use bevy::{prelude::*, render::{render_resource::{Sampler, BindGroupLayout, BindGroupLayoutEntries, ShaderStages, binding_types::{texture_2d, sampler, uniform_buffer}, TextureSampleType, SamplerBindingType, SamplerDescriptor, PipelineCache, RenderPipelineDescriptor, CachedRenderPipelineId, PrimitiveState, MultisampleState, FragmentState, ColorTargetState, TextureFormat, ColorWrites}, renderer::RenderDevice, texture::BevyDefault}, core_pipeline::fullscreen_vertex_shader::fullscreen_shader_vertex_state};

use super::components;

#[derive(Resource)]
pub struct OutlinePostProcessPipeline {
    pub layout: BindGroupLayout,
    pub screen_sampler: Sampler,
    pub normal_sampler: Sampler,
    pub pipeline_id: CachedRenderPipelineId,
}

impl FromWorld for OutlinePostProcessPipeline {
    fn from_world(world: &mut World) -> Self {
        let render_device = world.resource::<RenderDevice>();

        let layout = render_device.create_bind_group_layout(
            "outline_post_process_bind_group_layout",
            &BindGroupLayoutEntries::sequential(
                ShaderStages::FRAGMENT,
                (
                    texture_2d(TextureSampleType::Float{ filterable: true }),
                    sampler(SamplerBindingType::Filtering),
                    texture_2d(TextureSampleType::Float{ filterable: true }),
                    sampler(SamplerBindingType::Filtering),
                    uniform_buffer::<components::OutlinePostProcessSettings>(false),
                ),
            ),
        );

        let screen_sampler = render_device.create_sampler(&SamplerDescriptor::default());
        let normal_sampler = render_device.create_sampler(&SamplerDescriptor::default());

        let shader = world.resource::<AssetServer>().load::<Shader>("embedded://grex_outline_post_process/../assets/shaders/outline_post_process.wgsl");
        
        let pipeline_id = world.resource_mut::<PipelineCache>().queue_render_pipeline(RenderPipelineDescriptor {
            label: Some("outline_post_process_render_pipeline".into()),
            layout: vec![layout.clone()],
            push_constant_ranges: vec![],
            vertex: fullscreen_shader_vertex_state(),
            primitive: PrimitiveState::default(),
            depth_stencil: None,
            multisample: MultisampleState::default(),
            fragment: Some(FragmentState {
                shader,
                shader_defs: vec![],
                entry_point: "fragment".into(),
                targets: vec![Some(ColorTargetState { 
                    format: TextureFormat::bevy_default(),
                    blend: None,
                    write_mask: ColorWrites::ALL, 
                })],
            }),
        });

        Self {
            layout,
            screen_sampler,
            normal_sampler,
            pipeline_id,
        }
    }
}