import type {
  GraphLayoutV2,
  GraphNode,
  GraphSnapshot,
  ParameterValue,
} from "fxnode";
import { isPhysicalRenderGraph, reconstructRenderGraph } from "./physical";

type PlainObject = Record<string, any>;
type GraphSource = GraphLayoutV2 | GraphSnapshot;

const modeTypes = new Set([
  "yawn.rg.mode.beauty",
  "yawn.rg.mode.normals",
  "yawn.rg.mode.depth",
  "yawn.rg.mode.unlit",
  "yawn.rg.mode.object-id",
]);

const effectTypes = new Set([
  "yawn.rg.post.fxaa",
  "yawn.rg.post.bloom",
  "yawn.rg.post.edges",
  "yawn.rg.post.color-grade",
  "yawn.rg.post.vignette",
  "yawn.rg.post.grayscale",
  "yawn.rg.post.invert",
]);

function plainRecord(value: unknown): value is PlainObject {
  if (!value || typeof value !== "object" || Array.isArray(value)) return false;
  const prototype = Object.getPrototypeOf(value);
  return prototype === Object.prototype || prototype === null;
}

function encodeValue(value: unknown): string {
  if (value === null || typeof value === "boolean") return String(value);
  if (typeof value === "number") {
    if (!Number.isFinite(value))
      throw new TypeError("Render graph numbers must be finite");
    return String(value);
  }
  if (typeof value === "string") return JSON.stringify(value);
  if (Array.isArray(value))
    return `(array${value.map((item) => ` ${encodeValue(item)}`).join("")})`;
  if (plainRecord(value))
    return `(object${Object.keys(value)
      .sort()
      .map(
        (key) => ` (field ${JSON.stringify(key)} ${encodeValue(value[key])})`,
      )
      .join("")})`;
  throw new TypeError("Render graph values must be plain data");
}

/** Encodes a Yawn render graph into the core's versioned S-expression wire format. */
export function encodeRenderGraph(graph: object): string {
  if (!plainRecord(graph))
    throw new TypeError("Render graph must be a plain object");
  return `(yawn-graph 1 ${encodeValue(graph)})`;
}

function value<T>(node: GraphNode | any, key: string, fallback: T): T {
  const parameter = node.parameters?.[key] as ParameterValue | undefined;
  return (parameter && "value" in parameter ? parameter.value : fallback) as T;
}

function activeChain(layout: GraphSource): any[] {
  if (!layout || !Array.isArray(layout.nodes) || !Array.isArray(layout.links))
    throw new TypeError("FxNode loadout is not a graph layout");
  const nodes = new Map(
    layout.nodes.map((node: any) => [String(node.id), node]),
  );
  const outputs = layout.nodes.filter(
    (node: any) => node.typeId === "yawn.rg.output.present" && !node.muted,
  );
  if (outputs.length !== 1)
    throw new Error("Loadout must contain exactly one active Present node");
  const incoming = new Map<string, any>();
  for (const link of layout.links) {
    if (link.muted) continue;
    if (incoming.has(String(link.toSocketId)))
      throw new Error(
        `Loadout input ${String(link.toSocketId)} has multiple links`,
      );
    incoming.set(String(link.toSocketId), link);
  }

  const chain: any[] = [outputs[0]];
  const seen = new Set<string>();
  let current = outputs[0];
  while (current.typeId !== "yawn.rg.input.scene") {
    if (seen.has(String(current.id)))
      throw new Error("Loadout contains a cycle");
    seen.add(String(current.id));
    const link = incoming.get(`${String(current.id)}:surface`);
    if (!link)
      throw new Error(
        `${String(current.label || current.typeId)} is not connected to Scene`,
      );
    current = nodes.get(String(link.fromNodeId));
    if (!current)
      throw new Error(
        `Loadout link references missing node ${String(link.fromNodeId)}`,
      );
    if (current.muted) {
      const bypass = incoming.get(`${String(current.id)}:surface`);
      current = bypass ? nodes.get(String(bypass.fromNodeId)) : undefined;
      if (!current)
        throw new Error("Muted stage has no connected bypass input");
    }
    chain.unshift(current);
  }
  return chain;
}

