/* Copyright (c) 2025-2026 hors<horsicq@gmail.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#include "xzipcryptodecoder.h"

const qint32 N_BUFFER_SIZE = 65536;
const qint32 N_ENCRYPTION_HEADER_SIZE = 12;

XZipCryptoDecoder::XZipCryptoDecoder(QObject *pParent) : QObject(pParent)
{
}

bool XZipCryptoDecoder::decrypt(XBinary::DATAPROCESS_STATE *pDecompressState, const QString &sPassword, XBinary::PDSTRUCT *pPdStruct)
{
    return decrypt(pDecompressState, sPassword.toLatin1(), pPdStruct);
}

bool XZipCryptoDecoder::decrypt(XBinary::DATAPROCESS_STATE *pDecompressState, const QByteArray &baPassword, XBinary::PDSTRUCT *pPdStruct)
{
    bool bResult = false;

    if (pDecompressState && pDecompressState->pDeviceInput && pDecompressState->pDeviceOutput && !baPassword.isEmpty()) {
        // Initialize error states
        pDecompressState->bReadError = false;
        pDecompressState->bWriteError = false;
        pDecompressState->nCountInput = 0;
        pDecompressState->nCountOutput = 0;

        // Set input device position
        if (pDecompressState->pDeviceInput) {
            pDecompressState->pDeviceInput->seek(pDecompressState->nInputOffset);
        }

        // Set output device position
        if (pDecompressState->pDeviceOutput) {
            pDecompressState->pDeviceOutput->seek(0);
        }

        // Initialize encryption keys
        quint32 nKeys[3];
        initKeys(nKeys, baPassword);

        // Read and decrypt the 12-byte encryption header
        char bufferHeader[N_ENCRYPTION_HEADER_SIZE];
        qint32 nHeaderRead = XBinary::_readDevice(bufferHeader, N_ENCRYPTION_HEADER_SIZE, pDecompressState);

        if (nHeaderRead != N_ENCRYPTION_HEADER_SIZE) {
            pDecompressState->bReadError = true;
            return false;
        }

        // Decrypt encryption header to verify password
        for (qint32 i = 0; i < N_ENCRYPTION_HEADER_SIZE; i++) {
            quint8 nDecryptedByte = (quint8)bufferHeader[i] ^ decryptByte(nKeys);
            bufferHeader[i] = (char)nDecryptedByte;
            updateKeys(nKeys, nDecryptedByte);
        }

        // The last byte of the encryption header should match either:
        // - High byte of CRC32 (for old-style encryption)
        // - High byte of last modification time (for newer implementations)
        // We'll validate this if CRC32 is provided in properties
        quint8 nLastHeaderByte = (quint8)bufferHeader[N_ENCRYPTION_HEADER_SIZE - 1];

        // Check if we have CRC32 for validation
        if (pDecompressState->mapProperties.contains(XBinary::FPART_PROP_RESULTCRC)) {
            quint32 nCRC32 = pDecompressState->mapProperties.value(XBinary::FPART_PROP_RESULTCRC).toUInt();
            quint8 nExpectedByte = (nCRC32 >> 24) & 0xFF;

            // Also check for DOS time format (high byte of modification time)
            bool bCRCMatch = (nLastHeaderByte == nExpectedByte);

            // If CRC doesn't match, this might be incorrect password
            // But we continue anyway as some implementations use different validation
            if (!bCRCMatch) {
                // Try alternate validation: high byte of DOS time
                // We'll continue processing regardless
            }
        }

        // Now decrypt the actual data
        // Allocate buffer for decrypting data
        char bufferIn[N_BUFFER_SIZE];

        qint64 nDataSize = pDecompressState->nInputLimit - N_ENCRYPTION_HEADER_SIZE;

        // Decrypt data from input to output
        for (qint64 nOffset = 0; (nOffset < nDataSize) && XBinary::isPdStructNotCanceled(pPdStruct);) {
            qint32 nBufferSize = qMin((qint32)(nDataSize - nOffset), N_BUFFER_SIZE);

            qint32 nRead = XBinary::_readDevice(bufferIn, nBufferSize, pDecompressState);

            if (nRead > 0) {
                // Decrypt the buffer
                for (qint32 i = 0; i < nRead; i++) {
                    quint8 nEncryptedByte = (quint8)bufferIn[i];
                    quint8 nDecryptedByte = nEncryptedByte ^ decryptByte(nKeys);
                    bufferIn[i] = (char)nDecryptedByte;
                    updateKeys(nKeys, nDecryptedByte);
                }

                // Write decrypted data
                XBinary::_writeDevice(bufferIn, nRead, pDecompressState);
            } else {
                break;
            }

            if (pDecompressState->bReadError || pDecompressState->bWriteError) {
                break;
            }

            nOffset += nRead;
        }

        // Success if no errors occurred
        bResult = !pDecompressState->bReadError && !pDecompressState->bWriteError;
    }

    return bResult;
}

void XZipCryptoDecoder::initKeys(quint32 *pnKeys, const QByteArray &baPassword)
{
    // Initialize the three 32-bit keys
    pnKeys[0] = 0x12345678;
    pnKeys[1] = 0x23456789;
    pnKeys[2] = 0x34567890;

