/*
 * SPDX-FileCopyrightText: 2020 Nextcloud GmbH and Nextcloud contributors
 * SPDX-License-Identifier: CC0-1.0
 *
 * This software is in the public domain, furnished "as is", without technical
 * support, and with no warranty, express or implied, as to its usefulness for
 * any purpose.
 */

#include <QtTest>

#include <QTemporaryFile>
#include <QRandomGenerator>

#include <common/constants.h>

#include "clientsideencryption.h"
#include "logger.h"

using namespace OCC;

class TestClientSideEncryption : public QObject
{
    Q_OBJECT

    QByteArray convertToOldStorageFormat(const QByteArray &data)
    {
        return data.split('|').join("fA==");
    }

private slots:
    void initTestCase()
    {
        OCC::Logger::instance()->setLogFlush(true);
        OCC::Logger::instance()->setLogDebug(true);

        QStandardPaths::setTestModeEnabled(true);
    }

    void shouldEncryptPrivateKeys()
    {
        // GIVEN
        const auto encryptionKey = QByteArrayLiteral("foo");
        const auto privateKey = QByteArrayLiteral("bar");
        const auto originalSalt = QByteArrayLiteral("baz");

        // WHEN
        const auto cipher = EncryptionHelper::encryptPrivateKey(encryptionKey, privateKey, originalSalt);

        // THEN
        const auto parts = cipher.split('|');
        QCOMPARE(parts.size(), 3);

        const auto encryptedKey = QByteArray::fromBase64(parts[0]);
        const auto iv = QByteArray::fromBase64(parts[1]);
        const auto salt = QByteArray::fromBase64(parts[2]);

        // We're not here to check the merits of the encryption but at least make sure it's been
        // somewhat ciphered
        QVERIFY(!encryptedKey.isEmpty());
        QVERIFY(encryptedKey != privateKey);

        QVERIFY(!iv.isEmpty());
        QCOMPARE(salt, originalSalt);
    }

    void shouldDecryptPrivateKeys()
    {
        // GIVEN
        const auto encryptionKey = QByteArrayLiteral("foo");
        const auto originalPrivateKey = QByteArrayLiteral("bar");
        const auto originalSalt = QByteArrayLiteral("baz");
        const auto cipher = EncryptionHelper::encryptPrivateKey(encryptionKey, originalPrivateKey, originalSalt);

        // WHEN
        const auto privateKey = EncryptionHelper::decryptPrivateKey(encryptionKey, cipher);
        const auto salt = EncryptionHelper::extractPrivateKeySalt(cipher);

        // THEN
        QCOMPARE(privateKey, originalPrivateKey);
        QCOMPARE(salt, originalSalt);
    }

    void shouldDecryptPrivateKeysInOldStorageFormat()
    {
        // GIVEN
        const auto encryptionKey = QByteArrayLiteral("foo");
        const auto originalPrivateKey = QByteArrayLiteral("bar");
        const auto originalSalt = QByteArrayLiteral("baz");
        const auto cipher = convertToOldStorageFormat(EncryptionHelper::encryptPrivateKey(encryptionKey, originalPrivateKey, originalSalt));

        // WHEN
        const auto privateKey = EncryptionHelper::decryptPrivateKey(encryptionKey, cipher);
        const auto salt = EncryptionHelper::extractPrivateKeySalt(cipher);

        // THEN
        QCOMPARE(privateKey, originalPrivateKey);
        QCOMPARE(salt, originalSalt);
    }

    void shouldSymmetricEncryptStrings()
    {
        // GIVEN
        const auto encryptionKey = QByteArrayLiteral("foo");
        const auto data = QByteArrayLiteral("bar");

        // WHEN
        const auto cipher = EncryptionHelper::encryptStringSymmetric(encryptionKey, data);

        // THEN
        const auto parts = cipher.split('|');
        QCOMPARE(parts.size(), 2);

        const auto encryptedData = QByteArray::fromBase64(parts[0]);
        const auto iv = QByteArray::fromBase64(parts[1]);

        // We're not here to check the merits of the encryption but at least make sure it's been
        // somewhat ciphered
        QVERIFY(!encryptedData.isEmpty());
        QVERIFY(encryptedData != data);

        QVERIFY(!iv.isEmpty());
    }

    void shouldSymmetricDecryptStrings()
    {
        // GIVEN
        const auto encryptionKey = QByteArrayLiteral("foo");
        const auto originalData = QByteArrayLiteral("bar");
        const auto cipher = EncryptionHelper::encryptStringSymmetric(encryptionKey, originalData);

        // WHEN
        const auto data = EncryptionHelper::decryptStringSymmetric(encryptionKey, cipher);

        // THEN
        QCOMPARE(data, originalData);
    }

    void shouldSymmetricDecryptStringsInOldStorageFormat()
    {
        // GIVEN
        const auto encryptionKey = QByteArrayLiteral("foo");
        const auto originalData = QByteArrayLiteral("bar");
        const auto cipher = convertToOldStorageFormat(EncryptionHelper::encryptStringSymmetric(encryptionKey, originalData));

        // WHEN
        const auto data = EncryptionHelper::decryptStringSymmetric(encryptionKey, cipher);

        // THEN
        QCOMPARE(data, originalData);
    }

    void testStreamingDecryptor_data()
    {
        QTest::addColumn<int>("totalBytes");
        QTest::addColumn<int>("bytesToRead");

        QTest::newRow("data1") << 64  << 2;
        QTest::newRow("data2") << 32  << 8;
        QTest::newRow("data3") << 76  << 64;
        QTest::newRow("data4") << 272 << 256;
    }

    void testStreamingDecryptor()
    {
        QFETCH(int, totalBytes);

