#include <hex/helpers/crypto.hpp>

#include <hex/providers/provider.hpp>
#include <hex/helpers/utils.hpp>

#include <mbedtls/version.h>
#include <mbedtls/base64.h>
#include <mbedtls/bignum.h>
#include <mbedtls/md5.h>
#include <mbedtls/sha1.h>
#include <mbedtls/sha256.h>
#include <mbedtls/sha512.h>
#include <mbedtls/aes.h>
#include <mbedtls/cipher.h>

#include <array>
#include <span>
#include <concepts>
#include <functional>
#include <algorithm>
#include <cstddef>
#include <cstdint>

#if MBEDTLS_VERSION_MAJOR <= 2

#define mbedtls_md5_starts mbedtls_md5_starts_ret
#define mbedtls_md5_update mbedtls_md5_update_ret
#define mbedtls_md5_finish mbedtls_md5_finish_ret

#define mbedtls_sha1_starts mbedtls_sha1_starts_ret
#define mbedtls_sha1_update mbedtls_sha1_update_ret
#define mbedtls_sha1_finish mbedtls_sha1_finish_ret

#define mbedtls_sha256_starts mbedtls_sha256_starts_ret
#define mbedtls_sha256_update mbedtls_sha256_update_ret
#define mbedtls_sha256_finish mbedtls_sha256_finish_ret

#define mbedtls_sha512_starts mbedtls_sha512_starts_ret
#define mbedtls_sha512_update mbedtls_sha512_update_ret
#define mbedtls_sha512_finish mbedtls_sha512_finish_ret

#endif

namespace hex::crypt {
    using namespace std::placeholders;

    template<std::invocable<unsigned char*, size_t> Func>
    void processDataByChunks(prv::Provider* data, u64 offset, size_t size, Func func)
    {
        std::array<u8, 512> buffer = { 0 };
        for (size_t bufferOffset = 0; bufferOffset < size; bufferOffset += buffer.size()) {
            const auto readSize = std::min(buffer.size(), size - bufferOffset);
            data->read(offset + bufferOffset, buffer.data(), readSize);
            func(buffer.data(), readSize);
        }
    }

    template<typename T>
    T reflect(T in, std::size_t bits)
    {
        T out{};

        for(std::size_t i = 0; i < bits; i++)
        {
            out <<= 1;
            if (in & 0b1)
                out |= 1;
            in >>= 1;
        }
        return out;
    }

    template<typename T>
    T reflect(T in)
    {
        if constexpr (sizeof(T) == 1)
        {
            T out{in};

            out = ((out & 0xf0u) >> 4) | ((out & 0x0fu) << 4);
            out = ((out & 0xccu) >> 2) | ((out & 0x33u) << 2);
            out = ((out & 0xaau) >> 1) | ((out & 0x55u) << 1);

            return out;
        }
        else
        {
            return reflect(in, sizeof(T) *8 );
        }
    }

    class Crc {
        // use reflected algorithm, so we reflect only if refin / refout is FALSE
        // mask values, 0b1 << 64 is UB, so use 0b10 << 63

    public:
        using calc_type = uint64_t;

        Crc(int bits, calc_type polynomial, calc_type init, calc_type xorout, bool refin, bool refout) :
            m_bits(bits),
            m_init(init & ((0b10ull << (bits-1)) - 1)),
            m_xorout(xorout & ((0b10ull << (bits-1)) - 1)),
            m_refin(refin),
            m_refout(refout),
            table([polynomial, bits](){
                auto reflectedpoly= reflect(polynomial & ((0b10ull << (bits-1)) - 1), bits);
                std::array<uint64_t, 256> table = {0};

                for (uint32_t i = 0; i < 256; i++) {
                    uint64_t c = i;
                    for (std::size_t j = 0; j < 8; j++) {
                        if (c & 0b1)
                            c = reflectedpoly ^ (c >> 1);
                        else
                            c >>= 1;
                    }
                    table[i] = c;
                }

                return table;
            }()) {
            reset();
        };

        void reset() {
            c = reflect(m_init, m_bits);
        }

        void processBytes(const unsigned char *data, std::size_t size) {
            for (std::size_t i = 0; i < size; i++) {
                unsigned char d;
                if (m_refin)
                    d = data[i];
                else
                    d = reflect(data[i]);

