// Copyright (c) Advanced Micro Devices, Inc.
// SPDX-License-Identifier: MIT

#pragma once

#include <array>
#include <cstdint>
#include <cstring>
#include <iomanip>
#include <string_view>
#include <type_traits>

#include "traits.hpp"

namespace rocprofsys
{
inline namespace common
{

class md5sum
{
public:
    using size_type                = std::uint32_t;  // must be 32bit
    using raw_digest_t             = std::array<std::uint8_t, 16>;
    static constexpr int blocksize = 64;

    template <typename Tp, typename... Args>
    explicit md5sum(Tp&& arg, Args&&... args);

    md5sum()              = default;
    ~md5sum()             = default;
    md5sum(const md5sum&) = default;
    md5sum(md5sum&&)      = default;

    md5sum& operator=(const md5sum&) = default;
    md5sum& operator=(md5sum&&)      = default;

    md5sum&      update(std::string_view inp);
    md5sum&      update(const unsigned char* buf, size_type length);
    md5sum&      update(const char* buf, size_type length);
    md5sum&      finalize();
    std::string  hexdigest() const;
    std::string  hexliteral() const;
    raw_digest_t rawdigest() const { return digest; }

    template <typename Tp>
        requires std::is_arithmetic_v<Tp>
    md5sum& update(Tp inp);

    friend std::ostream& operator<<(std::ostream&, md5sum md5);

private:
    void transform(const std::uint8_t block[blocksize]);

    bool finalized = false;
    // 64bit counter for number of bits (lo, hi)
    std::array<std::uint32_t, 2> count = { 0, 0 };
    std::array<std::uint8_t, blocksize>
        buffer{};  // overflow bytes from last 64 byte chunk
    // digest so far, initialized to magic initialization constants.
    std::array<std::uint32_t, 4> state = { 0x67452301, 0xefcdab89, 0x98badcfe,
                                           0x10325476 };
    std::array<std::uint8_t, 16> digest{};  // result
};

template <typename Tp, typename... Args>
md5sum::md5sum(Tp&& arg, Args&&... args)
{
    auto _update = [&](auto&& _val) {
        using value_type =
            std::remove_reference_t<std::remove_cv_t<std::decay_t<decltype(_val)>>>;
        static_assert(!std::is_pointer<value_type>::value,
                      "constructor cannot be called with pointer argument");
        update(std::forward<decltype(_val)>(_val));
    };

    _update(std::forward<Tp>(arg));
    (_update(std::forward<Args>(args)), ...);
    finalize();
}

template <typename Tp>
    requires std::is_arithmetic_v<Tp>
md5sum&
md5sum::update(Tp inp)
{
    return update(reinterpret_cast<const char*>(&inp), sizeof(Tp));
}

template <template <typename, typename...> class ContainerT, typename Tp,
          typename... TailT>
    requires(traits::is_string_literal<Tp>())
std::string
compute_md5sum(const ContainerT<Tp, TailT...>& inp)
{
    auto _val = md5sum{};
    for(const auto& itr : inp)
        _val.update(std::string_view{ inp });
    _val.finalize();
    return _val.hexdigest();
}

namespace
{

using size_type = typename md5sum::size_type;

// Constants for md5sumTransform routine.
constexpr std::uint32_t S11 = 7;
constexpr std::uint32_t S12 = 12;
constexpr std::uint32_t S13 = 17;
constexpr std::uint32_t S14 = 22;
constexpr std::uint32_t S21 = 5;
constexpr std::uint32_t S22 = 9;
constexpr std::uint32_t S23 = 14;
constexpr std::uint32_t S24 = 20;
constexpr std::uint32_t S31 = 4;
constexpr std::uint32_t S32 = 11;
constexpr std::uint32_t S33 = 16;
constexpr std::uint32_t S34 = 23;
constexpr std::uint32_t S41 = 6;
constexpr std::uint32_t S42 = 10;
constexpr std::uint32_t S43 = 15;
constexpr std::uint32_t S44 = 21;

