/***************************************************************************
 *   This file is part of the Lime Report project                          *
 *   Copyright (C) 2021 by Alexander Arin                                  *
 *   arin_a@bk.ru                                                          *
 *                                                                         *
 **                   GNU General Public License Usage                    **
 *                                                                         *
 *   This library is free software: you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation, either version 3 of the License, or     *
 *   (at your option) any later version.                                   *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
 *                                                                         *
 **                  GNU Lesser General Public License                    **
 *                                                                         *
 *   This library is free software: you can redistribute it and/or modify  *
 *   it under the terms of the GNU Lesser General Public License as        *
 *   published by the Free Software Foundation, either version 3 of the    *
 *   License, or (at your option) any later version.                       *
 *   You should have received a copy of the GNU Lesser General Public      *
 *   License along with this library.                                      *
 *   If not, see <http://www.gnu.org/licenses/>.                           *
 *                                                                         *
 *   This library is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 ****************************************************************************/
#include "lrsimplecrypt.h"

namespace LimeReport {

#if defined(LP64) || defined(_LP64) || defined(__LP64__)
typedef unsigned int WORD; /* Should be 32-bit = 4 bytes        */
#else
typedef unsigned long int WORD; /* Should be 32-bit = 4 bytes        */
#endif

const int w = 32; /* word size in bits                 */
const int r = 12; /* number of rounds                  */
const int b = 16; /* number of bytes in key            */
const int c = 4; /* number  words in key = ceil(8*b/w)*/
const int t = 26; /* size of table S = 2*(r+1) words   */

const char* passPhrase = "HjccbzHjlbyfCkjy";

WORD P = 0xb7e15163, Q = 0x9e3779b9;

#define ROTL(x, y) (((x) << (y & (w - 1))) | ((x) >> (w - (y & (w - 1)))))
#define ROTR(x, y) (((x) >> (y & (w - 1))) | ((x) << (w - (y & (w - 1)))))

union WTB {
    WORD word[2];
    char bytes[8];
};

void initPt(WTB& pt, QByteArray::Iterator* it, QByteArray::Iterator end)
{
    for (int i = 0; i < 8; i++) {
        if (*it != end) {
            pt.bytes[i] = **it;
            ++*it;
        } else
            break;
    }
}

class ChipperPrivate {
    friend class Chipper;

public:
    ChipperPrivate(): m_prepared(false) { }
    bool isPrepared() { return m_prepared; }

private:
    void RC5_SETUP(const char* K);
    void RC5_ENCRYPT(WORD* pt, WORD* ct);
    void RC5_DECRYPT(WORD* ct, WORD* pt);
    WORD S[26] = { 0 };
    bool m_prepared;
};

void ChipperPrivate::RC5_SETUP(const char* K)
{
    WORD i, j, k, u = w / 8, A, B, L[c];
    for (i = b, L[c - 1] = 0; i != 0; i--)
        L[(i - 1) / u] = (L[(i - 1) / u] << 8) + K[i - 1];
    for (S[0] = P, i = 1; i < t; i++)
        S[i] = S[i - 1] + Q;
    for (A = B = i = j = k = 0; k < 3 * t; k++, i = (i + 1) % t, j = (j + 1) % c) { /* 3*t > 3*c */
        A = S[i] = ROTL(S[i] + (A + B), 3);
        B = L[j] = ROTL(L[j] + (A + B), (A + B));
    }
    m_prepared = true;
}

void ChipperPrivate::RC5_ENCRYPT(WORD* pt, WORD* ct)
{
    WORD i, A = pt[0] + S[0], B = pt[1] + S[1];
    for (i = 1; i <= r; i++) {
        A = ROTL(A ^ B, B) + S[2 * i];
        B = ROTL(B ^ A, A) + S[2 * i + 1];
    }
    ct[0] = A;
    ct[1] = B;
}

void ChipperPrivate::RC5_DECRYPT(WORD* ct, WORD* pt)
{
    WORD i, B = ct[1], A = ct[0];
    for (i = r; i > 0; i--) {
        B = ROTR(B - S[2 * i + 1], A) ^ A;
        A = ROTR(A - S[2 * i], B) ^ B;
    }
    pt[1] = B - S[1];
    pt[0] = A - S[0];
}

QByteArray Chipper::cryptString(QString value)
{
    QByteArray buff;
    QByteArray result;
    buff += value.toUtf8();
    WTB pt, ct, prior;

    if (!d->isPrepared())
        d->RC5_SETUP(passPhrase);

    prior.word[0] = 0;
    prior.word[1] = 0;

    QByteArray::Iterator it = buff.begin();
    while (it != buff.end()) {

        pt.word[0] = 0;
        pt.word[1] = 0;

        initPt(pt, &it, buff.end());

        pt.word[0] = pt.word[0] ^ prior.word[0];
        pt.word[1] = pt.word[1] ^ prior.word[1];

        d->RC5_ENCRYPT(pt.word, ct.word);

        prior.word[0] = pt.word[0];
        prior.word[1] = pt.word[1];

        for (int i = 0; i < 8; i++) {
            result += ct.bytes[i];
        }
    }
    return result;
}

QString Chipper::decryptByteArray(QByteArray value)
{
    QByteArray result;
    WTB pt, ct, prior;

    if (!d->isPrepared())
        d->RC5_SETUP(passPhrase);
    prior.word[0] = 0;
    prior.word[1] = 0;

    QByteArray::Iterator it = value.begin();
    while (it != value.end()) {

        pt.word[0] = 0;
        pt.word[1] = 0;

        initPt(pt, &it, value.end());

        d->RC5_DECRYPT(pt.word, ct.word);

        ct.word[0] = ct.word[0] ^ prior.word[0];
        ct.word[1] = ct.word[1] ^ prior.word[1];

        prior.word[0] = ct.word[0];
        prior.word[1] = ct.word[1];

        for (int i = 0; i < 8; i++) {
            result += ct.bytes[i];
        }
    }
    return QString(result);
}

Chipper::Chipper(): d(new ChipperPrivate()) { }

Chipper::Chipper(QString passphrase): d(new ChipperPrivate())
{
    if (!passphrase.trimmed().isEmpty()) {
        passphrase = passphrase.leftJustified(16, '#');
        d->RC5_SETUP(passphrase.toLatin1().data());
    }
}

Chipper::~Chipper() { delete d; }

} // namespace LimeReport