#include <FTGL/ftgl.h>
#include <SDL2/SDL.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <iostream>

using namespace std;

#define WIDTH   500
#define HEIGHT  500
#define FONT_SIZE 20

static FTFont * font;

void init(void)
{
    glViewport(0, 0, WIDTH, HEIGHT);
    glClearColor (0.0, 0.0, 0.0, 0.0);
    glShadeModel(GL_FLAT);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0, WIDTH, 0, HEIGHT);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    font = new FTTextureFont("/usr/share/fonts/truetype/freefont/FreeMono.ttf");
    if (font->Error())
    {
        cerr << "Could not create font" << endl;
    }
    font->FaceSize(FONT_SIZE);
}

void display(SDL_Window * window)
{
    float line_height = font->LineHeight();
    float advance = font->Advance("M");
    float low = font->BBox("g").Lower().Y();
    float high = font->BBox("M").Upper().X();
    float shift = (high + low) / 2.0 - line_height / 2.0;
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glBegin(GL_QUADS);
        glColor4f(1.0, 1.0, 0.0, 1.0);
        glVertex3f(10 + advance * ('J' - 'A'), HEIGHT - line_height * 3 + shift, 0.0);
        glVertex3f(10 + advance * ('J' - 'A'), HEIGHT - line_height * 2 + shift, 0.0);
        glVertex3f(10 + advance * ('J' - 'A' + 1), HEIGHT - line_height * 2 + shift, 0.0);
        glVertex3f(10 + advance * ('J' - 'A' + 1), HEIGHT - line_height * 3 + shift, 0.0);
    glEnd();
    glColor4f(1, 1, 1, 1);
    font->Render("abcdefghijklmnopqrstuvwxyz_", -1, FTPoint(10, HEIGHT - line_height, 0));
    font->Render("ABCDEFGHIJKLMNOPQRSTUVWXYZ_", -1, FTPoint(10, HEIGHT - line_height * 2, 0));
    for (int i = 0; i < 26; i++)
    {
        char s[2];
        s[0] = 'A' + i;
        s[1] = '\0';
        if (i == 'J' - 'A')
            glColor4f(0, 0, 0, 1);
        else
            glColor4f(1, 1, 1, 1);
        font->Render(s, -1, FTPoint(10 + advance * i, HEIGHT - line_height * 3, 0));
    }
    font->Render("0123456789", -1, FTPoint(10, HEIGHT - line_height * 4, 0));
    SDL_GL_SwapWindow(window);
}

int main(int argc, char *argv[])
{
    if (SDL_Init(SDL_INIT_VIDEO))
    {
        printf("Failed to initialize SDL!\n");
        return 1;
    }

    atexit(SDL_Quit);

    SDL_Window * window = SDL_CreateWindow(argv[0],
                                           SDL_WINDOWPOS_UNDEFINED,
                                           SDL_WINDOWPOS_UNDEFINED,
                                           WIDTH,
                                           HEIGHT,
                                           SDL_WINDOW_OPENGL);
    if (!window)
    {
        printf("Failed to create window!\n");
        SDL_Quit();
        return 2;
    }

    SDL_GLContext gl_context = SDL_GL_CreateContext(window);

    init();
    display(window);
    SDL_Event event;
    while (SDL_WaitEvent(&event))
    {
        if (event.type == SDL_QUIT)
            break;
        else if (event.type == SDL_KEYDOWN)
        {
            if (event.key.keysym.sym == SDLK_ESCAPE)
                break;
            if (event.key.keysym.sym == SDLK_RETURN)
                display(window);
        }
    }
}