/* 

flext - C++ layer for Max/MSP and pd (pure data) externals

Copyright (c) 2001-2003 Thomas Grill (xovo@gmx.net)
For information on usage and redistribution, and for a DISCLAIMER OF ALL
WARRANTIES, see the file, "license.txt," in this distribution.  

*/

/*! \file flqueue.cpp
    \brief Implementation of the flext message queuing functionality.

    \todo Let's see if queuing can be implemented for Max/MSP with defer_low

    if FLEXT_PDLOCK is defined, the new PD thread lock functions are used
*/

#include "flext.h"
#include "flinternal.h"


#ifdef FLEXT_THREADS
//! Thread id of message queue thread
flext::thrid_t flext::thrmsgid = 0;
#endif


#define QUEUE_LENGTH 256
#define QUEUE_ATOMS 1024

class qmsg
{
public:
    void Set(flext_base *t,int o,const t_symbol *s,int ac,const t_atom *av) { th = t,out = o,sym = s,argc = ac,argv = av; }

    // \note PD lock must already be held by caller
    void Send() const
    {
        if(out < 0)
            // message to self
            th->m_methodmain(-1-out,sym,argc,argv); 
        else
            // message to outlet
            th->ToSysAnything(out,sym,argc,argv);
    }

    int Args() const { return argc; }

private:
    flext_base *th;
    int out;
    const t_symbol *sym; 
    int argc; 
    const t_atom *argv;
};

// _should_ work without locks.... have yet to check if it really does....
class Queue:
    public flext
{
public:
    Queue()
    {
        qhead = qtail = 0;
        ahead = atail = 0;
    }

    bool Empty() const { return qhead == qtail; }

    int Count() const 
    { 
        int c = qtail-qhead;
        return c >= 0?c:c+QUEUE_LENGTH; 
    }

    const qmsg &Head() { return lst[qhead]; }

    void Pop() 
    { 
        PopAtoms(Head().Args());
        qhead = (qhead+1)%QUEUE_LENGTH;
    }

    void Push(flext_base *th,int o) // bang
    { 
        Set(th,o,sym_bang,0,NULL); 
    }

    void Push(flext_base *th,int o,float dt) 
    { 
        t_atom *at = GetAtoms(1); 
        SetFloat(*at,dt);
        Set(th,o,sym_float,1,at); 
    }

    void Push(flext_base *th,int o,int dt) 
    { 
        t_atom *at = GetAtoms(1); 
        SetInt(*at,dt);
#if FLEXT_SYS == FLEXT_SYS_PD
        const t_symbol *sym = sym_float;
#elif FLEXT_SYS == FLEXT_SYS_MAX
        const t_symbol *sym = sym_int;
#else
#error Not implemented!
#endif
        Set(th,o,sym,1,at); 
    }

    void Push(flext_base *th,int o,const t_symbol *dt) 
    { 
        t_atom *at = GetAtoms(1); 
        SetSymbol(*at,dt);
        Set(th,o,sym_symbol,1,at); 
    }

    void Push(flext_base *th,int o,int argc,const t_atom *argv) 
    {
        t_atom *at = GetAtoms(argc);
        memcpy(at,argv,argc*sizeof(t_atom));
        Set(th,o,sym_list,argc,at); 
    }

    void Push(flext_base *th,int o,const t_symbol *sym,int argc,const t_atom *argv) 
    { 
        t_atom *at = GetAtoms(argc);
        memcpy(at,argv,argc*sizeof(t_atom));
        Set(th,o,sym,argc,at); 
    }

protected:
    void Set(flext_base *th,int o,const t_symbol *sym,int argc,const t_atom *argv)
    {
        FLEXT_ASSERT(Count() < QUEUE_LENGTH-1);
        lst[qtail].Set(th,o,sym,argc,argv);
        qtail = (qtail+1)%QUEUE_LENGTH;
    }

    int CntAtoms() const 
    { 
        int c = atail-ahead;
        return c >= 0?c:c+QUEUE_ATOMS;
    }

    // must return contiguous region
    t_atom *GetAtoms(int argc)
    {
        // \todo check for available space

        if(atail+argc >= QUEUE_ATOMS) {
            atail = argc;
            return atoms;
        }
        else {
            t_atom *at = atoms+atail;
            atail += argc;
            return at;
        }
    }

    void PopAtoms(int argc) 
    {
        const int p = ahead+argc;
        ahead = p >= QUEUE_ATOMS?argc:p;
    }

    int qhead,qtail;
    qmsg lst[QUEUE_LENGTH];
    int ahead,atail;
    t_atom atoms[QUEUE_ATOMS];
};

static Queue queue;