function passResources(pass: PlainObject): string[] {
  return [
    ...(pass.bindings ?? []),
    ...(pass.color ?? []),
    ...(pass.vertexBuffers ?? []),
    ...(pass.depth ? [pass.depth] : []),
    ...(pass.indexBuffer ? [pass.indexBuffer] : []),
  ]
    .map((item: PlainObject) => item?.resource)
    .filter(
      (resource: unknown): resource is string => typeof resource === "string",
    );
}

function debugShader(mode: string, normalBuffer: boolean, node: any): string {
  const contrast = Number(value(node, "contrast", 1.35));
  const clay = value<readonly number[]>(node, "color", [0.36, 0.68, 0.9, 1]);
  const usesNormals = mode === "normals" || mode === "unlit";
  const usesObjectId = mode === "object-id";
  const fragment =
    mode === "normals"
      ? "return vec4<f32>(normalize(input.normal) * 0.5 + 0.5, 1.0);"
      : mode === "depth"
        ? `let depth = pow(clamp(1.0 - input.position.z, 0.0, 1.0), ${(Math.max(0.01, contrast) * 0.12).toFixed(4)}); return vec4<f32>(vec3<f32>(depth), 1.0);`
        : mode === "unlit"
          ? `let base = vec3<f32>(${Number(clay[0] ?? 0.36).toFixed(5)}, ${Number(clay[1] ?? 0.68).toFixed(5)}, ${Number(clay[2] ?? 0.9).toFixed(5)}); let light = 0.32 + max(dot(normalize(input.normal), normalize(vec3<f32>(0.35, 0.8, 0.45))), 0.0) * 0.68; return vec4<f32>(base * light, 1.0);`
          : "let seed = f32(input.objectId) * 0.61803398875; let color = 0.42 + 0.58 * cos(vec3<f32>(0.0, 2.1, 4.2) + seed * 6.28318); return vec4<f32>(color, 1.0);";
  return `
struct VertexOutput {
  @invariant @builtin(position) position: vec4<f32>,
  ${usesNormals ? "@location(0) normal: vec3<f32>," : ""}
  ${usesObjectId ? `@location(${usesNormals ? 1 : 0}) @interpolate(flat) objectId: u32,` : ""}
}
@group(0) @binding(0) var<storage, read> positions: array<vec4<f32>>;
@group(0) @binding(1) var<storage, read> rotors: array<vec4<f32>>;
@group(0) @binding(2) var<storage, read> scales: array<vec4<f32>>;
@group(0) @binding(3) var<storage, read> meshInfo: array<u32>;
@group(0) @binding(4) var<storage, read> cameraMatrices: array<vec4<f32>>;
fn rotate(rotor: vec4<f32>, point: vec3<f32>) -> vec3<f32> {
  return point + 2.0 * cross(rotor.xyz, cross(rotor.xyz, point) + rotor.w * point);
}
@vertex fn vertex(
  @location(0) point: vec3<f32>,
  ${normalBuffer ? "@location(1) localNormal: vec3<f32>," : ""}
  @builtin(instance_index) packed: u32,
) -> VertexOutput {
  let instance = packed & 65535u;
  let transformed = rotate(rotors[instance], point * scales[instance].xyz) + positions[instance].xyz;
  let world = vec4<f32>(transformed, 1.0);
  var output: VertexOutput;
  output.position = vec4<f32>(
    dot(cameraMatrices[0], world), dot(cameraMatrices[1], world),
    dot(cameraMatrices[2], world), dot(cameraMatrices[3], world));
  if (cameraMatrices[4].w == 0.0) { output.position = world; }
  output.position = select(vec4<f32>(2.0, 2.0, 2.0, 1.0), output.position, meshInfo[instance * 4u + 2u] != 0u);
  ${usesNormals ? `output.normal = normalize(rotate(rotors[instance], ${normalBuffer ? "localNormal / scales[instance].xyz" : "vec3<f32>(0.0, 0.0, 1.0)"}));` : ""}
  ${usesObjectId ? "output.objectId = instance;" : ""}
  return output;
}
@fragment fn fragment(input: VertexOutput) -> @location(0) vec4<f32> {
  ${fragment}
}`;
}

