// This file Copyright (C) 2013-2022 Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0), GPLv3 (SPDX: GPL-3.0),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.

#include <array>
#include <cstring>
#include <numeric>
#include <string>
#include <string_view>
#include <unordered_set>

#include "transmission.h"

#include "crypto.h"
#include "crypto-utils.h"
#include "utils.h"

#include "crypto-test-ref.h"

#include "gtest/gtest.h"

using namespace std::literals;

namespace
{

auto constexpr SomeHash = tr_sha1_digest_t{
    std::byte{ 0 },  std::byte{ 1 },  std::byte{ 2 },  std::byte{ 3 },  std::byte{ 4 },  std::byte{ 5 },  std::byte{ 6 },
    std::byte{ 7 },  std::byte{ 8 },  std::byte{ 9 },  std::byte{ 10 }, std::byte{ 11 }, std::byte{ 12 }, std::byte{ 13 },
    std::byte{ 14 }, std::byte{ 15 }, std::byte{ 16 }, std::byte{ 17 }, std::byte{ 18 }, std::byte{ 19 },
};

} // namespace

TEST(Crypto, torrentHash)
{

    auto a = tr_crypto{};
    EXPECT_FALSE(tr_cryptoGetTorrentHash(&a));

    tr_cryptoSetTorrentHash(&a, SomeHash);
    EXPECT_TRUE(tr_cryptoGetTorrentHash(&a));
    EXPECT_EQ(SomeHash, *tr_cryptoGetTorrentHash(&a));

    a = tr_crypto{ &SomeHash, false };
    EXPECT_TRUE(tr_cryptoGetTorrentHash(&a));
    EXPECT_EQ(SomeHash, *tr_cryptoGetTorrentHash(&a));
}

TEST(Crypto, encryptDecrypt)
{
    auto a = tr_crypto{ &SomeHash, false };
    auto b = tr_crypto_{ &SomeHash, true };

    auto public_key_length = int{};
    EXPECT_TRUE(tr_cryptoComputeSecret(&a, tr_cryptoGetMyPublicKey_(&b, &public_key_length)));
    EXPECT_TRUE(tr_cryptoComputeSecret_(&b, tr_cryptoGetMyPublicKey(&a, &public_key_length)));

    auto const input1 = std::string{ "test1" };
    auto encrypted1 = std::array<char, 128>{};
    auto decrypted1 = std::array<char, 128>{};

    tr_cryptoEncryptInit(&a);
    tr_cryptoEncrypt(&a, input1.size(), input1.data(), encrypted1.data());
    tr_cryptoDecryptInit_(&b);
    tr_cryptoDecrypt_(&b, input1.size(), encrypted1.data(), decrypted1.data());
    EXPECT_EQ(input1, std::string(decrypted1.data(), input1.size()));

    auto const input2 = std::string{ "@#)C$@)#(*%bvkdjfhwbc039bc4603756VB3)" };
    auto encrypted2 = std::array<char, 128>{};
    auto decrypted2 = std::array<char, 128>{};

    tr_cryptoEncryptInit_(&b);
    tr_cryptoEncrypt_(&b, input2.size(), input2.data(), encrypted2.data());
    tr_cryptoDecryptInit(&a);
    tr_cryptoDecrypt(&a, input2.size(), encrypted2.data(), decrypted2.data());
    EXPECT_EQ(input2, std::string(decrypted2.data(), input2.size()));
}

TEST(Crypto, sha1)
{
    auto hash1 = tr_sha1("test"sv);
    EXPECT_TRUE(hash1);
    EXPECT_EQ(
        0,
        memcmp(
            std::data(*hash1),
            "\xa9\x4a\x8f\xe5\xcc\xb1\x9b\xa6\x1c\x4c\x08\x73\xd3\x91\xe9\x87\x98\x2f\xbb\xd3",
            std::size(*hash1)));

    auto hash2 = tr_sha1("test"sv);
    EXPECT_TRUE(hash1);
    EXPECT_EQ(*hash1, *hash2);

    hash1 = tr_sha1("1"sv, "22"sv, "333"sv);
    hash2 = tr_sha1("1"sv, "22"sv, "333"sv);
    EXPECT_TRUE(hash1);
    EXPECT_TRUE(hash2);
    EXPECT_EQ(*hash1, *hash2);
    EXPECT_EQ(
        0,
        memcmp(
            std::data(*hash1),
            "\x1f\x74\x64\x8e\x50\xa6\xa6\x70\x8e\xc5\x4a\xb3\x27\xa1\x63\xd5\x53\x6b\x7c\xed",
            std::size(*hash1)));

    auto const hash3 = tr_sha1("test"sv);
    EXPECT_TRUE(hash3);
    EXPECT_EQ("a94a8fe5ccb19ba61c4c0873d391e987982fbbd3"sv, tr_sha1_to_string(*hash3));

    auto const hash4 = tr_sha1("te"sv, "st"sv);
    EXPECT_TRUE(hash4);
    EXPECT_EQ("a94a8fe5ccb19ba61c4c0873d391e987982fbbd3"sv, tr_sha1_to_string(*hash4));

    auto const hash5 = tr_sha1("t"sv, "e"sv, std::string{ "s" }, std::array<char, 1>{ { 't' } });
    EXPECT_TRUE(hash5);
    EXPECT_EQ("a94a8fe5ccb19ba61c4c0873d391e987982fbbd3"sv, tr_sha1_to_string(*hash5));
}