// low level logic operations
static inline std::uint32_t
F(std::uint32_t x, std::uint32_t y, std::uint32_t z);

static inline std::uint32_t
G(std::uint32_t x, std::uint32_t y, std::uint32_t z);

static inline std::uint32_t
H(std::uint32_t x, std::uint32_t y, std::uint32_t z);

static inline std::uint32_t
I(std::uint32_t x, std::uint32_t y, std::uint32_t z);

static inline std::uint32_t
rotate_left(std::uint32_t x, int n);

static inline void
FF(std::uint32_t& a, std::uint32_t b, std::uint32_t c, std::uint32_t d, std::uint32_t x,
   std::uint32_t s, std::uint32_t ac);

static inline void
GG(std::uint32_t& a, std::uint32_t b, std::uint32_t c, std::uint32_t d, std::uint32_t x,
   std::uint32_t s, std::uint32_t ac);

static inline void
HH(std::uint32_t& a, std::uint32_t b, std::uint32_t c, std::uint32_t d, std::uint32_t x,
   std::uint32_t s, std::uint32_t ac);

static inline void
II(std::uint32_t& a, std::uint32_t b, std::uint32_t c, std::uint32_t d, std::uint32_t x,
   std::uint32_t s, std::uint32_t ac);

// F, G, H and I are basic md5sum functions.
inline std::uint32_t
F(std::uint32_t x, std::uint32_t y, std::uint32_t z)
{
    return (x & y) | (~x & z);
}

inline std::uint32_t
G(std::uint32_t x, std::uint32_t y, std::uint32_t z)
{
    return (x & z) | (y & ~z);
}

inline std::uint32_t
H(std::uint32_t x, std::uint32_t y, std::uint32_t z)
{
    return x ^ y ^ z;
}

inline std::uint32_t
I(std::uint32_t x, std::uint32_t y, std::uint32_t z)
{
    return y ^ (x | ~z);
}

// rotate_left rotates x left n bits.
inline std::uint32_t
rotate_left(std::uint32_t x, int n)
{
    return (x << n) | (x >> (32 - n));
}

// FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
// Rotation is separate from addition to prevent recomputation.
inline void
FF(std::uint32_t& a, std::uint32_t b, std::uint32_t c, std::uint32_t d, std::uint32_t x,
   std::uint32_t s, std::uint32_t ac)
{
    a = rotate_left(a + F(b, c, d) + x + ac, s) + b;
}

inline void
GG(std::uint32_t& a, std::uint32_t b, std::uint32_t c, std::uint32_t d, std::uint32_t x,
   std::uint32_t s, std::uint32_t ac)
{
    a = rotate_left(a + G(b, c, d) + x + ac, s) + b;
}

inline void
HH(std::uint32_t& a, std::uint32_t b, std::uint32_t c, std::uint32_t d, std::uint32_t x,
   std::uint32_t s, std::uint32_t ac)
{
    a = rotate_left(a + H(b, c, d) + x + ac, s) + b;
}

inline void
II(std::uint32_t& a, std::uint32_t b, std::uint32_t c, std::uint32_t d, std::uint32_t x,
   std::uint32_t s, std::uint32_t ac)
{
    a = rotate_left(a + I(b, c, d) + x + ac, s) + b;
}

// decodes input (unsigned char) into output (std::uint32_t). Assumes len is a multiple
// of 4.
void
decode(std::uint32_t output[], const std::uint8_t input[], size_type len)
{
    for(unsigned int i = 0, j = 0; j < len; i++, j += 4)
        output[i] = ((std::uint32_t) input[j]) | (((std::uint32_t) input[j + 1]) << 8) |
                    (((std::uint32_t) input[j + 2]) << 16) |
                    (((std::uint32_t) input[j + 3]) << 24);
}

