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

#[path = "../book/tuto-07-teapot.rs"]
mod teapot;

mod support;
use support::view_matrix;

fn main() {
    let event_loop = glium::winit::event_loop::EventLoop::builder()
        .build()
        .expect("event loop building");
    let (window, display) = glium::backend::glutin::SimpleWindowBuilder::new()
        .with_title("Glium tutorial #13")
        .build(&event_loop);

    let positions = glium::VertexBuffer::new(&display, &teapot::VERTICES).unwrap();
    let normals = glium::VertexBuffer::new(&display, &teapot::NORMALS).unwrap();
    let indices = glium::IndexBuffer::new(&display, glium::index::PrimitiveType::TrianglesList,
                                        &teapot::INDICES).unwrap();

    let vertex_shader_src = r#"
        #version 150

        in vec3 position;
        in vec3 normal;

        out vec3 v_normal;
        out vec3 v_position;

        uniform mat4 perspective;
        uniform mat4 view;
        uniform mat4 model;

        void main() {
            mat4 modelview = view * model;
            v_normal = transpose(inverse(mat3(modelview))) * normal;
            gl_Position = perspective * modelview * vec4(position, 1.0);
            v_position = gl_Position.xyz / gl_Position.w;
        }
    "#;

    let fragment_shader_src = r#"
        #version 150

        in vec3 v_normal;
        in vec3 v_position;

        out vec4 color;

        uniform vec3 u_light;

        const vec3 ambient_color = vec3(0.2, 0.0, 0.0);
        const vec3 diffuse_color = vec3(0.6, 0.0, 0.0);
        const vec3 specular_color = vec3(1.0, 1.0, 1.0);

        void main() {
            float diffuse = max(dot(normalize(v_normal), normalize(u_light)), 0.0);

            vec3 camera_dir = normalize(-v_position);
            vec3 half_direction = normalize(normalize(u_light) + camera_dir);
            float specular = pow(max(dot(half_direction, normalize(v_normal)), 0.0), 16.0);

            color = vec4(ambient_color + diffuse * diffuse_color + specular * specular_color, 1.0);
        }
    "#;

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

    #[allow(deprecated)]
    event_loop.run(move |ev, window_target| {
        match ev {
            glium::winit::event::Event::WindowEvent { event, .. } => match event {
                glium::winit::event::WindowEvent::CloseRequested => {
                    window_target.exit();
                },
                // We now need to render everyting in response to a RedrawRequested event due to the animation
                glium::winit::event::WindowEvent::RedrawRequested => {
                    let mut target = display.draw();
                    target.clear_color_and_depth((0.0, 0.0, 1.0, 1.0), 1.0);

                    let model = [
                        [0.01, 0.0, 0.0, 0.0],
                        [0.0, 0.01, 0.0, 0.0],
                        [0.0, 0.0, 0.01, 0.0],
                        [0.0, 0.0, 2.0, 1.0f32]
                    ];

                    let view = view_matrix(&[2.0, 1.0, 1.0], &[-2.0, -1.0, 1.0], &[0.0, 1.0, 0.0]);

                    let perspective = {
                        let (width, height) = target.get_dimensions();
                        let aspect_ratio = height as f32 / width as f32;

                        let fov: f32 = 3.141592 / 3.0;
                        let zfar = 1024.0;
                        let znear = 0.1;

                        let f = 1.0 / (fov / 2.0).tan();

                        [
                            [f *   aspect_ratio   ,    0.0,              0.0              ,   0.0],
                            [         0.0         ,     f ,              0.0              ,   0.0],
                            [         0.0         ,    0.0,  (zfar+znear)/(zfar-znear)    ,   1.0],
                            [         0.0         ,    0.0, -(2.0*zfar*znear)/(zfar-znear),   0.0],
                        ]
                    };

                    let light = [1.4, 0.4, -0.7f32];

                    let params = glium::DrawParameters {
                        depth: glium::Depth {
                            test: glium::draw_parameters::DepthTest::IfLess,
                            write: true,
                            .. Default::default()
                        },
                        //backface_culling: glium::draw_parameters::BackfaceCullingMode::CullClockWise,
                        .. Default::default()
                    };

                    target.draw((&positions, &normals), &indices, &program,
                                &uniform! { model: model, view: view, perspective: perspective, u_light: light },
                                &params).unwrap();
                    target.finish().unwrap();
                },
                // Because glium doesn't know about windows we need to resize the display
                // when the window's size has changed.
                glium::winit::event::WindowEvent::Resized(window_size) => {
                    display.resize(window_size.into());
                },
                _ => (),
            },
            // By requesting a redraw in response to a AboutToWait event we get continuous rendering.
            // For applications that only change due to user input you could remove this handler.
            glium::winit::event::Event::AboutToWait => {
                window.request_redraw();
            },
            _ => (),
        }
    })
    .unwrap();
}