lumen-engine 0.2.1

use crate::node::{NodeId, NodeParamEvalContext, NodeParams, PortRef, compositing::BlendMode};

use crate::gpu::{
    BoundFrame, CompiledOutput, FrameBindContext, GpuCompileNode, GpuCompiledNode, RasterHandle,
    compiler,
};

pub(crate) const SHADER: &str = include_str!("merge.wgsl");

/// Composites an overlay raster over a base raster.
#[derive(Debug, Clone, lumen_macros::Delegate)]
pub struct MergeParams {
    /// Overlay opacity applied before compositing.
    #[meta(min = 0, max = 1, step = 0.05)]
    pub opacity: f64,
    /// Blend mode used when combining the overlay with the base raster.
    #[meta()]
    pub blend_mode: BlendMode,
}

impl Default for MergeParams {
    fn default() -> Self {
        Self {
            opacity: 1.0,
            blend_mode: BlendMode::Normal,
        }
    }
}

/// Composites an overlay raster over a base raster.
#[derive(Debug, Clone, lumen_macros::Node)]
#[node(kind = "merge", name = "Merge", category = "compositing")]
pub struct Merge {
    pub id: NodeId,
    #[params]
    pub params: MergeParamsDelegate,

    #[input()]
    pub base: PortRef,
    #[input()]
    pub overlay: PortRef,
    #[input(optional)]
    pub mask: PortRef,
}

impl Default for Merge {
    fn default() -> Self {
        Self {
            id: NodeId::new(0),
            params: MergeParamsDelegate::default(),
            base: PortRef::empty(),
            overlay: PortRef::empty(),
            mask: PortRef::empty(),
        }
    }
}

#[derive(Debug, Clone)]
struct CompiledMerge {
    node_id: NodeId,
    params: MergeParamsDelegate,
    has_mask: bool,
    buffer: lumen_gpu::BufferId,
}

impl GpuCompiledNode for CompiledMerge {
    fn node_id(&self) -> NodeId {
        self.node_id
    }

    fn bind(&self, ctx: &FrameBindContext<'_>, bound: &mut BoundFrame) -> crate::Result<()> {
        let evaluated = self.params.eval(&NodeParamEvalContext {
            node_id: self.node_id,
            expr: &ctx.expr_context(self.node_id, "params"),
        })?;
        let params = compiler::MergeParams {
            opacity: evaluated.opacity as f32,
            blend_mode: evaluated.blend_mode as u32,
            has_mask: u32::from(self.has_mask),
            _pad: 0,
        };
        bound.write_buffer(self.buffer, 0, bytemuck::bytes_of(&params));
        Ok(())
    }
}

impl GpuCompileNode for Merge {
    fn compile_gpu(
        &self,
        ctx: &mut crate::gpu::CompileContext<'_>,
        port: &PortRef,
    ) -> crate::Result<CompiledOutput> {
        if port.port != "output" {
            return Err(ctx.missing_output(self.id, &port.port));
        }

        let base = ctx
            .compile_port(&self.base)?
            .into_raster(self.base.id, &self.base.port)?;
        let overlay = ctx
            .compile_port(&self.overlay)?
            .into_raster(self.overlay.id, &self.overlay.port)?;
        let mask = if self.mask.is_empty() {
            None
        } else {
            Some(
                ctx.compile_port(&self.mask)?
                    .into_raster(self.mask.id, &self.mask.port)?,
            )
        };

        let size = base.domain.storage_size;
        let texture = ctx.builder_mut().texture_for(
            lumen_gpu::NodeKey(self.id.0),
            Some(format!("merge:{}:output", self.id.0)),
            lumen_gpu::TextureDesc::storage(size, lumen_gpu::wgpu::TextureFormat::Rgba8Unorm),
        );
        let params = ctx.builder_mut().buffer_for(
            lumen_gpu::NodeKey(self.id.0),
            Some(format!("merge:{}:params", self.id.0)),
            lumen_gpu::BufferDesc::uniform(std::mem::size_of::<compiler::MergeParams>() as u64),
        );
        let program = ctx.builder_mut().program_for(
            lumen_gpu::NodeKey(self.id.0),
            lumen_gpu::ProgramDesc::Compute(lumen_gpu::ComputeProgramDesc {
                label: Some("merge".to_string()),
                shader: SHADER.to_string(),
                entry: "cs_main".to_string(),
                bind_groups: lumen_gpu::BindGroupLayoutSpec::single(vec![
                    lumen_gpu::BindingLayoutEntry::texture(
                        0,
                        lumen_gpu::wgpu::ShaderStages::COMPUTE,
                    ),
                    lumen_gpu::BindingLayoutEntry::texture(
                        1,
                        lumen_gpu::wgpu::ShaderStages::COMPUTE,
                    ),
                    lumen_gpu::BindingLayoutEntry::texture(
                        2,
                        lumen_gpu::wgpu::ShaderStages::COMPUTE,
                    ),
                    lumen_gpu::BindingLayoutEntry::uniform(
                        3,
                        lumen_gpu::wgpu::ShaderStages::COMPUTE,
                    ),
                    lumen_gpu::BindingLayoutEntry::storage_texture(
                        4,
                        lumen_gpu::wgpu::ShaderStages::COMPUTE,
                        lumen_gpu::wgpu::TextureFormat::Rgba8Unorm,
                        lumen_gpu::wgpu::StorageTextureAccess::WriteOnly,
                    ),
                ]),
            }),
        );
        ctx.builder_mut().compute_pass(lumen_gpu::ComputePassDesc {
            label: Some(format!("merge:{}:blend", self.id.0)),
            owner: Some(lumen_gpu::NodeKey(self.id.0)),
            program,
            bindings: vec![
                lumen_gpu::Binding::sampled_texture(0, 0, base.texture),
                lumen_gpu::Binding::sampled_texture(0, 1, overlay.texture),
                lumen_gpu::Binding::sampled_texture(
                    0,
                    2,
                    mask.map(|mask| mask.texture).unwrap_or(base.texture),
                ),
                lumen_gpu::Binding::uniform(0, 3, params),
                lumen_gpu::Binding::storage_texture(0, 4, texture),
            ],
            dispatch: compiler::dispatch_for(size).into(),
        });
        ctx.builder_mut().param(
            lumen_gpu::ParamKey {
                owner: lumen_gpu::NodeKey(self.id.0),
                slot: 0,
            },
            lumen_gpu::ParamTarget::Buffer(params),
        );
        ctx.register_compiled_node(CompiledMerge {
            node_id: self.id,
            params: self.params.clone(),
            has_mask: !self.mask.is_empty(),
            buffer: params,
        });

        Ok(CompiledOutput::Raster(RasterHandle {
            texture,
            domain: lumen_gpu::TextureDomain::full_frame(size),
            metadata: base.metadata,
        }))
    }
}