function initializeBVH(args) {
  const { scene, triangleIntersect } = args;
  const getComponents = (triangle, idx) => [triangle.pt0[idx], triangle.pt1[idx], triangle.pt2[idx]];
  const getTriangleAABB = (triangle) => ({
    min: [
      Math.min(...getComponents(triangle, 0)),
      Math.min(...getComponents(triangle, 1)),
      Math.min(...getComponents(triangle, 2)),
    ],
    max: [
      Math.max(...getComponents(triangle, 0)),
      Math.max(...getComponents(triangle, 1)),
      Math.max(...getComponents(triangle, 2)),
    ],
    triangles: [triangle],
  });
  const joinAABBs = (a, b) => ({
    min: [Math.min(a.min[0], b.min[0]), Math.min(a.min[1], b.min[1]), Math.min(a.min[2], b.min[2])],
    max: [Math.max(a.max[0], b.max[0]), Math.max(a.max[1], b.max[1]), Math.max(a.max[2], b.max[2])],
    triangles: [...a.triangles, ...b.triangles],
  });

  // Temporarily extend the triangles to add their bounding box
  scene.forEach((triangle) => {
    triangle.aabb = getTriangleAABB(triangle);
  });

  let totalTriangles = 0;

  // Octree-based implementation
  // Recursively divide the space used by the triangles in octants
  // and use them to decide the best space division into two halves
  // stop when the number of triangles to divide is four or less
  const recursiveOctreeBuild = (triangles) => {
    if (!triangles || !triangles.length) return null;

    const aabb = triangles.map(getTriangleAABB).reduce(joinAABBs);

    if (aabb.triangles.length <= 4) {
      totalTriangles += aabb.triangles.length;
      return {
        aabb,
        left: null,
        right: null,
      };
    }

    const center = aabb.min.map((v, i) => (v + aabb.max[i]) / 2);

    // Helper functiont to find the octant a given point falls into
    const calculateSectorNumber = (point) => {
      let sector = 0;
      if (point[0] > center[0]) sector |= 1;
      if (point[1] > center[1]) sector |= 2;
      if (point[2] > center[2]) sector |= 4;
      return sector;
    };

    // Function to collect the number of triangles in a given sector
    // this requires the use of the triangle bounding box centroid
    const sectors = new Array(8).fill(0).map(() => []);
    triangles.forEach((t) => {
      const triangleAABB = t.aabb;
      const triangleCentroid = [
        (triangleAABB.min[0] + triangleAABB.max[0]) / 2,
        (triangleAABB.min[1] + triangleAABB.max[1]) / 2,
        (triangleAABB.min[2] + triangleAABB.max[2]) / 2,
      ];
      const sectorNumber = calculateSectorNumber(triangleCentroid);
      sectors[sectorNumber].push(t);
    });

    const sectorsDifference = (a, b) =>
      Math.abs(
        sectors[a[0]].length +
          sectors[a[1]].length +
          sectors[a[2]].length +
          sectors[a[3]].length -
          sectors[b[0]].length -
          sectors[b[1]].length -
          sectors[b[2]].length -
          sectors[b[3]].length
      );

    const leftX = [0, 2, 4, 6];
    const rightX = [1, 3, 5, 7];
    const leftY = [0, 1, 4, 5];
    const rightY = [2, 3, 6, 7];
    const leftZ = [0, 1, 2, 3];
    const rightZ = [4, 5, 6, 7];

    const xdiff = sectorsDifference(leftX, rightX);

    const ydiff = sectorsDifference(leftY, rightY);

    const zdiff = sectorsDifference(leftZ, rightZ);

    const sectorsTriangles = (a) => [...sectors[a[0]], ...sectors[a[1]], ...sectors[a[2]], ...sectors[a[3]]];

    const minDiff = Math.min(xdiff, ydiff, zdiff);
    let leftSector = leftZ;
    let rightSector = rightZ;
    if (minDiff == xdiff) {
      leftSector = leftX;
      rightSector = rightX;
    } else if (minDiff == ydiff) {
      leftSector = leftY;
      rightSector = rightY;
    }

    return {
      aabb: {
        ...aabb,
        triangles: null,
      },
      left: recursiveOctreeBuild(sectorsTriangles(leftSector)),
      right: recursiveOctreeBuild(sectorsTriangles(rightSector)),
    };
  };

