#![allow(non_snake_case)]
#![allow(unused_variables)]

use anyhow::Result;
use cgmath::prelude::*;
use std::path::PathBuf;
use std::time::Duration;
use wgpu::util::DeviceExt;
use winit::event::*;
use Graphics::Camera::*;
use Graphics::Render::*;
use Graphics::{Display, Runtime, State};

struct Cubes {
    render_pipeline: wgpu::RenderPipeline,
    obj_model: Model,
    camera: Camera,
    camera_controller: CameraController,
    camera_uniform: CameraUniform,
    camera_buffer: wgpu::Buffer,
    camera_bind_group: wgpu::BindGroup,
    instances: Vec<Instance>,
    instance_buffer: wgpu::Buffer,
    depth_texture: Texture,
}

impl State for Cubes {
    fn Init(display: &Display) -> Result<Self> {
        let texture_bind_group_layout =
            display
                .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 {
                                comparison: false,
                                filtering: true,
                            },
                            count: None,
                        },
                    ],
                    label: Some("texture_bind_group_layout"),
                });

        // Camera

        let camera = Camera {
            eye: (0.0, 5.0, -10.0).into(),
            target: (0.0, 0.0, 0.0).into(),
            up: cgmath::Vector3::unit_y(),
            aspect: display.config.width as f32 / display.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.UpdateViewProjection(&camera);

        let camera_buffer = display
            .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,
            });

        const SPACE_BETWEEN: f32 = 3.0;
        let instances = (0..NUM_INSTANCES_PER_ROW)
            .flat_map(|z| {
                (0..NUM_INSTANCES_PER_ROW).map(move |x| {
                    let x = SPACE_BETWEEN * (x as f32 - NUM_INSTANCES_PER_ROW as f32 / 2.0);
                    let z = SPACE_BETWEEN * (z as f32 - NUM_INSTANCES_PER_ROW as f32 / 2.0);

                    let position = cgmath::Vector3 { x, y: 0.0, z };

                    let rotation = if position.is_zero() {
                        cgmath::Quaternion::from_axis_angle(
                            cgmath::Vector3::unit_z(),
                            cgmath::Deg(0.0),
                        )
                    } else {
                        cgmath::Quaternion::from_axis_angle(position.normalize(), cgmath::Deg(45.0))
                    };

                    Instance { position, rotation }
                })
            })
            .collect::<Vec<_>>();

        let instance_data = instances.iter().map(Instance::ToRaw).collect::<Vec<_>>();
        let instance_buffer =
            display
                .device
                .create_buffer_init(&wgpu::util::BufferInitDescriptor {
                    label: Some("Instance Buffer"),
                    contents: bytemuck::cast_slice(&instance_data),
                    usage: wgpu::BufferUsages::VERTEX,
                });

        let camera_bind_group_layout =
            display
                .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 = display
            .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"),
            });

        // Model

        let obj_model = Model::Load(
            &display.device,
            &display.queue,
            &texture_bind_group_layout,
            PathBuf::from("./Content/SM_Cube.obj"),
        )
        .unwrap();

        // Shader

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

        // Texture

        let depth_texture =
            Texture::CreateDepthTexture(&display.device, &display.config, "depth_texture");

        // Pipeline

        let render_pipeline_layout =
            display
                .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 =
            display
                .device
                .create_render_pipeline(&wgpu::RenderPipelineDescriptor {
                    label: Some("Render Pipeline"),
                    layout: Some(&render_pipeline_layout),
                    vertex: wgpu::VertexState {
                        module: &shader,
                        entry_point: "vs_main",
                        buffers: &[ModelVertex::GetDescriptor(), InstanceRaw::GetDescriptor()],
                    },
                    fragment: Some(wgpu::FragmentState {
                        module: &shader,
                        entry_point: "fs_main",
                        targets: &[wgpu::ColorTargetState {
                            format: display.config.format,
                            blend: Some(wgpu::BlendState {
                                color: wgpu::BlendComponent::REPLACE,
                                alpha: wgpu::BlendComponent::REPLACE,
                            }),
                            write_mask: wgpu::ColorWrites::ALL,
                        }],
                    }),
                    primitive: wgpu::PrimitiveState {
                        topology: wgpu::PrimitiveTopology::TriangleList,
                        strip_index_format: None,
                        front_face: wgpu::FrontFace::Ccw,
                        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: Some(wgpu::DepthStencilState {
                        format: Texture::DEPTH_FORMAT,
                        depth_write_enabled: true,
                        depth_compare: wgpu::CompareFunction::Less,
                        stencil: wgpu::StencilState::default(),
                        bias: wgpu::DepthBiasState::default(),
                    }),
                    multisample: wgpu::MultisampleState {
                        count: 1,
                        mask: !0,
                        alpha_to_coverage_enabled: false,
                    },
                });

        Ok(Self {
            render_pipeline,
            obj_model,
            camera,
            camera_controller,
            camera_buffer,
            camera_bind_group,
            camera_uniform,
            instances,
            instance_buffer,
            depth_texture,
        })
    }

    fn Input(&mut self, display: &Display, event: &WindowEvent) -> bool {
        self.camera_controller.ProcessEvents(event)
    }

    fn Update(&mut self, display: &Display, delta: Duration) {
        self.camera_controller.UpdateCamera(&mut self.camera);
        self.camera_uniform.UpdateViewProjection(&self.camera);
        display.queue.write_buffer(
            &self.camera_buffer,
            0,
            bytemuck::cast_slice(&[self.camera_uniform]),
        );
    }

    fn Resize(&mut self, display: &Display) {
        self.depth_texture =
            Texture::CreateDepthTexture(&display.device, &display.config, "depth_texture");
    }

    fn Draw(&mut self, display: &mut Display) -> Result<(), wgpu::SurfaceError> {
        let output = display.surface.get_current_texture().unwrap();
        let view = output
            .texture
            .create_view(&wgpu::TextureViewDescriptor::default());

        let mut encoder = display
            .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: &[wgpu::RenderPassColorAttachment {
                    view: &view,
                    resolve_target: None,
                    ops: wgpu::Operations {
                        load: wgpu::LoadOp::Clear(wgpu::Color {
                            r: 0.1,
                            g: 0.2,
                            b: 0.3,
                            a: 1.0,
                        }),
                        store: true,
                    },
                }],
                depth_stencil_attachment: Some(wgpu::RenderPassDepthStencilAttachment {
                    view: &self.depth_texture.view,
                    depth_ops: Some(wgpu::Operations {
                        load: wgpu::LoadOp::Clear(1.0),
                        store: true,
                    }),
                    stencil_ops: None,
                }),
            });

            render_pass.set_vertex_buffer(1, self.instance_buffer.slice(..));
            render_pass.set_pipeline(&self.render_pipeline);
            render_pass.DrawModelInstanced(
                &self.obj_model,
                0..self.instances.len() as u32,
                &self.camera_bind_group,
            );
        }

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

        Ok(())
    }
}

fn main() -> Result<()> {
    Runtime::Execute::<Cubes>()
}