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

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2017 - ROLI Ltd.

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For this technical preview, this file is not subject to commercial licensing.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR 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 inline uint32_t rotate (uint32_t x, uint32_t y) noexcept            { return (x >> y) | (x << (32 - y)); }
    static inline uint32_t ch  (uint32_t x, uint32_t y, uint32_t z) noexcept   { return z ^ ((y ^ z) & x); }
    static inline uint32_t maj (uint32_t x, uint32_t y, uint32_t z) noexcept   { return y ^ ((y ^ z) & (x ^ y)); }

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