#[macro_use]
extern crate glium;
use glium::glutin;
use glium::Surface;

#[derive(Clone, Copy)]
struct Vertex {
    position: [f32; 2],
}

fn main() {
    // 1. The **winit::EventsLoop** for handling events.
    let mut events_loop = glium::glutin::EventsLoop::new();
    // 2. Parameters for building the Window.
    let window = glium::glutin::WindowBuilder::new()
        .with_dimensions(1024, 768)
        .with_title("Hello world");
    // 3. Parameters for building the OpenGL context.
    let context = glium::glutin::ContextBuilder::new();
    // 4. Build the Display with the given window and OpenGL context parameters and register the
    //    window with the events_loop.
    let display = glium::Display::new(window, context, &events_loop).unwrap();

    implement_vertex!(Vertex, position);

    // we create the shape an add `t` to each x coordinate
    let shape = vec![
        Vertex { position: [-0.5, -0.5] },
        Vertex { position: [ 0.0,  0.5] },
        Vertex { position: [ 0.5, -0.25] },
    ];
    let vertex_buffer = glium::VertexBuffer::new(&display, &shape).unwrap();
    let index_buffer = glium::IndexBuffer::new(&display, glium::index::PrimitiveType::LineLoop, &vec![0, 1, 1, 2u16]).unwrap();

    let vertex_shader_src = r#"
        #version 140

        in vec2 position;

        void main() {
            gl_Position = vec4(position, 0.0, 1.0);
        }
    "#;

    let fragment_shader_src = r#"
        #version 140

        out vec4 color;

        void main() {
            color = vec4(1.0, 0.0, 0.0, 1.0);
        }
    "#;

    let program = glium::Program::from_source(&display, vertex_shader_src, fragment_shader_src, None).unwrap();

    let mut closed = false;
    while !closed {
        // drawing
        let mut target = display.draw();
        target.clear_color(0.0, 0.0, 1.0, 1.0);
        target.draw(&vertex_buffer, &index_buffer, &program, &uniform! {

        },
        &glium::DrawParameters {
            line_width: Some(10.0),
            .. Default::default()
        }).unwrap();
        target.finish().unwrap();

        events_loop.poll_events(|event| {
            match event {
                glutin::Event::WindowEvent { event, .. } => match event {
                    glutin::WindowEvent::Closed => closed = true,
                    _ => ()
                },
                _ => (),
            }
        });
    }
}