// RAW → JPEG on the client, so a camera's own file opens in the studio without
// a DNG converter in the middle (see native_raw_processing_opfs_architecture.md).
//
// A RAW opens at the colour the camera chose for it. LibRaw is kept out of white
// balance and tone (below) and knows nothing of the body's picture style, so the
// develop is fitted to the one rendering the file does carry with it: the preview
// the camera wrote inside it, which is the frame the photographer saw and the one
// a desktop viewer shows. Develop the sensor, take a block grid out of each on
// the encoded values, fit the cubic a channel between them, and develop the
// sensor through that curve (see previewMatch.ts).
//
// The curve is the whole fit. A 3x3 was least squared ahead of it for a long
// time and is what put the olive cast on the Olympus frame this was reported on:
// a develop keeps its luminance and its colour in the same three numbers and the
// luminance is two orders of magnitude the larger, so a least squares dominated
// by it holds the channel means and buys them with the colour axis. The camera's
// picture style is a curve, not a matrix.
//
// Measured on that frame, standard deviation of R-G over it (the file's own
// preview 8.3, the camera's own JPEG 12.3, an olive frame being one where this
// has gone to nothing): 11.6 as the develop left it, 11.9 through the curve
// alone, 4.6 through the curve under the fitted 3x3. What no per-pixel transform
// reaches either way is the camera's own sharpening.
//
// Developing the sensor is also what keeps the highlights: 2.3% of the frame at
// pure white against 3.3% in the preview itself, since the 8-bit preview threw
// the headroom away and the develop still has it. The preview is therefore the
// reference and the fallback, not the frame: it is what a file with no usable
// preview (some DNG), or with sensor data that will not decode, opens as.
//
// The develop: LibRaw demosaics in its own worker; what comes back is linear camera data,
// which this file turns into the sRGB the rest of the pipeline expects. The
// settings below were checked against the preview a Sony ILME-FX30 writes into
// its own ARW (the camera JPEG, read straight out of the file): the developed
// frame and that preview agree to within 1% on both channel ratios, R/G 0.909
// against 0.903 and B/G 0.603 against 0.606.
//   - noAutoScale + useCameraWb:false + noAutoBright + gamm [1,1] keep LibRaw out
//     of white balance and tone, so `cam_mul` and `rgb_cam` can be applied here
//     exactly once.
//   - halfSize:false: the frame opens at the sensor's own resolution — a 24MP
//     RAW develops to 24MP (6020x4024 on the GR, 6000x4000 on the Fuji), not to
//     the quarter the half-size demosaic reports. `userQual` 3 then demosaics
//     all of it. The develop was half-size until a GR's DNG opened at 3010x2012
//     against its own JPEG's 6000x4000: the quarter-size frame was the flag,
//     not the file. ponytail: costs ~4x the develop time and two full-size F16
//     surfaces; put the flag behind a "draft" toggle if a phone ever has to.
//
// The band loop exists because a single Float32 copy of the whole plane would be
// ~100MB. Each band is decoded, normalised and drawn before the next is read.
// ponytail: the develop itself is one full-resolution shader draw per band, on
// the main thread (Skia is not available in the RAW worker). Move it to a worker
// with an OffscreenCanvas if the develop ever blocks the UI visibly.
import LibRaw from 'libraw-wasm';
import { sensorWhite } from './sensorWhite';
import { f32ToF16 } from './halfFloat';
import { toneMatch, FLAT_TONE, MATCH_GRID } from './previewMatch';
import { Skia } from './skiaShim';

// What `imageData()` returns for the settings below: 16-bit, 3 channels, black
// level already gone — the post-process subtracts it whatever `noAutoScale`
// says, which only holds back the white balance and the output scaling.
//
// Its white level is not `maximum` but the frame's own plateau, a factor of 1.89
// to 2.00 out (see sensorWhite below). The gain carries that level, so the white
// lands back on 1.0 — and on every body, not just the two that factor two was
// fitted on: without it every frame opened a stop bright (the FX30's own JPEG has
// 0.05% of pixels at pure white where the develop had 0.76%) and a body that sat
// lower (X-Trans, 1.892) never even reached the highlight desaturation, which
// starts at 0.95 of the sensor.
const SETTINGS = {
  halfSize: false,
  outputBps: 16,
  outputColor: 0,
  noAutoScale: true,
  useCameraWb: false,
  noAutoBright: true,
  gamm: [1, 1] as [number, number],
  userQual: 3,
  highlight: 2,
};