        QTemporaryFile dummyInputFile;

        QVERIFY(dummyInputFile.open());

        const auto dummyFileRandomContents = EncryptionHelper::generateRandom(totalBytes);

        QCOMPARE(dummyInputFile.write(dummyFileRandomContents), dummyFileRandomContents.size());

        const auto generateHash = [](const QByteArray &data) {
            QCryptographicHash hash(QCryptographicHash::Sha1);
            hash.addData(data);
            return hash.result();
        };

        const QByteArray originalFileHash = generateHash(dummyFileRandomContents);

        QVERIFY(!originalFileHash.isEmpty());

        dummyInputFile.close();
        QVERIFY(!dummyInputFile.isOpen());

        const auto encryptionKey = EncryptionHelper::generateRandom(16);
        const auto initializationVector = EncryptionHelper::generateRandom(16);

        // test normal file encryption/decryption
        QTemporaryFile dummyEncryptionOutputFile;

        QByteArray tag;

        QVERIFY(EncryptionHelper::fileEncryption(encryptionKey, initializationVector, &dummyInputFile, &dummyEncryptionOutputFile, tag));
        dummyInputFile.close();
        QVERIFY(!dummyInputFile.isOpen());

        dummyEncryptionOutputFile.close();
        QVERIFY(!dummyEncryptionOutputFile.isOpen());

        QTemporaryFile dummyDecryptionOutputFile;

        QVERIFY(EncryptionHelper::fileDecryption(encryptionKey, initializationVector, &dummyEncryptionOutputFile, &dummyDecryptionOutputFile));
        QVERIFY(dummyDecryptionOutputFile.open());
        const auto dummyDecryptionOutputFileHash = generateHash(dummyDecryptionOutputFile.readAll());
        QCOMPARE(dummyDecryptionOutputFileHash, originalFileHash);

        // test streaming decryptor
        EncryptionHelper::StreamingDecryptor streamingDecryptor(encryptionKey, initializationVector, dummyEncryptionOutputFile.size());
        QVERIFY(streamingDecryptor.isInitialized());

        QBuffer chunkedOutputDecrypted;
        QVERIFY(chunkedOutputDecrypted.open(QBuffer::WriteOnly));

        QVERIFY(dummyEncryptionOutputFile.open());

        QByteArray pendingBytes;

        QFETCH(int, bytesToRead);

        while (dummyEncryptionOutputFile.pos() < dummyEncryptionOutputFile.size()) {
            const auto bytesRemaining = dummyEncryptionOutputFile.size() - dummyEncryptionOutputFile.pos();
            auto toRead = bytesRemaining > bytesToRead ? bytesToRead : bytesRemaining;

            if (dummyEncryptionOutputFile.pos() + toRead > dummyEncryptionOutputFile.size()) {
                toRead = dummyEncryptionOutputFile.size() - dummyEncryptionOutputFile.pos();
            }

            if (bytesRemaining - toRead != 0 && bytesRemaining - toRead < OCC::Constants::e2EeTagSize) {
                // decryption is going to fail if last chunk does not include or does not equal to OCC::Constants::e2EeTagSize bytes tag
                // since we are emulating random size of network packets, we may end up reading beyond OCC::Constants::e2EeTagSize bytes tag at the end
                // in that case, we don't want to try and decrypt less than OCC::Constants::e2EeTagSize ending bytes of tag, we will accumulate all the incoming data till the end
                // and then, we are going to decrypt the entire chunk containing OCC::Constants::e2EeTagSize bytes at the end
                pendingBytes += dummyEncryptionOutputFile.read(bytesRemaining);
                continue;
            }

            const auto decryptedChunk = streamingDecryptor.chunkDecryption(dummyEncryptionOutputFile.read(toRead).constData(), toRead);

            QVERIFY(decryptedChunk.size() == toRead || streamingDecryptor.isFinished() || !pendingBytes.isEmpty());

            chunkedOutputDecrypted.write(decryptedChunk);
        }

        if (!pendingBytes.isEmpty()) {
            const auto decryptedChunk = streamingDecryptor.chunkDecryption(pendingBytes.constData(), pendingBytes.size());

            QVERIFY(decryptedChunk.size() == pendingBytes.size() || streamingDecryptor.isFinished());

            chunkedOutputDecrypted.write(decryptedChunk);
        }

        chunkedOutputDecrypted.close();

        QVERIFY(chunkedOutputDecrypted.open(QBuffer::ReadOnly));
        QCOMPARE(generateHash(chunkedOutputDecrypted.readAll()), originalFileHash);
        chunkedOutputDecrypted.close();
    }

    void testGzipThenEncryptDataAndBack()
    {
        const auto metadataKeySize = 16;

        const auto keyForEncryption = EncryptionHelper::generateRandom(metadataKeySize);
        const auto inputData = QByteArrayLiteral("sample text for encryption test");
        const auto initializationVector = EncryptionHelper::generateRandom(metadataKeySize);

        QByteArray authenticationTag;
        const auto gzippedThenEncryptData = EncryptionHelper::gzipThenEncryptData(keyForEncryption, inputData, initializationVector, authenticationTag);

        QVERIFY(!gzippedThenEncryptData.isEmpty());

        const auto decryptedThebGzipUnzippedData = EncryptionHelper::decryptThenUnGzipData(keyForEncryption, gzippedThenEncryptData, initializationVector);

        QVERIFY(!decryptedThebGzipUnzippedData.isEmpty());

        QCOMPARE(inputData, decryptedThebGzipUnzippedData);
    }
};

QTEST_APPLESS_MAIN(TestClientSideEncryption)
#include "testclientsideencryption.moc"