#![allow(non_snake_case)]

#[path = "Camera.rs"]
mod _Camera;
use _Camera::*;

#[path = "Texture.rs"]
mod _Texture;
use _Texture::*;

use bytemuck::{Pod, Zeroable};
use image::GenericImageView;
use std::mem;
use wgpu::util::DeviceExt;
use winit::dpi::LogicalSize;
use winit::event::*;
use winit::event_loop::{ControlFlow, EventLoop};
use winit::window::Window;
use winit::window::WindowBuilder;

#[repr(C)]
#[derive(Copy, Clone, Debug, Pod, Zeroable)]
struct Vertex {
    position: [f32; 3],
    tex_coords: [f32; 2],
}

impl Vertex {
    fn desc<'a>() -> wgpu::VertexBufferLayout<'a> {
        wgpu::VertexBufferLayout {
            array_stride: mem::size_of::<Vertex>() as wgpu::BufferAddress,
            step_mode: wgpu::VertexStepMode::Vertex,
            attributes: &[
                wgpu::VertexAttribute {
                    offset: 0,
                    shader_location: 0,
                    format: wgpu::VertexFormat::Float32x3,
                },
                wgpu::VertexAttribute {
                    offset: mem::size_of::<[f32; 3]>() as wgpu::BufferAddress,
                    shader_location: 1,
                    format: wgpu::VertexFormat::Float32x2, // NEW!
                },
            ],
        }
    }
}

/// Texture coordinates.
///
/// ```no_run
///  (0.0)               (1.0)
///   V1 ----------------- V2
///   |                   / |
///   |     Q1         /    |
///   |             /       |
///   |          /          |
///   |       /             |
///   |    /         Q2     |
///   | /                   |
///   V3 ----------------- V4
///  (0.1)               (1.1)
/// ```
#[rustfmt::skip]
const VERTICES: &[Vertex] = &[
    Vertex { position: [-0.5, 0.5, 0.0], tex_coords: [0.0, 0.0] }, // A
    Vertex { position: [0.5, 0.5, 0.0], tex_coords: [1.0, 0.0] }, // B
    Vertex { position: [-0.5, -0.5, 0.0], tex_coords: [0.0, 1.0] }, // C
    Vertex { position: [0.5, -0.5, 0.0], tex_coords: [1.0, 1.0] }, // D
];

#[rustfmt::skip]
const INDICES: &[u16] = &[
    1, 0, 2,
    1, 2, 3,
];

struct State {
    surface: wgpu::Surface,
    device: wgpu::Device,
    queue: wgpu::Queue,
    config: wgpu::SurfaceConfiguration,
    size: winit::dpi::PhysicalSize<u32>,
    render_pipeline: wgpu::RenderPipeline,
    vertex_buffer: wgpu::Buffer,
    index_buffer: wgpu::Buffer,
    num_indices: u32,
    diffuse_bind_group: wgpu::BindGroup,
    diffuse_texture: Texture,
    camera: Camera,
    camera_uniform: CameraUniform,
    camera_buffer: wgpu::Buffer,
    camera_bind_group: wgpu::BindGroup,
    camera_controller: CameraController,
}

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

        // The instance is a handle to our GPU
        // Backends::all => Vulkan + Metal + DX12 + Browser WebGPU
        let instance = wgpu::Instance::new(wgpu::Backends::all());

        let surface = unsafe { instance.create_surface(window) };

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

        let (device, queue) = adapter
            .request_device(
                &wgpu::DeviceDescriptor {
                    features: wgpu::Features::empty(),
                    limits: wgpu::Limits::default(),
                    label: None,
                },
                None, // Trace path
            )
            .await
            .unwrap();

        let config = wgpu::SurfaceConfiguration {
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
            format: surface.get_preferred_format(&adapter).unwrap(),
            width: size.width,
            height: size.height,
            present_mode: wgpu::PresentMode::Fifo,
        };

        surface.configure(&device, &config);