function applyDebugMode(graph: PlainObject, node: any): void {
  const mode = String(node.typeId).slice("yawn.rg.mode.".length);
  if (mode === "beauty") return;
  const renderPipelines = graph.pipelines?.render;
  if (!Array.isArray(renderPipelines) || !Array.isArray(graph.passes))
    throw new Error("Base render graph has no render pipeline declarations");
  const byId = new Map(
    renderPipelines.map((pipeline: any) => [pipeline.id, pipeline]),
  );
  const passesById = new Map(
    graph.passes.map((pass: PlainObject) => [pass.id, pass]),
  );
  const detachedComputePasses = new Set<string>();
  const generated = new Map<string, string>();
  for (const pass of graph.passes) {
    if (
      pass.type !== "render" ||
      typeof pass.pipeline !== "string" ||
      !pass.pipeline.startsWith("forward-") ||
      pass.pipeline === "empty-forward" ||
      pass.draw?.vertices === 0
    )
      continue;
    const original = byId.get(pass.pipeline);
    if (!original)
      throw new Error(`Forward pipeline ${pass.pipeline} is missing`);
    const detailed = (original.vertex?.buffers?.length ?? 0) >= 2;
    const format = original.fragment?.targets?.[0]?.format;
    if (typeof format !== "string")
      throw new Error(`Forward pipeline ${pass.pipeline} has no color target`);
    const normalBuffer = (mode === "normals" || mode === "unlit") && detailed;
    const key = `${mode}:${normalBuffer}:${format}`;
    let id = generated.get(key);
    if (!id) {
      id = `rg-${mode}-${normalBuffer ? "detailed" : "basic"}`;
      let suffix = 1;
      while (byId.has(id))
        id = `rg-${mode}-${normalBuffer ? "detailed" : "basic"}-${suffix++}`;
      const pipeline = {
        id,
        code: debugShader(mode, normalBuffer, node),
        vertex: {
          entry: "vertex",
          buffers: original.vertex.buffers.slice(0, normalBuffer ? 2 : 1),
        },
        fragment: { entry: "fragment", targets: [{ format }] },
        depthStencil: original.depthStencil ?? null,
        primitive: original.primitive ?? null,
      };
      renderPipelines.push(pipeline);
      byId.set(id, pipeline);
      generated.set(key, id);
    }
    pass.pipeline = id;
    const resources = [
      "node-positions",
      "node-rotors",
      "node-scales",
      "mesh-info",
      "camera-matrices",
    ];
    pass.bindings = resources.map((resource, binding) => ({
      group: 0,
      binding,
      resource,
    }));
    pass.vertexBuffers = (pass.vertexBuffers ?? []).filter(
      (binding: any) =>
        binding.slot === 0 || (normalBuffer && binding.slot === 1),
    );
    const used = new Set(passResources(pass));
    pass.after = (pass.after ?? []).filter((dependency: string) => {
      const candidate = passesById.get(dependency);
      if (
        candidate?.type !== "compute" ||
        passResources(candidate).some((resource) => used.has(resource))
      )
        return true;
      detachedComputePasses.add(dependency);
      return false;
    });
  }
  const retainedDependencies = new Set(
    graph.passes.flatMap((pass: PlainObject) => pass.after ?? []),
  );
  graph.passes = graph.passes.filter((pass: PlainObject) => {
    if (
      !detachedComputePasses.has(pass.id) ||
      retainedDependencies.has(pass.id)
    )
      return true;
    const resources = new Set(passResources(pass));
    return graph.passes.some(
      (other: PlainObject) =>
        other !== pass &&
        passResources(other).some((resource) => resources.has(resource)),
    );
  });
}

