#include <stdlib.h>
#include <time.h>
#include <math.h>
#include <sys/types.h>
#include <unistd.h>

#include <GL/gl.h>
#include <GL/glu.h>

#include "Starfield.h"

Starfield::Starfield(GnomeScreensaver & gs)
{
    uint64_t ticks = gs.getTicks();
    m_last_ticks = ticks;
    srand(time(NULL) + getpid());
    for (int i = 0; i < NUM_STARS; i++)
        newStar(NUM_STARS - i - 1,
                ticks - (uint64_t) (i * FLYBY_TICKS / (double)NUM_STARS));
    m_star_idx = 0;
}

Starfield::~Starfield()
{
}

bool Starfield::expose (GnomeScreensaver & gs)
{
    uint64_t ticks = gs.getTicks();

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glViewport(0, 0, gs.getWidth(), gs.getHeight());

    for (int i = 0; i < NUM_STARS; i++)
    {
        glPushMatrix();
        glTranslatef(m_stars[i].x, m_stars[i].y,
                (ticks - m_stars[i].create_time) /
                    (double) FLYBY_TICKS * MAX_STAR_DIST
                    - MAX_STAR_DIST);
        glRotatef(m_stars[i].rot,
                m_stars[i].axis[0], m_stars[i].axis[1], m_stars[i].axis[2]);
        m_logobox.draw();
        glPopMatrix();
    }

    while ((m_stars[m_star_idx].create_time + FLYBY_TICKS) <= ticks)
    {
        newStar(m_star_idx, ticks);
        m_star_idx++;
        if (m_star_idx >= NUM_STARS)
            m_star_idx = 0;
    }

    m_last_ticks = gs.getTicks();

    return true;
}

bool Starfield::configure (GnomeScreensaver & gs)
{
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(60.0, gs.getAspectRatio(), 0.01, MAX_STAR_DIST);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    gluLookAt(0, 0, 0, 0, 0, -1, 0, 1, 0);

    return true;
}

bool Starfield::update (GnomeScreensaver & gs)
{
    return true;
}

void Starfield::getRandomAxis(float (*axis)[3])
{
    double alpha = rand() / (double)RAND_MAX * 2.0 * M_PI;
    double beta = rand() / (double)RAND_MAX * M_PI;
    (*axis)[0] = cos(alpha) * sin(beta);
    (*axis)[1] = sin(alpha) * sin(beta);
    (*axis)[2] = cos(beta);
}

void Starfield::newStar(int idx, uint64_t ticks)
{
    m_stars[idx].create_time = ticks;
    getRandomAxis(&m_stars[idx].axis);
    m_stars[idx].x = ((rand() / (double)RAND_MAX) - 0.5) * STAR_MAXX * 2;
    m_stars[idx].y = ((rand() / (double)RAND_MAX) - 0.5) * STAR_MAXY * 2;
    m_stars[idx].rot = rand() / (double)RAND_MAX * 360.0;
}