                c = table[(c ^ d) & 0xFFL] ^ (c >> 8);
            }
        }

        calc_type checksum() const {
            if (m_refout)
                return c ^ m_xorout;
            else
                return reflect(c, m_bits) ^ m_xorout;
        }

    private:
        const int m_bits;
        const calc_type m_init;
        const calc_type m_xorout;
        const bool m_refin;
        const bool m_refout;
        const std::array<uint64_t, 256> table;

        calc_type c;
    };

    template<int bits>
    auto calcCrc(prv::Provider* data, u64 offset, std::size_t size, u32 polynomial, u32 init,  u32 xorout, bool reflectIn, bool reflectOut) {
        Crc crc(bits, polynomial, init, xorout, reflectIn, reflectOut);

        processDataByChunks(data, offset, size, std::bind(&Crc::processBytes, &crc, _1, _2));

        return crc.checksum();
    }

    u16 crc8(prv::Provider* &data, u64 offset, size_t size, u32 polynomial, u32 init,  u32 xorout, bool reflectIn, bool reflectOut) {
        return calcCrc<8>(data, offset, size, polynomial, init, xorout, reflectIn, reflectOut);
    }

    u16 crc16(prv::Provider* &data, u64 offset, size_t size, u32 polynomial, u32 init,  u32 xorout, bool reflectIn, bool reflectOut) {
        return calcCrc<16>(data, offset, size, polynomial, init, xorout, reflectIn, reflectOut);
    }

    u32 crc32(prv::Provider* &data, u64 offset, size_t size, u32 polynomial, u32 init,  u32 xorout, bool reflectIn, bool reflectOut) {
        return calcCrc<32>(data, offset, size, polynomial, init, xorout, reflectIn, reflectOut);
    }


    std::array<u8, 16> md5(prv::Provider* &data, u64 offset, size_t size) {
        std::array<u8, 16> result = { 0 };

        mbedtls_md5_context ctx;
        mbedtls_md5_init(&ctx);

        mbedtls_md5_starts(&ctx);

        processDataByChunks(data, offset, size, std::bind(mbedtls_md5_update, &ctx, _1, _2));

        mbedtls_md5_finish(&ctx, result.data());

        mbedtls_md5_free(&ctx);

        return result;
    }

    std::array<u8, 16> md5(const std::vector<u8> &data) {
        std::array<u8, 16> result = { 0 };

        mbedtls_md5_context ctx;
        mbedtls_md5_init(&ctx);

        mbedtls_md5_starts(&ctx);
        mbedtls_md5_update(&ctx, data.data(), data.size());
        mbedtls_md5_finish(&ctx, result.data());

        mbedtls_md5_free(&ctx);

        return result;
    }

    std::array<u8, 20> sha1(prv::Provider* &data, u64 offset, size_t size) {
        std::array<u8, 20> result = { 0 };

        mbedtls_sha1_context ctx;
        mbedtls_sha1_init(&ctx);

        mbedtls_sha1_starts(&ctx);

        processDataByChunks(data, offset, size, std::bind(mbedtls_sha1_update, &ctx, _1, _2));

        mbedtls_sha1_finish(&ctx, result.data());

        mbedtls_sha1_free(&ctx);

        return result;
    }

    std::array<u8, 20> sha1(const std::vector<u8> &data) {
        std::array<u8, 20> result = { 0 };

        mbedtls_sha1_context ctx;
        mbedtls_sha1_init(&ctx);

        mbedtls_sha1_starts(&ctx);
        mbedtls_sha1_update(&ctx, data.data(), data.size());
        mbedtls_sha1_finish(&ctx, result.data());

        mbedtls_sha1_free(&ctx);

        return result;
    }

    std::array<u8, 28> sha224(prv::Provider* &data, u64 offset, size_t size) {
        std::array<u8, 28> result = { 0 };

        mbedtls_sha256_context ctx;
        mbedtls_sha256_init(&ctx);

        mbedtls_sha256_starts(&ctx, true);