type Rgb = readonly [number, number, number];

const luma = ([red, green, blue]: Rgb) =>
  red * 0.2126 + green * 0.7152 + blue * 0.0722;

function rgbParameter(node: any, key: string): Rgb {
  const color = value<readonly number[]>(node, key, [1, 1, 1, 1]);
  return [Number(color[0] ?? 1), Number(color[1] ?? 1), Number(color[2] ?? 1)];
}

function normalizedBalance(color: Rgb): Rgb {
  const luminance = Math.max(0.001, luma(color));
  return [color[0] / luminance, color[1] / luminance, color[2] / luminance];
}

function mapRgb(
  color: Rgb,
  transform: (channel: number, index: number) => number,
): Rgb {
  return [
    transform(color[0], 0),
    transform(color[1], 1),
    transform(color[2], 2),
  ];
}

function wgslRgb(color: Rgb): string {
  return `vec3<f32>(${color.map((channel) => channel.toFixed(5)).join(", ")})`;
}

function colorTemperature(kelvin: number): Rgb {
  const temperature = Math.min(40000, Math.max(1000, kelvin)) / 100;
  const red =
    temperature <= 66
      ? 255
      : 329.698727446 * Math.pow(temperature - 60, -0.1332047592);
  const green =
    temperature <= 66
      ? 99.4708025861 * Math.log(temperature) - 161.1195681661
      : 288.1221695283 * Math.pow(temperature - 60, -0.0755148492);
  const blue =
    temperature >= 66
      ? 255
      : temperature <= 19
        ? 0
        : 138.5177312231 * Math.log(temperature - 10) - 305.0447927307;
  const linear = (channel: number) => {
    const srgb = Math.min(1, Math.max(0, channel / 255));
    return srgb <= 0.04045
      ? srgb / 12.92
      : Math.pow((srgb + 0.055) / 1.055, 2.4);
  };
  return [linear(red), linear(green), linear(blue)];
}

function whitePoint(node: any, prefix: "input" | "output"): Rgb {
  const temperature = colorTemperature(
    Number(value(node, `${prefix}Temperature`, 6500)),
  );
  const tint = Math.min(
    1,
    Math.max(-1, Number(value(node, `${prefix}Tint`, 0))),
  );
  const color = rgbParameter(node, `${prefix}Color`);
  return [
    temperature[0] * (1 - tint * 0.18) * color[0],
    temperature[1] * (1 + tint * 0.24) * color[1],
    temperature[2] * (1 - tint * 0.18) * color[2],
  ];
}

function colorBalanceExpression(node: any): string {
  const mode = String(value(node, "mode", "Lift/Gamma/Gain"));
  if (mode === "Offset/Power/Slope") {
    const offset = Number(value(node, "offset", 0));
    const power = Number(value(node, "power", 1));
    const slope = Number(value(node, "slope", 1));
    const offsetBalance = mapRgb(
      normalizedBalance(rgbParameter(node, "offsetColor")),
      (channel) => channel - 1 + offset,
    );
    const powerBalance = mapRgb(
      normalizedBalance(rgbParameter(node, "powerColor")),
      (channel) => Math.max(0.01, channel * power),
    );
    const slopeBalance = mapRgb(
      normalizedBalance(rgbParameter(node, "slopeColor")),
      (channel) => Math.max(0, channel * slope),
    );
    return `
  let offsetBalance = ${wgslRgb(offsetBalance)};
  let powerBalance = ${wgslRgb(powerBalance)};
  let slopeBalance = ${wgslRgb(slopeBalance)};
  color = pow(max(color * slopeBalance + offsetBalance, vec3<f32>(0.0)), powerBalance);`;
  }
  if (mode === "White Point") {
    const input = whitePoint(node, "input");
    const output = whitePoint(node, "output");
    const adaptation = mapRgb(
      output,
      (channel, index) => channel / Math.max(0.001, input[index]!),
    );
    return `
  let whitePointAdaptation = ${wgslRgb(adaptation)};
  color *= whitePointAdaptation;`;
  }

