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

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

   JUCE is an open source library subject to commercial or open-source
   licensing.

   The code included in this file is provided 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.

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

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

class NamedPipe::Pimpl
{
public:
    Pimpl (const String& pipePath, bool createPipe)
       : pipeInName  (pipePath + "_in"),
         pipeOutName (pipePath + "_out"),
         pipeIn (-1), pipeOut (-1),
         createdFifoIn (false),
         createdFifoOut (false),
         createdPipe (createPipe),
         stopReadOperation (false)
    {
        signal (SIGPIPE, signalHandler);
        juce_siginterrupt (SIGPIPE, 1);
    }

    ~Pimpl()
    {
        if (pipeIn  != -1)  ::close (pipeIn);
        if (pipeOut != -1)  ::close (pipeOut);

        if (createdPipe)
        {
            if (createdFifoIn)  unlink (pipeInName.toUTF8());
            if (createdFifoOut) unlink (pipeOutName.toUTF8());
        }
    }

    int read (char* destBuffer, int maxBytesToRead, int timeOutMilliseconds)
    {
        const uint32 timeoutEnd = getTimeoutEnd (timeOutMilliseconds);

        if (pipeIn == -1)
        {
            pipeIn = openPipe (createdPipe ? pipeInName : pipeOutName, O_RDWR | O_NONBLOCK, timeoutEnd);

            if (pipeIn == -1)
                return -1;
        }

        int bytesRead = 0;

        while (bytesRead < maxBytesToRead)
        {
            const int bytesThisTime = maxBytesToRead - bytesRead;
            const int numRead = (int) ::read (pipeIn, destBuffer, (size_t) bytesThisTime);

            if (numRead <= 0)
            {
                if (errno != EWOULDBLOCK || stopReadOperation || hasExpired (timeoutEnd))
                    return -1;

                const int maxWaitingTime = 30;
                waitForInput (pipeIn, timeoutEnd == 0 ? maxWaitingTime
                                                      : jmin (maxWaitingTime,
                                                              (int) (timeoutEnd - Time::getMillisecondCounter())));
                continue;
            }

            bytesRead += numRead;
            destBuffer += numRead;
        }

        return bytesRead;
    }

    int write (const char* sourceBuffer, int numBytesToWrite, int timeOutMilliseconds)
    {
        const uint32 timeoutEnd = getTimeoutEnd (timeOutMilliseconds);

        if (pipeOut == -1)
        {
            pipeOut = openPipe (createdPipe ? pipeOutName : pipeInName, O_WRONLY, timeoutEnd);

            if (pipeOut == -1)
                return -1;
        }

        int bytesWritten = 0;

        while (bytesWritten < numBytesToWrite && ! hasExpired (timeoutEnd))
        {
            const int bytesThisTime = numBytesToWrite - bytesWritten;
            const int numWritten = (int) ::write (pipeOut, sourceBuffer, (size_t) bytesThisTime);

            if (numWritten <= 0)
                return -1;

            bytesWritten += numWritten;
            sourceBuffer += numWritten;
        }

        return bytesWritten;
    }

    static bool createFifo (const String& name, bool mustNotExist)
    {
        return mkfifo (name.toUTF8(), 0666) == 0 || ((! mustNotExist) && errno == EEXIST);
    }

    bool createFifos (bool mustNotExist)
    {
        createdFifoIn  = createFifo (pipeInName, mustNotExist);
        createdFifoOut = createFifo (pipeOutName, mustNotExist);

        return createdFifoIn && createdFifoOut;
    }

    const String pipeInName, pipeOutName;
    int pipeIn, pipeOut;
    bool createdFifoIn, createdFifoOut;

    const bool createdPipe;
    bool stopReadOperation;

private:
    static void signalHandler (int) {}

    static uint32 getTimeoutEnd (const int timeOutMilliseconds)
    {
        return timeOutMilliseconds >= 0 ? Time::getMillisecondCounter() + (uint32) timeOutMilliseconds : 0;
    }

    static bool hasExpired (const uint32 timeoutEnd)
    {
        return timeoutEnd != 0 && Time::getMillisecondCounter() >= timeoutEnd;
    }

    int openPipe (const String& name, int flags, const uint32 timeoutEnd)
    {
        for (;;)
        {
            const int p = ::open (name.toUTF8(), flags);

            if (p != -1 || hasExpired (timeoutEnd) || stopReadOperation)
                return p;

            Thread::sleep (2);
        }
    }

    static void waitForInput (const int handle, const int timeoutMsecs) noexcept
    {
        struct timeval timeout;
        timeout.tv_sec = timeoutMsecs / 1000;
        timeout.tv_usec = (timeoutMsecs % 1000) * 1000;

        fd_set rset;
        FD_ZERO (&rset);
        FD_SET (handle, &rset);

        select (handle + 1, &rset, nullptr, 0, &timeout);
    }

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (Pimpl)
};

void NamedPipe::close()
{
    if (pimpl != nullptr)
    {
        pimpl->stopReadOperation = true;

        char buffer[1] = { 0 };
        ssize_t done = ::write (pimpl->pipeIn, buffer, 1);
        ignoreUnused (done);

        ScopedWriteLock sl (lock);
        pimpl = nullptr;
    }
}

bool NamedPipe::openInternal (const String& pipeName, const bool createPipe, bool mustNotExist)
{
   #if JUCE_IOS
    pimpl = new Pimpl (File::getSpecialLocation (File::tempDirectory)
                         .getChildFile (File::createLegalFileName (pipeName)).getFullPathName(), createPipe);
   #else
    String file (pipeName);

    if (! File::isAbsolutePath (file))
        file = "/tmp/" + File::createLegalFileName (file);

    pimpl = new Pimpl (file, createPipe);
   #endif

    if (createPipe && ! pimpl->createFifos (mustNotExist))
    {
        pimpl = nullptr;
        return false;
    }

    return true;
}

int NamedPipe::read (void* destBuffer, int maxBytesToRead, int timeOutMilliseconds)
{
    ScopedReadLock sl (lock);
    return pimpl != nullptr ? pimpl->read (static_cast<char*> (destBuffer), maxBytesToRead, timeOutMilliseconds) : -1;
}

int NamedPipe::write (const void* sourceBuffer, int numBytesToWrite, int timeOutMilliseconds)
{
    ScopedReadLock sl (lock);
    return pimpl != nullptr ? pimpl->write (static_cast<const char*> (sourceBuffer), numBytesToWrite, timeOutMilliseconds) : -1;
}