// encodes input (std::uint32_t) into output (unsigned char). Assumes len is
// a multiple of 4.
void
encode(std::uint8_t output[], const std::uint32_t input[], size_type len)
{
    for(size_type i = 0, j = 0; j < len; i++, j += 4)
    {
        output[j]     = input[i] & 0xff;
        output[j + 1] = (input[i] >> 8) & 0xff;
        output[j + 2] = (input[i] >> 16) & 0xff;
        output[j + 3] = (input[i] >> 24) & 0xff;
    }
}

}  // namespace

// apply md5sum algo on a block
void
md5sum::transform(const std::uint8_t block[blocksize])
{
    std::uint32_t a = state[0], b = state[1], c = state[2], d = state[3], x[16];
    decode(x, block, blocksize);

    /* Round 1 */
    FF(a, b, c, d, x[0], S11, 0xd76aa478);  /* 1 */
    FF(d, a, b, c, x[1], S12, 0xe8c7b756);  /* 2 */
    FF(c, d, a, b, x[2], S13, 0x242070db);  /* 3 */
    FF(b, c, d, a, x[3], S14, 0xc1bdceee);  /* 4 */
    FF(a, b, c, d, x[4], S11, 0xf57c0faf);  /* 5 */
    FF(d, a, b, c, x[5], S12, 0x4787c62a);  /* 6 */
    FF(c, d, a, b, x[6], S13, 0xa8304613);  /* 7 */
    FF(b, c, d, a, x[7], S14, 0xfd469501);  /* 8 */
    FF(a, b, c, d, x[8], S11, 0x698098d8);  /* 9 */
    FF(d, a, b, c, x[9], S12, 0x8b44f7af);  /* 10 */
    FF(c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
    FF(b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
    FF(a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
    FF(d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
    FF(c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
    FF(b, c, d, a, x[15], S14, 0x49b40821); /* 16 */

    /* Round 2 */
    GG(a, b, c, d, x[1], S21, 0xf61e2562);  /* 17 */
    GG(d, a, b, c, x[6], S22, 0xc040b340);  /* 18 */
    GG(c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
    GG(b, c, d, a, x[0], S24, 0xe9b6c7aa);  /* 20 */
    GG(a, b, c, d, x[5], S21, 0xd62f105d);  /* 21 */
    GG(d, a, b, c, x[10], S22, 0x2441453);  /* 22 */
    GG(c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
    GG(b, c, d, a, x[4], S24, 0xe7d3fbc8);  /* 24 */
    GG(a, b, c, d, x[9], S21, 0x21e1cde6);  /* 25 */
    GG(d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
    GG(c, d, a, b, x[3], S23, 0xf4d50d87);  /* 27 */
    GG(b, c, d, a, x[8], S24, 0x455a14ed);  /* 28 */
    GG(a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
    GG(d, a, b, c, x[2], S22, 0xfcefa3f8);  /* 30 */
    GG(c, d, a, b, x[7], S23, 0x676f02d9);  /* 31 */
    GG(b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */

    /* Round 3 */
    HH(a, b, c, d, x[5], S31, 0xfffa3942);  /* 33 */
    HH(d, a, b, c, x[8], S32, 0x8771f681);  /* 34 */
    HH(c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
    HH(b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
    HH(a, b, c, d, x[1], S31, 0xa4beea44);  /* 37 */
    HH(d, a, b, c, x[4], S32, 0x4bdecfa9);  /* 38 */
    HH(c, d, a, b, x[7], S33, 0xf6bb4b60);  /* 39 */
    HH(b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
    HH(a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
    HH(d, a, b, c, x[0], S32, 0xeaa127fa);  /* 42 */
    HH(c, d, a, b, x[3], S33, 0xd4ef3085);  /* 43 */
    HH(b, c, d, a, x[6], S34, 0x4881d05);   /* 44 */
    HH(a, b, c, d, x[9], S31, 0xd9d4d039);  /* 45 */
    HH(d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
    HH(c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
    HH(b, c, d, a, x[2], S34, 0xc4ac5665);  /* 48 */