  const lift = Number(value(node, "lift", 0));
  const gamma = Number(value(node, "gamma", 1));
  const gain = Number(value(node, "gain", 1));
  const liftBalance = mapRgb(
    normalizedBalance(rgbParameter(node, "liftColor")),
    (channel) => channel - 1 + lift,
  );
  const gammaBalance = mapRgb(
    normalizedBalance(rgbParameter(node, "gammaColor")),
    (channel) => Math.max(0.01, channel * gamma),
  );
  const gainBalance = mapRgb(
    normalizedBalance(rgbParameter(node, "gainColor")),
    (channel) => Math.max(0, channel * gain),
  );
  return `
  let liftBalance = ${wgslRgb(liftBalance)};
  let gammaBalance = ${wgslRgb(gammaBalance)};
  let gainBalance = ${wgslRgb(gainBalance)};
  color = max(color + liftBalance, vec3<f32>(0.0));
  color = pow(color, vec3<f32>(1.0) / gammaBalance) * gainBalance;`;
}

const fullScreenVertex = `
struct VertexOutput { @builtin(position) position: vec4<f32>, @location(0) uv: vec2<f32> }
@vertex fn vertex(@builtin(vertex_index) index: u32) -> VertexOutput {
  let points = array<vec2<f32>, 3>(vec2(-1.0, -1.0), vec2(3.0, -1.0), vec2(-1.0, 3.0));
  var output: VertexOutput;
  output.position = vec4(points[index], 0.0, 1.0);
  output.uv = points[index] * vec2(0.5, -0.5) + vec2(0.5);
  return output;
}`;