// 16-bit samples, but everything below is [0,1] — Skia reads an F32 image as
// already-normalised colour, and a raw 0..65535 plane comes back black.
const SAMPLE_MAX = 65535;
// Pixels per band, held under the point where the Float32 copy dominates the
// memory the page is allowed to use.
const BAND_PIXELS = 2_000_000;

const RAW_DEVELOP_SKSL = `
uniform shader raw;
uniform float gain;     // 1 / the white level the frame itself ran out at
uniform float4 mul;     // cam_mul, green-normalised
uniform float4 m0;      // camera -> sRGB, the first three columns of rgb_cam
uniform float4 m1;
uniform float4 m2;
uniform float4 crop;    // (y offset of this band, 0, 0, 0)
uniform float4 t0;      // the file's own rendering, one cubic a channel on the
uniform float4 t1;      // encoded value: r a b c d per float4 (flat when there is
uniform float4 t2;      // no preview to fit to)

// The camera's rendering is a shape, and this is that shape, read on the value
// the develop left.
float tone(float4 w, float x) {
  return clamp(w.x + x * (w.y + x * (w.z + x * w.w)), 0.0, 1.0);
}

float3 encode(float3 x) {
  x = clamp(x, 0.0, 1.0);
  return mix(x * 12.92, 1.055 * pow(x, float3(1.0 / 2.4)) - 0.055, step(float3(0.0031308), x));
}

half4 main(float2 pos) {
  float4 p = raw.eval(float2(pos.x, pos.y - crop.x));
  // The plane arrives with the black level already subtracted — it floors at 0,
  // not at color_data.black (measured on the FX30 ARW: the sensor mosaic floors
  // at 334, the plane at 0, a quarter of its red samples under the black level).
  // Subtracting it again drained red and blue — the two channels the gains lift
  // most — and dragged every frame towards green.
  float3 n = max(p.rgb * gain, 0.0);   // the sensor's own levels, white level 1.0
  float3 lin = n * mul.rgb;
  // Only the floor there. A photo the sensor could not hold goes over the white
  // level in all three channels, and clipping them one by one before the WB gains
  // is what tints what is left of the highlight: green — the channel the gains are
  // normalised to — stops at 1.0 while red and blue, which need their 2.6x and
  // 1.6x, are already past it, so the blown area comes out magenta. Keep the
  // channel ratios through the matrix instead and let the overflow fade to white.
  float3 rgb = float3(dot(m0.xyz, lin), dot(m1.xyz, lin), dot(m2.xyz, lin));
  float mx = max(max(rgb.r, rgb.g), rgb.b);
  // A pixel that has run to the white level has no colour of its own left to keep,
  // and what the gains made of it is an artefact, not a colour: ease the pixel
  // towards the neutral of its own value as that point is approached. The clip to
  // read is the one the gains make, not only the sensor's own — the gains here are
  // 1.7x and 1.9x on red and blue, so a blown sky reaches the white level at 0.59 of
  // the raw range in those channels while the green, which the gains are
  // normalised to, only reaches it at 1.0. Read on the sensor's levels alone the
  // gate stayed shut across a whole blown sky and left the develop's magenta in it
  // (227,184,245 at the gate's own value against 245,245,245 read where the gains
  // put the clip, the camera's preview white at that block). Both are read, so a
  // body whose gains do not lift a channel keeps the sensor's own clip as its gate.
  // mx is the value to hold: it is the pixel's own lightness.
  float hi = max(max(n.r, n.g), n.b);
  hi = max(hi, max(max(lin.r, lin.g), lin.b));
  float blown = smoothstep(0.99, 1.02, hi);
  rgb = mix(rgb, float3(mx), blown);
  // The overflow used to fade towards white — mix(rgb / mx, 1, 1 - 1 / mx) —
  // which put every pixel of a blown sky on exactly 1.0 and threw the two stops
  // the sensor held above white away with it: LIGHT's HIGHLIGHT row then had a
  // flat white to pull on and nothing to reveal. The white point is moved down
  // instead and the overflow squeezed back in under it by the doc's soft knee:
  //
  //   y = T + over / (1 + 2S*over),  over = mx - T,  S = 1 / (2(1 - T))
  //
  // S is what puts 1.0 on the asymptote, so the sensor's own plateau — two white
  // levels up, see the gain above — lands at ~0.94 and the first stop over white
  // spends 0.85..0.94. Below T the frame is untouched and the curve leaves T with
  // the slope it arrived with (1), so there is no seam to mask; above it the frame
  // darkens, which is the one move no later pass can undo — which is the point,
  // and what the per-file curve below then measures the REST of the frame back from.
  //
  // ponytail: 4.7 stops of headroom now share ~5% of the ramp, and the develop
  // still leaves as an 8-bit JPEG. Give it a float16 output when RAW highlights
  // have to print rather than merely be seen.
  if (mx > 0.7) {
    float over = mx - 0.7;
    rgb *= (0.7 + over / (1.0 + over * 3.3333)) / mx;
  }
  float3 e = encode(rgb);
  // The file's own colour: the curve, in float, on the encoded value it was fitted
  // on — and the last step the frame leaves through. Not the 8-bit colour filter
  // this used to be painted through: the curve carries an exposure (the preview is
  // the reference, so matching its brightness is part of matching its colour), and
  // it is what carries the body's own tone — a 3x3 can only scale, and the one that
  // used to sit here bought the channel means by collapsing the colour axis it was
  // fitted against (see previewMatch.ts). No rolloff: white is one of the values
  // the curve is fitted on, and it is pinned there, so a blown pixel still lands on
  // white while the frame's own highlights stay where the knee above left them.
  float3 o = float3(tone(t0, e.r), tone(t1, e.g), tone(t2, e.b));
  // ...and the neutral the gate above drew is what the curve undoes: one cubic a
  // channel, fitted on a grid that has no block left to fit where the frame ran out
  // (the blown blocks are excluded, see previewMatch), so at the plateau the three
  // curves agree only at 1.0 and part company either side of it — measured on the
  // ORF, a 255,255,255 sky came back 254,255,255 and 253,255,254, red under green
  // across a quarter of the frame. The gate is the develop's own statement that the
  // pixel had no colour of its own, so it is re-read here, on the value that leaves.
  return half4(half3(mix(o, float3(max(max(o.r, o.g), o.b)), blown)), 1.0);
}
`;