    /* Round 4 */
    II(a, b, c, d, x[0], S41, 0xf4292244);  /* 49 */
    II(d, a, b, c, x[7], S42, 0x432aff97);  /* 50 */
    II(c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
    II(b, c, d, a, x[5], S44, 0xfc93a039);  /* 52 */
    II(a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
    II(d, a, b, c, x[3], S42, 0x8f0ccc92);  /* 54 */
    II(c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
    II(b, c, d, a, x[1], S44, 0x85845dd1);  /* 56 */
    II(a, b, c, d, x[8], S41, 0x6fa87e4f);  /* 57 */
    II(d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
    II(c, d, a, b, x[6], S43, 0xa3014314);  /* 59 */
    II(b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
    II(a, b, c, d, x[4], S41, 0xf7537e82);  /* 61 */
    II(d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
    II(c, d, a, b, x[2], S43, 0x2ad7d2bb);  /* 63 */
    II(b, c, d, a, x[9], S44, 0xeb86d391);  /* 64 */

    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;

    // Zeroize sensitive information.
    memset(x, 0, sizeof x);
}

md5sum&
md5sum::update(std::string_view inp)
{
    return update(inp.data(), inp.length());
}

// md5sum block update operation. Continues an md5sum message-digest
// operation, processing another message block
md5sum&
md5sum::update(const unsigned char input[], size_type length)
{
    // compute number of bytes mod 64
    size_type index = count[0] / 8 % blocksize;

    // Update number of bits
    if((count[0] += (length << 3)) < (length << 3)) count[1]++;
    count[1] += (length >> 29);

    // number of bytes we need to fill in buffer
    size_type firstpart = 64 - index;
    size_type i         = 0;

    // transform as many times as possible.
    if(length >= firstpart)
    {
        // fill buffer first, transform
        memcpy(&buffer[index], input, firstpart);
        transform(buffer.data());

        // transform chunks of blocksize (64 bytes)
        for(i = firstpart; i + blocksize <= length; i += blocksize)
            transform(&input[i]);

        index = 0;
    }

    // buffer remaining input
    memcpy(&buffer[index], &input[i], length - i);

    return *this;
}

// for convenience provide a verson with signed char
md5sum&
md5sum::update(const char input[], size_type length)
{
    return update((const unsigned char*) input, length);
}

// md5sum finalization. Ends an md5sum message-digest operation, writing the
// the message digest and zeroizing the context.
md5sum&
md5sum::finalize()
{
    static unsigned char padding[64] = { 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                                         0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                                         0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                                         0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                                         0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

    if(!finalized)
    {
        // Save number of bits
        unsigned char bits[8];
        encode(bits, count.data(), 8);

        // pad out to 56 mod 64.
        size_type index  = count[0] / 8 % 64;
        size_type padLen = (index < 56) ? (56 - index) : (120 - index);
        update(padding, padLen);

        // Append length (before padding)
        update(bits, 8);

        // Store state in digest
        encode(digest.data(), state.data(), 16);

        // Zeroize sensitive information.
        memset(buffer.data(), 0, sizeof buffer);
        memset(count.data(), 0, sizeof count);

        finalized = true;
    }

    return *this;
}

// return hex representation of digest as string
std::string
md5sum::hexdigest() const
{
    if(!finalized) return std::string{};

    char buf[33];
    for(int i = 0; i < 16; i++)
        snprintf(buf + i * 2, 3, "%02x", digest[i]);
    buf[32] = '\0';

    return std::string(buf);
}

std::string
md5sum::hexliteral() const
{
    if(!finalized) return std::string{};

    auto _oss = std::ostringstream{};
    _oss << "X'";
    for(auto itr : rawdigest())
        _oss << std::hex << std::setw(2) << std::setfill('0') << static_cast<int>(itr);
    _oss << "'";
    return _oss.str();
}

std::ostream&
operator<<(std::ostream& out, md5sum md5)
{
    return out << md5.hexdigest();
}

std::string
compute_md5sum(std::string_view inp)
{
    return md5sum{ inp }.finalize().hexdigest();
}

}  // namespace common
}  // namespace rocprofsys