use std::{iter, time::{Duration, Instant}};

use camera::{camera_buffer, camera_controller, camera_struct::Camera, camera_uniform};
use wgpu::{util::DeviceExt, BlendState, ColorTargetState, PipelineLayoutDescriptor, RenderPipelineDescriptor};
use winit::{
    event::*,
    event_loop::EventLoop,
    keyboard::{KeyCode, PhysicalKey},
    window::{Window, WindowBuilder},
};
mod camera;
mod object;
mod sky;

#[cfg(target_arch = "wasm32")]
use wasm_bindgen::prelude::*;

struct State<'a> {
    surface: wgpu::Surface<'a>,
    device: wgpu::Device,
    queue: wgpu::Queue,
    config: wgpu::SurfaceConfiguration,
    size: winit::dpi::PhysicalSize<u32>,
    render_pipeline : wgpu::RenderPipeline,
    vertex_buffer: wgpu::Buffer,

    camera: camera::camera_struct::Camera,
    camera_buffer : wgpu::Buffer,
    camera_bind_group: wgpu::BindGroup,
    camera_uniform : camera_uniform::CameraUniform,
    camera_controller: camera_controller::CameraController,
    // The window must be declared after the surface so
    // it gets dropped after it as the surface contains
    // unsafe references to the window's resources.
    window: &'a Window,
    num_vertices: u32,
    last_frame: Instant,
    framecount: u64,

    frametime: f64,
    old_frame_times: Vec<f64>,
    max_history_size: usize,
    //sky_pipeline: wgpu::RenderPipeline,
    last_fps: Instant,
}

impl<'a> State<'a> {
    async fn new(window: &'a Window) -> State<'a> {
        let size = window.inner_size();

        // The instance is a handle to our GPU
        // BackendBit::PRIMARY => Vulkan + Metal + DX12 + Browser WebGPU
        let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
            #[cfg(not(target_arch = "wasm32"))]
            backends: wgpu::Backends::PRIMARY,
            #[cfg(target_arch = "wasm32")]
            backends: wgpu::Backends::GL,
            ..Default::default()
        });

        let surface = instance.create_surface(window).unwrap();

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

        let (device, queue) = adapter
            .request_device(
                &wgpu::DeviceDescriptor {
                    label: None,
                    required_features: wgpu::Features::POLYGON_MODE_LINE,
                    // WebGL doesn't support all of wgpu's features, so if
                    // we're building for the web we'll have to disable some.
                    required_limits: if cfg!(target_arch = "wasm32") {
                        wgpu::Limits::downlevel_webgl2_defaults()
                    } else {
                        wgpu::Limits::default()
                    },
                },
                // Some(&std::path::Path::new("trace")), // Trace path
                None,
            )
            .await
            .unwrap();

        let surface_caps = surface.get_capabilities(&adapter);
        // Shader code in this tutorial assumes an Srgb surface texture. Using a different
        // one will result all the colors comming out darker. If you want to support non
        // Srgb surfaces, you'll need to account for that when drawing to the frame.
        let surface_format = surface_caps
            .formats
            .iter()
            .copied()
            .find(|f| f.is_srgb())
            .unwrap_or(surface_caps.formats[0]);
        let config = wgpu::SurfaceConfiguration {
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
            format: surface_format,
            width: size.width,
            height: size.height,
            present_mode: surface_caps.present_modes[0],
            alpha_mode: surface_caps.alpha_modes[0],
            desired_maximum_frame_latency: 2,
            view_formats: vec![],
        };

        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("Shader 1 from shader.wgsl"),
            source: wgpu::ShaderSource::Wgsl(include_str!("./shaders/shader.wgsl").into()),
        });
        


        let plan1 = object::generate_plane(512,512,100.,100.);
        //println!("{:?}", plan1.positions_list());
        let plan2 = plan1.clone();
        let vertex_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor{
            label: Some("Vertex Buffer 1"),
            contents: bytemuck::cast_slice(&plan1.vertices()),
            usage: wgpu::BufferUsages::VERTEX | wgpu::BufferUsages::COPY_DST,
        });

        let num_vertices = plan2.len();
        let (camera, camera_uniform, camera_buffer,camera_bind_group, camera_bind_group_layout) = camera_buffer::new(&device, &config);
        let camera_controller = camera_controller::CameraController::new(0.1);

