// Copyright (c) 2017 Thomas Fussell
//
// 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, WRISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE
//
// @license: http://www.opensource.org/licenses/mit-license.php
// @author: see AUTHORS file

#include <array>
#include <cstring>
#include <iomanip>
#include <string>
#include <sstream>

#include <detail/crypto/sha.hpp>

namespace {

class SHA1
{
public:
    SHA1();
    void update(const std::string &s);
    void update(std::istream &is);
    std::string final_();

private:
    uint32_t digest[5];
    std::string buffer;
    uint64_t transforms;
};

static const size_t BLOCK_INTS = 16;  /* number of 32bit integers per SHA1 block */
static const size_t BLOCK_BYTES = BLOCK_INTS * 4;

static void sha1_reset(uint32_t digest[], std::string &buffer, uint64_t &transforms)
{
    /* SHA1 initialization constants */
    digest[0] = 0x67452301;
    digest[1] = 0xefcdab89;
    digest[2] = 0x98badcfe;
    digest[3] = 0x10325476;
    digest[4] = 0xc3d2e1f0;

    /* Reset counters */
    buffer = "";
    transforms = 0;
}


static uint32_t sha1_rol(const uint32_t value, const size_t bits)
{
    return (value << bits) | (value >> (32 - bits));
}


static uint32_t sha1_blk(const uint32_t block[BLOCK_INTS], const size_t i)
{
    return sha1_rol(block[(i+13)&15] ^ block[(i+8)&15] ^ block[(i+2)&15] ^ block[i], 1);
}


/*
 * (R0+R1), R2, R3, R4 are the different operations used in SHA1
 */

static void sha1_R0(const uint32_t block[BLOCK_INTS], const uint32_t v, uint32_t &w, const uint32_t x, const uint32_t y, uint32_t &z, const size_t i)
{
    z += ((w&(x^y))^y) + block[i] + 0x5a827999 + sha1_rol(v, 5);
    w = sha1_rol(w, 30);
}


static void sha1_R1(uint32_t block[BLOCK_INTS], const uint32_t v, uint32_t &w, const uint32_t x, const uint32_t y, uint32_t &z, const size_t i)
{
    block[i] = sha1_blk(block, i);
    z += ((w&(x^y))^y) + block[i] + 0x5a827999 + sha1_rol(v, 5);
    w = sha1_rol(w, 30);
}


static void sha1_R2(uint32_t block[BLOCK_INTS], const uint32_t v, uint32_t &w, const uint32_t x, const uint32_t y, uint32_t &z, const size_t i)
{
    block[i] = sha1_blk(block, i);
    z += (w^x^y) + block[i] + 0x6ed9eba1 + sha1_rol(v, 5);
    w = sha1_rol(w, 30);
}


static void sha1_R3(uint32_t block[BLOCK_INTS], const uint32_t v, uint32_t &w, const uint32_t x, const uint32_t y, uint32_t &z, const size_t i)
{
    block[i] = sha1_blk(block, i);
    z += (((w|x)&y)|(w&x)) + block[i] + 0x8f1bbcdc + sha1_rol(v, 5);
    w = sha1_rol(w, 30);
}


static void sha1_R4(uint32_t block[BLOCK_INTS], const uint32_t v, uint32_t &w, const uint32_t x, const uint32_t y, uint32_t &z, const size_t i)
{
    block[i] = sha1_blk(block, i);
    z += (w^x^y) + block[i] + 0xca62c1d6 + sha1_rol(v, 5);
    w = sha1_rol(w, 30);
}

/*
 * Hash a single 512-bit block. This is the core of the algorithm.
 */

static void sha1_transform(uint32_t digest[], uint32_t block[BLOCK_INTS], uint64_t &transforms)
{
    /* Copy digest[] to working vars */
    uint32_t a = digest[0];
    uint32_t b = digest[1];
    uint32_t c = digest[2];
    uint32_t d = digest[3];
    uint32_t e = digest[4];

