#include <SDL.h>
#include <SDL_draw.h>
#include <SDL_ttf.h>
#include <math.h>
#define X 740
#define Y 640



///функция рисования координатной плоскости
void koordinatnaya_ploskost(SDL_Surface *screen , double razmer)
{

        SDL_Rect ramka={30, 30, X-60, Y-60 };
        SDL_FillRect(screen, 0, SDL_MapRGB(screen->format, 0, 0, 0)-100);
        SDL_FillRect(screen, &ramka, SDL_MapRGB(screen->format, 255, 255, 255));

        int cx=X/2, cy=Y/2;


        Draw_VLine(screen ,X/2, 40, Y-40, SDL_MapRGB(screen->format, 0,0,0)); ///ось Y
        Draw_HLine(screen ,40, Y/2, X-40, SDL_MapRGB(screen->format, 0,0,0)); ///ось X

        for(int cord_x=X/2+razmer; cord_x<X-40; cord_x+=razmer)
        {
            cx-=razmer;
            Draw_VLine(screen ,cord_x, 40, Y-40, SDL_MapRGB(screen->format, 192,192,192));
            Draw_VLine(screen ,cx , 40, Y-40, SDL_MapRGB(screen->format, 192,192,192));
        }

        for(int cord_y=Y/2+razmer; cord_y<Y-40; cord_y+=razmer)
        {   cy-=razmer;
            Draw_HLine(screen ,40, cord_y, X-40, SDL_MapRGB(screen->format, 192,192,192));
            Draw_HLine(screen ,40, cy, X-40, SDL_MapRGB(screen->format, 192,192,192));
        }

}

///функция расставления координат
void koordinati(SDL_Surface *screen,int razmer)
{
     int razmer_ttf=16, cx=X/2, temp, temp1, f=8;
     char pol_cord[]="987654321";
        SDL_Rect cord_text={X/2,10,16,16}, cord_text_snizu={20,Y-30,16,16};
        SDL_Surface *text, *otr;
        TTF_Font* font=TTF_OpenFont("shrifts/ttf3.ttf",razmer_ttf);
        SDL_Color color={100, 50, 25};
        otr=TTF_RenderText_Solid(font, "-" ,color);

    ///расставление координат сверху и снизу
    for(cord_text.x=X/2+razmer*2; cord_text.x<X-40; cord_text.x+=razmer*2)
      {
        cx-=razmer*2;
        text=TTF_RenderText_Solid(font, pol_cord+f ,color);
        SDL_BlitSurface(text, NULL, screen, &cord_text);
        cord_text_snizu.x=cord_text.x;
        SDL_BlitSurface(text, NULL, screen, &cord_text_snizu);

        temp=cord_text.x;

        cord_text.x=cx-8;
        cord_text_snizu.x=cx-8;
        SDL_BlitSurface(otr, NULL, screen, &cord_text);
        SDL_BlitSurface(otr, NULL, screen, &cord_text_snizu);

        cord_text.x=cx;
        cord_text_snizu.x=cx;
        SDL_BlitSurface(text, NULL, screen, &cord_text);
        SDL_BlitSurface(text, NULL, screen, &cord_text_snizu);

        cord_text.x=temp;
        pol_cord[f]='\0';
        --f;
      }

    ///расставление координат по бокам
    char pol_cord1[]="987654321";
    cord_text.x=20;
    cord_text_snizu.x=X-15;
    cx=Y/2;
    f=8;

    for(cord_text.y=Y/2-8+razmer*2; cord_text.y<Y-50; cord_text.y+=razmer*2)
    {
        cx-=razmer*2;
        text=TTF_RenderText_Solid(font, pol_cord1+f ,color);
        SDL_BlitSurface(text, NULL, screen, &cord_text);
        cord_text_snizu.y=cord_text.y;
        SDL_BlitSurface(text, NULL, screen, &cord_text_snizu);

        temp=cord_text.x;
        temp1=cord_text.y;

        cord_text.x=X-25;
        SDL_BlitSurface(otr, NULL, screen, &cord_text);
        cord_text.x=8;
        SDL_BlitSurface(otr, NULL, screen, &cord_text);

        cord_text.x=temp;
        temp=cord_text.y;

        cord_text.y=cx-8;
        cord_text_snizu.y=cx-8;

        SDL_BlitSurface(text, NULL, screen, &cord_text);
        SDL_BlitSurface(text, NULL, screen, &cord_text_snizu);

        cord_text.y=temp;
        pol_cord1[f]='\0';
        --f;
    }

}

///функция рисования графика
void grafik(SDL_Surface *screen, int razmer)
{
        double x=-25, y, a, b;
        int kostil=1;

        while(x<25)
        {
               y=sin(x)/(1-x);
               a=X/2+razmer*x;
               b=Y/2+razmer*y;
               if(x==0)
                       a=X/2;
               if(y==0)
                       b=Y/2;
               a-=razmer*3;

               if(a<X-40 && b<Y-40 && a>40 && b>40 )
                       Draw_FillEllipse(screen, -a+kostil , b+2 , 1, 1, SDL_MapRGB(screen->format, 255,0,0));
               x+=0.0001;
               kostil=0;
        }
}


int main ( int argc, char** argv )
{
    if ( SDL_Init( SDL_INIT_VIDEO ) < 0 )
    {
        printf( "Unable to init SDL: %s\n", SDL_GetError() );
        return 1;
    }

     TTF_Init();

    atexit(SDL_Quit);

    SDL_Surface *screen = SDL_SetVideoMode(X, Y, 16, SDL_HWSURFACE|SDL_DOUBLEBUF);
    if ( !screen )
    {
        printf("Unable to set 640x480 video: %s\n", SDL_GetError());
        return 1;
    }
    bool done = false;
    int razmer=30;

    while (!done)
    {

        SDL_Event event;
        while (SDL_PollEvent(&event))
        {

            switch (event.type)
            {

            case SDL_QUIT:
                done = true;
                break;

            case SDL_KEYDOWN:
                {
                    if (event.key.keysym.sym == SDLK_ESCAPE)
                        done = true;

                    if(event.key.keysym.sym == SDLK_UP)
                        if((razmer+10)<X/10 && (razmer+10)<Y/10)
                        razmer+=5;

                    if(event.key.keysym.sym == SDLK_DOWN)
                        if((razmer-10)>10 && (razmer-10)>10)
                        razmer-=5;
                    break;
                 }
            }
        }

        koordinatnaya_ploskost(screen , razmer);
        koordinati(screen, razmer);
        grafik(screen, razmer);

        SDL_Flip(screen);
    }
    TTF_Quit();
    return 0;
}