  // Naive implementation
  // Using a recursive function, divide the triangles array in halves and create BVH nodes for them
  // Stop when there are 4 triangles or less
  // return the root of the BVH

  const recursiveNaiveBuild = (triangles) => {
    if (!triangles || !triangles.length) return null;

    const aabb = triangles.map(getTriangleAABB).reduce(joinAABBs);

    if (aabb.triangles.length <= 4) {
      totalTriangles += aabb.triangles.length;
      return {
        aabb,
        left: null,
        right: null,
      };
    }

    const mid = Math.floor(triangles.length / 2);
    const left = recursiveNaiveBuild(triangles.slice(0, mid));
    const right = recursiveNaiveBuild(triangles.slice(mid, triangles.length));

    return {
      aabb,
      left,
      right,
    };
  };

  const bvh = recursiveOctreeBuild(scene);

  // Remove the per-triangle bounding boxes as they are no longer needed
  scene.forEach((triangle) => {
    triangle.aabb = getTriangleAABB(triangle);
  });

  const intersectBvh = (ray, bvh) => {
    if (!bvh) return false;

    let dxi = 1.0 / ray.direction[0];
    let dyi = 1.0 / ray.direction[1];
    let dzi = 1.0 / ray.direction[2];

    let sx = bvh.aabb.min;
    let rsx = bvh.aabb.max;
    if (dxi < 0.0) {
      sx = bvh.aabb.max;
      rsx = bvh.aabb.min;
    }
    let sy = bvh.aabb.min;
    let rsy = bvh.aabb.max;
    if (dyi < 0.0) {
      sy = bvh.aabb.max;
      rsy = bvh.aabb.min;
    }
    let sz = bvh.aabb.min;
    let rsz = bvh.aabb.max;
    if (dzi < 0.0) {
      sz = bvh.aabb.max;
      rsz = bvh.aabb.min;
    }

    let tmin = (sx[0] - ray.origin[0]) * dxi;
    let tymax = (rsy[1] - ray.origin[1]) * dyi;
    if (tmin > tymax) {
      return false;
    }

    let tmax = (rsx[0] - ray.origin[0]) * dxi;
    let tymin = (sy[1] - ray.origin[1]) * dyi;
    if (tymin > tmax) {
      return false;
    }

    tmin = tymin > tmin ? tymin : tmin;
    tmax = tymax < tmax ? tymax : tmax;
    let tzmin = (sz[2] - ray.origin[2]) * dzi;
    let tzmax = (rsz[2] - ray.origin[2]) * dzi;
    return !(tmin > tzmax || tzmin > tmax);
  };

  // recursively find the triangles in the leaves of the BVH that intersect the given ray

  const recTraverseBvh = (ray, acc, node) => {
    // Check if there is a hit
    if (!intersectBvh(ray, node)) return;

    // Check if this is a leaf
    if (!node.left && !node.right) {
      acc.push(...node.aabb.triangles);
      return;
    }

    recTraverseBvh(ray, acc, node.left);
    recTraverseBvh(ray, acc, node.right);
  };

  // To use with the regular rendering pipeline, return a trace function that works like the regular trace one
  const traceBvh = (ray) => {
    const trianglesFound = [];
    recTraverseBvh(ray, trianglesFound, bvh);
    return trianglesFound
      .map((obj) => ({ ...triangleIntersect(ray, obj), obj }))
      .filter(({ hit }) => hit)
      .reduce((acc, intersection) => (intersection.distance < acc.distance ? intersection : acc), {
        hit: false,
        distance: Number.MAX_VALUE,
      });
  };

  return {
    traceBvh,
  };
}

function createScene(args) {
  const {
    vector: { sub, unit, cross },
    memory: { allocStaticFloat32Array, set },
  } = args;

  function rotatePoint([x, y, z], [ax, ay, az]) {
    let sinax = Math.sin(ax);
    let cosax = Math.cos(ax);

