/***************************************************************************
 *                                                                         *
 *   LinuxSampler - modular, streaming capable sampler                     *
 *                                                                         *
 *   Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck   *
 *   Copyright (C) 2005 - 2020 Christian Schoenebeck                       *
 *   Copyright (C) 2009 - 2012 Grigor Iliev                                *
 *   Copyright (C) 2013 - 2016 Andreas Persson                             *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the Free Software           *
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston,                 *
 *   MA  02111-1307  USA                                                   *
 ***************************************************************************/

#ifndef __LS_DISKTHREADBASE_H__
#define __LS_DISKTHREADBASE_H__

#include <map>

#include "StreamBase.h"
#include "../EngineChannel.h"
#include "../InstrumentManagerBase.h"

#include "../../common/global_private.h"

#include "../../common/Thread.h"
#include "../../common/RingBuffer.h"
#include "../../common/atomic.h"

namespace LinuxSampler {

    int CompareStreamWriteSpace(const void* A, const void* B);

    /** @brief Disk Reader Thread
     *
     * The disk reader thread is responsible for periodically refilling
     * disk streams in parallel to the audio thread's rendering process.
     *
     * There is also a function for releasing parts of instruments not
     * in use anymore (as this is not real time safe, the audio thread
     * cannot do it directly).
     */
    template <class R /* Resource */, class IM /* Instrument Manager */>
    class DiskThreadBase : public Thread {
        private:
            // Private Types
            struct create_command_t {
                Stream::OrderID_t    OrderID;
                Stream::Handle       hStream;
                Stream::reference_t* pStreamRef;
                R*                   pRegion;
                unsigned long        SampleOffset;
                bool                 DoLoop;
            };
            struct delete_command_t {
                Stream*           pStream;
                Stream::Handle    hStream;
                Stream::OrderID_t OrderID;
                bool              bNotify;
            };
            struct program_change_command_t {
                uint32_t Program;
                EngineChannel* pEngineChannel;
            };
            // Attributes
            bool                           IsIdle;
            uint                           Streams;
            RingBuffer<create_command_t,false>* CreationQueue;                      ///< Contains commands to create streams
            RingBuffer<delete_command_t,false>* DeletionQueue;                      ///< Contains commands to delete streams
            RingBuffer<delete_command_t,false>* GhostQueue;                         ///< Contains handles to streams that are not used anymore and weren't deletable immediately
            RingBuffer<Stream::Handle,false>    DeletionNotificationQueue;          ///< In case the original sender requested a notification for its stream deletion order, this queue will receive the handle of the respective stream once actually be deleted by the disk thread.
            RingBuffer<R*,false>*               DeleteRegionQueue;          ///< Contains dimension regions that are not used anymore and should be handed back to the instrument resource manager
            RingBuffer<program_change_command_t,false> ProgramChangeQueue;          ///< Contains requests for MIDI program change
            unsigned int                   RefillStreamsPerRun;                    ///< How many streams should be refilled in each loop run
            Stream**                       pStreams; ///< Contains all disk streams (whether used or unused)
            Stream**                       pCreatedStreams; ///< This is where the voice (audio thread) picks up it's meanwhile hopefully created disk stream.
            static Stream*                 SLOT_RESERVED;                          ///< This value is used to mark an entry in pCreatedStreams[] as reserved.

            // Methods

            void CreateStream(create_command_t& Command) {
                // search for unused stream
                Stream* newstream = NULL;
                for (int i = Streams - 1; i >= 0; i--) {
                    if (pStreams[i]->GetState() == Stream::state_unused) {
                        newstream = pStreams[i];
                        break;
                    }
                }
                if (!newstream) {
                    std::cerr << "No unused stream found (OrderID:" << Command.OrderID;
                    std::cerr << ") - report if this happens, this is a bug!\n" << std::flush;
                    return;
                }
                LaunchStream(newstream, Command.hStream, Command.pStreamRef, Command.pRegion, Command.SampleOffset, Command.DoLoop);
                dmsg(4,("new Stream launched by disk thread (OrderID:%d,StreamHandle:%d)\n", Command.OrderID, Command.hStream));
                if (pCreatedStreams[Command.OrderID] != SLOT_RESERVED) {
                    std::cerr << "DiskThread: Slot " << Command.OrderID << " already occupied! Please report this!\n" << std::flush;
                    newstream->Kill();
                    return;
                }
                pCreatedStreams[Command.OrderID] = newstream;
            }

            void DeleteStream(delete_command_t& Command) {
                if (Command.pStream) {
                    Command.pStream->Kill();
                    if (Command.bNotify) DeletionNotificationQueue.push(&Command.hStream);
                }
                else { // the stream wasn't created by disk thread or picked up by audio thread yet

