use std::collections::HashMap;

use crate::{GPU_TEXTURE_FORMAT, GpuError};

const FULLSCREEN_SHADER_SOURCE: &str = include_str!("shaders/fullscreen.wgsl");
const GAUSSIAN_BLUR_SHADER_SOURCE: &str = include_str!("shaders/gaussian_blur.wgsl");
const BLIT_SHADER_SOURCE: &str = include_str!("shaders/blit.wgsl");
pub const GAUSSIAN_BLUR_SHADER_ID: &str = "gaussian-blur";

pub struct ShaderRegistry {
    effect_texture_bind_group_layout: wgpu::BindGroupLayout,
    effect_uniform_bind_group_layout: wgpu::BindGroupLayout,
    effect_pipelines: HashMap<String, wgpu::RenderPipeline>,
    blit_pipeline: wgpu::RenderPipeline,
}

impl ShaderRegistry {
    pub fn new(device: &wgpu::Device) -> Self {
        let effect_texture_bind_group_layout =
            device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                label: Some("gpu-effect-texture-bind-group-layout"),
                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,
                    },
                ],
            });
        let effect_uniform_bind_group_layout =
            device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                label: Some("gpu-effect-uniform-bind-group-layout"),
                entries: &[wgpu::BindGroupLayoutEntry {
                    binding: 0,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Buffer {
                        ty: wgpu::BufferBindingType::Uniform,
                        has_dynamic_offset: false,
                        min_binding_size: None,
                    },
                    count: None,
                }],
            });

        let vertex_shader_module = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("gpu-fullscreen-shader"),
            source: wgpu::ShaderSource::Wgsl(FULLSCREEN_SHADER_SOURCE.into()),
        });
        let gaussian_blur_shader_module =
            device.create_shader_module(wgpu::ShaderModuleDescriptor {
                label: Some("gpu-gaussian-blur-shader"),
                source: wgpu::ShaderSource::Wgsl(GAUSSIAN_BLUR_SHADER_SOURCE.into()),
            });
        let blit_shader_module = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("gpu-blit-shader"),
            source: wgpu::ShaderSource::Wgsl(BLIT_SHADER_SOURCE.into()),
        });
        let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("gpu-effect-pipeline-layout"),
            bind_group_layouts: &[
                Some(&effect_texture_bind_group_layout),
                Some(&effect_uniform_bind_group_layout),
            ],
            immediate_size: 0,
        });
        let blit_pipeline_layout =
            device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
                label: Some("gpu-blit-pipeline-layout"),
                bind_group_layouts: &[Some(&effect_texture_bind_group_layout)],
                immediate_size: 0,
            });
        let gaussian_blur_pipeline =
            device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
                label: Some("gpu-gaussian-blur-pipeline"),
                layout: Some(&pipeline_layout),
                vertex: wgpu::VertexState {
                    module: &vertex_shader_module,
                    entry_point: Some("vertex_main"),
                    buffers: &[wgpu::VertexBufferLayout {
                        array_stride: std::mem::size_of::<[f32; 2]>() as u64,
                        step_mode: wgpu::VertexStepMode::Vertex,
                        attributes: &[wgpu::VertexAttribute {
                            format: wgpu::VertexFormat::Float32x2,
                            offset: 0,
                            shader_location: 0,
                        }],
                    }],
                    compilation_options: wgpu::PipelineCompilationOptions::default(),
                },
                fragment: Some(wgpu::FragmentState {
                    module: &gaussian_blur_shader_module,
                    entry_point: Some("fragment_main"),
                    targets: &[Some(wgpu::ColorTargetState {
                        format: GPU_TEXTURE_FORMAT,
                        blend: None,
                        write_mask: wgpu::ColorWrites::ALL,
                    })],
                    compilation_options: wgpu::PipelineCompilationOptions::default(),
                }),
                primitive: wgpu::PrimitiveState::default(),
                depth_stencil: None,
                multisample: wgpu::MultisampleState::default(),
                multiview_mask: None,
                cache: None,
            });
        let blit_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("gpu-blit-pipeline"),
            layout: Some(&blit_pipeline_layout),
            vertex: wgpu::VertexState {
                module: &vertex_shader_module,
                entry_point: Some("vertex_main"),
                buffers: &[wgpu::VertexBufferLayout {
                    array_stride: std::mem::size_of::<[f32; 2]>() as u64,
                    step_mode: wgpu::VertexStepMode::Vertex,
                    attributes: &[wgpu::VertexAttribute {
                        format: wgpu::VertexFormat::Float32x2,
                        offset: 0,
                        shader_location: 0,
                    }],
                }],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &blit_shader_module,
                entry_point: Some("fragment_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format: GPU_TEXTURE_FORMAT,
                    blend: None,
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState::default(),
            depth_stencil: None,
            multisample: wgpu::MultisampleState::default(),
            multiview_mask: None,
            cache: None,
        });

        let effect_pipelines = HashMap::from([(
            GAUSSIAN_BLUR_SHADER_ID.to_string(),
            gaussian_blur_pipeline,
        )]);

        Self {
            effect_texture_bind_group_layout,
            effect_uniform_bind_group_layout,
            effect_pipelines,
            blit_pipeline,
        }
    }

    pub fn get_effect_pipeline(&self, shader: &str) -> Result<&wgpu::RenderPipeline, GpuError> {
        self.effect_pipelines
            .get(shader)
            .ok_or_else(|| GpuError::UnknownEffectShader {
                shader: shader.to_string(),
            })
    }

    pub fn effect_texture_bind_group_layout(&self) -> &wgpu::BindGroupLayout {
        &self.effect_texture_bind_group_layout
    }

    pub fn effect_uniform_bind_group_layout(&self) -> &wgpu::BindGroupLayout {
        &self.effect_uniform_bind_group_layout
    }

    pub fn blit_pipeline(&self) -> &wgpu::RenderPipeline {
        &self.blit_pipeline
    }
}