    [y, z] = [y * cosax - z * sinax, y * sinax + z * cosax];

    let sinay = Math.sin(ay);
    let cosay = Math.cos(ay);

    [x, z] = [x * cosay + z * sinay, -x * sinay + z * cosay];

    let sinaz = Math.sin(az);
    let cosaz = Math.cos(az);

    [x, y] = [x * cosaz - y * sinaz, x * sinaz + y * cosaz];

    return [x, y, z];
  }

  function translatePoint(point, [x, y, z]) {
    return [point[0] + x, point[1] + y, point[2] + z];
  }

  function createTorus(radius = 1.0, tubeRadius = 0.3, center, rotation, props) {
    const triangles = [];
    const rings = [];
    const ringSegments = 12;
    const tubeSegments = 24;
    const sourceRing = [];

    const ringSegmentRad = (2 * Math.PI) / ringSegments;
    for (let i = 0; i < ringSegments; i++) {
      sourceRing.push(rotatePoint([tubeRadius, 0, 0], [0, 0, ringSegmentRad * i]));
    }

    const tubeSegmentRad = (2 * Math.PI) / tubeSegments;
    for (let i = 0; i < tubeSegments; i++) {
      const ring = structuredClone(sourceRing)
        .map((pt) => translatePoint(pt, [radius, 0, 0]))
        .map((pt) => rotatePoint(pt, [0, tubeSegmentRad * i, 0]))
        .map((pt) => translatePoint(pt, center))
        .map((pt) => rotatePoint(pt, rotation));
      rings.push(ring);
    }

    for (let i = 0; i < tubeSegments; i++) {
      const ni = (i + 1) % tubeSegments;
      for (let j = 0; j < ringSegments; j++) {
        let pt0 = rings[i][j];
        let pt1 = rings[ni][j];
        let pt2 = rings[i][(j + 1) % ringSegments];
        triangles.push({
          pt0,
          pt1,
          pt2,
          ...props,
        });
        pt0 = rings[i][(j + 1) % ringSegments];
        pt1 = rings[ni][j];
        pt2 = rings[ni][(j + 1) % ringSegments];
        triangles.push({
          pt0,
          pt1,
          pt2,
          ...props,
        });
      }
    }

    return triangles;
  }

  function createPlane(width, height, center, rotation, props) {
    const triangles = [];
    let pt0 = [-width / 2, height / 2, 0];
    let pt1 = [width / 2, height / 2, 0];
    let pt2 = [-width / 2, -height / 2, 0];

    pt0 = translatePoint(rotatePoint(pt0, rotation), center);
    pt1 = translatePoint(rotatePoint(pt1, rotation), center);
    pt2 = translatePoint(rotatePoint(pt2, rotation), center);
    triangles.push({
      pt0,
      pt1,
      pt2,
      ...props,
    });

    pt0 = [width / 2, height / 2, 0];
    pt1 = [width / 2, -height / 2, 0];
    pt2 = [-width / 2, -height / 2, 0];
    pt0 = translatePoint(rotatePoint(pt0, rotation), center);
    pt1 = translatePoint(rotatePoint(pt1, rotation), center);
    pt2 = translatePoint(rotatePoint(pt2, rotation), center);
    triangles.push({
      pt0,
      pt1,
      pt2,
      ...props,
    });

    return triangles;
  }

  const scene1 = [
    ...createTorus(4, 2, [0, 0, 0], [Math.PI / 2, 0, 0], { color: [0, 1, 0], isLight: false }),
    ...createPlane(20, 20, [0, 10, 0], [Math.PI / 2, 0, 0], { color: [3, 3, 3], isLight: true }),
    ...createPlane(1000, 1000, [0, -5, 0], [Math.PI / 2, 0, 0], { color: [1, 1, 1], isLight: false }),
  ];