        let pipeline_layout = device.create_pipeline_layout(&PipelineLayoutDescriptor{
            label: Some("Pipeline Layout"),
            bind_group_layouts: &[
                &camera_bind_group_layout,
            ],
            push_constant_ranges: &[]
        });

        let render_pipeline = device.create_render_pipeline(&RenderPipelineDescriptor{
            label: Some("RenderPipeline"),
            layout: Some(&pipeline_layout),
            vertex: wgpu::VertexState {
                module: &shader,
                entry_point: "vs_main".into(),
                buffers: &[
                    object::Vertex::desc(),
                ],
            },
            primitive: wgpu::PrimitiveState{
                topology: wgpu::PrimitiveTopology::TriangleList,
                strip_index_format: None,
                front_face: wgpu::FrontFace::Ccw,
                cull_mode: None,
                unclipped_depth: false,
                polygon_mode: wgpu::PolygonMode::Line,
                conservative: false
            },
            depth_stencil: None,
            multisample: wgpu::MultisampleState{
                count: 1,
                mask: !0,
                alpha_to_coverage_enabled: false,
            },
            fragment: Some(wgpu::FragmentState{
                module: &shader,
                entry_point: "fs_main",
                targets: &[Some(ColorTargetState{
                    format: config.format,
                    blend: Some(BlendState::REPLACE),
                    write_mask: wgpu::ColorWrites::ALL
                })]
            }),
            multiview: None
        });

        let last_frame: Instant = Instant::now();
        let delta: f64 = 0.2;

        //let sky_pipeline = sky::sky_pipeline::new_sky_pipeline(&device, &config);
        let framecount: u64 = 0;
        let old_frame_times : Vec<f64> = vec![];
        let max_history: usize = 60;
        let last_fps = Instant::now();
        Self {
            surface,
            vertex_buffer,
            render_pipeline,
            device,
            queue,
            config,
            size,
            window,
            camera,
            camera_bind_group,
            camera_buffer,
            camera_uniform,
            camera_controller,
            num_vertices: num_vertices,
            last_frame: last_frame,
            frametime: delta,
            //sky_pipeline: sky_pipeline
            framecount,
            old_frame_times: old_frame_times,
            max_history_size: max_history,
            last_fps: last_fps
        }
    }

    fn window(&self) -> &Window {
        &self.window
    }

    pub fn resize(&mut self, new_size: winit::dpi::PhysicalSize<u32>) {
        if new_size.width > 0 && new_size.height > 0 {
            self.size = new_size;
            self.config.width = new_size.width;
            self.config.height = new_size.height;
            self.surface.configure(&self.device, &self.config);

            self.camera.aspect = self.config.width as f32 / self.config.height as f32;
        }
    }

    fn input(&mut self, event: &WindowEvent) -> bool {
        self.camera_controller.process_events(event)
    }

    fn update(&mut self) {
        self.camera_controller.update_camera(&mut self.camera);
        self.camera_uniform.update_view_proj(&self.camera);
        self.queue.write_buffer(
            &self.camera_buffer,
            0,
            bytemuck::cast_slice(&[self.camera_uniform]),
        );



        // self.queue.write_buffer(
        //     &self.vertex_buffer,
        //     0,
        //     bytemuck::cast_slice(todo!())
        // );  
    }
    fn render(&mut self) -> Result<(), wgpu::SurfaceError> {
        let output = self.surface.get_current_texture()?;
        let view = output
            .texture
            .create_view(&wgpu::TextureViewDescriptor::default());

        let mut encoder = self
            .device
            .create_command_encoder(&wgpu::CommandEncoderDescriptor {
                label: Some("Render Encoder"),
        });

        //Modify the buffer


        {
            let mut render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                label: Some("Render Pass"),
                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                    view: &view,
                    resolve_target: None,
                    ops: wgpu::Operations {
                        load: wgpu::LoadOp::Clear(wgpu::Color {
                            r: 0.52,
                            g: 0.80,
                            b: 0.92,
                            a: 1.0,
                        }),
                        store: wgpu::StoreOp::Store,
                    },
                })],
                depth_stencil_attachment: None,
                occlusion_query_set: None,
                timestamp_writes: None,
            });
            //render_pass.set_pipeline(&self.sky_pipeline);

            render_pass.set_pipeline(&self.render_pipeline);
            render_pass.set_vertex_buffer(0, self.vertex_buffer.slice(..));
            render_pass.set_bind_group(0, &self.camera_bind_group, &[]);
            render_pass.draw(0..self.num_vertices, 0..1);
            //render_pass.draws
        }

        self.queue.submit(iter::once(encoder.finish()));
        output.present();