TEST(Crypto, ssha1)
{
    struct LocalTest
    {
        std::string_view plain_text;
        std::string_view ssha1;
    };

    auto constexpr Tests = std::array<LocalTest, 2>{ {
        { "test"sv, "{15ad0621b259a84d24dcd4e75b09004e98a3627bAMbyRHJy"sv },
        { "QNY)(*#$B)!_X$B !_B#($^!)*&$%CV!#)&$C!@$(P*)"sv, "{10e2d7acbb104d970514a147cd16d51dfa40fb3c0OSwJtOL"sv },
    } };

    auto constexpr HashCount = size_t{ 4 * 1024 };

    for (auto const& [plain_text, ssha1] : Tests)
    {
        auto hashes = std::unordered_set<std::string>{};
        hashes.reserve(HashCount);

        EXPECT_TRUE(tr_ssha1_matches(ssha1, plain_text));
        EXPECT_TRUE(tr_ssha1_matches_(ssha1, plain_text));

        using ssha1_func = std::string (*)(std::string_view plain_text);
        static auto constexpr Ssha1Funcs = std::array<ssha1_func, 2>{ tr_ssha1, tr_ssha1_ };

        for (size_t j = 0; j < HashCount; ++j)
        {
            auto const hash = Ssha1Funcs[j % 2](plain_text);

            // phrase matches each of generated hashes
            EXPECT_TRUE(tr_ssha1_matches(hash, plain_text));
            EXPECT_TRUE(tr_ssha1_matches_(hash, plain_text));

            hashes.insert(hash);
        }

        // confirm all hashes are different
        EXPECT_EQ(HashCount, hashes.size());

        /* exchange two first chars */
        auto phrase = std::string{ plain_text };
        phrase[0] ^= phrase[1];
        phrase[1] ^= phrase[0];
        phrase[0] ^= phrase[1];

        for (auto const& hash : hashes)
        {
            /* changed phrase doesn't match the hashes */
            EXPECT_FALSE(tr_ssha1_matches(hash, phrase));
            EXPECT_FALSE(tr_ssha1_matches_(hash, phrase));
        }
    }

    /* should work with different salt lengths as well */
    EXPECT_TRUE(tr_ssha1_matches("{a94a8fe5ccb19ba61c4c0873d391e987982fbbd3", "test"));
    EXPECT_TRUE(tr_ssha1_matches("{d209a21d3bc4f8fc4f8faf347e69f3def597eb170pySy4ai1ZPMjeU1", "test"));
}

TEST(Crypto, sha1FromString)
{
    // bad lengths
    EXPECT_FALSE(tr_sha1_from_string(""));
    EXPECT_FALSE(tr_sha1_from_string("a94a8fe5ccb19ba61c4c0873d391e987982fbbd"sv));
    EXPECT_FALSE(tr_sha1_from_string("a94a8fe5ccb19ba61c4c0873d391e987982fbbd33"sv));
    // nonhex
    EXPECT_FALSE(tr_sha1_from_string("a94a8fe5ccb19ba61c4cz873d391e987982fbbd3"sv));
    EXPECT_FALSE(tr_sha1_from_string("a94a8fe5ccb19  61c4c0873d391e987982fbbd3"sv));

    // lowercase hex
    auto const baseline = "a94a8fe5ccb19ba61c4c0873d391e987982fbbd3"sv;
    auto const lc = tr_sha1_from_string(baseline);
    EXPECT_TRUE(lc);
    EXPECT_EQ(baseline, tr_sha1_to_string(*lc));

    // uppercase hex should yield the same result
    auto const uc = tr_sha1_from_string(tr_strupper(baseline));
    EXPECT_TRUE(uc);
    EXPECT_EQ(*lc, *uc);
}

TEST(Crypto, random)
{
    /* test that tr_rand_int() stays in-bounds */
    for (int i = 0; i < 100000; ++i)
    {
        int const val = tr_rand_int(100);
        EXPECT_LE(0, val);
        EXPECT_LT(val, 100);
    }
}

TEST(Crypto, base64)
{
    auto raw = std::string_view{ "YOYO!"sv };
    auto encoded = tr_base64_encode(raw);
    EXPECT_EQ("WU9ZTyE="sv, encoded);
    EXPECT_EQ(raw, tr_base64_decode(encoded));

    EXPECT_EQ(""sv, tr_base64_encode(""sv));
    EXPECT_EQ(""sv, tr_base64_decode(""sv));

    static auto constexpr MaxBufSize = size_t{ 1024 };
    for (size_t i = 1; i <= MaxBufSize; ++i)
    {
        auto buf = std::string{};
        for (size_t j = 0; j < i; ++j)
        {
            buf += char(tr_rand_int_weak(256));
        }
        EXPECT_EQ(buf, tr_base64_decode(tr_base64_encode(buf)));

        buf = std::string{};
        for (size_t j = 0; j < i; ++j)
        {
            buf += char(1 + tr_rand_int_weak(255));
        }
        EXPECT_EQ(buf, tr_base64_decode(tr_base64_encode(buf)));
    }
}