use crate::{
    render::{data::PrimitiveInstance, util::ArrBuf},
    UI,
};
use data::WindowUniform;
use wgpu::{
    util::{BufferInitDescriptor, DeviceExt},
    *,
};
use winit::dpi::PhysicalSize;

mod data;
pub mod primitive;
mod util;

const SHAPE_SHADER: &str = include_str!("./shader.wgsl");

pub struct UIRenderNode {
    bind_group_layout: BindGroupLayout,
    bind_group: BindGroup,
    pipeline: RenderPipeline,

    window_buffer: Buffer,
    instance: ArrBuf<PrimitiveInstance>,
    data: ArrBuf<u32>,
}

impl UIRenderNode {
    pub fn draw<'a>(&'a self, pass: &mut RenderPass<'a>) {
        pass.set_pipeline(&self.pipeline);
        pass.set_bind_group(0, &self.bind_group, &[]);
        if self.instance.len() != 0 {
            pass.set_vertex_buffer(0, self.instance.buffer.slice(..));
            pass.draw(0..4, 0..self.instance.len() as u32);
        }
    }

    pub fn update(&mut self, device: &Device, queue: &Queue, ui: &UI) {
        let primitives = ui.to_primitives();
        self.instance.update(device, queue, &primitives.instances);
        self.data.update(device, queue, &primitives.data);
        self.bind_group = Self::bind_group(
            device,
            &self.bind_group_layout,
            &self.window_buffer,
            &self.data.buffer,
        )
    }

    pub fn resize(&mut self, size: &PhysicalSize<u32>, queue: &Queue) {
        let slice = &[WindowUniform {
            width: size.width as f32,
            height: size.height as f32,
        }];
        queue.write_buffer(&self.window_buffer, 0, bytemuck::cast_slice(slice));
    }

    pub fn new(device: &Device, config: &SurfaceConfiguration) -> Self {
        let shader = device.create_shader_module(ShaderModuleDescriptor {
            label: Some("UI Shape Shader"),
            source: ShaderSource::Wgsl(SHAPE_SHADER.into()),
        });

        let window_uniform = WindowUniform::default();
        let window_buffer = device.create_buffer_init(&BufferInitDescriptor {
            label: Some("Camera Buffer"),
            contents: bytemuck::cast_slice(&[window_uniform]),
            usage: BufferUsages::UNIFORM | BufferUsages::COPY_DST,
        });

        let instance = ArrBuf::new(
            device,
            BufferUsages::VERTEX | BufferUsages::COPY_DST,
            "instance",
        );
        let data = ArrBuf::new(
            device,
            BufferUsages::STORAGE | BufferUsages::COPY_DST,
            "data",
        );

        let bind_group_layout = device.create_bind_group_layout(&BindGroupLayoutDescriptor {
            entries: &[
                BindGroupLayoutEntry {
                    binding: 0,
                    visibility: ShaderStages::VERTEX,
                    ty: BindingType::Buffer {
                        ty: BufferBindingType::Uniform,
                        has_dynamic_offset: false,
                        min_binding_size: None,
                    },
                    count: None,
                },
                BindGroupLayoutEntry {
                    binding: 1,
                    visibility: ShaderStages::FRAGMENT,
                    ty: BindingType::Buffer {
                        ty: BufferBindingType::Storage { read_only: true },
                        has_dynamic_offset: false,
                        min_binding_size: None,
                    },
                    count: None,
                },
            ],
            label: Some("camera_bind_group_layout"),
        });

        let bind_group = Self::bind_group(device, &bind_group_layout, &window_buffer, &data.buffer);

        let pipeline_layout = device.create_pipeline_layout(&PipelineLayoutDescriptor {
            label: Some("UI Shape Pipeline Layout"),
            bind_group_layouts: &[&bind_group_layout],
            push_constant_ranges: &[],
        });
        let pipeline = device.create_render_pipeline(&RenderPipelineDescriptor {
            label: Some("UI Shape Pipeline"),
            layout: Some(&pipeline_layout),
            vertex: VertexState {
                module: &shader,
                entry_point: Some("vs_main"),
                buffers: &[PrimitiveInstance::desc()],
                compilation_options: Default::default(),
            },
            fragment: Some(FragmentState {
                module: &shader,
                entry_point: Some("fs_main"),
                targets: &[Some(ColorTargetState {
                    format: config.format,
                    blend: Some(BlendState::ALPHA_BLENDING),
                    write_mask: ColorWrites::ALL,
                })],
                compilation_options: Default::default(),
            }),
            primitive: PrimitiveState {
                topology: PrimitiveTopology::TriangleStrip,
                strip_index_format: None,
                front_face: FrontFace::Cw,
                cull_mode: Some(Face::Back),
                polygon_mode: PolygonMode::Fill,
                unclipped_depth: false,
                conservative: false,
            },
            depth_stencil: None,
            multisample: MultisampleState {
                count: 1,
                mask: !0,
                alpha_to_coverage_enabled: false,
            },
            multiview: None,
            cache: None,
        });

        Self {
            bind_group_layout,
            bind_group,
            pipeline,
            window_buffer,
            instance,
            data,
        }
    }

    pub fn bind_group(
        device: &Device,
        layout: &BindGroupLayout,
        window_buffer: &Buffer,
        data: &Buffer,
    ) -> BindGroup {
        device.create_bind_group(&BindGroupDescriptor {
            layout,
            entries: &[
                BindGroupEntry {
                    binding: 0,
                    resource: window_buffer.as_entire_binding(),
                },
                BindGroupEntry {
                    binding: 1,
                    resource: data.as_entire_binding(),
                },
            ],
            label: Some("ui_bind_group"),
        })
    }
}