        //FPS logic
        self.frametime = (self.last_frame.elapsed().as_secs() as f64) + (self.last_frame.elapsed().as_nanos() as f64 / 1_000_000_000.0);
        self.last_frame = Instant::now();
        
        let interval_fps = Duration::from_millis(100);

        self.old_frame_times.push(self.frametime);
        if self.old_frame_times.len() > self.max_history_size {
            self.old_frame_times.remove(0);
        }
        let smoothed_frame_time = self.old_frame_times.iter().sum::<f64>() / self.old_frame_times.len() as f64;
        let smoothed_fps = 1.0 / smoothed_frame_time;

        if self.last_fps.elapsed() > interval_fps{
            self.last_fps = Instant::now();
            println!("{:?}", smoothed_fps.ceil());
        }
        Ok(())
    }
}

#[cfg_attr(target_arch = "wasm32", wasm_bindgen(start))]
pub async fn run() {
    cfg_if::cfg_if! {
        if #[cfg(target_arch = "wasm32")] {
            std::panic::set_hook(Box::new(console_error_panic_hook::hook));
            console_log::init_with_level(log::Level::Info).expect("Couldn't initialize logger");
        } else {
            env_logger::init();
        }
    }

    let event_loop = EventLoop::new().unwrap();
    let window = WindowBuilder::new().build(&event_loop).unwrap();

    #[cfg(target_arch = "wasm32")]
    {
        // Winit prevents sizing with CSS, so we have to set
        // the size manually when on web.
        use winit::dpi::PhysicalSize;

        use winit::platform::web::WindowExtWebSys;
        web_sys::window()
            .and_then(|win| win.document())
            .and_then(|doc| {
                let dst = doc.get_element_by_id("wasm-example")?;
                let canvas = web_sys::Element::from(window.canvas()?);
                dst.append_child(&canvas).ok()?;
                Some(())
            })
            .expect("Couldn't append canvas to document body.");

        let _ = window.request_inner_size(PhysicalSize::new(450, 400));
    }

    // State::new uses async code, so we're going to wait for it to finish
    let mut state = State::new(&window).await;
    let mut surface_configured = false;

    event_loop
        .run(move |event, control_flow| {
            match event {
                Event::WindowEvent {
                    ref event,
                    window_id,
                } if window_id == state.window().id() => {
                    if !state.input(event) {
                        // UPDATED!
                        match event {
                            WindowEvent::CloseRequested
                            | WindowEvent::KeyboardInput {
                                event:
                                    KeyEvent {
                                        state: ElementState::Pressed,
                                        physical_key: PhysicalKey::Code(KeyCode::Escape),
                                        ..
                                    },
                                ..
                            } => control_flow.exit(),
                            WindowEvent::Resized(physical_size) => {
                                log::info!("physical_size: {physical_size:?}");
                                surface_configured = true;
                                state.resize(*physical_size);
                            }
                            WindowEvent::RedrawRequested => {
                                // This tells winit that we want another frame after this one
                                state.window().request_redraw();

                                if !surface_configured {
                                    return;
                                }

                                state.update();
                                match state.render() {
                                    Ok(_) => {}
                                    // Reconfigure the surface if it's lost or outdated
                                    Err(
                                        wgpu::SurfaceError::Lost | wgpu::SurfaceError::Outdated,
                                    ) => state.resize(state.size),
                                    // The system is out of memory, we should probably quit
                                    Err(wgpu::SurfaceError::OutOfMemory) => {
                                        log::error!("OutOfMemory");
                                        control_flow.exit();
                                    }

                                    // This happens when the a frame takes too long to present
                                    Err(wgpu::SurfaceError::Timeout) => {
                                        log::warn!("Surface timeout")
                                    }
                                }
                            }
                            _ => {}
                        }
                    }
                }
                _ => {}
            }
        })
        .unwrap();
}