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

   This file is part of the JUCE library.
   Copyright (c) 2016 - ROLI Ltd.

   Permission is granted to use this software under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license/

   Permission to use, copy, modify, and/or distribute this software for any
   purpose with or without fee is hereby granted, provided that the above
   copyright notice and this permission notice appear in all copies.

   THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH REGARD
   TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
   FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT,
   OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
   USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
   TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
   OF THIS SOFTWARE.

   -----------------------------------------------------------------------------

   To release a closed-source product which uses other parts of JUCE not
   licensed under the ISC terms, commercial licenses are available: visit
   www.juce.com for more information.

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

AbstractFifo::AbstractFifo (const int capacity) noexcept
    : bufferSize (capacity)
{
    jassert (bufferSize > 0);
}

AbstractFifo::~AbstractFifo() {}

int AbstractFifo::getTotalSize() const noexcept           { return bufferSize; }
int AbstractFifo::getFreeSpace() const noexcept           { return bufferSize - getNumReady() - 1; }

int AbstractFifo::getNumReady() const noexcept
{
    const int vs = validStart.get();
    const int ve = validEnd.get();
    return ve >= vs ? (ve - vs) : (bufferSize - (vs - ve));
}

void AbstractFifo::reset() noexcept
{
    validEnd = 0;
    validStart = 0;
}

void AbstractFifo::setTotalSize (int newSize) noexcept
{
    jassert (newSize > 0);
    reset();
    bufferSize = newSize;
}

//==============================================================================
void AbstractFifo::prepareToWrite (int numToWrite, int& startIndex1, int& blockSize1, int& startIndex2, int& blockSize2) const noexcept
{
    const int vs = validStart.get();
    const int ve = validEnd.value;

    const int freeSpace = ve >= vs ? (bufferSize - (ve - vs)) : (vs - ve);
    numToWrite = jmin (numToWrite, freeSpace - 1);

    if (numToWrite <= 0)
    {
        startIndex1 = 0;
        startIndex2 = 0;
        blockSize1 = 0;
        blockSize2 = 0;
    }
    else
    {
        startIndex1 = ve;
        startIndex2 = 0;
        blockSize1 = jmin (bufferSize - ve, numToWrite);
        numToWrite -= blockSize1;
        blockSize2 = numToWrite <= 0 ? 0 : jmin (numToWrite, vs);
    }
}

void AbstractFifo::finishedWrite (int numWritten) noexcept
{
    jassert (numWritten >= 0 && numWritten < bufferSize);
    int newEnd = validEnd.value + numWritten;
    if (newEnd >= bufferSize)
        newEnd -= bufferSize;

    validEnd = newEnd;
}

void AbstractFifo::prepareToRead (int numWanted, int& startIndex1, int& blockSize1, int& startIndex2, int& blockSize2) const noexcept
{
    const int vs = validStart.value;
    const int ve = validEnd.get();

    const int numReady = ve >= vs ? (ve - vs) : (bufferSize - (vs - ve));
    numWanted = jmin (numWanted, numReady);

    if (numWanted <= 0)
    {
        startIndex1 = 0;
        startIndex2 = 0;
        blockSize1 = 0;
        blockSize2 = 0;
    }
    else
    {
        startIndex1 = vs;
        startIndex2 = 0;
        blockSize1 = jmin (bufferSize - vs, numWanted);
        numWanted -= blockSize1;
        blockSize2 = numWanted <= 0 ? 0 : jmin (numWanted, ve);
    }
}

void AbstractFifo::finishedRead (int numRead) noexcept
{
    jassert (numRead >= 0 && numRead <= bufferSize);

    int newStart = validStart.value + numRead;
    if (newStart >= bufferSize)
        newStart -= bufferSize;

    validStart = newStart;
}

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

class AbstractFifoTests  : public UnitTest
{
public:
    AbstractFifoTests() : UnitTest ("Abstract Fifo") {}

    class WriteThread  : public Thread
    {
    public:
        WriteThread (AbstractFifo& f, int* b, Random rng)
            : Thread ("fifo writer"), fifo (f), buffer (b), random (rng)
        {
            startThread();
        }

        ~WriteThread()
        {
            stopThread (5000);
        }

        void run()
        {
            int n = 0;

            while (! threadShouldExit())
            {
                int num = random.nextInt (2000) + 1;

                int start1, size1, start2, size2;
                fifo.prepareToWrite (num, start1, size1, start2, size2);

                jassert (size1 >= 0 && size2 >= 0);
                jassert (size1 == 0 || (start1 >= 0 && start1 < fifo.getTotalSize()));
                jassert (size2 == 0 || (start2 >= 0 && start2 < fifo.getTotalSize()));

                for (int i = 0; i < size1; ++i)
                    buffer [start1 + i] = n++;

                for (int i = 0; i < size2; ++i)
                    buffer [start2 + i] = n++;

                fifo.finishedWrite (size1 + size2);
            }
        }

    private:
        AbstractFifo& fifo;
        int* buffer;
        Random random;
    };

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

        int buffer [5000];
        AbstractFifo fifo (numElementsInArray (buffer));

        WriteThread writer (fifo, buffer, getRandom());

        int n = 0;
        Random r = getRandom();
        r.combineSeed (12345);

        for (int count = 100000; --count >= 0;)
        {
            int num = r.nextInt (6000) + 1;

            int start1, size1, start2, size2;
            fifo.prepareToRead (num, start1, size1, start2, size2);

            if (! (size1 >= 0 && size2 >= 0)
                    && (size1 == 0 || (start1 >= 0 && start1 < fifo.getTotalSize()))
                    && (size2 == 0 || (start2 >= 0 && start2 < fifo.getTotalSize())))
            {
                expect (false, "prepareToRead returned -ve values");
                break;
            }

            bool failed = false;

            for (int i = 0; i < size1; ++i)
                failed = (buffer [start1 + i] != n++) || failed;

            for (int i = 0; i < size2; ++i)
                failed = (buffer [start2 + i] != n++) || failed;

            if (failed)
            {
                expect (false, "read values were incorrect");
                break;
            }

            fifo.finishedRead (size1 + size2);
        }
    }
};

static AbstractFifoTests fifoUnitTests;

#endif