function effectExpression(node: any): string {
  if (node.typeId === "yawn.rg.post.fxaa")
    return `
  let size = vec2<f32>(textureDimensions(source));
  let step = 1.0 / size;
  let center = textureSample(source, sourceSampler, input.uv);
  let horizontal = textureSample(source, sourceSampler, input.uv + vec2(step.x, 0.0)) + textureSample(source, sourceSampler, input.uv - vec2(step.x, 0.0));
  let vertical = textureSample(source, sourceSampler, input.uv + vec2(0.0, step.y)) + textureSample(source, sourceSampler, input.uv - vec2(0.0, step.y));
  return center * 0.5 + (horizontal + vertical) * 0.125;`;
  if (node.typeId === "yawn.rg.post.bloom") {
    const threshold = Number(value(node, "threshold", 0.7));
    const strength = Number(value(node, "strength", 0.3));
    return `
  let size = vec2<f32>(textureDimensions(source));
  let step = 2.0 / size;
  let center = textureSample(source, sourceSampler, input.uv);
  var glow = vec4<f32>(0.0);
  glow += textureSample(source, sourceSampler, input.uv + vec2(step.x, 0.0));
  glow += textureSample(source, sourceSampler, input.uv - vec2(step.x, 0.0));
  glow += textureSample(source, sourceSampler, input.uv + vec2(0.0, step.y));
  glow += textureSample(source, sourceSampler, input.uv - vec2(0.0, step.y));
  glow *= 0.25;
  let bright = max(glow.rgb - vec3<f32>(${threshold.toFixed(5)}), vec3<f32>(0.0));
  return vec4<f32>(center.rgb + bright * ${strength.toFixed(5)}, center.a);`;
  }
  if (node.typeId === "yawn.rg.post.edges") {
    const strength = Number(value(node, "strength", 0.8));
    const style = String(value(node, "style", "ink"));
    if (style === "blueprint")
      return `
  let size = vec2<f32>(textureDimensions(source));
  let step = 1.0 / size;
  let center = textureSample(source, sourceSampler, input.uv);
  let right = textureSample(source, sourceSampler, input.uv + vec2(step.x, 0.0));
  let down = textureSample(source, sourceSampler, input.uv + vec2(0.0, step.y));
  let edge = length(center.rgb - right.rgb) + length(center.rgb - down.rgb);
  let value = dot(center.rgb, vec3<f32>(0.2126, 0.7152, 0.0722));
  let cell = fract(input.uv * vec2<f32>(24.0, 16.0));
  let gridDistance = min(min(cell.x, 1.0 - cell.x), min(cell.y, 1.0 - cell.y));
  let grid = 1.0 - smoothstep(0.0, 0.035, gridDistance);
  var paper = mix(vec3<f32>(0.008, 0.045, 0.11), vec3<f32>(0.025, 0.24, 0.46), clamp(value, 0.0, 1.0));
  paper += grid * vec3<f32>(0.012, 0.045, 0.075);
  let line = clamp(smoothstep(0.035, 0.24, edge) * ${strength.toFixed(5)}, 0.0, 1.0);
  return vec4<f32>(mix(paper, vec3<f32>(0.68, 0.94, 1.0), line), 1.0);`;
    return `
  let size = vec2<f32>(textureDimensions(source));
  let step = 1.0 / size;
  let center = textureSample(source, sourceSampler, input.uv);
  let right = textureSample(source, sourceSampler, input.uv + vec2(step.x, 0.0));
  let down = textureSample(source, sourceSampler, input.uv + vec2(0.0, step.y));
  let edge = length(center.rgb - right.rgb) + length(center.rgb - down.rgb);
  let ink = smoothstep(0.05, 0.35, edge) * ${strength.toFixed(5)};
  return vec4<f32>(mix(center.rgb, vec3<f32>(0.015, 0.08, 0.14), ink), center.a);`;
  }
  if (node.typeId === "yawn.rg.post.color-grade") {
    const exposure = Number(value(node, "exposure", 0));
    const contrast = Number(value(node, "contrast", 1));
    const pivot = Number(value(node, "pivot", 0.18));
    const saturation = Number(value(node, "saturation", 1));
    const mixAmount = Number(value(node, "mix", 1));
    const tint = value<readonly number[]>(node, "tint", [0.5, 0.62, 0.72, 1]);
    const tintAmount = Number(value(node, "tintAmount", 0));
    return `
  let sourceColor = textureSample(source, sourceSampler, input.uv);
  var color = sourceColor.rgb * ${Math.pow(2, exposure).toFixed(5)};
  ${colorBalanceExpression(node)}
  color = (color - vec3<f32>(${pivot.toFixed(5)})) * ${contrast.toFixed(5)} + vec3<f32>(${pivot.toFixed(5)});
  let luminance = dot(color, vec3<f32>(0.2126, 0.7152, 0.0722));
  color = mix(vec3<f32>(luminance), color, ${saturation.toFixed(5)});
  color = mix(color, color * vec3<f32>(${Number(tint[0] ?? 0.5).toFixed(5)}, ${Number(tint[1] ?? 0.62).toFixed(5)}, ${Number(tint[2] ?? 0.72).toFixed(5)}) * 2.0, ${tintAmount.toFixed(5)});
  color = mix(sourceColor.rgb, max(color, vec3<f32>(0.0)), ${mixAmount.toFixed(5)});
  return vec4<f32>(color, sourceColor.a);`;
  }
  if (node.typeId === "yawn.rg.post.vignette") {
    const amount = Number(value(node, "amount", 0.35));
    return `
  let sourceColor = textureSample(source, sourceSampler, input.uv);
  let centered = input.uv * 2.0 - 1.0;
  let vignette = 1.0 - smoothstep(0.35, 1.35, dot(centered, centered)) * ${amount.toFixed(5)};
  return vec4<f32>(sourceColor.rgb * vignette, sourceColor.a);`;
  }
  if (node.typeId === "yawn.rg.post.grayscale")
    return `let sourceColor = textureSample(source, sourceSampler, input.uv); let luminance = dot(sourceColor.rgb, vec3<f32>(0.2126, 0.7152, 0.0722)); return vec4<f32>(vec3<f32>(luminance), sourceColor.a);`;
  return `let sourceColor = textureSample(source, sourceSampler, input.uv); return vec4<f32>(vec3<f32>(1.0) - sourceColor.rgb, sourceColor.a);`;
}