                    // if stream was created but not picked up yet
                    Stream* pStream = pCreatedStreams[Command.OrderID];
                    if (pStream && pStream != SLOT_RESERVED) {
                        pStream->Kill();
                        pCreatedStreams[Command.OrderID] = NULL; // free slot for new order
                        // if original sender requested a notification, let him know now
                        if (Command.bNotify)
                            DeletionNotificationQueue.push(&Command.hStream);
                        return;
                    }

                    // the stream was not created yet
                    if (GhostQueue->write_space() > 0) {
                        GhostQueue->push(&Command);
                    } else { // error, queue full
                        if (Command.bNotify) {
                            dmsg(1,("DiskThread: GhostQueue full! (might lead to dead lock with instrument editor!)\n"));
                        } else {
                            dmsg(1,("DiskThread: GhostQueue full!\n"));
                        }
                    }
                }
            }

            void RefillStreams() {
                // sort the streams by most empty stream
                qsort(pStreams, Streams, sizeof(Stream*), CompareStreamWriteSpace);

                // refill the most empty streams
                for (uint i = 0; i < RefillStreamsPerRun; i++) {
                    if (pStreams[i]->GetState() == Stream::state_active) {

                        //float filledpercentage = (float) pStreams[i]->GetReadSpace() / 131072.0 * 100.0;
                        //dmsg(("\nbuffer fill: %.1f%\n", filledpercentage));

                        int writespace = pStreams[i]->GetWriteSpaceToEnd();
                        if (writespace == 0) break;

                        int capped_writespace = writespace;
                        // if there is too much buffer space available then cut the read/write
                        // size to CONFIG_STREAM_MAX_REFILL_SIZE which is by default 65536 samples = 256KBytes
                        if (writespace > CONFIG_STREAM_MAX_REFILL_SIZE) capped_writespace = CONFIG_STREAM_MAX_REFILL_SIZE;

                        // adjust the amount to read in order to ensure that the buffer wraps correctly
                        int read_amount = pStreams[i]->AdjustWriteSpaceToAvoidBoundary(writespace, capped_writespace);
                        // if we wasn't able to refill one of the stream buffers by more than
                        // CONFIG_STREAM_MIN_REFILL_SIZE we'll send the disk thread to sleep later
                        if (pStreams[i]->ReadAhead(read_amount) > CONFIG_STREAM_MIN_REFILL_SIZE) this->IsIdle = false;
                    }
                }
            }

            Stream::Handle CreateHandle() {
                static uint32_t counter = 0;
                if (counter == 0xffffffff) counter = 1; // we use '0' as 'invalid handle' only, so we skip 0
                else                       counter++;
                return counter;
            }

            Stream::OrderID_t CreateOrderID() {
                static Stream::OrderID_t counter(0);
                for (int i = 0; i < Streams; i++) {
                    if (counter == Streams) counter = 1; // we use '0' as 'invalid order' only, so we skip 0
                    else                    counter++;
                    if (!pCreatedStreams[counter]) {
                        pCreatedStreams[counter] = SLOT_RESERVED; // mark this slot as reserved
                        return counter;                           // found empty slot
                    }
                }
                return 0; // no free slot
            }

            atomic_t ActiveStreamCount;
        public:
            // Methods
            DiskThreadBase(int MaxStreams, uint BufferWrapElements, IM* pInstruments) :
                Thread(true, false, 1, -2),
                DeletionNotificationQueue(4*MaxStreams),
                ProgramChangeQueue(512),
                pInstruments(pInstruments)
            {
                CreationQueue       = new RingBuffer<create_command_t,false>(4*MaxStreams);
                DeletionQueue       = new RingBuffer<delete_command_t,false>(4*MaxStreams);
                GhostQueue          = new RingBuffer<delete_command_t,false>(MaxStreams);
                DeleteRegionQueue   = new RingBuffer<R*,false>(4*MaxStreams);
                pStreams            = new Stream*[MaxStreams];
                pCreatedStreams     = new Stream*[MaxStreams + 1];
                Streams             = MaxStreams;
                RefillStreamsPerRun = CONFIG_REFILL_STREAMS_PER_RUN;

                for (int i = 1; i <= MaxStreams; i++) {
                    pCreatedStreams[i] = NULL;
                }
                ActiveStreamCountMax = 0;
            }

            virtual ~DiskThreadBase() {
                for (int i = 0; i < Streams; i++) {
                    if (pStreams[i]) delete pStreams[i];
                }
                if (CreationQueue) delete CreationQueue;
                if (DeletionQueue) delete DeletionQueue;
                if (GhostQueue)    delete GhostQueue;
                if (DeleteRegionQueue) delete DeleteRegionQueue;
                if (pStreams)        delete[] pStreams;
                if (pCreatedStreams) delete[] pCreatedStreams;
            }