  const scene = scene1.map((obj, id) => {
    const edge0 = sub(obj.pt1, obj.pt0);
    const edge1 = sub(obj.pt2, obj.pt0);
    obj.normal = unit(cross(edge0, edge1));
    obj.centroid = [
      (obj.pt0[0] + obj.pt1[0] + obj.pt2[0]) / 3,
      (obj.pt0[1] + obj.pt1[1] + obj.pt2[1]) / 3,
      (obj.pt0[2] + obj.pt1[2] + obj.pt2[2]) / 3,
    ];

    obj.id = id;
    return obj;
  });

  return {
    scene,
  };
}

function createMemoryFunctions(args) {
  const { wasm } = args;
  const totalAvailable = 1024 * 4;
  const memPtr = wasm.alloc(totalAvailable);
  const memView = new DataView(wasm.memory.buffer, memPtr, totalAvailable);
  let staOffset = 0;
  let dynOffset = 2048; // half of totalAvailable

  function get(A, idx) {
    return memView.getFloat32(A + idx * 4 - memPtr, true);
  }
  function set(A, idx, v) {
    memView.setFloat32(A + idx * 4 - memPtr, v, true);
  }
  const allocFloat32Array = (size) => {
    const byteOffset = memPtr + dynOffset;
    dynOffset += size * 4;
    return byteOffset;
  };

  const allocStaticFloat32Array = (size) => {
    const byteOffset = memPtr + staOffset;
    staOffset += size * 4;
    return byteOffset;
  };
  const free = () => (dynOffset = 2048);
  return {
    memory: {
      allocFloat32Array,
      allocStaticFloat32Array,
      free,
      get,
      set,
    },
  };
}

function createAspectRatioFunction() {
  return {
    aspectRatio: (width, height) => {
      let gcd = width;
      let reminder = height;
      while (reminder != 0) {
        const temp = reminder;
        reminder = gcd % reminder;
        gcd = temp;
      }
      return [width / gcd, height / gcd];
    },
  };
}

function createCamera(args) {
  const { width, height, aspectRatio } = args;
  const [w, h] = aspectRatio(width, height);
  return {
    camera: {
      leftTop: [-w, h + 1, -50.0],
      rightTop: [w, h + 1, -50.0],
      leftBottom: [-w, -h + 1, -50.0],
      eye: [0.0, 0.0, -65.0],
    },
  };
}

function createImageGeometry({ width, height }) {
  return {
    imageGeometry: {
      width,
      height,
    },
  };
}

function createVectorFunctions() {
  const sub = (A, B) => [A[0] - B[0], A[1] - B[1], A[2] - B[2]];
  const add = (A, B) => [A[0] + B[0], A[1] + B[1], A[2] + B[2]];
  const mul = (A, B) => [A[0] * B[0], A[1] * B[1], A[2] * B[2]];
  const dot = (A, B) => A[0] * B[0] + A[1] * B[1] + A[2] * B[2];
  // 135ms
  const scale = (A, s) => [A[0] * s, A[1] * s, A[2] * s];
  const norm = (A) => Math.sqrt(dot(A, A));
  const unit = (A) => scale(A, 1.0 / norm(A));
  const abs = (A) => [Math.abs(A[0]), Math.abs(A[1]), Math.abs(A[2])];
  const maxDimension = (A) => {
    if (A[0] > A[1] && A[0] > A[2]) return 0;
    if (A[1] > A[0] && A[1] > A[3]) return 1;
    return 2;
  };
  const permute = (A, i, j, k) => [A[i], A[j], A[k]];
  const cross = (A, B) => {
    const j = A[1] * B[2] - B[1] * A[2];
    const k = A[2] * B[0] - A[0] * B[2];
    const l = A[0] * B[1] - A[1] * B[0];
    return [j, k, l];
  };
  const vector = {
    sub,
    add,
    mul,
    dot,
    scale,
    norm,
    unit,
    abs,
    maxDimension,
    permute,
    cross,
  };