function effectShader(node: any): string {
  return `${fullScreenVertex}
@group(0) @binding(0) var source: texture_2d<f32>;
@group(0) @binding(1) var sourceSampler: sampler;
@fragment fn fragment(input: VertexOutput) -> @location(0) vec4<f32> {
  ${effectExpression(node)}
}`;
}

function applyEffects(graph: PlainObject, effects: any[]): void {
  if (!effects.length) return;
  const present = graph.passes?.find(
    (pass: any) =>
      pass.type === "render" &&
      pass.color?.some((attachment: any) => attachment.resource === "canvas"),
  );
  if (!present)
    throw new Error("Base render graph has no canvas presentation pass");
  const sourceBinding = present.bindings?.find(
    (binding: any) => binding.group === 0 && binding.binding === 0,
  );
  const samplerBinding = present.bindings?.find(
    (binding: any) => binding.group === 0 && binding.binding === 1,
  );
  if (!sourceBinding || !samplerBinding)
    throw new Error("Canvas presentation pass has no sampled source");
  const textures = graph.resources?.textures;
  const pipelines = graph.pipelines?.render;
  if (!Array.isArray(textures) || !Array.isArray(pipelines))
    throw new Error("Base render graph cannot host post-processing stages");
  const sourceTexture = textures.find(
    (texture: any) => texture.id === sourceBinding.resource,
  );
  if (!sourceTexture?.format)
    throw new Error(
      `Presentation texture ${sourceBinding.resource} is not declared`,
    );

  let input = sourceBinding.resource;
  let after = Array.isArray(present.after) ? [...present.after] : [];
  for (const [index, node] of effects.entries()) {
    const suffix = `${index}-${String(node.id).replace(/[^a-z0-9-]/gi, "-")}`;
    const final = index === effects.length - 1;
    const output = final ? "canvas" : `rg-effect-${suffix}`;
    const pipeline = `rg-effect-pipeline-${suffix}`;
    const pass = `rg-effect-pass-${suffix}`;
    if (!final)
      textures.push({
        id: output,
        format: sourceTexture.format,
        size: ["canvas", "canvas", 1],
        usage: ["render", "sampled"],
        transient: true,
      });
    pipelines.push({
      id: pipeline,
      code: effectShader(node),
      vertex: { entry: "vertex", buffers: [] },
      fragment: {
        entry: "fragment",
        targets: [{ format: final ? "canvas" : sourceTexture.format }],
      },
    });
    graph.passes.push({
      id: pass,
      type: "render",
      pipeline,
      after,
      bindings: [
        { group: 0, binding: 0, resource: input },
        { group: 0, binding: 1, resource: samplerBinding.resource },
      ],
      color: [{ resource: output, clear: [0, 0, 0, 1] }],
      draw: { vertices: 3 },
    });
    input = output;
    after = [pass];
  }
  graph.passes = graph.passes.filter((pass: PlainObject) => pass !== present);
}