        // #########################################################################
        // # Foreign Thread Section
        // #         (following code intended to be interface for audio thread)

            /**
             * Suspend disk thread, kill all active streams, clear all queues and the
             * pickup array and reset all streams. Call this method to bring everything
             * in the disk thread to day one. If the disk thread was running, it will be
             * respawned right after everything was reset.
             */
            void Reset() {
                bool running = this->IsRunning();
                if (running) this->StopThread();
                for (int i = 0; i < Streams; i++) {
                    pStreams[i]->Kill();
                }
                for (int i = 1; i <= Streams; i++) {
                    pCreatedStreams[i] = NULL;
                }
                GhostQueue->init();
                CreationQueue->init();
                DeletionQueue->init();
                DeletionNotificationQueue.init();

                // make sure that all DimensionRegions are released
                while (DeleteRegionQueue->read_space() > 0) {
                    R* pRgn;
                    DeleteRegionQueue->pop(&pRgn);
                    pInstruments->HandBackRegion(pRgn);
                }
                DeleteRegionQueue->init();
                SetActiveStreamCount(0);
                ActiveStreamCountMax = 0;
                if (running) this->StartThread(); // start thread only if it was running before
            }

            String GetBufferFillBytes() {
                bool activestreams = false;
                std::stringstream ss;
                for (uint i = 0; i < this->Streams; i++) {
                    if (pStreams[i]->GetState() == Stream::state_unused) continue;
                    uint bufferfill = pStreams[i]->GetReadSpace() * sizeof(sample_t);
                    uint streamid   = (uint) pStreams[i]->GetHandle();
                    if (!streamid) continue;

                    if (activestreams) ss << ",[" << streamid << ']' << bufferfill;
                    else {
                        ss << '[' << streamid << ']' << bufferfill;
                        activestreams = true;
                    }
                }
                return ss.str();
            }

            String GetBufferFillPercentage() {
                bool activestreams = false;
                std::stringstream ss;
                for (uint i = 0; i < this->Streams; i++) {
                    if (pStreams[i]->GetState() == Stream::state_unused) continue;
                    uint bufferfill = (uint) ((float) pStreams[i]->GetReadSpace() / (float) CONFIG_STREAM_BUFFER_SIZE * 100);
                    uint streamid   = (uint) pStreams[i]->GetHandle();
                    if (!streamid) continue;

                    if (activestreams) ss << ",[" << streamid << ']' << bufferfill << '%';
                    else {
                        ss << '[' << streamid << ']' << bufferfill;
                        activestreams = true;
                    }
                }
                return ss.str();
            }

            /**
             * Returns -1 if command queue or pickup pool is full, 0 on success (will be
             * called by audio thread within the voice class).
             */
            int OrderNewStream(Stream::reference_t* pStreamRef, R* pRegion, unsigned long SampleOffset, bool DoLoop) {
                dmsg(4,("Disk Thread: new stream ordered\n"));
                if (CreationQueue->write_space() < 1) {
                    dmsg(1,("DiskThread: Order queue full!\n"));
                    return -1;
                }

        	const Stream::OrderID_t newOrder = CreateOrderID();
        	if (!newOrder) {
        		dmsg(1,("DiskThread: there was no free slot\n"));
        		return -1; // there was no free slot
        	}

                pStreamRef->State   = Stream::state_active;
                pStreamRef->OrderID = newOrder;
                pStreamRef->hStream = CreateHandle();
                pStreamRef->pStream = NULL; // a stream has to be activated by the disk thread first

                create_command_t cmd;
                cmd.OrderID      = pStreamRef->OrderID;
                cmd.hStream      = pStreamRef->hStream;
                cmd.pStreamRef   = pStreamRef;
                cmd.pRegion      = pRegion;
                cmd.SampleOffset = SampleOffset;
                cmd.DoLoop       = DoLoop;