        processDataByChunks(data, offset, size, std::bind(mbedtls_sha256_update, &ctx, _1, _2));

        mbedtls_sha256_finish(&ctx, result.data());

        mbedtls_sha256_free(&ctx);

        return result;
    }

    std::array<u8, 28> sha224(const std::vector<u8> &data) {
        std::array<u8, 28> result = { 0 };

        mbedtls_sha256_context ctx;
        mbedtls_sha256_init(&ctx);

        mbedtls_sha256_starts(&ctx, true);
        mbedtls_sha256_update(&ctx, data.data(), data.size());
        mbedtls_sha256_finish(&ctx, result.data());

        mbedtls_sha256_free(&ctx);

        return result;
    }

    std::array<u8, 32> sha256(prv::Provider* &data, u64 offset, size_t size) {
        std::array<u8, 32> result = { 0 };

        mbedtls_sha256_context ctx;
        mbedtls_sha256_init(&ctx);

        mbedtls_sha256_starts(&ctx, false);

        processDataByChunks(data, offset, size, std::bind(mbedtls_sha256_update, &ctx, _1, _2));

        mbedtls_sha256_finish(&ctx, result.data());

        mbedtls_sha256_free(&ctx);

        return result;
    }

    std::array<u8, 32> sha256(const std::vector<u8> &data) {
        std::array<u8, 32> result = { 0 };

        mbedtls_sha256_context ctx;
        mbedtls_sha256_init(&ctx);

        mbedtls_sha256_starts(&ctx, false);
        mbedtls_sha256_update(&ctx, data.data(), data.size());
        mbedtls_sha256_finish(&ctx, result.data());

        mbedtls_sha256_free(&ctx);

        return result;
    }

    std::array<u8, 48> sha384(prv::Provider* &data, u64 offset, size_t size) {
        std::array<u8, 48> result = { 0 };

        mbedtls_sha512_context ctx;
        mbedtls_sha512_init(&ctx);

        mbedtls_sha512_starts(&ctx, true);

        processDataByChunks(data, offset, size, std::bind(mbedtls_sha512_update, &ctx, _1, _2));

        mbedtls_sha512_finish(&ctx, result.data());

        mbedtls_sha512_free(&ctx);

        return result;
    }

    std::array<u8, 48> sha384(const std::vector<u8> &data) {
        std::array<u8, 48> result = { 0 };

        mbedtls_sha512_context ctx;
        mbedtls_sha512_init(&ctx);

        mbedtls_sha512_starts(&ctx, true);
        mbedtls_sha512_update(&ctx, data.data(), data.size());
        mbedtls_sha512_finish(&ctx, result.data());

        mbedtls_sha512_free(&ctx);

        return result;
    }

    std::array<u8, 64> sha512(prv::Provider* &data, u64 offset, size_t size) {
        std::array<u8, 64> result = { 0 };

        mbedtls_sha512_context ctx;
        mbedtls_sha512_init(&ctx);

        mbedtls_sha512_starts(&ctx, false);

        processDataByChunks(data, offset, size, std::bind(mbedtls_sha512_update, &ctx, _1, _2));

        mbedtls_sha512_finish(&ctx, result.data());

        mbedtls_sha512_free(&ctx);

        return result;
    }

    std::array<u8, 64> sha512(const std::vector<u8> &data) {
        std::array<u8, 64> result = { 0 };

        mbedtls_sha512_context ctx;
        mbedtls_sha512_init(&ctx);

        mbedtls_sha512_starts(&ctx, false);
        mbedtls_sha512_update(&ctx, data.data(), data.size());
        mbedtls_sha512_finish(&ctx, result.data());

        mbedtls_sha512_free(&ctx);

        return result;
    }


    std::vector<u8> decode64(const std::vector<u8> &input) {

        size_t written = 0;
        mbedtls_base64_decode(nullptr, 0, &written, reinterpret_cast<const unsigned char *>(input.data()), input.size());
        std::vector<u8> output(written, 0x00);
        if (mbedtls_base64_decode(output.data(), output.size(), &written, reinterpret_cast<const unsigned char *>(input.data()), input.size()))
            return { };

        output.resize(written);

