extern crate tobj;
extern crate winit;

use std::{iter, mem, num::NonZeroU32, ops::Range, rc::Rc};
#[cfg(not(target_arch = "wasm32"))]
use std::time::{Duration, Instant};

use bytemuck::{Pod, Zeroable};
use futures::task::LocalSpawn;
use wgpu::util::DeviceExt;
use wgpu_subscriber;
use winit::{
    event::{self, WindowEvent},
    event_loop::{ControlFlow, EventLoop},
};
use crate::render::Renderer;

mod framework;
mod geometry;
mod light;
mod render;
mod runtime;

/*

Collision detection
https://crates.io/crates/mgf

Obj file format
http://paulbourke.net/dataformats/obj/

tobj obj loader
https://docs.rs/tobj/2.0.3/tobj/index.html

mesh generator lib, might be useful
https://docs.rs/genmesh/0.6.2/genmesh/

legion ECS
https://github.com/amethyst/legion


mvp:

ECS
    animation
    render 3d
    input/io
    collision / physics
    entities & behaviours

 */




#[cfg_attr(rustfmt, rustfmt_skip)]
#[allow(unused)]
pub const OPENGL_TO_WGPU_MATRIX: cgmath::Matrix4<f32> = cgmath::Matrix4::new(
    1.0, 0.0, 0.0, 0.0,
    0.0, 1.0, 0.0, 0.0,
    0.0, 0.0, 0.5, 0.0,
    0.0, 0.0, 0.5, 1.0,
);

#[allow(dead_code)]
pub fn cast_slice<T>(data: &[T]) -> &[u8] {
    use std::{mem::size_of, slice::from_raw_parts};

    unsafe { from_raw_parts(data.as_ptr() as *const u8, data.len() * size_of::<T>()) }
}

#[allow(dead_code)]
pub enum ShaderStage {
    Vertex,
    Fragment,
    Compute,
}

/*
    window: winit::window::Window,
    event_loop: EventLoop<()>,
    instance: wgpu::Instance,
    size: winit::dpi::PhysicalSize<u32>,
    surface: wgpu::Surface,
    adapter: wgpu::Adapter,
    device: wgpu::Device,
    queue: wgpu::Queue,
 */

fn main() {

    // #[cfg(not(target_arch = "wasm32"))]
    // {
    //     let chrome_tracing_dir = std::env::var("WGPU_CHROME_TRACE");
    //     wgpu_subscriber::initialize_default_subscriber(
    //         chrome_tracing_dir.as_ref().map(std::path::Path::new).ok(),
    //     );
    // };
    // #[cfg(target_arch = "wasm32")]
    // console_log::init().expect("could not initialize logger");


    let event_loop = EventLoop::new();
    let mut builder = winit::window::WindowBuilder::new();
    builder = builder.with_title(title);

    // I don't know what they are doing here
    #[cfg(windows_OFF)] // TODO
        {
            use winit::platform::windows::WindowBuilderExtWindows;
            builder = builder.with_no_redirection_bitmap(true);
        }

    let window = builder.build(&event_loop).unwrap();

    log::info!("Initializing the surface...");

    // Grab the GPU instance, and query its features
    let instance = wgpu::Instance::new(wgpu::BackendBit::PRIMARY);
    let (size, surface) = unsafe {
        let size = window.inner_size();
        let surface = instance.create_surface(&window);
        (size, surface)
    };

    let adapter = instance
        .request_adapter(&wgpu::RequestAdapterOptions {
            power_preference: wgpu::PowerPreference::HighPerformance,
            compatible_surface: Some(&surface),
        })
        .await
        .unwrap();


    let optional_features = Renderer::optional_features();
    let required_features = Renderer::required_features();
    let adapter_features = adapter.features();
    assert!(
        adapter_features.contains(required_features),
        "Adapter does not support required features for this example: {:?}",
        required_features - adapter_features
    );

    let needed_limits = wgpu::Limits::default();//Renderer::required_limits();

    // Maybe for debug tracing???
    let trace_dir = std::env::var("WGPU_TRACE");

    // And then get the device we want
    let (device, queue) = adapter
        .request_device(
            &wgpu::DeviceDescriptor {
                features: (optional_features & adapter_features) | required_features,
                limits: needed_limits,
                shader_validation: true,
            },
            trace_dir.ok().as_ref().map(std::path::Path::new),
        )
        .await
        .unwrap();


    #[cfg(not(target_arch = "wasm32"))]
        let (mut pool, spawner) = {
        let local_pool = futures::executor::LocalPool::new();
        let spawner = local_pool.spawner();
        (local_pool, spawner)
    };