                CreationQueue->push(&cmd);
                return 0;
            }

            /**
             * Request the disk thread to delete the given disk stream. This method
             * will return immediately, thus it won't block until the respective voice
             * was actually deleted. (Called by audio thread within the Voice class).
             *
             * @param pStreamRef           - stream that shall be deleted
             * @param bRequestNotification - set to true in case you want to receive a
             *                               notification once the stream has actually
             *                               been deleted
             * @returns 0 on success, -1 if command queue is full
             * @see AskForDeletedStream()
             */
            int OrderDeletionOfStream(Stream::reference_t* pStreamRef, bool bRequestNotification = false) {
                dmsg(4,("Disk Thread: stream deletion ordered\n"));
                if (DeletionQueue->write_space() < 1) {
                    dmsg(1,("DiskThread: Deletion queue full!\n"));
                    return -1;
                }

                delete_command_t cmd;
                cmd.pStream = pStreamRef->pStream;
                cmd.hStream = pStreamRef->hStream;
                cmd.OrderID = pStreamRef->OrderID;
                cmd.bNotify = bRequestNotification;

                DeletionQueue->push(&cmd);
                return 0;
            }

            /**
             * Tell the disk thread to release a dimension region that belongs
             * to an instrument which isn't loaded anymore. The disk thread
             * will hand back the dimension region to the instrument resource
             * manager. (OrderDeletionOfDimreg is called from the audio thread
             * when a voice dies.)
             */
            int OrderDeletionOfRegion(R* pReg) {
                dmsg(4,("Disk Thread: dimreg deletion ordered\n"));
                if (DeleteRegionQueue->write_space() < 1) {
                    dmsg(1,("DiskThread: DeleteRegion queue full!\n"));
                    return -1;
                }
                DeleteRegionQueue->push(&pReg);
                return 0;
            }

            /**
             * Tell the disk thread to do a program change on the specified
             * EngineChannel.
             */
            int OrderProgramChange(uint32_t Program, EngineChannel* pEngineChannel) {
                program_change_command_t cmd;
                cmd.Program = Program;
                cmd.pEngineChannel = pEngineChannel;

                dmsg(4,("Disk Thread: program change ordered\n"));
                if (ProgramChangeQueue.write_space() < 1) {
                    dmsg(1,("DiskThread: ProgramChange queue full!\n"));
                    return -1;
                }
                ProgramChangeQueue.push(&cmd);
                return 0;
            }

            /**
             * Returns the pointer to a disk stream if the ordered disk stream
             * represented by the \a StreamOrderID was already activated by the disk
             * thread, returns NULL otherwise. If the call was successful, thus if it
             * returned a valid stream pointer, the caller has to the store that pointer
             * by himself, because it's not possible to call this method again with the
             * same used order ID; this method is just intended for picking up an ordered
             * disk stream. This method will usually be called by the voice class (within
             * the audio thread).
             *
             * @param StreamOrderID - ID previously returned by OrderNewStream()
             * @returns               pointer to created stream object, NULL otherwise
             */
            Stream* AskForCreatedStream(Stream::OrderID_t StreamOrderID) {
                dmsg(4,("Disk Thread: been asked if stream already created, OrderID=%x ", StreamOrderID));
                Stream* pStream = pCreatedStreams[StreamOrderID];
                if (pStream && pStream != SLOT_RESERVED) {
                    dmsg(4,("(yes created)\n"));
                    pCreatedStreams[StreamOrderID] = NULL; // free the slot for a new order
                    return pStream;
                }
                dmsg(4,("(no not yet created)\n"));
                return NULL;
            }

            /**
             * In case the original sender requested a notification with his stream
             * deletion order, he can use this method to poll if the respective stream
             * has actually been deleted.
             *
             * @returns handle / identifier of the deleted stream, or
             *          Stream::INVALID_HANDLE if no notification present
             */
            Stream::Handle AskForDeletedStream() {
                if (DeletionNotificationQueue.read_space()) {
                    Stream::Handle hStream;
                    DeletionNotificationQueue.pop(&hStream);
                    return hStream;
                } else return Stream::INVALID_HANDLE; // no notification received yet
            }

            // the number of streams currently in usage
            // printed on the console the main thread (along with the active voice count)
            uint GetActiveStreamCount() { return atomic_read(&ActiveStreamCount); }
            void SetActiveStreamCount(uint Streams) { atomic_set(&ActiveStreamCount, Streams); }
            int ActiveStreamCountMax;

        protected:
            IM* pInstruments;   ///< The instrument resource manager of the engine that is using this disk thread. Used by the dimension region deletion feature.

