use glium::winit::event::{Event, WindowEvent};
use glium::Surface;

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

#[macro_use]
extern crate glium;

fn main() {
    let event_loop = glium::winit::event_loop::EventLoopBuilder::new().build().expect("event loop building");
    let (_window, display) = glium::backend::glutin::SimpleWindowBuilder::new().build(&event_loop);

    let vertex1 = Vertex { position: [ -0.5, -0.5 ] };
    let vertex2 = Vertex { position: [ 0.0, 0.5 ] };
    let vertex3 = Vertex { position: [ 0.5, -0.25 ] };
    let shape = vec![vertex1, vertex2, vertex3];

    let vertex_buffer = glium::VertexBuffer::new(&display, &shape).unwrap();
    let indices = glium::index::NoIndices(glium::index::PrimitiveType::TrianglesList);

    let vertex_shader_src = r#"
        in vec2 position;

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

    let fragment_shader_src = r#"
        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 frame = display.draw();
    frame.clear_color(0.0, 0.0, 0.0, 1.0);
    frame.draw(&vertex_buffer, &indices, &program, &glium::uniforms::EmptyUniforms,
        &Default::default()).unwrap();
    frame.finish().unwrap();

    let _ = event_loop.run(move |event, window_target| {
        match event {
            Event::WindowEvent { event, .. } => match event {
                WindowEvent::CloseRequested => window_target.exit(),
                _ => (),
            },
            _ => (),
        };
    });
}