  return {
    vector,
  };
}

function calculatePrimaryRays(args) {
  const {
    camera: { rightTop, leftTop, leftBottom, eye },
    imageGeometry: { width, height },
    vector: { scale, add, sub, unit },
  } = args;
  const vdu = scale(sub(rightTop, leftTop), 1.0 / width);
  const vdv = scale(sub(leftBottom, leftTop), 1.0 / height);
  const primaryRays = [];
  for (let y = 0; y < height; y++) {
    for (let x = 0; x < width; x++) {
      const pixel = y * width + x;
      const origin = eye;
      const direction = unit(sub(add(add(scale(vdu, x), scale(vdv, y)), leftTop), origin));
      primaryRays[pixel] = {
        pixel,
        origin,
        direction,
      };
    }
  }

  return {
    primaryRays,
  };
}

function createRandomDirectionFunction(args) {
  const {
    vector: { dot, norm },
  } = args;

  const randomDirection = (normal) => {
    const p = [0, 0, 0];
    while (true) {
      p[0] = Math.random() - 0.5;
      p[1] = Math.random() - 0.5;
      p[2] = Math.random() - 0.5;
      const n = 1.0 / norm(p);
      p[0] *= n;
      p[1] *= n;
      p[2] *= n;
      if (dot(p, normal) >= 0) {
        return p;
      }
    }
  };
  return {
    randomDirection,
  };
}

function createTriangleIntersectFunction(args) {
  const { sub, abs, maxDimension, permute, scale, add } = args.vector;
  const triangleIntersect = (ray, triangle) => {
    const { pt0, pt1, pt2, normal } = triangle;
    let pt0_t = sub(pt0, ray.origin);
    let pt1_t = sub(pt1, ray.origin);
    let pt2_t = sub(pt2, ray.origin);
    const k = maxDimension(abs(ray.origin));
    const i = (k + 1) % 3;
    const j = (i + 1) % 3;

    const [pdx, pdy, pdz] = permute(ray.direction, i, j, k);
    const sz = 1.0 / pdz;
    const sx = -pdx * sz;
    const sy = -pdy * sz;

    pt0_t = permute(pt0_t, i, j, k);
    pt1_t = permute(pt1_t, i, j, k);
    pt2_t = permute(pt2_t, i, j, k);

    const pt0_t_0 = pt0_t[0] + sx * pt0_t[2];
    const pt0_t_1 = pt0_t[1] + sy * pt0_t[2];
    const pt0_t_2 = pt0_t[2] * sz;
    const pt1_t_0 = pt1_t[0] + sx * pt1_t[2];
    const pt1_t_1 = pt1_t[1] + sy * pt1_t[2];
    const pt1_t_2 = pt1_t[2] * sz;
    const pt2_t_0 = pt2_t[0] + sx * pt2_t[2];
    const pt2_t_1 = pt2_t[1] + sy * pt2_t[2];
    const pt2_t_2 = pt2_t[2] * sz;

    const e0 = pt1_t_0 * pt2_t_1 - pt1_t_1 * pt2_t_0;
    const e1 = pt2_t_0 * pt0_t_1 - pt2_t_1 * pt0_t_0;
    const e2 = pt0_t_0 * pt1_t_1 - pt0_t_1 * pt1_t_0;

    if ((e0 < 0.0 || e1 < 0.0 || e2 < 0.0) && (e0 > 0.0 || e1 > 0.0 || e2 > 0.0)) {
      return { hit: false };
    }

    const det = e0 + e1 + e2;
    if (det == 0.0) {
      return { hit: false };
    }

    const t_scaled = e0 * pt0_t_2 + e1 * pt1_t_2 + e2 * pt2_t_2;

    if (det < 0.0 && t_scaled >= 0.0) {
      return { hit: false };
    }

    if (det > 0.0 && t_scaled <= 0.0) {
      return { hit: false };
    }

    const t = t_scaled / det;

