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

   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 MD5Generator
{
    void processBlock (const void* data, size_t dataSize) noexcept
    {
        auto bufferPos = ((count[0] >> 3) & 0x3f);

        count[0] += (uint32_t) (dataSize << 3);

        if (count[0] < ((uint32_t) dataSize << 3))
            count[1]++;

        count[1] += (uint32_t) (dataSize >> 29);

        auto spaceLeft = (size_t) 64 - (size_t) bufferPos;
        size_t i = 0;

        if (dataSize >= spaceLeft)
        {
            memcpy (buffer + bufferPos, data, spaceLeft);
            transform (buffer);

            for (i = spaceLeft; i + 64 <= dataSize; i += 64)
                transform (static_cast<const char*> (data) + i);

            bufferPos = 0;
        }

        memcpy (buffer + bufferPos, static_cast<const char*> (data) + i, dataSize - i);
    }

    void transform (const void* bufferToTransform) noexcept
    {
        auto a = state[0];
        auto b = state[1];
        auto c = state[2];
        auto d = state[3];

        uint32_t x[16];
        copyWithEndiannessConversion (x, bufferToTransform, 64);

        enum Constants
        {
            S11 = 7, S12 = 12, S13 = 17, S14 = 22, S21 = 5, S22 = 9,  S23 = 14, S24 = 20,
            S31 = 4, S32 = 11, S33 = 16, S34 = 23, S41 = 6, S42 = 10, S43 = 15, S44 = 21
        };

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

        GG (a, b, c, d, x[ 1], S21, 0xf61e2562);     GG (d, a, b, c, x[ 6], S22, 0xc040b340);
        GG (c, d, a, b, x[11], S23, 0x265e5a51);     GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa);
        GG (a, b, c, d, x[ 5], S21, 0xd62f105d);     GG (d, a, b, c, x[10], S22, 0x02441453);
        GG (c, d, a, b, x[15], S23, 0xd8a1e681);     GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8);
        GG (a, b, c, d, x[ 9], S21, 0x21e1cde6);     GG (d, a, b, c, x[14], S22, 0xc33707d6);
        GG (c, d, a, b, x[ 3], S23, 0xf4d50d87);     GG (b, c, d, a, x[ 8], S24, 0x455a14ed);
        GG (a, b, c, d, x[13], S21, 0xa9e3e905);     GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8);
        GG (c, d, a, b, x[ 7], S23, 0x676f02d9);     GG (b, c, d, a, x[12], S24, 0x8d2a4c8a);

        HH (a, b, c, d, x[ 5], S31, 0xfffa3942);     HH (d, a, b, c, x[ 8], S32, 0x8771f681);
        HH (c, d, a, b, x[11], S33, 0x6d9d6122);     HH (b, c, d, a, x[14], S34, 0xfde5380c);
        HH (a, b, c, d, x[ 1], S31, 0xa4beea44);     HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9);
        HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60);     HH (b, c, d, a, x[10], S34, 0xbebfbc70);
        HH (a, b, c, d, x[13], S31, 0x289b7ec6);     HH (d, a, b, c, x[ 0], S32, 0xeaa127fa);
        HH (c, d, a, b, x[ 3], S33, 0xd4ef3085);     HH (b, c, d, a, x[ 6], S34, 0x04881d05);
        HH (a, b, c, d, x[ 9], S31, 0xd9d4d039);     HH (d, a, b, c, x[12], S32, 0xe6db99e5);
        HH (c, d, a, b, x[15], S33, 0x1fa27cf8);     HH (b, c, d, a, x[ 2], S34, 0xc4ac5665);

        II (a, b, c, d, x[ 0], S41, 0xf4292244);     II (d, a, b, c, x[ 7], S42, 0x432aff97);
        II (c, d, a, b, x[14], S43, 0xab9423a7);     II (b, c, d, a, x[ 5], S44, 0xfc93a039);
        II (a, b, c, d, x[12], S41, 0x655b59c3);     II (d, a, b, c, x[ 3], S42, 0x8f0ccc92);
        II (c, d, a, b, x[10], S43, 0xffeff47d);     II (b, c, d, a, x[ 1], S44, 0x85845dd1);
        II (a, b, c, d, x[ 8], S41, 0x6fa87e4f);     II (d, a, b, c, x[15], S42, 0xfe2ce6e0);
        II (c, d, a, b, x[ 6], S43, 0xa3014314);     II (b, c, d, a, x[13], S44, 0x4e0811a1);
        II (a, b, c, d, x[ 4], S41, 0xf7537e82);     II (d, a, b, c, x[11], S42, 0xbd3af235);
        II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb);     II (b, c, d, a, x[ 9], S44, 0xeb86d391);

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

    void finish (uint8_t* result) noexcept
    {
        uint8_t encodedLength[8];
        copyWithEndiannessConversion (encodedLength, count, 8);

        // Pad out to 56 mod 64.
        auto index = (count[0] >> 3) & 0x3f;
        auto paddingLength = (index < 56 ? 56 : 120) - index;

        uint8_t paddingBuffer[64] = { 0x80 }; // first byte is 0x80, remaining bytes are zero.