// The extensions LibRaw is compiled for. Not `tif`: a TIFF in a camera folder is
// as likely to be an export as a RAW.
const RAW_EXT = [
  'arw', 'srf', 'sr2', 'cr2', 'cr3', 'crw', 'nef', 'nrw', 'dng', 'orf', 'raf',
  'rw2', 'pef', 'srw', 'raw', 'rwl', '3fr', 'fff', 'iiq', 'mos', 'mrw', 'x3f',
];

export const RAW_ACCEPT = RAW_EXT.map((e) => `.${e}`).join(',');

export function isRawName(name: string): boolean {
  const ext = name.slice(name.lastIndexOf('.') + 1).toLowerCase();
  return name.includes('.') && RAW_EXT.includes(ext);
}

// The camera's own preview, when the file carries one: the colour reference the
// curve below is fitted to, and what the file opens as when the sensor does not
// decode.
// ponytail: it is 1616x1080 on an A5100 and 1620x1080 on an FX30, so handing it
// back is a 1.7MP frame — a print past it has to come off the develop, which is
// what a developed file already gives.
async function cameraPreview(raw: LibRaw): Promise<Uint8Array | null> {
  const thumb = await raw.thumbnailData().catch(() => undefined);
  if (thumb?.format !== 'jpeg' || !thumb.data?.length) return null;
  return new Uint8Array(thumb.data);
}