    if (t > 0.007) {
      const point = add(scale(ray.direction, t), ray.origin);
      return {
        hit: true,
        distance: t,
        point,
        normal,
      };
    }

    return {
      hit: false,
    };
  };

  return {
    triangleIntersect,
  };
}

function createTraceFunction(args) {
  const { scene, triangleIntersect } = args;
  const trace = (ray) =>
    scene
      .map((obj) => ({ ...triangleIntersect(ray, obj), obj }))
      .filter(({ hit }) => hit)
      .reduce((acc, intersection) => (intersection.distance < acc.distance ? intersection : acc), {
        hit: false,
        distance: Number.MAX_VALUE,
      });
  return {
    trace,
  };
}

function createTracePrimaryRaysFunction(args) {
  const { trace, traceBvh, primaryRays, width } = args;
  const traceResults = [];
  const tracePrimaryRays = (section, tileSize) => {
    let idx = 0;
    const startPixel = section;
    const endPixel = section + width * tileSize;
    for (let i = startPixel; i < endPixel; i++) {
      const ray = primaryRays[i];
      traceResults[idx++] = traceBvh(ray);
    }
    return traceResults;
  };
  return {
    tracePrimaryRays,
  };
}

function createGenerateBitmapFunction(args) {
  const {
    shading,
    vector: { mul },
  } = args;

  const generateBitmap = (traceResults, section, bbp) => {
    let idx = section * 4 * 3;
    for (const it of traceResults) {
      let pixel = [0, 0, 0];
      if (it.hit) {
        pixel = it.obj.color;
        if (!it.obj.isLight) {
          const intensity = shading(it.point, it.normal, 0);
          pixel = mul(pixel, intensity);
        }
      }
      bbp.setFloat32(idx, pixel[0], true);
      bbp.setFloat32(idx + 4, pixel[1], true);
      bbp.setFloat32(idx + 8, pixel[2], true);
      idx += 12;
    }
  };
  return { generateBitmap };
}

function createRenderFunction(args) {
  const { tracePrimaryRays, generateBitmap, width, height } = args;
  const totalPixels = width * height;
  const render = (tileSize, bitmap, syncBuffer) => {
    const sync = new Uint32Array(syncBuffer);
    const sectionSize = tileSize * width;
    let section = Atomics.add(sync, 0, sectionSize);
    const bpp = new DataView(bitmap, 0, bitmap.length);
    while (section < totalPixels) {
      const traceResults = tracePrimaryRays(section, tileSize);
      generateBitmap(traceResults, section, bpp);
      section = Atomics.add(sync, 0, sectionSize);
    }
  };
  return { render };
}

function pipeline(fns) {
  return (args) => {
    let acc = { ...args };
    for (const fn of fns) {
      const result = fn(acc);
      acc = { ...acc, ...result };
    }
    return acc;
  };
}

function createShadingFunction(args) {
  const {
    vector: { dot },
    trace,
    traceBvh,
    randomDirection,
  } = args;
  const shading = (shadingPoint, pointNormal, depth) => {
    const color = [0, 0, 0];
    if (depth === 5) {
      return color;
    }
    const origin = [];
    origin[0] = pointNormal[0] * 0.1 + shadingPoint[0];
    origin[1] = pointNormal[1] * 0.1 + shadingPoint[1];
    origin[2] = pointNormal[2] * 0.1 + shadingPoint[2];

    const direction = randomDirection(pointNormal);
    const d = dot(pointNormal, direction);
    const ray = { origin, direction };
    const tr = traceBvh(ray);
    if (!tr.hit) {
      return color; //black up to this point;
    }
    color[0] = tr.obj.color[0] * d;
    color[1] = tr.obj.color[0] * d;
    color[2] = tr.obj.color[0] * d;
    if (!tr.obj.isLight) {
      const ncolor = shading(tr.point, tr.normal, depth + 1);
      color[0] *= ncolor[0];
      color[1] *= ncolor[1];
      color[2] *= ncolor[2];
    }
    return color;
  };