    /* 4 rounds of 20 operations each. Loop unrolled. */
    sha1_R0(block, a, b, c, d, e,  0);
    sha1_R0(block, e, a, b, c, d,  1);
    sha1_R0(block, d, e, a, b, c,  2);
    sha1_R0(block, c, d, e, a, b,  3);
    sha1_R0(block, b, c, d, e, a,  4);
    sha1_R0(block, a, b, c, d, e,  5);
    sha1_R0(block, e, a, b, c, d,  6);
    sha1_R0(block, d, e, a, b, c,  7);
    sha1_R0(block, c, d, e, a, b,  8);
    sha1_R0(block, b, c, d, e, a,  9);
    sha1_R0(block, a, b, c, d, e, 10);
    sha1_R0(block, e, a, b, c, d, 11);
    sha1_R0(block, d, e, a, b, c, 12);
    sha1_R0(block, c, d, e, a, b, 13);
    sha1_R0(block, b, c, d, e, a, 14);
    sha1_R0(block, a, b, c, d, e, 15);
    sha1_R1(block, e, a, b, c, d,  0);
    sha1_R1(block, d, e, a, b, c,  1);
    sha1_R1(block, c, d, e, a, b,  2);
    sha1_R1(block, b, c, d, e, a,  3);
    sha1_R2(block, a, b, c, d, e,  4);
    sha1_R2(block, e, a, b, c, d,  5);
    sha1_R2(block, d, e, a, b, c,  6);
    sha1_R2(block, c, d, e, a, b,  7);
    sha1_R2(block, b, c, d, e, a,  8);
    sha1_R2(block, a, b, c, d, e,  9);
    sha1_R2(block, e, a, b, c, d, 10);
    sha1_R2(block, d, e, a, b, c, 11);
    sha1_R2(block, c, d, e, a, b, 12);
    sha1_R2(block, b, c, d, e, a, 13);
    sha1_R2(block, a, b, c, d, e, 14);
    sha1_R2(block, e, a, b, c, d, 15);
    sha1_R2(block, d, e, a, b, c,  0);
    sha1_R2(block, c, d, e, a, b,  1);
    sha1_R2(block, b, c, d, e, a,  2);
    sha1_R2(block, a, b, c, d, e,  3);
    sha1_R2(block, e, a, b, c, d,  4);
    sha1_R2(block, d, e, a, b, c,  5);
    sha1_R2(block, c, d, e, a, b,  6);
    sha1_R2(block, b, c, d, e, a,  7);
    sha1_R3(block, a, b, c, d, e,  8);
    sha1_R3(block, e, a, b, c, d,  9);
    sha1_R3(block, d, e, a, b, c, 10);
    sha1_R3(block, c, d, e, a, b, 11);
    sha1_R3(block, b, c, d, e, a, 12);
    sha1_R3(block, a, b, c, d, e, 13);
    sha1_R3(block, e, a, b, c, d, 14);
    sha1_R3(block, d, e, a, b, c, 15);
    sha1_R3(block, c, d, e, a, b,  0);
    sha1_R3(block, b, c, d, e, a,  1);
    sha1_R3(block, a, b, c, d, e,  2);
    sha1_R3(block, e, a, b, c, d,  3);
    sha1_R3(block, d, e, a, b, c,  4);
    sha1_R3(block, c, d, e, a, b,  5);
    sha1_R3(block, b, c, d, e, a,  6);
    sha1_R3(block, a, b, c, d, e,  7);
    sha1_R3(block, e, a, b, c, d,  8);
    sha1_R3(block, d, e, a, b, c,  9);
    sha1_R3(block, c, d, e, a, b, 10);
    sha1_R3(block, b, c, d, e, a, 11);
    sha1_R4(block, a, b, c, d, e, 12);
    sha1_R4(block, e, a, b, c, d, 13);
    sha1_R4(block, d, e, a, b, c, 14);
    sha1_R4(block, c, d, e, a, b, 15);
    sha1_R4(block, b, c, d, e, a,  0);
    sha1_R4(block, a, b, c, d, e,  1);
    sha1_R4(block, e, a, b, c, d,  2);
    sha1_R4(block, d, e, a, b, c,  3);
    sha1_R4(block, c, d, e, a, b,  4);
    sha1_R4(block, b, c, d, e, a,  5);
    sha1_R4(block, a, b, c, d, e,  6);
    sha1_R4(block, e, a, b, c, d,  7);
    sha1_R4(block, d, e, a, b, c,  8);
    sha1_R4(block, c, d, e, a, b,  9);
    sha1_R4(block, b, c, d, e, a, 10);
    sha1_R4(block, a, b, c, d, e, 11);
    sha1_R4(block, e, a, b, c, d, 12);
    sha1_R4(block, d, e, a, b, c, 13);
    sha1_R4(block, c, d, e, a, b, 14);
    sha1_R4(block, b, c, d, e, a, 15);