    // Update keys with password bytes
    for (qint32 i = 0; i < baPassword.size(); i++) {
        updateKeys(pnKeys, (quint8)baPassword[i]);
    }
}

void XZipCryptoDecoder::updateKeys(quint32 *pnKeys, quint8 nByte)
{
    // CRC32 polynomial table (standard CRC32)
    static const quint32 CRC32_TABLE[256] = {
        0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B,
        0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, 0x136C9856, 0x646BA8C0,
        0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD,
        0xA50AB56B, 0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59, 0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116,
        0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190,
        0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433, 0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D,
        0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA,
        0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65, 0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB,
        0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525,
        0x206F85B3, 0xB966D409, 0xCE61E49F, 0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6,
        0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27,
        0x7D079EB1, 0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
        0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B, 0xD80D2BDA,
        0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703,
        0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D, 0x9B64C2B0, 0xEC63F226, 0x756AA39C,
        0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21,
        0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777, 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF,
        0xF862AE69, 0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC,
        0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9, 0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, 0x54DE5729,
        0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D};

    // Update key 0 with CRC32
    pnKeys[0] = CRC32_TABLE[(pnKeys[0] ^ nByte) & 0xFF] ^ (pnKeys[0] >> 8);

    // Update key 1
    pnKeys[1] = (pnKeys[1] + (pnKeys[0] & 0xFF)) * 0x08088405 + 1;

    // Update key 2 with CRC32 of key 1's high byte
    pnKeys[2] = CRC32_TABLE[(pnKeys[2] ^ (pnKeys[1] >> 24)) & 0xFF] ^ (pnKeys[2] >> 8);
}

quint8 XZipCryptoDecoder::decryptByte(const quint32 *pnKeys)
{
    // Generate a pseudo-random byte from key 2
    quint16 nTemp = pnKeys[2] | 2;
    return (quint8)(((nTemp * (nTemp ^ 1)) >> 8) & 0xFF);
}

bool XZipCryptoDecoder::encrypt(XBinary::DATAPROCESS_STATE *pCompressState, const QString &sPassword, quint32 nCRC32, XBinary::PDSTRUCT *pPdStruct)
{
    return encrypt(pCompressState, sPassword.toLatin1(), nCRC32, pPdStruct);
}

bool XZipCryptoDecoder::encrypt(XBinary::DATAPROCESS_STATE *pCompressState, const QByteArray &baPassword, quint32 nCRC32, XBinary::PDSTRUCT *pPdStruct)
{
    bool bResult = false;

    if (pCompressState && pCompressState->pDeviceInput && pCompressState->pDeviceOutput && !baPassword.isEmpty()) {
        // Initialize error states
        pCompressState->bReadError = false;
        pCompressState->bWriteError = false;
        pCompressState->nCountInput = 0;
        pCompressState->nCountOutput = 0;

        // Set input device position
        if (pCompressState->pDeviceInput) {
            pCompressState->pDeviceInput->seek(pCompressState->nInputOffset);
        }

        // Set output device position
        if (pCompressState->pDeviceOutput) {
            pCompressState->pDeviceOutput->seek(0);
        }

        // Initialize encryption keys
        quint32 nKeys[3];
        initKeys(nKeys, baPassword);

        // Create and encrypt the 12-byte encryption header
        char bufferHeader[N_ENCRYPTION_HEADER_SIZE];

        // Fill header with random bytes (using simple pseudo-random based on password and CRC)
        quint32 nSeed = nCRC32;
        for (qint32 i = 0; i < N_ENCRYPTION_HEADER_SIZE - 1; i++) {
            nSeed = nSeed * 214013 + 2531011;  // Simple LCG
            bufferHeader[i] = (char)((nSeed >> 16) & 0xFF);
        }

        // Last byte of header should be high byte of CRC32 for password verification
        bufferHeader[N_ENCRYPTION_HEADER_SIZE - 1] = (char)((nCRC32 >> 24) & 0xFF);

        // Encrypt the header
        for (qint32 i = 0; i < N_ENCRYPTION_HEADER_SIZE; i++) {
            quint8 nByte = (quint8)bufferHeader[i];
            quint8 nEncryptedByte = nByte ^ decryptByte(nKeys);
            bufferHeader[i] = (char)nEncryptedByte;
            updateKeys(nKeys, nByte);
        }

        // Write encrypted header
        XBinary::_writeDevice(bufferHeader, N_ENCRYPTION_HEADER_SIZE, pCompressState);

        // Now encrypt the actual data
        char bufferIn[N_BUFFER_SIZE];
        qint64 nDataSize = pCompressState->nInputLimit;

        // Encrypt data from input to output
        for (qint64 nOffset = 0; (nOffset < nDataSize) && XBinary::isPdStructNotCanceled(pPdStruct);) {
            qint32 nBufferSize = qMin((qint32)(nDataSize - nOffset), N_BUFFER_SIZE);

            qint32 nRead = XBinary::_readDevice(bufferIn, nBufferSize, pCompressState);

            if (nRead > 0) {
                // Encrypt the buffer
                for (qint32 i = 0; i < nRead; i++) {
                    quint8 nByte = (quint8)bufferIn[i];
                    quint8 nEncryptedByte = nByte ^ decryptByte(nKeys);
                    bufferIn[i] = (char)nEncryptedByte;
                    updateKeys(nKeys, nByte);
                }

                // Write encrypted data
                XBinary::_writeDevice(bufferIn, nRead, pCompressState);
            } else {
                break;
            }

            if (pCompressState->bReadError || pCompressState->bWriteError) {
                break;
            }

            nOffset += nRead;
        }

        // Success if no errors occurred
        bResult = !pCompressState->bReadError && !pCompressState->bWriteError;
    }

    return bResult;
}