#ifdef FLEXT_QTHR
static flext::ThrCond qthrcond;
#else
static t_qelem *qclk = NULL;
#endif


#define CHUNK 10

static void QWork(bool syslock)
{
    for(;;) {
        // Since qcnt can only be increased from any other function than QWork
        // qc will be a minimum guaranteed number of present queue elements.
        // On the other hand, if new queue elements are added by the methods called
        // in the loop, these will be sent in the next tick to avoid recursion overflow.
        int qc = queue.Count();
        if(!qc) break;

    #ifdef FLEXT_QTHR
        if(syslock) sys_lock();
    #endif

        for(int i = 0; i < qc; ++i) {
            queue.Head().Send();
            queue.Pop();
        } // inner loop

    #ifdef FLEXT_QTHR
        if(syslock) sys_unlock();
    #endif

    }
}

#if !defined(FLEXT_QTHR)
#if FLEXT_SYS == FLEXT_SYS_JMAX
static void QTick(fts_object_t *c,int winlet, fts_symbol_t s, int ac, const fts_atom_t *at)
{
#else
static void QTick(flext_base *c)
{
#endif
#ifdef FLEXT_THREADS
    FLEXT_ASSERT(flext::IsSystemThread());
#endif
    QWork(false);
}
#endif

/*
It would be sufficient to only flush messages belonging to object th
But then the order of sent messages is not as intended
*/
void flext_base::QFlush(flext_base *th)
{
#ifdef FLEXT_THREADS
    if(!IsSystemThread()) {
        error("flext - Queue flush called by wrong thread!");
        return;
    }
#endif

    while(!queue.Empty()) QWork(false);
}

static void Trigger()
{
#if FLEXT_SYS == FLEXT_SYS_PD
    #ifdef FLEXT_QTHR
        // wake up a worker thread 
        // (instead of triggering the clock)
        qthrcond.Signal();
    #else
        clock_delay(qclk,0);
    #endif
#elif FLEXT_SYS == FLEXT_SYS_MAX
    qelem_set(qclk); 
#elif FLEXT_SYS == FLEXT_SYS_JMAX
    // this is dangerous because there may be other timers on this object!
    fts_timebase_add_call(fts_get_timebase(), (fts_object_t *)thisHdr(), QTick, NULL, 0);
#else
#error Not implemented
#endif
}

#ifdef FLEXT_QTHR
void flext_base::QWorker(thr_params *)
{
    thrmsgid = GetThreadId();
    for(;;) {
        qthrcond.Wait();
        QWork(true);
    }
}
#endif

void flext_base::StartQueue()
{
    static bool started = false;
    if(started) return;
    else started = true;

#ifdef FLEXT_QTHR
    LaunchThread(QWorker,NULL);
#else
#if FLEXT_SYS == FLEXT_SYS_PD || FLEXT_SYS == FLEXT_SYS_MAX
    qclk = (t_qelem *)(qelem_new(NULL,(t_method)QTick));
#else
#error Not implemented!
#endif
#endif
}

void flext_base::ToQueueBang(int o) const 
{
    queue.Push(const_cast<flext_base *>(this),o);
    Trigger();
}

void flext_base::ToQueueFloat(int o,float f) const
{
    queue.Push(const_cast<flext_base *>(this),o,f);
    Trigger();
}

void flext_base::ToQueueInt(int o,int f) const
{
    queue.Push(const_cast<flext_base *>(this),o,f);
    Trigger();
}

void flext_base::ToQueueSymbol(int o,const t_symbol *s) const
{
    queue.Push(const_cast<flext_base *>(this),o,s);
    Trigger();
}

void flext_base::ToQueueList(int o,int argc,const t_atom *argv) const
{
    queue.Push(const_cast<flext_base *>(this),o,argc,argv);
    Trigger();
}

void flext_base::ToQueueAnything(int o,const t_symbol *s,int argc,const t_atom *argv) const
{
    queue.Push(const_cast<flext_base *>(this),o,s,argc,argv);
    Trigger();
}