    /* Add the working vars back into digest[] */
    digest[0] += a;
    digest[1] += b;
    digest[2] += c;
    digest[3] += d;
    digest[4] += e;

    /* Count the number of transformations */
    transforms++;
}

static void sha1_buffer_to_block(const std::string &buffer, uint32_t block[BLOCK_INTS])
{
    /* Convert the std::string (byte buffer) to a uint32_t array (MSB) */
    for (size_t i = 0; i < BLOCK_INTS; i++)
    {
        block[i] = static_cast<std::uint32_t>((buffer[4*i+3] & 0xff)
            | (buffer[4*i+2] & 0xff)<<8
            | (buffer[4*i+1] & 0xff)<<16
            | (buffer[4*i+0] & 0xff)<<24);
    }
}

SHA1::SHA1()
{
    sha1_reset(digest, buffer, transforms);
}

void SHA1::update(const std::string &s)
{
    std::istringstream is(s);
    update(is);
}

void SHA1::update(std::istream &is)
{
    while (true)
    {
        char sbuf[BLOCK_BYTES];
        is.read(sbuf, static_cast<std::streamsize>(BLOCK_BYTES - buffer.size()));
        buffer.append(sbuf, static_cast<std::size_t>(is.gcount()));
        if (buffer.size() != BLOCK_BYTES)
        {
            return;
        }
        uint32_t block[BLOCK_INTS];
        sha1_buffer_to_block(buffer, block);
        sha1_transform(digest, block, transforms);
        buffer.clear();
    }
}

/*
 * Add padding and return the message digest.
 */

std::string SHA1::final_()
{
    /* Total number of hashed bits */
    uint64_t total_bits = (transforms*BLOCK_BYTES + buffer.size()) * 8;

    /* Padding */
    buffer.append(1, static_cast<char>(0x80u));
    auto  orig_size = buffer.size();

    while (buffer.size() < BLOCK_BYTES)
    {
        buffer.append(1, '\0');
    }

    uint32_t block[BLOCK_INTS];
    sha1_buffer_to_block(buffer, block);

    if (orig_size > BLOCK_BYTES - 8)
    {
        sha1_transform(digest, block, transforms);
        for (size_t i = 0; i < BLOCK_INTS - 2; i++)
        {
            block[i] = 0;
        }
    }

    /* Append total_bits, split this uint64_t into two uint32_t */
    block[BLOCK_INTS - 1] = static_cast<std::uint32_t>(total_bits);
    block[BLOCK_INTS - 2] = static_cast<std::uint32_t>(total_bits >> 32);
    sha1_transform(digest, block, transforms);

    /* Hex std::string */
    std::ostringstream result;
    for (size_t i = 0; i < sizeof(digest) / sizeof(digest[0]); i++)
    {
        result << std::hex << std::setfill('0') << std::setw(8);
        result << digest[i];
    }

    /* Reset for next run */
    sha1_reset(digest, buffer, transforms);

    return result.str();
}

struct sha512_state
{
    std::uint64_t length;
    std::uint64_t state[8];
    std::uint32_t curlen;
    unsigned char buf[128];
};
    
typedef std::uint32_t u32;
typedef std::uint64_t u64;

