#include "config.h"

#include "AL/alc.h"
#include "AL/al.h"
#include "AL/alext.h"
#include "alMain.h"
#include "alError.h"
#include "ringbuffer.h"


static int EventThread(void *arg)
{
    ALCcontext *context = arg;

    /* Clear all pending posts on the semaphore. */
    while(alsem_trywait(&context->EventSem) == althrd_success)
    {
    }

    while(1)
    {
        ALbitfieldSOFT enabledevts;
        AsyncEvent evt;

        if(ll_ringbuffer_read(context->AsyncEvents, (char*)&evt, 1) == 0)
        {
            alsem_wait(&context->EventSem);
            continue;
        }
        if(!evt.EnumType)
            break;

        almtx_lock(&context->EventCbLock);
        enabledevts = ATOMIC_LOAD(&context->EnabledEvts, almemory_order_acquire);
        if(context->EventCb && (enabledevts&evt.EnumType) == evt.EnumType)
            context->EventCb(evt.Type, evt.ObjectId, evt.Param, (ALsizei)strlen(evt.Message),
                             evt.Message, context->EventParam);
        almtx_unlock(&context->EventCbLock);
    }
    return 0;
}

AL_API void AL_APIENTRY alEventControlSOFT(ALsizei count, const ALenum *types, ALboolean enable)
{
    ALCcontext *context;
    ALbitfieldSOFT enabledevts;
    ALbitfieldSOFT flags = 0;
    bool isrunning;
    ALsizei i;

    context = GetContextRef();
    if(!context) return;

    if(count < 0) SETERR_GOTO(context, AL_INVALID_VALUE, done, "Controlling %d events", count);
    if(count == 0) goto done;
    if(!types) SETERR_GOTO(context, AL_INVALID_VALUE, done, "NULL pointer");

    for(i = 0;i < count;i++)
    {
        if(types[i] == AL_EVENT_TYPE_BUFFER_COMPLETED_SOFT)
            flags |= EventType_BufferCompleted;
        else if(types[i] == AL_EVENT_TYPE_SOURCE_STATE_CHANGED_SOFT)
            flags |= EventType_SourceStateChange;
        else if(types[i] == AL_EVENT_TYPE_ERROR_SOFT)
            flags |= EventType_Error;
        else if(types[i] == AL_EVENT_TYPE_PERFORMANCE_SOFT)
            flags |= EventType_Performance;
        else if(types[i] == AL_EVENT_TYPE_DEPRECATED_SOFT)
            flags |= EventType_Deprecated;
        else if(types[i] == AL_EVENT_TYPE_DISCONNECTED_SOFT)
            flags |= EventType_Disconnected;
        else
            SETERR_GOTO(context, AL_INVALID_ENUM, done, "Invalid event type 0x%04x", types[i]);
    }

    almtx_lock(&context->EventThrdLock);
    if(enable)
    {
        if(!context->AsyncEvents)
            context->AsyncEvents = ll_ringbuffer_create(63, sizeof(AsyncEvent), false);
        enabledevts = ATOMIC_LOAD(&context->EnabledEvts, almemory_order_relaxed);
        isrunning = !!enabledevts;
        while(ATOMIC_COMPARE_EXCHANGE_WEAK(&context->EnabledEvts, &enabledevts, enabledevts|flags,
                                           almemory_order_acq_rel, almemory_order_acquire) == 0)
        {
            /* enabledevts is (re-)filled with the current value on failure, so
             * just try again.
             */
        }
        if(!isrunning && flags)
            althrd_create(&context->EventThread, EventThread, context);
    }
    else
    {
        enabledevts = ATOMIC_LOAD(&context->EnabledEvts, almemory_order_relaxed);
        isrunning = !!enabledevts;
        while(ATOMIC_COMPARE_EXCHANGE_WEAK(&context->EnabledEvts, &enabledevts, enabledevts&~flags,
                                           almemory_order_acq_rel, almemory_order_acquire) == 0)
        {
        }
        if(isrunning && !(enabledevts&~flags))
        {
            static const AsyncEvent kill_evt = { 0 };
            while(ll_ringbuffer_write(context->AsyncEvents, (const char*)&kill_evt, 1) == 0)
                althrd_yield();
            alsem_post(&context->EventSem);
            althrd_join(context->EventThread, NULL);
        }
        else
        {
            /* Wait to ensure the event handler sees the changed flags before
             * returning.
             */
            almtx_lock(&context->EventCbLock);
            almtx_unlock(&context->EventCbLock);
        }
    }
    almtx_unlock(&context->EventThrdLock);

done:
    ALCcontext_DecRef(context);
}

AL_API void AL_APIENTRY alEventCallbackSOFT(ALEVENTPROCSOFT callback, void *userParam)
{
    ALCcontext *context;

    context = GetContextRef();
    if(!context) return;

    almtx_lock(&context->PropLock);
    almtx_lock(&context->EventCbLock);
    context->EventCb = callback;
    context->EventParam = userParam;
    almtx_unlock(&context->EventCbLock);
    almtx_unlock(&context->PropLock);

    ALCcontext_DecRef(context);
}