  return {
    shading,
  };
}

module.exports = {
  createScene,
  createMemoryFunctions,
  createAspectRatioFunction,
  createCamera,
  createImageGeometry,
  createVectorFunctions,
  calculatePrimaryRays,
  createRandomDirectionFunction,
  createTriangleIntersectFunction,
  initializeBVH,
  createTraceFunction,
  createTracePrimaryRaysFunction,
  createGenerateBitmapFunction,
  createRenderFunction,
  pipeline,
  createShadingFunction,
};

function workerFunction() {
  async function loadWasm(wasmFile) {
    const {
      instance: { exports: wasm },
    } = await WebAssembly.instantiate(wasmFile, {});
    return wasm;
  }

  function parseFunctions(functions) {
    const fns = {};
    for (const fn of functions) {
      fns[fn[0]] = new Function(`return ${fn[1]}`)();
    }
    return fns;
  }
  let render = null;

  async function init(wasmFile, width, height, functions) {
    const wasm = await loadWasm(wasmFile);
    const fns = parseFunctions(functions);
    const renderingPipeline = fns.pipeline([
      fns.createMemoryFunctions,
      fns.createVectorFunctions,
      fns.createAspectRatioFunction,
      fns.createScene,
      fns.createCamera,
      fns.createImageGeometry,
      fns.createRandomDirectionFunction,
      fns.calculatePrimaryRays,
      fns.createTriangleIntersectFunction,
      fns.initializeBVH,
      fns.createTraceFunction,
      fns.createShadingFunction,
      fns.createTracePrimaryRaysFunction,
      fns.createGenerateBitmapFunction,
      fns.createRenderFunction,
    ]);
    render = renderingPipeline({
      wasm,
      width,
      height,
      sceneSelector: 1,
    }).render;
  }

  this.onmessage = async (msg) => {
    const { data } = msg;
    if (data.operation === 'init') {
      const { wasmFile, width, height, functions } = data;
      await init(wasmFile, width, height, functions);
      this.postMessage(0);
    } else {
      render(data.tileSize, data.bitmap, data.syncBuffer);
      this.postMessage(1);
    }
  };
}

module.exports = workerFunction;

class WorkersPool {
  #blobUrl;
  poolSize;
  maxPoolSize;
  #pool = [];
  results = [];
  constructor(poolSize, maxPoolSize, workerFunction) {
    const workerFunctionString = `(${workerFunction.toString()})()`;
    const blob = new Blob([workerFunctionString], {
      type: 'application/javascript',
    });
    this.#blobUrl = URL.createObjectURL(blob);
    this.poolSize = poolSize;
    this.maxPoolSize = maxPoolSize;
  }

  init(initPayload) {
    this.#pool = [];
    this.poolSize = Math.max(1, this.poolSize);
    return new Promise((resolve) => {
      let workersDone = 0;
      for (let i = 0; i < this.maxPoolSize; i++) {
        const worker = new Worker(this.#blobUrl);
        this.#pool.push(worker);
        worker.onmessage = () => {
          if (++workersDone === this.maxPoolSize) {
            resolve();
          }
        };
        worker.postMessage(initPayload);
      }
    });
  }

  resize(newSize) {
    this.poolSize = Math.max(1, newSize);
  }

  async process(payload) {
    return new Promise((resolve) => {
      let currentJob = 0;
      for (let i = 0; i < this.poolSize; i++) {
        let wrk = this.#pool[i];
        wrk.onmessage = async (msg) => {
          if (++currentJob === this.poolSize) {
            resolve();
          }
        };
        wrk.postMessage(payload);
      }
    });
  }
}

module.exports = WorkersPool;

const workerFunction = require('./worker-function.js');
const WorkersPool = require('./workers-pool.js');
const pathTracerFunctions = require('./path-tracer-functions.js');
const workersPool = new WorkersPool(1, 1 /* navigator.hardwareConcurrency */, workerFunction);