static const u64 K[80] =
{
    0x428a2f98d728ae22ULL, 0x7137449123ef65cdULL, 0xb5c0fbcfec4d3b2fULL, 0xe9b5dba58189dbbcULL, 0x3956c25bf348b538ULL,
    0x59f111f1b605d019ULL, 0x923f82a4af194f9bULL, 0xab1c5ed5da6d8118ULL, 0xd807aa98a3030242ULL, 0x12835b0145706fbeULL,
    0x243185be4ee4b28cULL, 0x550c7dc3d5ffb4e2ULL, 0x72be5d74f27b896fULL, 0x80deb1fe3b1696b1ULL, 0x9bdc06a725c71235ULL,
    0xc19bf174cf692694ULL, 0xe49b69c19ef14ad2ULL, 0xefbe4786384f25e3ULL, 0x0fc19dc68b8cd5b5ULL, 0x240ca1cc77ac9c65ULL,
    0x2de92c6f592b0275ULL, 0x4a7484aa6ea6e483ULL, 0x5cb0a9dcbd41fbd4ULL, 0x76f988da831153b5ULL, 0x983e5152ee66dfabULL,
    0xa831c66d2db43210ULL, 0xb00327c898fb213fULL, 0xbf597fc7beef0ee4ULL, 0xc6e00bf33da88fc2ULL, 0xd5a79147930aa725ULL,
    0x06ca6351e003826fULL, 0x142929670a0e6e70ULL, 0x27b70a8546d22ffcULL, 0x2e1b21385c26c926ULL, 0x4d2c6dfc5ac42aedULL,
    0x53380d139d95b3dfULL, 0x650a73548baf63deULL, 0x766a0abb3c77b2a8ULL, 0x81c2c92e47edaee6ULL, 0x92722c851482353bULL,
    0xa2bfe8a14cf10364ULL, 0xa81a664bbc423001ULL, 0xc24b8b70d0f89791ULL, 0xc76c51a30654be30ULL, 0xd192e819d6ef5218ULL,
    0xd69906245565a910ULL, 0xf40e35855771202aULL, 0x106aa07032bbd1b8ULL, 0x19a4c116b8d2d0c8ULL, 0x1e376c085141ab53ULL,
    0x2748774cdf8eeb99ULL, 0x34b0bcb5e19b48a8ULL, 0x391c0cb3c5c95a63ULL, 0x4ed8aa4ae3418acbULL, 0x5b9cca4f7763e373ULL,
    0x682e6ff3d6b2b8a3ULL, 0x748f82ee5defb2fcULL, 0x78a5636f43172f60ULL, 0x84c87814a1f0ab72ULL, 0x8cc702081a6439ecULL,
    0x90befffa23631e28ULL, 0xa4506cebde82bde9ULL, 0xbef9a3f7b2c67915ULL, 0xc67178f2e372532bULL, 0xca273eceea26619cULL,
    0xd186b8c721c0c207ULL, 0xeada7dd6cde0eb1eULL, 0xf57d4f7fee6ed178ULL, 0x06f067aa72176fbaULL, 0x0a637dc5a2c898a6ULL,
    0x113f9804bef90daeULL, 0x1b710b35131c471bULL, 0x28db77f523047d84ULL, 0x32caab7b40c72493ULL, 0x3c9ebe0a15c9bebcULL,
    0x431d67c49c100d4cULL, 0x4cc5d4becb3e42b6ULL, 0x597f299cfc657e2aULL, 0x5fcb6fab3ad6faecULL, 0x6c44198c4a475817ULL
};

static u32 min(u32 x, u32 y)
{
    return x < y ? x : y;
}

static void store64(u64 x, unsigned char* y)
{
    for(int i = 0; i != 8; ++i)
        y[i] = (x >> ((7-i) * 8)) & 255;
}

static u64 load64(const unsigned char* y)
{
    u64 res = 0;
    for(int i = 0; i != 8; ++i)
        res |= u64(y[i]) << ((7-i) * 8);
    return res;
}

static u64 Ch(u64 x, u64 y, u64 z)  { return z ^ (x & (y ^ z)); }
static u64 Maj(u64 x, u64 y, u64 z) { return ((x | y) & z) | (x & y); }
static u64 Rot(u64 x, u64 n)        { return (x >> (n & 63)) | (x << (64 - (n & 63))); }
static u64 Sh(u64 x, u64 n)         { return x >> n; }
static u64 Sigma0(u64 x)            { return Rot(x, 28) ^ Rot(x, 34) ^ Rot(x, 39); }
static u64 Sigma1(u64 x)            { return Rot(x, 14) ^ Rot(x, 18) ^ Rot(x, 41); }
static u64 Gamma0(u64 x)            { return Rot(x, 1) ^ Rot(x, 8) ^ Sh(x, 7); }
static u64 Gamma1(u64 x)            { return Rot(x, 19) ^ Rot(x, 61) ^ Sh(x, 6); }

static void sha_compress(sha512_state& md, const unsigned char *buf)
{
    u64 S[8], W[80], t0, t1;

    // Copy state into S
    for(int i = 0; i < 8; i++)
        S[i] = md.state[i];

    // Copy the state into 1024-bits into W[0..15]
    for(int i = 0; i < 16; i++)
        W[i] = load64(buf + (8*i));

