(0x159); // Skip data, checksum and footer
            state = 0;
            break;
        default:
            break;
        }
    }
    return [];
}

export function jsonEncode(cur, pretty) {
    var data = [];
    var format = 'dsk';
    for (var t = 0; t < cur.tracks.length; t++) {
        data[t] = [];
        if (cur.format === 'nib') {
            format = 'nib';
            data[t] = base64_encode(cur.tracks[t]);
        } else {
            for (var s = 0; s < 0x10; s++) {
                data[t][s] = base64_encode(readSector(cur, t, s));
            }
        }
    }
    return JSON.stringify({
        'type': format,
        'encoding': 'base64',
        'volume': cur.volume,
        'data': data
    }, null, pretty ? '    ' : null);
}

export function jsonDecode(data) {
    var cur = {};
    var tracks = [];
    var json = JSON.parse(data);
    var v = json.volume;
    for (var t = 0; t < json.data.length; t++) {
        var track = [];
        for (var s = 0; s < json.data[t].length; s++) {
            var _s = 15 - s;
            var d = base64_decode(json.data[t][_s]);
            track = track.concat(explodeSector16(v, t, s, d));
        }
        tracks[t] = bytify(track);
    }
    cur.volume = v;
    cur.format = json.type;
    cur.tracks = tracks;
    cur.trackMap = null;

    return cur;
}