function routeDebugModeToCanvas(graph: PlainObject, mode: string): void {
  const present = graph.passes?.find(
    (pass: PlainObject) =>
      pass.type === "render" &&
      pass.color?.some(
        (attachment: PlainObject) => attachment.resource === "canvas",
      ),
  );
  const source = present?.bindings?.find(
    (binding: PlainObject) => binding.group === 0 && binding.binding === 0,
  )?.resource;
  if (!present || typeof source !== "string")
    throw new Error("Base render graph has no sampled presentation pass");
  const producers = graph.passes.filter(
    (pass: PlainObject) =>
      pass.type === "render" &&
      pass.color?.some(
        (attachment: PlainObject) => attachment.resource === source,
      ) &&
      String(pass.pipeline).startsWith(`rg-${mode}-`),
  );
  if (!producers.length)
    throw new Error(`Debug mode ${mode} has no render passes`);
  const pipelines = new Map(
    (graph.pipelines?.render ?? []).map((pipeline: PlainObject) => [
      pipeline.id,
      pipeline,
    ]),
  );
  for (const pass of producers) {
    for (const attachment of pass.color)
      if (attachment.resource === source) attachment.resource = "canvas";
    const pipeline = pipelines.get(pass.pipeline);
    const targets = pipeline?.fragment?.targets;
    if (!Array.isArray(targets) || !targets.length)
      throw new Error(`Debug pipeline ${String(pass.pipeline)} has no target`);
    targets[0].format = "canvas";
  }
  graph.passes = graph.passes.filter((pass: PlainObject) => pass !== present);
}

function pruneDeclarations(graph: PlainObject): void {
  const usedResources = new Set(
    (graph.passes ?? []).flatMap((pass: PlainObject) => passResources(pass)),
  );
  for (const kind of ["buffers", "textures", "samplers"])
    if (Array.isArray(graph.resources?.[kind]))
      graph.resources[kind] = graph.resources[kind].filter(
        (resource: PlainObject) => usedResources.has(resource.id),
      );
  const renderPipelines = new Set(
    (graph.passes ?? [])
      .filter((pass: PlainObject) => pass.type === "render")
      .map((pass: PlainObject) => pass.pipeline),
  );
  const computePipelines = new Set(
    (graph.passes ?? [])
      .filter((pass: PlainObject) => pass.type === "compute")
      .map((pass: PlainObject) => pass.pipeline),
  );
  if (Array.isArray(graph.pipelines?.render))
    graph.pipelines.render = graph.pipelines.render.filter(
      (pipeline: PlainObject) => renderPipelines.has(pipeline.id),
    );
  if (Array.isArray(graph.pipelines?.compute))
    graph.pipelines.compute = graph.pipelines.compute.filter(
      (pipeline: PlainObject) => computePipelines.has(pipeline.id),
    );
}

/**
 * Resolves an FxNode loadout into the concrete graph that Yawn will compile.
 */
export function buildFxNodeRenderGraph(
  layout: GraphSource,
  baseGraph: object,
): object {
  if (!plainRecord(baseGraph))
    throw new TypeError("Base render graph must be plain data");
  if (isPhysicalRenderGraph(layout)) return reconstructRenderGraph(layout);
  const graph = structuredClone(baseGraph) as PlainObject;
  const chain = activeChain(layout);
  const mode = chain.findLast((node) => modeTypes.has(String(node.typeId)));
  if (mode) applyDebugMode(graph, mode);
  const effects = chain.filter((node) => effectTypes.has(String(node.typeId)));
  if (mode && mode.typeId !== "yawn.rg.mode.beauty" && effects.length === 0)
    routeDebugModeToCanvas(
      graph,
      String(mode.typeId).slice("yawn.rg.mode.".length),
    );
  else applyEffects(graph, effects);
  pruneDeclarations(graph);
  const suffix = chain
    .filter(
      (node) =>
        modeTypes.has(String(node.typeId)) ||
        effectTypes.has(String(node.typeId)),
    )
    .map((node) => String(node.typeId).split(".").at(-1))
    .map((stage) => (stage === "beauty" ? "standard" : stage))
    .join("-");
  graph.id = `${String(graph.id || "scene")}-fxnode-${suffix || "standard"}`;
  return graph;
}

/**
 * Compiles an FxNode loadout over a scene-authored graph and returns the exact
 * S-expression consumed by `YawnCore.compileGraph`.
 */
export function compileFxNodeRenderGraph(
  layout: GraphSource,
  baseGraph: object,
): string {
  return encodeRenderGraph(buildFxNodeRenderGraph(layout, baseGraph));
}