        // Texture

        let diffuse_bytes = include_bytes!("../Resources/Tree.png");
        let diffuse_image = image::load_from_memory(diffuse_bytes).unwrap();
        let diffuse_rgba = diffuse_image.as_rgba8().unwrap();

        let dimensions = diffuse_image.dimensions();

        let texture_size = wgpu::Extent3d {
            width: dimensions.0,
            height: dimensions.1,
            depth_or_array_layers: 1,
        };

        let diffuse_texture = device.create_texture(&wgpu::TextureDescriptor {
            // All textures are stored as 3D, we represent our 2D texture
            // by setting depth to 1.
            size: texture_size,
            mip_level_count: 1, // We'll talk about this a little later
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            // Most images are stored using sRGB so we need to reflect that here.
            format: wgpu::TextureFormat::Rgba8UnormSrgb,
            // TEXTURE_BINDING tells wgpu that we want to use this texture in shaders
            // COPY_DST means that we want to copy data to this texture
            usage: wgpu::TextureUsages::TEXTURE_BINDING | wgpu::TextureUsages::COPY_DST,
            label: Some("diffuse_texture"),
        });

        queue.write_texture(
            // Tells wgpu where to copy the pixel data
            wgpu::ImageCopyTexture {
                texture: &diffuse_texture,
                mip_level: 0,
                origin: wgpu::Origin3d::ZERO,
                aspect: wgpu::TextureAspect::All,
            },
            // The actual pixel data
            diffuse_rgba,
            // The layout of the texture
            wgpu::ImageDataLayout {
                offset: 0,
                bytes_per_row: std::num::NonZeroU32::new(4 * dimensions.0),
                rows_per_image: std::num::NonZeroU32::new(dimensions.1),
            },
            texture_size,
        );

        let diffuse_bytes = include_bytes!("../Resources/Tree.png");
        let diffuse_texture =
            Texture::from_bytes(&device, &queue, diffuse_bytes, "Tree.png").unwrap();

        let texture_bind_group_layout =
            device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                entries: &[
                    wgpu::BindGroupLayoutEntry {
                        binding: 0,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Texture {
                            multisampled: false,
                            view_dimension: wgpu::TextureViewDimension::D2,
                            sample_type: wgpu::TextureSampleType::Float { filterable: true },
                        },
                        count: None,
                    },
                    wgpu::BindGroupLayoutEntry {
                        binding: 1,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Sampler {
                            // This is only for TextureSampleType::Depth
                            comparison: false,
                            // This should be true if the sample_type of the texture is:
                            //     TextureSampleType::Float { filterable: true }
                            // Otherwise you'll get an error.
                            filtering: true,
                        },
                        count: None,
                    },
                ],
                label: Some("texture_bind_group_layout"),
            });

        let diffuse_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: &texture_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&diffuse_texture.view),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&diffuse_texture.sampler),
                },
            ],
            label: Some("diffuse_bind_group"),
        });

        // Camera

        let camera = Camera {
            // position the camera one unit up and 2 units back
            // +z is out of the screen
            eye: (0.0, 1.0, 2.0).into(),
            // have it look at the origin
            target: (0.0, 0.0, 0.0).into(),
            // which way is "up"
            up: cgmath::Vector3::unit_y(),
            aspect: config.width as f32 / config.height as f32,
            fovy: 45.0,
            znear: 0.1,
            zfar: 100.0,
        };

        let camera_controller = CameraController::new(0.2);

        let mut camera_uniform = CameraUniform::new();
        camera_uniform.update_view_proj(&camera);

        let camera_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: Some("Camera Buffer"),
            contents: bytemuck::cast_slice(&[camera_uniform]),
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
        });

        let camera_bind_group_layout =
            device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                entries: &[wgpu::BindGroupLayoutEntry {
                    binding: 0,
                    visibility: wgpu::ShaderStages::VERTEX,
                    ty: wgpu::BindingType::Buffer {
                        ty: wgpu::BufferBindingType::Uniform,
                        has_dynamic_offset: false,
                        min_binding_size: None,
                    },
                    count: None,
                }],
                label: Some("camera_bind_group_layout"),
            });

        let camera_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: &camera_bind_group_layout,
            entries: &[wgpu::BindGroupEntry {
                binding: 0,
                resource: camera_buffer.as_entire_binding(),
            }],
            label: Some("camera_bind_group"),
        });

