#include <allegro.h>
#include <alleggl.h>
#include <vector>
#include <string>

// The font we will be using
FONT* Font;

// Possible primitives
const int NumPrimitives = 10;
const int Primitives[NumPrimitives] =
{
    GL_POINTS,
    GL_LINES,
    GL_LINE_STRIP,
    GL_LINE_LOOP,
    GL_TRIANGLES,
    GL_TRIANGLE_STRIP,
    GL_TRIANGLE_FAN,
    GL_QUADS,
    GL_QUAD_STRIP,
    GL_POLYGON
};

// Primitive names
string PrimitiveNames[NumPrimitives] =
{
    "GL_POINTS",
    "GL_LINES",
    "GL_LINE_STRIP",
    "GL_LINE_LOOP",
    "GL_TRIANGLES",
    "GL_TRIANGLE_STRIP",
    "GL_TRIANGLE_FAN",
    "GL_QUADS",
    "GL_QUAD_STRIP",
    "GL_POLYGON"
};

// A struct to hold a point.
struct Point
{
    float x, y;
    Point(float x, float y) : x(x), y(y) {}
};

void Init()
{
    // Start up Allegro and AllegroGL systems
    allegro_init();
    install_allegro_gl();
    install_keyboard();
    install_mouse();

    // Set some AllegroGL options
    allegro_gl_set(AGL_DOUBLEBUFFER, true);
    allegro_gl_set(AGL_COLOR_DEPTH, 16);
    allegro_gl_set(AGL_RENDERMETHOD, true);
    allegro_gl_set(AGL_SUGGEST, AGL_DOUBLEBUFFER | AGL_COLOR_DEPTH | AGL_RENDERMETHOD);

    // Set up a suitable viewing window
    set_color_depth(16);
    set_gfx_mode(GFX_OPENGL_WINDOWED, 640, 480, 0, 0);

    // Fill front-facing polygons and line back-facing ones.
    glPolygonMode(GL_FRONT, GL_FILL);
    glPolygonMode(GL_BACK, GL_LINE);

    // Set the background color to black
    glClearColor(0.0, 0.0, 0.0, 0.0);
}

int main()
{
    Init();

    std::vector<Point> vertices;
    bool mouse_b1 = false;
    bool upd_title = true;
    char* title_buf = 0;
    float mx = 0.0, my = 0.0;
    int prim = 0;

    while(!key[KEY_ESC])
    {
        // Clear the screen
        glClear(GL_COLOR_BUFFER_BIT);

        // Poll the mouse
        poll_mouse();
        mx = (mouse_x / 320.0) - 1.0;
        my = (-mouse_y / 240.0) + 1.0;

        // Check to see if a vertex needs to be added
        if(!(mouse_b & 1) && mouse_b1)  // Mouse button 1 up
        {
            vertices.push_back(Point(mx, my));
        }
        mouse_b1 = mouse_b & 1;

        // Check to see if the primitive should be drawn
        if((mouse_b & 2) && (vertices.size() > 0))
        {
            glBegin(Primitives[prim]);
                glColor3f(0.0, 0.0, 1.0);
                for(unsigned int i = 0; i < vertices.size(); i++)
                {
                    glVertex2f(vertices[i].x, vertices[i].y);
                }
            glEnd();
            glFlush();
            allegro_gl_flip();
            set_window_title("Press any key to continue.");
            upd_title = true;
            clear_keybuf();
            readkey();
        }

        // Clear the vertex list if necessary
        if(key[KEY_DEL] && (vertices.size() > 0))
        {
            vertices.clear();
        }

        // Draw the vertices and the mouse cursor
        glPointSize(5.0);
        glBegin(GL_POINTS);
            glColor3f(1.0, 0.0, 0.0);
            for(unsigned int i = 0; i < vertices.size(); i++)
            {
                glVertex2f(vertices[i].x, vertices[i].y);
            }
            glColor3f(0.8, 0.8, 0.8);
            glVertex2f(mx, my);
        glEnd();

        // Cycle through the available primitives.
        if(key[KEY_1])  { prim = 0; upd_title = true; }
        if(key[KEY_2])  { prim = 1; upd_title = true; }
        if(key[KEY_3])  { prim = 2; upd_title = true; }
        if(key[KEY_4])  { prim = 3; upd_title = true; }
        if(key[KEY_5])  { prim = 4; upd_title = true; }
        if(key[KEY_6])  { prim = 5; upd_title = true; }
        if(key[KEY_7])  { prim = 6; upd_title = true; }
        if(key[KEY_8])  { prim = 7; upd_title = true; }
        if(key[KEY_9])  { prim = 8; upd_title = true; }
        if(key[KEY_0])  { prim = 9; upd_title = true; }

        // Set the window title
        if(upd_title)
        {
            std::string title = string("Type: ") +
                PrimitiveNames[prim] +
                string(" | LMB: Add vtx | RMB: Draw prim. | 0-9: Change prim. type | DEL: Clear");
            delete[] title_buf;
            title_buf = new char[title.size()];
            strcpy(title_buf, title.c_str());
            set_window_title(title_buf);
            upd_title = false;
        }

        // Flush & flip.
        glFlush();
        allegro_gl_flip();
    }

    return 0;
}
END_OF_MAIN();