    // This is some gross-ass web shit
    /*#[cfg(target_arch = "wasm32")]
        let spawner = {
        use futures::{future::LocalFutureObj, task::SpawnError};
        use winit::platform::web::WindowExtWebSys;

        struct WebSpawner {}
        impl LocalSpawn for WebSpawner {
            fn spawn_local_obj(
                &self,
                future: LocalFutureObj<'static, ()>,
            ) -> Result<(), SpawnError> {
                Ok(wasm_bindgen_futures::spawn_local(future))
            }
        }

        std::panic::set_hook(Box::new(console_error_panic_hook::hook));

        // On wasm, append the canvas to the document body
        web_sys::window()
            .and_then(|win| win.document())
            .and_then(|doc| doc.body())
            .and_then(|body| {
                body.append_child(&web_sys::Element::from(window.canvas()))
                    .ok()
            })
            .expect("couldn't append canvas to document body");

        WebSpawner {}
    };*/


    let mut sc_desc = wgpu::SwapChainDescriptor {
        // Allows a texture to be a output attachment of a renderpass.
        usage: wgpu::TextureUsage::OUTPUT_ATTACHMENT,
        format: if cfg!(target_arch = "wasm32") {
            wgpu::TextureFormat::Bgra8Unorm
        } else {
            wgpu::TextureFormat::Bgra8UnormSrgb
        },
        width: size.width,
        height: size.height,
        // The presentation engine waits for the next vertical blanking period to update
        present_mode: wgpu::PresentMode::Mailbox,
    };

    let mut swap_chain = device.create_swap_chain(&surface, &sc_desc);
    log::info!("Done doing the loading part...");

    // Init
    let mut runtime = runtime::Runtime::init(&sc_desc, &device, &queue);

    // Not sure why this is guarded, maybe we don't handle the event loop timing?
    #[cfg(not(target_arch = "wasm32"))]
        let mut last_update_inst = Instant::now();


    log::info!("Entering render loop...");

    let mut renderer = render::Renderer::init();


    // This is just an winit event loop
    event_loop.run(move |event, _, control_flow| {
        let _ = (&instance, &adapter); // force ownership by the closure (wtf??)

        // Override the control flow behaviour based on our system
        *control_flow = if cfg!(feature = "metal-auto-capture") {
            ControlFlow::Exit
        } else {
            #[cfg(not(target_arch = "wasm32"))]
                {
                    // Artificially slows the loop rate to 10 millis
                    // This is called after redraw events cleared
                    ControlFlow::WaitUntil(Instant::now() + Duration::from_millis(10))
                }
            #[cfg(target_arch = "wasm32")]
                {
                    ControlFlow::Poll
                }
        };

        match event {
            event::Event::MainEventsCleared => {
                #[cfg(not(target_arch = "wasm32"))]
                    {
                        // ask for a redraw every 20 millis
                        if last_update_inst.elapsed() > Duration::from_millis(20) {
                            window.request_redraw();
                            last_update_inst = Instant::now();
                        }

                        pool.run_until_stalled();
                    }

                #[cfg(target_arch = "wasm32")]
                    window.request_redraw();
            }

            // Resizing will queue a request_redraw
            event::Event::WindowEvent {
                event: WindowEvent::Resized(size),
                ..
            } => {
                log::info!("Resizing to {:?}", size);
                sc_desc.width = size.width;
                sc_desc.height = size.height;

                renderer.resize(&sc_desc, &device, &queue);

                swap_chain = device.create_swap_chain(&surface, &sc_desc);
            }
            event::Event::WindowEvent { event, .. } => match event {
                WindowEvent::KeyboardInput {
                    input:
                    event::KeyboardInput {
                        virtual_keycode: Some(event::VirtualKeyCode::Escape),
                        state: event::ElementState::Pressed,
                        ..
                    },
                    ..
                }
                | WindowEvent::CloseRequested => {
                    *control_flow = ControlFlow::Exit;
                }
                _ => {
                    renderer.update(event);
                }
            },
            event::Event::RedrawRequested(_) => {
                let frame = match swap_chain.get_current_frame() {
                    Ok(frame) => frame,
                    Err(_) => {
                        swap_chain = device.create_swap_chain(&surface, &sc_desc);
                        swap_chain
                            .get_current_frame()
                            .expect("Failed to acquire next swap chain texture!")
                    }
                };

                renderer.render(&frame.output, &device, &queue, &spawner);
            }
            _ => {}
        }
    });

    //framework::run::<Example>("shadow");
}