        // Shader

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

        // Pipeline

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

        let render_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Render Pipeline"),
            layout: Some(&render_pipeline_layout),
            vertex: wgpu::VertexState {
                module: &shader,
                entry_point: "main",
                buffers: &[Vertex::desc()],
            },
            fragment: Some(wgpu::FragmentState {
                // 3.
                module: &shader,
                entry_point: "main",
                targets: &[wgpu::ColorTargetState {
                    // 4.
                    format: config.format,
                    blend: Some(wgpu::BlendState::REPLACE),
                    write_mask: wgpu::ColorWrites::ALL,
                }],
            }),
            primitive: wgpu::PrimitiveState {
                topology: wgpu::PrimitiveTopology::TriangleList, // 1.
                strip_index_format: None,
                front_face: wgpu::FrontFace::Ccw, // 2.
                cull_mode: Some(wgpu::Face::Back),
                // Setting this to anything other than Fill requires Features::NON_FILL_POLYGON_MODE
                polygon_mode: wgpu::PolygonMode::Fill,
                // Requires Features::DEPTH_CLAMPING
                clamp_depth: false,
                // Requires Features::CONSERVATIVE_RASTERIZATION
                conservative: false,
            },
            depth_stencil: None, // 1.
            multisample: wgpu::MultisampleState {
                count: 1,                         // 2.
                mask: !0,                         // 3.
                alpha_to_coverage_enabled: false, // 4.
            },
        });

        //  Buffers

        let vertex_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: Some("Vertex Buffer"),
            contents: bytemuck::cast_slice(VERTICES),
            usage: wgpu::BufferUsages::VERTEX,
        });

        let index_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: Some("Index Buffer"),
            contents: bytemuck::cast_slice(INDICES),
            usage: wgpu::BufferUsages::INDEX,
        });

        let num_indices = INDICES.len() as u32;

        Self {
            surface,
            device,
            queue,
            config,
            size,
            render_pipeline,
            vertex_buffer,
            index_buffer,
            num_indices,
            diffuse_bind_group,
            diffuse_texture,
            camera,
            camera_uniform,
            camera_buffer,
            camera_bind_group,
            camera_controller,
        }
    }

    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);
        }
    }

    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]),
        );
    }

    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"),
            });

        {
            let mut render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                label: Some("Render Pass"),
                color_attachments: &[
                    // This is what [[location(0)]] in the fragment shader targets
                    wgpu::RenderPassColorAttachment {
                        view: &view,
                        resolve_target: None,
                        ops: wgpu::Operations {
                            load: wgpu::LoadOp::Clear(wgpu::Color {
                                r: 0.0,
                                g: 0.0,
                                b: 0.0,
                                a: 1.0,
                            }),
                            store: true,
                        },
                    },
                ],
                depth_stencil_attachment: None,
            });

            render_pass.set_pipeline(&self.render_pipeline);

            render_pass.set_bind_group(0, &self.diffuse_bind_group, &[]);
            render_pass.set_bind_group(1, &self.camera_bind_group, &[]);

            render_pass.set_vertex_buffer(0, self.vertex_buffer.slice(..));
            render_pass.set_index_buffer(self.index_buffer.slice(..), wgpu::IndexFormat::Uint16);

            render_pass.draw_indexed(0..self.num_indices, 0, 0..1);
        }

        // submit will accept anything that implements IntoIter
        self.queue.submit(std::iter::once(encoder.finish()));
        output.present();

        Ok(())
    }
}

fn main() {
    env_logger::init();

    let event_loop = EventLoop::new();

    let window = WindowBuilder::new()
        .with_title("Renderer")
        .with_inner_size(LogicalSize::new(1280, 720))
        .build(&event_loop)
        .unwrap();

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

    event_loop.run(move |event, _, control_flow| {
        match event {
            Event::WindowEvent {
                ref event,
                window_id,
            } if window_id == window.id() => {
                if !state.input(event) {
                    match event {
                        WindowEvent::CloseRequested
                        | WindowEvent::KeyboardInput {
                            input:
                                KeyboardInput {
                                    state: ElementState::Pressed,
                                    virtual_keycode: Some(VirtualKeyCode::Escape),
                                    ..
                                },
                            ..
                        } => *control_flow = ControlFlow::Exit,
                        WindowEvent::Resized(physical_size) => {
                            state.resize(*physical_size);
                        }
                        WindowEvent::ScaleFactorChanged { new_inner_size, .. } => {
                            state.resize(**new_inner_size);
                        }
                        _ => {}
                    }
                }
            }
            Event::RedrawRequested(_) => {
                state.update();
                match state.render() {
                    Ok(_) => {}
                    // Reconfigure the surface if lost
                    Err(wgpu::SurfaceError::Lost) => state.resize(state.size),
                    // The system is out of memory, we should probably quit
                    Err(wgpu::SurfaceError::OutOfMemory) => *control_flow = ControlFlow::Exit,
                    // All other errors (Outdated, Timeout) should be resolved by the next frame
                    Err(e) => eprintln!("{:?}", e),
                }
            }
            Event::MainEventsCleared => {
                // RedrawRequested will only trigger once, unless we manually
                // request it.
                window.request_redraw();
            }
            _ => {}
        }
    });
}