    // Fill W[16..79]
    for(int i = 16; i < 80; i++)
        W[i] = Gamma1(W[i - 2]) + W[i - 7] + Gamma0(W[i - 15]) + W[i - 16];

    // Compress
    auto RND = [&](u64 a, u64 b, u64 c, u64& d, u64 e, u64 f, u64 g, u64& h, u64 i)
    {
        t0 = h + Sigma1(e) + Ch(e, f, g) + K[i] + W[i];
        t1 = Sigma0(a) + Maj(a, b, c);
        d += t0;
        h  = t0 + t1;
    };

    for(auto i = std::uint64_t(0); i < 80; i += 8)
    {
        RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],i+0);
        RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],i+1);
        RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],i+2);
        RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],i+3);
        RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],i+4);
        RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],i+5);
        RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],i+6);
        RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],i+7);
    }

     // Feedback
     for(int i = 0; i < 8; i++)
         md.state[i] = md.state[i] + S[i];
}

static void sha_init(sha512_state& md)
{
    md.curlen = 0;
    md.length = 0;
    md.state[0] = 0x6a09e667f3bcc908ULL;
    md.state[1] = 0xbb67ae8584caa73bULL;
    md.state[2] = 0x3c6ef372fe94f82bULL;
    md.state[3] = 0xa54ff53a5f1d36f1ULL;
    md.state[4] = 0x510e527fade682d1ULL;
    md.state[5] = 0x9b05688c2b3e6c1fULL;
    md.state[6] = 0x1f83d9abfb41bd6bULL;
    md.state[7] = 0x5be0cd19137e2179ULL;
}

static void sha_process(sha512_state& md, const void* src, u32 inlen)
{
    const u32 block_size = sizeof(sha512_state::buf);
    auto in = static_cast<const unsigned char*>(src);

    while(inlen > 0)
    {
        if(md.curlen == 0 && inlen >= block_size)
        {
            sha_compress(md, in);
            md.length += block_size * 8;
            in        += block_size;
            inlen     -= block_size;
        }
        else
        {
            u32 n = min(inlen, (block_size - md.curlen));
            std::memcpy(md.buf + md.curlen, in, n);
            md.curlen += n;
            in        += n;
            inlen     -= n;

            if(md.curlen == block_size)
            {
                sha_compress(md, md.buf);
                md.length += 8*block_size;
                md.curlen = 0;
            }
        }
    }
}

static void sha_done(sha512_state& md, void *out)
{
    // Increase the length of the message
    md.length += md.curlen * 8ULL;

    // Append the '1' bit
    md.buf[md.curlen++] = static_cast<unsigned char>(0x80);

    // If the length is currently above 112 bytes we append zeros then compress.
    // Then we can fall back to padding zeros and length encoding like normal.
    if(md.curlen > 112)
    {
        while(md.curlen < 128)
            md.buf[md.curlen++] = 0;
        sha_compress(md, md.buf);
        md.curlen = 0;
    }

    // Pad upto 120 bytes of zeroes
    // note: that from 112 to 120 is the 64 MSB of the length.  We assume that
    // you won't hash 2^64 bits of data... :-)
    while(md.curlen < 120)
        md.buf[md.curlen++] = 0;

    // Store length
    store64(md.length, md.buf+120);
    sha_compress(md, md.buf);

    // Copy output
    for(int i = 0; i < 8; i++)
        store64(md.state[i], static_cast<unsigned char*>(out)+(8*i));
}

} // namespace SHA512

namespace xlnt {
namespace detail {

std::vector<std::uint8_t> sha1(const std::vector<std::uint8_t> &data)
{
    auto s = SHA1();
    s.update(std::string(data.begin(), data.end()));
    auto hex = s.final_();
    std::vector<std::uint8_t> bytes;

    for (unsigned int i = 0; i < hex.length(); i += 2)
    {
        std::string byteString = hex.substr(i, 2);
        auto byte = static_cast<std::uint8_t>(strtol(byteString.c_str(), NULL, 16));
        bytes.push_back(byte);
    }

    return bytes;
}

std::vector<std::uint8_t> sha512(const std::vector<std::uint8_t> &data)
{
    sha512_state md;
    sha_init(md);
    sha_process(md, data.data(), static_cast<std::uint32_t>(data.size()));
    std::vector<std::uint8_t> result(512 / 8, 0);
    sha_done(md, result.data());
    return result;
}

} // namespace detail
} // namespace xlnt