use wgpu::util::DeviceExt;
use winit::dpi::PhysicalSize;

use super::Filter;

pub struct SquareFilter {
    uniform_buffer: wgpu::Buffer,
    bind_group: wgpu::BindGroup,
    pipeline: wgpu::RenderPipeline,
}

impl SquareFilter {
    pub fn new(
        device: &wgpu::Device,
        screen: &wgpu::TextureView,
        resolution: PhysicalSize<u32>,
        surface_format: wgpu::TextureFormat,
    ) -> SquareFilter {
        let uniforms = Uniforms {
            texture_scale: texture_scale_from_resolution(resolution),
        };

        let uniform_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: None,
            contents: bytemuck::cast_slice(&[uniforms]),
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
        });

        let 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(wgpu::SamplerBindingType::Filtering),
                    count: None,
                },
                wgpu::BindGroupLayoutEntry {
                    binding: 2,
                    visibility: wgpu::ShaderStages::VERTEX_FRAGMENT,
                    ty: wgpu::BindingType::Buffer {
                        ty: wgpu::BufferBindingType::Uniform,
                        has_dynamic_offset: false,
                        min_binding_size: None,
                    },
                    count: None,
                },
            ],
            label: None,
        });

        let sampler = device.create_sampler(&wgpu::SamplerDescriptor {
            mag_filter: wgpu::FilterMode::Linear,
            ..Default::default()
        });

        let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: &bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&screen),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
                wgpu::BindGroupEntry {
                    binding: 2,
                    resource: uniform_buffer.as_entire_binding(),
                },
            ],
            label: None,
        });

        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: None,
            source: wgpu::ShaderSource::Wgsl(include_str!("square.wgsl").into()),
        });

        let render_pipeline_layout =
            device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
                label: None,
                bind_group_layouts: &[&bind_group_layout],
                push_constant_ranges: &[],
            });

        let render_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: None,
            layout: Some(&render_pipeline_layout),
            vertex: wgpu::VertexState {
                module: &shader,
                entry_point: "vs_main",
                buffers: &[],
            },
            fragment: Some(wgpu::FragmentState {
                module: &shader,
                entry_point: "fs_main",
                targets: &[Some(wgpu::ColorTargetState {
                    format: surface_format,
                    blend: None,
                    write_mask: wgpu::ColorWrites::ALL,
                })],
            }),
            primitive: Default::default(),
            depth_stencil: None,
            multisample: Default::default(),
            multiview: None,
        });

        SquareFilter {
            uniform_buffer,
            bind_group,
            pipeline: render_pipeline,
        }
    }
}

impl Filter for SquareFilter {
    fn resize(&self, queue: &wgpu::Queue, new_size: PhysicalSize<u32>) {
        let uniforms = Uniforms {
            texture_scale: texture_scale_from_resolution(new_size),
        };
        queue.write_buffer(&self.uniform_buffer, 0, bytemuck::cast_slice(&[uniforms]));
    }

    fn render<'a>(&'a self, render_pass: &mut wgpu::RenderPass<'a>) {
        render_pass.set_pipeline(&self.pipeline);
        render_pass.set_bind_group(0, &self.bind_group, &[]);
        render_pass.draw(0..6, 0..1);
    }
}

fn texture_scale_from_resolution(res: PhysicalSize<u32>) -> [f32; 4] {
    let scale = ((res.width as f32) / 160.0).min((res.height as f32) / 120.0);
    [
        scale / res.width as f32,
        scale / res.height as f32,
        2.0 / scale,
        0.0,
    ]
}

#[repr(C)]
#[derive(Debug, Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
struct Uniforms {
    texture_scale: [f32; 4],
}