async function renderAndPresent(canvas, frameCount, framesAcc, syncBuffer, sharedBuffer, finalBitmap) {
  const ctx = canvas.getContext('2d');
  const width = canvas.width;
  const renderStart = performance.now();
  const bitmap = new Float32Array(sharedBuffer);
  const sync = new Uint32Array(syncBuffer);
  const tileSize = 8;

  sync[0] = 0;
  await workersPool.process({ tileSize, bitmap: sharedBuffer, syncBuffer });

  for (let i = 0; i < bitmap.length; i += 3) {
    const r = bitmap[i] + (framesAcc[i] || 0);
    const g = bitmap[i + 1] + (framesAcc[i + 1] || 0);
    const b = bitmap[i + 2] + (framesAcc[i + 2] || 0);
    framesAcc[i] = r;
    framesAcc[i + 1] = g;
    framesAcc[i + 2] = b;
    finalBitmap[i / 3] =
      (255 << 24) |
      ((Math.min(b / frameCount, 1) * 255) << 16) |
      ((Math.min(g / frameCount, 1) * 255) << 8) |
      (Math.min(r / frameCount, 1) * 255);
  }
  const imageData = new ImageData(new Uint8ClampedArray(finalBitmap.buffer), width);
  ctx.putImageData(imageData, 0, 0);
  const elapsed = Math.floor(performance.now() - renderStart);
  const elapsedMs = `${elapsed}ms|${(Math.round(10000 / elapsed) / 10).toFixed(1)}fps|${workersPool.poolSize}/${
    workersPool.maxPoolSize
  }threads(${window.adjustPool ? '?' : '!'})`;
  ctx.font = '20px monospace';
  ctx.textBaseline = 'top';
  const measure = ctx.measureText(elapsedMs);
  ctx.fillStyle = '#000000';
  ctx.fillRect(0, 0, measure.width, measure.fontBoundingBoxDescent);
  ctx.fillStyle = '#999999';
  ctx.fillText(elapsedMs, 0, 0);
}

window.running = false;
(async () => {
  const canvas = document.getElementById('canvas-1');
  const width = canvas.width;
  const height = canvas.height;
  const wasmFile = await (await fetch('wasm/vector_simd.wasm')).arrayBuffer();
  await workersPool.init({
    operation: 'init',
    wasmFile,
    width,
    height,
    functions: Object.entries(pathTracerFunctions).map(([name, fn]) => [name, fn.toString()]),
  });
  let frameCount = 0;
  const framesAcc = new Array(width * height * 3);
  const sharedBuffer = new SharedArrayBuffer(width * height * 3 * 4);
  const syncBuffer = new SharedArrayBuffer(4);
  const finalBitmap = new Uint32Array(width * height);
  window.running = true;

  /* START: Auto adjust poolSize */
  const renderTimes = {};
  let renderStart = performance.now();
  window.adjustPool = true;
  /* END: Auto adjust poolSize */

  const animation = async () => {
    frameCount++;
    await renderAndPresent(canvas, frameCount, framesAcc, syncBuffer, sharedBuffer, finalBitmap);
    /* START: Auto adjust poolSize */
    renderTimes[workersPool.poolSize] += performance.now();
    if (window.adjustPool && frameCount % 10 === 0) {
      renderTimes[workersPool.poolSize] = performance.now() - renderStart;
      if (workersPool.poolSize < workersPool.maxPoolSize) {
        await workersPool.resize(workersPool.poolSize + 1);
        renderStart = performance.now();
      } else {
        window.adjustPool = false;
        let fastest = Number.MAX_VALUE;
        let poolSize = 0;
        for (const [size, time] of Object.entries(renderTimes)) {
          if (time < fastest) {
            fastest = time;
            poolSize = size;
          }
        }
        await workersPool.resize(poolSize);
      }
    }
    /* END: Auto adjust poolSize */
    window.running && window.requestAnimationFrame(animation);
  };
  window.requestAnimationFrame(animation);
})();