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

   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
{

Random::Random (int64 seedValue) noexcept  : seed (seedValue)
{
}

Random::Random()  : seed (1)
{
    setSeedRandomly();
}

void Random::setSeed (const int64 newSeed) noexcept
{
    if (this == &getSystemRandom())
    {
        // Resetting the system Random risks messing up
        // JUCE's internal state. If you need a predictable
        // stream of random numbers you should use a local
        // Random object.
        jassertfalse;
        return;
    }

    seed = newSeed;
}

void Random::combineSeed (const int64 seedValue) noexcept
{
    seed ^= nextInt64() ^ seedValue;
}

void Random::setSeedRandomly()
{
    static std::atomic<int64> globalSeed { 0 };

    combineSeed (globalSeed ^ (int64) (pointer_sized_int) this);
    combineSeed (Time::getMillisecondCounter());
    combineSeed (Time::getHighResolutionTicks());
    combineSeed (Time::getHighResolutionTicksPerSecond());
    combineSeed (Time::currentTimeMillis());
    globalSeed ^= seed;
}

Random& Random::getSystemRandom() noexcept
{
    static Random sysRand;
    return sysRand;
}

//==============================================================================
int Random::nextInt() noexcept
{
    seed = (int64) (((((uint64) seed) * 0x5deece66dLL) + 11) & 0xffffffffffffLL);

    return (int) (seed >> 16);
}

int Random::nextInt (const int maxValue) noexcept
{
    jassert (maxValue > 0);
    return (int) ((((unsigned int) nextInt()) * (uint64) maxValue) >> 32);
}

int Random::nextInt (Range<int> range) noexcept
{
    return range.getStart() + nextInt (range.getLength());
}

int64 Random::nextInt64() noexcept
{
    return (int64) ((((uint64) (unsigned int) nextInt()) << 32) | (uint64) (unsigned int) nextInt());
}

bool Random::nextBool() noexcept
{
    return (nextInt() & 0x40000000) != 0;
}

float Random::nextFloat() noexcept
{
    auto result = static_cast<float> (static_cast<uint32> (nextInt()))
                  / (static_cast<float> (std::numeric_limits<uint32>::max()) + 1.0f);
    return jmin (result, 1.0f - std::numeric_limits<float>::epsilon());
}

double Random::nextDouble() noexcept
{
    return static_cast<uint32> (nextInt()) / (std::numeric_limits<uint32>::max() + 1.0);
}

BigInteger Random::nextLargeNumber (const BigInteger& maximumValue)
{
    BigInteger n;

    do
    {
        fillBitsRandomly (n, 0, maximumValue.getHighestBit() + 1);
    }
    while (n >= maximumValue);

    return n;
}

void Random::fillBitsRandomly (void* const buffer, size_t bytes)
{
    int* d = static_cast<int*> (buffer);

    for (; bytes >= sizeof (int); bytes -= sizeof (int))
        *d++ = nextInt();

    if (bytes > 0)
    {
        const int lastBytes = nextInt();
        memcpy (d, &lastBytes, bytes);
    }
}

void Random::fillBitsRandomly (BigInteger& arrayToChange, int startBit, int numBits)
{
    arrayToChange.setBit (startBit + numBits - 1, true);  // to force the array to pre-allocate space

    while ((startBit & 31) != 0 && numBits > 0)
    {
        arrayToChange.setBit (startBit++, nextBool());
        --numBits;
    }

    while (numBits >= 32)
    {
        arrayToChange.setBitRangeAsInt (startBit, 32, (unsigned int) nextInt());
        startBit += 32;
        numBits -= 32;
    }

    while (--numBits >= 0)
        arrayToChange.setBit (startBit + numBits, nextBool());
}


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

class RandomTests final : public UnitTest
{
public:
    RandomTests()
        : UnitTest ("Random", UnitTestCategories::maths)
    {}

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

        Random r = getRandom();

        for (int i = 2000; --i >= 0;)
        {
            expect (r.nextDouble() >= 0.0 && r.nextDouble() < 1.0);
            expect (r.nextFloat() >= 0.0f && r.nextFloat() < 1.0f);
            expect (r.nextInt (5) >= 0 && r.nextInt (5) < 5);
            expect (r.nextInt (1) == 0);

            int n = r.nextInt (50) + 1;
            expect (r.nextInt (n) >= 0 && r.nextInt (n) < n);

            n = r.nextInt (0x7ffffffe) + 1;
            expect (r.nextInt (n) >= 0 && r.nextInt (n) < n);
        }
    }
};

static RandomTests randomTests;

#endif

} // namespace juce