        // #########################################################################
        // # Disk Thread Only Section
        // #         (following code should only be executed by the disk thread)

            // Implementation of virtual method from class Thread
            int Main() {
                dmsg(3,("Disk thread running\n"));

                #if DEBUG
                Thread::setNameOfCaller("DiskIO");
                #endif

                while (true) {

                    TestCancel();

                    IsIdle = true; // will be set to false if a stream got filled

                    // prevent disk thread from being cancelled
                    // (e.g. to prevent deadlocks while holding mutex lock(s))
                    pushCancelable(false);

                    // if there are ghost streams, delete them
                    for (int i = 0; i < GhostQueue->read_space(); i++) { //FIXME: unefficient
                        delete_command_t ghostStream;
                        GhostQueue->pop(&ghostStream);
                        bool found = false;
                        for (int i = 0; i < this->Streams; i++) {
                            if (pStreams[i]->GetHandle() == ghostStream.hStream) {
                                pStreams[i]->Kill();
                                found = true;
                                // if original sender requested a notification, let him know now
                                if (ghostStream.bNotify)
                                    DeletionNotificationQueue.push(&ghostStream.hStream);
                                break;
                            }
                        }
                        if (!found) GhostQueue->push(&ghostStream); // put ghost stream handle back to the queue
                    }

                    // if there are creation commands, create new streams
                    while (Stream::UnusedStreams > 0 && CreationQueue->read_space() > 0) {
                        create_command_t command;
                        CreationQueue->pop(&command);
                        CreateStream(command);
                    }

                    // if there are deletion commands, delete those streams
                    while (Stream::UnusedStreams < Stream::TotalStreams && DeletionQueue->read_space() > 0) {
                        delete_command_t command;
                        DeletionQueue->pop(&command);
                        DeleteStream(command);
                    }

                    // release DimensionRegions that belong to instruments
                    // that are no longer loaded
                    while (DeleteRegionQueue->read_space() > 0) {
                        R* pRgn;
                        DeleteRegionQueue->pop(&pRgn);
                        pInstruments->HandBackRegion(pRgn);
                    }

                    // perform MIDI program change commands
                    if (ProgramChangeQueue.read_space() > 0) {
                        program_change_command_t cmd;
                        std::map<EngineChannel*,uint32_t> cmds;
                        // skip all old ones, only process the latest program
                        // change command on each engine channel
                        do {
                            ProgramChangeQueue.pop(&cmd);
                            cmds[cmd.pEngineChannel] = cmd.Program;
                        } while (ProgramChangeQueue.read_space() > 0);
                        // now execute those latest program change commands on
                        // their respective engine channel
                        for (std::map<EngineChannel*,uint32_t>::const_iterator it = cmds.begin();
                             it != cmds.end(); ++it)
                        {
                            it->first->ExecuteProgramChange(it->second);
                        }
                    }

                    RefillStreams(); // refill the most empty streams

                    int streamsInUsage = 0;
                    for (int i = Streams - 1; i >= 0; i--) {
                        if (pStreams[i]->GetState() != Stream::state_unused) streamsInUsage++;
                    }
                    SetActiveStreamCount(streamsInUsage);
                    if (streamsInUsage > ActiveStreamCountMax) ActiveStreamCountMax = streamsInUsage;

                    // now allow disk thread being cancelled again
                    // (since all mutexes are now unlocked and data structures
                    // are at consistent states)
                    popCancelable();

                    // if nothing was done during this iteration (i.e. no
                    // stream buffer filled with data) then sleep for 30ms
                    if (IsIdle)
                        usleep(30000); //NOTE: defined as cancellation point by POSIX
                }

                return EXIT_FAILURE;
            }

            virtual Stream* CreateStream(long BufferSize, uint BufferWrapElements) = 0;

            void CreateAllStreams(int MaxStreams, uint BufferWrapElements) {
                for (int i = 0; i < MaxStreams; i++) {
                    pStreams[i] = CreateStream(CONFIG_STREAM_BUFFER_SIZE, BufferWrapElements);
                }
            }

            virtual void LaunchStream (
                Stream*               pStream,
                Stream::Handle        hStream,
                Stream::reference_t*  pExportReference,
                R*                    pRgn,
                unsigned long         SampleOffset,
                bool                  DoLoop
            ) = 0;

            friend class Stream;
    };
} // namespace LinuxSampler

#endif // __LS_DISKTHREADBASE_H__