/* Author: Josh Holtrop
 * DornerWorks screensaver
 * This module implements the main functionality of the DW screensaver.
 * It is responsible for handling input and timer events, as well
 * as instantiating and rotating through the various screensaver modes
 * that have been implemented.
 */

#include <stdlib.h>         /* srand() */
#include <time.h>           /* time() */
#include <GL/gl.h>
#include <GL/glu.h>
#include <SDL.h>
#include "SSMain.h"
#include "PlainSpin.h"
#include "LightBounce.h"
#ifndef WITHOUT_ODE
#include "TumblingLogos.h"
#include "Towers.h"
#endif

/* switch to the next screensaver mode after this many milliseconds */
#define SSMODE_TIMEOUT_MSEC (1000*45)
#define SCREENSAVER_MAX_RUNTIME (30u*60u*1000u)

static SDL_Event event;

/* create the main screensaver object */
SSMain::SSMain(int width, int height, int numMonitors, SDL_Surface * sdlSurface)
    : m_width (width), m_height (height),
      m_numMonitors (numMonitors), m_sdlSurface (sdlSurface),
      m_mode(NULL), m_drawing(false), m_switchmode(false)
{
    /* set up some common OpenGL defaults */
    glShadeModel(GL_SMOOTH);
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    glEnable(GL_CULL_FACE);
    GLfloat ambient[] = {0.0f, 0.0f, 0.0f, 1.0f};
    glLightModelfv(GL_LIGHT_MODEL_AMBIENT, ambient);

    /* setup redraw SDL event structure */
    event.type = SDL_USEREVENT;
    event.user.code = 0;

    srand(time(NULL));
}

/* called by SDL when the update timer expires */
Uint32 SSMain::updateCallback(Uint32 interval, void * param)
{
    SSMain * ssmain = (SSMain *) param;
    return ssmain->updateCallback(interval);
}

/* member update function to be called by our registered
 * SDL callback non-member function */
Uint32 SSMain::updateCallback(Uint32 interval)
{
    if (!m_drawing)
    {
        SDL_PushEvent(&event);
    }
    return interval;
}

/* called to begin the screensaver,
 * exits when the screensaver should terminate */
void SSMain::run()
{
    Uint32 elapsed_msec;
    Uint32 lastChanged_msec = 0;
    SDL_Event event;

    /* initially set the screensaver mode */
    m_mode = startMode();

    /* register a screen redrawing SDL event */
    SDL_AddTimer(12, &updateCallback, this);

    /* draw the screen */
    update();

    /* main event loop */
    while (SDL_WaitEvent(&event))
    {
        elapsed_msec = SDL_GetTicks();  /* get the time the event occurred at */
#if SCREENSAVER_MAX_RUNTIME > 0
        if (elapsed_msec >= SCREENSAVER_MAX_RUNTIME)
            goto RET;
#endif
        if (m_switchmode || (elapsed_msec - lastChanged_msec > SSMODE_TIMEOUT_MSEC))
        {
            delete m_mode;
            m_mode = startMode();
            lastChanged_msec = elapsed_msec;
            m_switchmode = false;
        }

        switch (event.type)
        {
        case SDL_KEYDOWN:
            if (event.key.keysym.sym == SDLK_n)
            {
                m_switchmode = true;    /* switch to next mode on 'N' key */
            }
            else
            {
                goto RET;               /* terminate on other key */
            }
            break;
        case SDL_QUIT:                  /* terminate on quit event */
            goto RET;
        case SDL_MOUSEBUTTONDOWN:
            if (event.button.button == 1)
            {
                delete m_mode;
                m_mode = startMode();
                lastChanged_msec = elapsed_msec;
            }
            break;
        case SDL_USEREVENT:
            if (event.user.code == 0)
            {
                update();
            }
            break;
        }
    }
RET:
    ;
}

/* return a new screensaver mode object to start displaying */
SSMode * SSMain::startMode()
{
    static int mode = 0;
#ifndef WITHOUT_ODE
    const int numModes = 4;
#else
    const int numModes = 2;
#endif

    mode++;
    if (mode >= numModes)
        mode = 0;

    switch (mode)
    {
        case 0:
            return new PlainSpin(this);
        case 1:
            return new LightBounce(this);
#ifndef WITHOUT_ODE
        case 2:
            return new Towers(this);
        default:
            return new TumblingLogos(this);
#endif
    }
}

/* call the update function to redraw the screen from the
 * currently active screensaver mode.
 * Uses a pseudo-semaphore to block new redraw requests
 * from coming in while current ones are being serviced.
 */
void SSMain::update()
{
    m_drawing = true;
    m_mode->update();
    m_drawing = false;
}