/*
  ==============================================================================

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

   By downloading, installing, or using the JUCE framework, or combining the
   JUCE framework with any other source code, object code, content or any other
   copyrightable work, you agree to the terms of the JUCE End User Licence
   Agreement, and all incorporated terms including the JUCE Privacy Policy and
   the JUCE Website Terms of Service, as applicable, which will bind you. If you
   do not agree to the terms of these agreements, we will not license the JUCE
   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

   JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
   JUCE Privacy Policy: https://juce.com/juce-privacy-policy
   JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/

   Or:

   You may also use this code under the terms of the AGPLv3:
   https://www.gnu.org/licenses/agpl-3.0.en.html

   THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
   WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

struct SHA256Processor
{
    // expects 64 bytes of data
    void processFullBlock (const void* data) noexcept
    {
        const uint32_t constants[] =
        {
            0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
            0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
            0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
            0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
            0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
            0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
            0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
            0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
        };

        uint32_t block[16], s[8];
        memcpy (s, state, sizeof (s));

        auto d = static_cast<const uint8_t*> (data);

        for (auto& b : block)
        {
            b = (uint32_t (d[0]) << 24) | (uint32_t (d[1]) << 16) | (uint32_t (d[2]) << 8) | d[3];
            d += 4;
        }

        auto convolve = [&] (uint32_t i, uint32_t j)
        {
            s[(7 - i) & 7] += S1 (s[(4 - i) & 7]) + ch (s[(4 - i) & 7], s[(5 - i) & 7], s[(6 - i) & 7]) + constants[i + j]
                                 + (j != 0 ? (block[i & 15] += s1 (block[(i - 2) & 15]) + block[(i - 7) & 15] + s0 (block[(i - 15) & 15]))
                                           : block[i]);
            s[(3 - i) & 7] += s[(7 - i) & 7];
            s[(7 - i) & 7] += S0 (s[(0 - i) & 7]) + maj (s[(0 - i) & 7], s[(1 - i) & 7], s[(2 - i) & 7]);
        };

        for (uint32_t j = 0; j < 64; j += 16)
            for (uint32_t i = 0; i < 16; ++i)
                convolve (i, j);

        for (int i = 0; i < 8; ++i)
            state[i] += s[i];

        length += 64;
    }

    void processFinalBlock (const void* data, uint32_t numBytes) noexcept
    {
        jassert (numBytes < 64);

        length += numBytes;
        length *= 8; // (the length is stored as a count of bits, not bytes)

        uint8_t finalBlocks[128];

        memcpy (finalBlocks, data, numBytes);
        finalBlocks[numBytes++] = 128; // append a '1' bit

        while (numBytes != 56 && numBytes < 64 + 56)
            finalBlocks[numBytes++] = 0; // pad with zeros

        for (int i = 8; --i >= 0;)
            finalBlocks[numBytes++] = (uint8_t) (length >> (i * 8)); // append the length

        jassert (numBytes == 64 || numBytes == 128);

        processFullBlock (finalBlocks);

        if (numBytes > 64)
            processFullBlock (finalBlocks + 64);
    }

    void copyResult (uint8_t* result) const noexcept
    {
        for (auto s : state)
        {
            *result++ = (uint8_t) (s >> 24);
            *result++ = (uint8_t) (s >> 16);
            *result++ = (uint8_t) (s >> 8);
            *result++ = (uint8_t) s;
        }
    }

    void processStream (InputStream& input, int64_t numBytesToRead, uint8_t* result)
    {
        if (numBytesToRead < 0)
            numBytesToRead = std::numeric_limits<int64_t>::max();

        for (;;)
        {
            uint8_t buffer[64];
            auto bytesRead = input.read (buffer, (int) jmin (numBytesToRead, (int64_t) sizeof (buffer)));

            if (bytesRead < (int) sizeof (buffer))
            {
                processFinalBlock (buffer, (unsigned int) bytesRead);
                break;
            }

            numBytesToRead -= (int64_t) sizeof (buffer);
            processFullBlock (buffer);
        }