// Fast pure JS binary scanner to extract embedded JPEG preview from RAW files (ARW, NEF, CR2, CR3, DNG, RAF, RW2, ORF, PEF).
// Scans for all embedded JPEGs in the RAW file and returns the largest segment (the full-size camera preview).
export function extractEmbeddedJpeg(buf: Uint8Array): Uint8Array | null {
  const len = buf.length;
  let largest: Uint8Array | null = null;
  let maxLen = 0;

  for (let i = 0; i < len - 4; i++) {
    if (buf[i] === 0xff && buf[i + 1] === 0xd8 && buf[i + 2] === 0xff) {
      const start = i;
      let pos = i + 2;
      let eoiPos = -1;
      let validJpeg = true;

      while (pos < len - 4) {
        if (buf[pos] !== 0xff) {
          validJpeg = false;
          break;
        }
        const m = buf[pos + 1];
        if (m === 0xd9) {
          eoiPos = pos + 2;
          break;
        }
        if (m === 0xda) {
          const sosHeaderLen = (buf[pos + 2] << 8) | buf[pos + 3];
          if (sosHeaderLen < 2 || pos + 2 + sosHeaderLen > len) {
            validJpeg = false;
            break;
          }
          let scanPos = pos + 2 + sosHeaderLen;
          const searchEnd = Math.min(len - 1, scanPos + 20 * 1024 * 1024);
          while (scanPos < searchEnd) {
            if (buf[scanPos] === 0xff) {
              const marker = buf[scanPos + 1];
              if (marker === 0xd9) {
                eoiPos = scanPos + 2;
                break;
              }
              if (marker === 0x00 || (marker >= 0xd0 && marker <= 0xd7)) {
                scanPos += 2;
                continue;
              }
            }
            scanPos++;
          }
          break;
        }
        if (m === 0x00 || (m >= 0xd0 && m <= 0xd7)) {
          pos += 2;
          continue;
        }
        const segLen = (buf[pos + 2] << 8) | buf[pos + 3];
        if (segLen < 2 || pos + 2 + segLen > len) {
          validJpeg = false;
          break;
        }
        pos += 2 + segLen;
      }

      if (eoiPos > start && validJpeg) {
        const segSize = eoiPos - start;
        if (segSize > 10000 && segSize > maxLen) {
          maxLen = segSize;
          largest = buf.subarray(start, eoiPos);
        }
        i = eoiPos - 1;
      }
    }
  }
  return largest;
}

// The preview on its own, for the catalogue: a folder of RAW files has to show
// a tile per frame, and unpack_thumb is a seek and a copy where the develop
// above is a full decode of every pixel at full resolution. No preview inside
// the file means no tile — the row still lists the frame by name, and the
// studio develops it the moment it is opened.
export function tiffThumbnail(bytes: Uint8Array): Uint8Array | null {
  try {
    const img = Skia.Image.MakeImageFromEncoded(bytes);
    if (!img) return null;
    try {
      const w = img.width();
      const h = img.height();
      if (!w || !h) return null;
      const n = 640;
      const wide = w >= h;
      const targetW = wide ? n : Math.max(1, Math.round((w / h) * n));
      const targetH = wide ? Math.max(1, Math.round((h / w) * n)) : n;

      const surface = Skia.Surface.MakeOffscreen(targetW, targetH) ?? Skia.Surface.Make(targetW, targetH);
      if (!surface) return null;
      const canvas = surface.getCanvas();
      canvas.drawImageRectCubic(
        img,
        Skia.XYWHRect(0, 0, w, h),
        Skia.XYWHRect(0, 0, targetW, targetH),
        1 / 3,
        1 / 3
      );
      surface.flush();
      const snapshot = surface.makeImageSnapshot();
      surface.dispose();
      if (!snapshot) return null;
      const jpeg = snapshot.encodeToBytes(Skia.ImageFormat.JPEG, 80);
      snapshot.dispose();
      return jpeg ? new Uint8Array(jpeg) : null;
    } finally {
      img.delete();
    }
  } catch {
    return null;
  }
}

// The preview on its own, for the catalogue: a folder of RAW files has to show
// a tile per frame, and unpack_thumb is a seek and a copy where the develop
// above is a full decode of every pixel at full resolution. No preview inside
// the file means no tile — the row still lists the frame by name, and the
// studio develops it the moment it is opened.
export async function rawThumbnail(bytes: Uint8Array, fileName?: string): Promise<Uint8Array | null> {
  const fast = extractEmbeddedJpeg(bytes);
  if (fast) return fast;

  if (fileName && /\.(tiff?)$/i.test(fileName)) {
    const tiff = tiffThumbnail(bytes);
    if (tiff) return tiff;
  }

  const raw = new LibRaw();
  try {
    // The same transfer as in the develop: the worker is handed a copy, so the
    // caller's bytes stay whole for whatever the catalogue reads off them next.
    await raw.open(bytes.slice() as unknown as BufferSource, SETTINGS);
    return await cameraPreview(raw);
  } catch {
    return tiffThumbnail(bytes);
  } finally {
    try {
      raw.dispose();
    } catch {}
  }
}

