#include "Video.h"
#include "anaglym.h"
#include "Engine.h"
#include "SDL.h"
#include <stdlib.h>                 /* exit() */
#include <iostream>
#include <string>
#include <queue>
using namespace std;

enum EventType { EVENT_UPDATE };

typedef struct
{
    EventType   type;
} Event;

static void usage();
static void mainloop();
static void update();
static void addEvent(const Event & event);
static Uint32 updateCallback(Uint32 interval, void * param);

static bool lastUpdateCompleted;
static bool engine_running;
static SDL_Event userEvent;
static SDL_cond * event_condition;
static SDL_mutex * event_mutex;
static SDL_mutex * event_queue_mutex;
static queue<Event> event_queue;
Uint32 g_ticks;

static void usage()
{
    cerr << "Usage: anaglym [options] program.lua[c]" << endl;
    exit(42);
}

static int engine_thread(void * param)
{
    const char * program = (const char *) param;
    if (g_engine->load(program))
    {
        for (;;)
        {
            SDL_mutexP(event_mutex);
            SDL_CondWait(event_condition, event_mutex);
            bool moreEvents = true;
            while (moreEvents)
            {
                Event event;
                SDL_mutexP(event_queue_mutex);
                if (event_queue.size() < 1)
                    moreEvents = false;
                else
                {
                    event = event_queue.front();
                    event_queue.pop();
                }
                SDL_mutexV(event_queue_mutex);
                if (moreEvents)
                {
                    /* process the event */
                    switch (event.type)
                    {
                        case EVENT_UPDATE:
                            g_engine->update();
                            lastUpdateCompleted = true;
                            break;
                    }
                }
            }
        }
    }
    engine_running = false;
    return 0;
}

int main(int argc, char * argv[])
{
    const char * program = NULL;
    for (int i = 1; i < argc; i++)
    {
        if (argv[i][0] != '-')
        {
            if (program == NULL)
            {
                program = argv[i];
            }
            else
            {
                cerr << "Warning: argument " << argv[i] << " ignored!" << endl;
                usage();
            }
        }
        else
        {
            cerr << "Warning: Unrecognized option '" << argv[i]+1
                 << "'" << endl;
            usage();
        }
    }

    if (program == NULL)
    {
        usage();
    }

    lastUpdateCompleted = true;
    engine_running = true;
    /* setup SDL update event */
    userEvent.type = SDL_USEREVENT;
    userEvent.user.code = 0;
    event_condition = SDL_CreateCond();
    event_mutex = SDL_CreateMutex();
    event_queue_mutex = SDL_CreateMutex();

    Video video;
#if 0
    /* start in windowed mode for debugging */
    video.start(0, 0, false, false);
#else
    video.start();
#endif

    g_engine = new Engine(argv[0]);
    SDL_CreateThread(engine_thread, (void *) program);

    mainloop();

    SDL_DestroyCond(event_condition);
    delete g_engine;
    video.stop();

    return 0;
}

/* called by SDL when the update timer expires */
static Uint32 updateCallback(Uint32 interval, void * param)
{
    if (lastUpdateCompleted)
        SDL_PushEvent(&userEvent);
    return interval;
}

static void mainloop()
{
    SDL_Event event;

    /* register a screen redrawing SDL event */
    SDL_AddTimer(25, &updateCallback, NULL);

    while (SDL_WaitEvent(&event))
    {
        if (!engine_running)
            goto RET;
        switch (event.type)
        {
            case SDL_KEYDOWN:
                if (event.key.keysym.sym == SDLK_ESCAPE)
                {
                    goto RET;
                }
                break;
            case SDL_QUIT:
                goto RET;
                break;
            case SDL_USEREVENT:
                if (event.user.code == 0)
                {
                    update();
                }
                break;
        }
    }
RET:
    ;
}

static void update()
{
    Event update_event;
    update_event.type = EVENT_UPDATE;
    lastUpdateCompleted = false;
    addEvent(update_event);
}

static void addEvent(const Event & event)
{
    SDL_mutexP(event_queue_mutex);
    event_queue.push(event);
    SDL_mutexV(event_queue_mutex);
    SDL_CondSignal(event_condition);
}