        copyResult (result);
    }

private:
    uint32_t state[8] = { 0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
                          0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19 };
    uint64_t length = 0;

    static uint32_t rotate (uint32_t x, uint32_t y) noexcept            { return (x >> y) | (x << (32 - y)); }
    static uint32_t ch  (uint32_t x, uint32_t y, uint32_t z) noexcept   { return z ^ ((y ^ z) & x); }
    static uint32_t maj (uint32_t x, uint32_t y, uint32_t z) noexcept   { return y ^ ((y ^ z) & (x ^ y)); }

    static uint32_t s0 (uint32_t x) noexcept     { return rotate (x, 7)  ^ rotate (x, 18) ^ (x >> 3); }
    static uint32_t s1 (uint32_t x) noexcept     { return rotate (x, 17) ^ rotate (x, 19) ^ (x >> 10); }
    static uint32_t S0 (uint32_t x) noexcept     { return rotate (x, 2)  ^ rotate (x, 13) ^ rotate (x, 22); }
    static uint32_t S1 (uint32_t x) noexcept     { return rotate (x, 6)  ^ rotate (x, 11) ^ rotate (x, 25); }
};

//==============================================================================
SHA256::SHA256() = default;
SHA256::~SHA256() = default;
SHA256::SHA256 (const SHA256&) = default;
SHA256& SHA256::operator= (const SHA256&) = default;

SHA256::SHA256 (const MemoryBlock& data)
{
    process (data.getData(), data.getSize());
}

SHA256::SHA256 (const void* data, size_t numBytes)
{
    process (data, numBytes);
}

SHA256::SHA256 (InputStream& input, int64 numBytesToRead)
{
    SHA256Processor processor;
    processor.processStream (input, numBytesToRead, result);
}

SHA256::SHA256 (const File& file)
{
    FileInputStream fin (file);

    if (fin.getStatus().wasOk())
    {
        SHA256Processor processor;
        processor.processStream (fin, -1, result);
    }
    else
    {
        zerostruct (result);
    }
}

SHA256::SHA256 (CharPointer_UTF8 utf8) noexcept
{
    jassert (utf8.getAddress() != nullptr);
    process (utf8.getAddress(), utf8.sizeInBytes() - 1);
}

void SHA256::process (const void* data, size_t numBytes)
{
    MemoryInputStream m (data, numBytes, false);
    SHA256Processor processor;
    processor.processStream (m, -1, result);
}

MemoryBlock SHA256::getRawData() const
{
    return MemoryBlock (result, sizeof (result));
}

String SHA256::toHexString() const
{
    return String::toHexString (result, sizeof (result), 0);
}

bool SHA256::operator== (const SHA256& other) const noexcept  { return memcmp (result, other.result, sizeof (result)) == 0; }
bool SHA256::operator!= (const SHA256& other) const noexcept  { return ! operator== (other); }


//==============================================================================
#if JUCE_UNIT_TESTS

class SHA256Tests final : public UnitTest
{
public:
    SHA256Tests()
        : UnitTest ("SHA-256", UnitTestCategories::cryptography)
    {}

    void test (const char* input, const char* expected)
    {
        {
            SHA256 hash (input, strlen (input));
            expectEquals (hash.toHexString(), String (expected));
        }

        {
            CharPointer_UTF8 utf8 (input);
            SHA256 hash (utf8);
            expectEquals (hash.toHexString(), String (expected));
        }

        {
            MemoryInputStream m (input, strlen (input), false);
            SHA256 hash (m);
            expectEquals (hash.toHexString(), String (expected));
        }
    }

    void runTest() override
    {
        beginTest ("SHA256");

        test ("", "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855");
        test ("The quick brown fox jumps over the lazy dog",  "d7a8fbb307d7809469ca9abcb0082e4f8d5651e46d3cdb762d02d0bf37c9e592");
        test ("The quick brown fox jumps over the lazy dog.", "ef537f25c895bfa782526529a9b63d97aa631564d5d789c2b765448c8635fb6c");
    }
};

static SHA256Tests sha256UnitTests;

#endif

} // namespace juce