        return output;
    }

    std::vector<u8> encode64(const std::vector<u8> &input) {

        size_t written = 0;
        mbedtls_base64_encode(nullptr, 0, &written, reinterpret_cast<const unsigned char *>(input.data()), input.size());

        std::vector<u8> output(written, 0x00);
        if (mbedtls_base64_encode(output.data(), output.size(), &written, reinterpret_cast<const unsigned char *>(input.data()), input.size()))
            return { };

        output.resize(written);

        return output;
    }

    std::vector<u8> decode16(const std::string &input) {
        std::vector<u8> output(input.length() / 2, 0x00);

        mbedtls_mpi ctx;
        mbedtls_mpi_init(&ctx);

        ON_SCOPE_EXIT { mbedtls_mpi_free(&ctx); };

        if (mbedtls_mpi_read_string(&ctx, 16, input.c_str()))
            return { };

        if (mbedtls_mpi_write_binary(&ctx, output.data(), output.size()))
            return { };

        return output;
    }

    std::string encode16(const std::vector<u8> &input) {

        if (input.empty())
            return { };

        std::string output(input.size() * 2, '\0');

        for(int i = 0; i < input.size(); i++) {
            output[2*i+0] = "0123456789ABCDEF"[input[i] / 16];
            output[2*i+1] = "0123456789ABCDEF"[input[i] % 16];
        }

        return output;
    }

    static std::vector<u8> aes(mbedtls_cipher_type_t type, mbedtls_operation_t operation, const std::vector<u8> &key, std::array<u8, 8> nonce, std::array<u8, 8> iv, const std::vector<u8> &input) {
        std::vector<u8> output;

        if (input.empty())
            return { };

        mbedtls_cipher_context_t ctx;
        auto cipherInfo = mbedtls_cipher_info_from_type(type);


        mbedtls_cipher_setup(&ctx, cipherInfo);
        mbedtls_cipher_setkey(&ctx, key.data(), key.size() * 8, operation);

        std::array<u8, 16> nonceCounter = { 0 };
        std::copy(nonce.begin(), nonce.end(), nonceCounter.begin());
        std::copy(iv.begin(), iv.end(), nonceCounter.begin() + 8);

        size_t outputSize = input.size() + mbedtls_cipher_get_block_size(&ctx);
        output.resize(outputSize, 0x00);
        mbedtls_cipher_crypt(&ctx, nonceCounter.data(), nonceCounter.size(), input.data(), input.size(), output.data(), &outputSize);

        mbedtls_cipher_free(&ctx);

        output.resize(input.size());

        return output;
    }

    std::vector<u8> aesDecrypt(AESMode mode, KeyLength keyLength, const std::vector<u8> &key, std::array<u8, 8> nonce, std::array<u8, 8> iv, const std::vector<u8> &input) {
        switch (keyLength) {
            case KeyLength::Key128Bits: if (key.size() != 128 / 8) return { }; break;
            case KeyLength::Key192Bits: if (key.size() != 192 / 8) return { }; break;
            case KeyLength::Key256Bits: if (key.size() != 256 / 8) return { }; break;
            default: return { };
        }

        mbedtls_cipher_type_t type;
        switch (mode) {
            case AESMode::ECB:      type = MBEDTLS_CIPHER_AES_128_ECB;      break;
            case AESMode::CBC:      type = MBEDTLS_CIPHER_AES_128_CBC;      break;
            case AESMode::CFB128:   type = MBEDTLS_CIPHER_AES_128_CFB128;   break;
            case AESMode::CTR:      type = MBEDTLS_CIPHER_AES_128_CTR;      break;
            case AESMode::GCM:      type = MBEDTLS_CIPHER_AES_128_GCM;      break;
            case AESMode::CCM:      type = MBEDTLS_CIPHER_AES_128_CCM;      break;
            case AESMode::OFB:      type = MBEDTLS_CIPHER_AES_128_OFB;      break;
            case AESMode::XTS:      type = MBEDTLS_CIPHER_AES_128_XTS;      break;
            default: return { };
        }

        type = mbedtls_cipher_type_t(type + u8(keyLength));

        return aes(type, MBEDTLS_DECRYPT, key, nonce, iv, input);
    }

}