#![allow(dead_code)]

extern crate genmesh;
extern crate clock_ticks;
extern crate obj;

use std::thread;
use std::time::Duration;
use glium_sdl2::Display;
use glium;
use glium::vertex::VertexBufferAny;

pub mod camera;

pub enum Action {
    Stop,
    Continue,
}

pub fn start_loop<F>(mut callback: F) where F: FnMut() -> Action {
    let mut accumulator = 0;
    let mut previous_clock = clock_ticks::precise_time_ns();

    loop {
        match callback() {
            Action::Stop => break,
            Action::Continue => ()
        };

        let now = clock_ticks::precise_time_ns();
        accumulator += now - previous_clock;
        previous_clock = now;

        const FIXED_TIME_STAMP: u64 = 16666667;
        while accumulator >= FIXED_TIME_STAMP {
            accumulator -= FIXED_TIME_STAMP;

            // if you have a game, update the state here
        }

        thread::sleep(Duration::from_millis(((FIXED_TIME_STAMP - accumulator) / 1000000) as u64));
    }
}

/// Returns a vertex buffer that should be rendered as `TrianglesList`.
pub fn load_wavefront(display: &Display, data: &[u8]) -> VertexBufferAny {
    #[derive(Copy, Clone)]
    struct Vertex {
        position: [f32; 3],
        normal: [f32; 3],
        texture: [f32; 2],
    }

    implement_vertex!(Vertex, position, normal, texture);

    let mut data = ::std::io::BufReader::new(data);
    let data = obj::Obj::load(&mut data);

    let mut vertex_data = Vec::new();

    for shape in data.object_iter().next().unwrap().group_iter().flat_map(|g| g.indices().iter()) {
        match shape {
            &genmesh::Polygon::PolyTri(genmesh::Triangle { x: v1, y: v2, z: v3 }) => {
                for v in [v1, v2, v3].iter() {
                    let position = data.position()[v.0];
                    let texture = v.1.map(|index| data.texture()[index]);
                    let normal = v.2.map(|index| data.normal()[index]);

                    let texture = texture.unwrap_or([0.0, 0.0]);
                    let normal = normal.unwrap_or([0.0, 0.0, 0.0]);

                    vertex_data.push(Vertex {
                        position: position,
                        normal: normal,
                        texture: texture,
                    })
                }
            },
            _ => unimplemented!()
        }
    }

    glium::vertex::VertexBuffer::new(display, &vertex_data).unwrap().into_vertex_buffer_any()
}