        processBlock (paddingBuffer, (size_t) paddingLength);
        processBlock (encodedLength, 8);

        copyWithEndiannessConversion (result, state, 16);
    }

private:
    uint8_t buffer[64] = {};
    uint32_t state[4] = { 0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476 };
    uint32_t count[2] = {};

    static void copyWithEndiannessConversion (void* output, const void* input, size_t numBytes) noexcept
    {
       #if JUCE_LITTLE_ENDIAN
        memcpy (output, input, numBytes);
       #else
        auto dst = static_cast<uint8_t*> (output);
        auto src = static_cast<const uint8_t*> (input);

        for (size_t i = 0; i < numBytes; i += 4)
        {
            dst[i + 0] = src[i + 3];
            dst[i + 1] = src[i + 2];
            dst[i + 2] = src[i + 1];
            dst[i + 3] = src[i + 0];
        }
       #endif
    }

    static inline uint32_t rotateLeft (uint32_t x, uint32_t n) noexcept     { return (x << n) | (x >> (32 - n)); }

    static inline uint32_t F (uint32_t x, uint32_t y, uint32_t z) noexcept  { return (x & y) | (~x & z); }
    static inline uint32_t G (uint32_t x, uint32_t y, uint32_t z) noexcept  { return (x & z) | (y & ~z); }
    static inline uint32_t H (uint32_t x, uint32_t y, uint32_t z) noexcept  { return x ^ y ^ z; }
    static inline uint32_t I (uint32_t x, uint32_t y, uint32_t z) noexcept  { return y ^ (x | ~z); }

    static void FF (uint32_t& a, uint32_t b, uint32_t c, uint32_t d, uint32_t x, uint32_t s, uint32_t ac) noexcept
    {
        a = rotateLeft (a + F (b, c, d) + x + ac, s) + b;
    }

    static void GG (uint32_t& a, uint32_t b, uint32_t c, uint32_t d, uint32_t x, uint32_t s, uint32_t ac) noexcept
    {
        a = rotateLeft (a + G (b, c, d) + x + ac, s) + b;
    }

    static void HH (uint32_t& a, uint32_t b, uint32_t c, uint32_t d, uint32_t x, uint32_t s, uint32_t ac) noexcept
    {
        a = rotateLeft (a + H (b, c, d) + x + ac, s) + b;
    }

    static void II (uint32_t& a, uint32_t b, uint32_t c, uint32_t d, uint32_t x, uint32_t s, uint32_t ac) noexcept
    {
        a = rotateLeft (a + I (b, c, d) + x + ac, s) + b;
    }
};

//==============================================================================
MD5::MD5() = default;
MD5::~MD5() = default;
MD5::MD5 (const MD5&) = default;
MD5& MD5::operator= (const MD5&) = default;

MD5::MD5 (const void* data, size_t numBytes) noexcept
{
    MD5Generator generator;
    generator.processBlock (data, numBytes);
    generator.finish (result);
}

MD5::MD5 (const MemoryBlock& data) noexcept : MD5 (data.getData(), data.getSize()) {}
MD5::MD5 (CharPointer_UTF8 utf8) noexcept : MD5 (utf8.getAddress(), utf8.getAddress() != nullptr ? utf8.sizeInBytes() - 1 : 0) {}

MD5 MD5::fromUTF32 (StringRef text)
{
    MD5 m;
    MD5Generator generator;

    for (auto t = text.text; t.isNotEmpty();)
    {
        auto unicodeChar = ByteOrder::swapIfBigEndian ((uint32_t) t.getAndAdvance());
        generator.processBlock (&unicodeChar, sizeof (unicodeChar));
    }

    generator.finish (m.result);
    return m;
}

MD5::MD5 (InputStream& input, int64 numBytesToRead)
{
    processStream (input, numBytesToRead);
}

MD5::MD5 (const File& file)
{
    FileInputStream fin (file);

    if (fin.openedOk())
        processStream (fin, -1);
}

void MD5::processStream (InputStream& input, int64 numBytesToRead)
{
    MD5Generator generator;

    if (numBytesToRead < 0)
        numBytesToRead = std::numeric_limits<int64>::max();

    while (numBytesToRead > 0)
    {
        uint8_t tempBuffer[512];
        auto bytesRead = input.read (tempBuffer, (int) jmin (numBytesToRead, (int64) sizeof (tempBuffer)));

        if (bytesRead <= 0)
            break;

        numBytesToRead -= bytesRead;
        generator.processBlock (tempBuffer, (size_t) bytesRead);
    }

    generator.finish (result);
}

//==============================================================================
MemoryBlock MD5::getRawChecksumData() const
{
    return MemoryBlock (result, sizeof (result));
}

String MD5::toHexString() const
{
    return String::toHexString (result, sizeof (result), 0);
}

//==============================================================================
bool MD5::operator== (const MD5& other) const noexcept   { return memcmp (result, other.result, sizeof (result)) == 0; }
bool MD5::operator!= (const MD5& other) const noexcept   { return ! operator== (other); }


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

class MD5Tests  : public UnitTest
{
public:
    MD5Tests()
        : UnitTest ("MD5", UnitTestCategories::cryptography)
    {}

    void test (const char* input, const char* expected)
    {
        {
            MD5 hash (input, strlen (input));
            expectEquals (hash.toHexString(), String (expected));
        }

        {
            MemoryInputStream m (input, strlen (input), false);
            MD5 hash (m);
            expectEquals (hash.toHexString(), String (expected));
        }
    }

    void runTest() override
    {
        beginTest ("MD5");

        test ("", "d41d8cd98f00b204e9800998ecf8427e");
        test ("The quick brown fox jumps over the lazy dog",  "9e107d9d372bb6826bd81d3542a419d6");
        test ("The quick brown fox jumps over the lazy dog.", "e4d909c290d0fb1ca068ffaddf22cbd0");

        expectEquals (MD5 (CharPointer_UTF8(nullptr)).toHexString(), String ("d41d8cd98f00b204e9800998ecf8427e"));
    }
};

static MD5Tests MD5UnitTests;

#endif

} // namespace juce