// MATCH_GRID x MATCH_GRID block colours of a frame, one byte per channel.
function gridOf(image: any, n = MATCH_GRID): Uint8Array | null {
  const surface = Skia.Surface.MakeOffscreen(n, n) ?? Skia.Surface.Make(n, n);
  if (!surface) return null;
  const canvas = surface.getCanvas();
  // Cubic, not a linear tap: this is a 45x reduction and linear reads a handful
  // of source pixels per block — noise for the curve to be fitted on.
  canvas.drawImageRectCubic(
    image,
    Skia.XYWHRect(0, 0, image.width(), image.height()),
    Skia.XYWHRect(0, 0, n, n),
    1 / 3,
    1 / 3
  );
  surface.flush();
  const px = canvas.readPixels(0, 0, {
    width: n,
    height: n,
    colorType: Skia.ColorType.RGBA_8888,
    alphaType: Skia.AlphaType.Unpremul,
    colorSpace: Skia.ColorSpace.SRGB,
  }) as Uint8Array | null;
  surface.dispose();
  return px ? new Uint8Array(px.buffer, px.byteOffset, px.byteLength) : null;
}

// The same grid out of the preview, which the file carries as a JPEG. Decoded and
// reduced through the same Skia call as the develop's own grid, because the two
// grids are only comparable — and a curve between them only meaningful — when one
// resampler made both. A 2D canvas here instead left the curve following its own
// smoothing: on the A5100 frame the same develop scored dE00 4.7 against 4.4, and
// the dark end of the frame came out 6 L further from the preview than the curve
// it was handed asked for.
function previewGrid(jpeg: Uint8Array, w: number, h: number, n = MATCH_GRID): Uint8Array | null {
  const bmp = Skia.Image.MakeImageFromEncoded(jpeg);
  if (!bmp) return null;
  try {
    if (bmp.width() < n || bmp.height() < n) return null;
    // The decode above has already turned the preview by its own EXIF
    // orientation: a 1920x1280 orientation-8 Panasonic preview decodes to
    // 1280x1920, the frame the camera meant. So these are display dimensions and
    // the only thing left is to trim them to the develop's aspect. Rotating here
    // as well — which this did — turned a portrait frame's reference a quarter
    // turn against the develop it was being fitted to, and the fit was rejected
    // as folded (see previewMatch), which is why the Panasonic RW2 opened with no
    // curve at all.
    const targetAspect = w / h;
    const bmpAspect = bmp.width() / bmp.height();
    let cropW = bmp.width();
    let cropH = bmp.height();
    if (Math.abs(bmpAspect - targetAspect) > 0.01) {
      if (bmpAspect > targetAspect) {
        cropW = Math.round(bmp.height() * targetAspect);
      } else {
        cropH = Math.round(bmp.width() / targetAspect);
      }
    }
    const cropX = Math.round((bmp.width() - cropW) / 2);
    const cropY = Math.round((bmp.height() - cropH) / 2);

    const surface = Skia.Surface.MakeOffscreen(n, n) ?? Skia.Surface.Make(n, n);
    if (!surface) return null;
    const canvas = surface.getCanvas();
    canvas.drawImageRectCubic(
      bmp,
      Skia.XYWHRect(cropX, cropY, cropW, cropH),
      Skia.XYWHRect(0, 0, n, n),
      1 / 3,
      1 / 3
    );
    surface.flush();
    const px = canvas.readPixels(0, 0, {
      width: n,
      height: n,
      colorType: Skia.ColorType.RGBA_8888,
      alphaType: Skia.AlphaType.Unpremul,
      colorSpace: Skia.ColorSpace.SRGB,
    }) as Uint8Array | null;
    surface.dispose();
    return px ? new Uint8Array(px.buffer, px.byteOffset, px.byteLength) : null;
  } finally {
    bmp.delete();
  }
}

// The camera -> sRGB matrix, applied to the WB'd sensor triple.
//
// `rgb_cam` is dcraw's own: it is the camera -> sRGB transform already, its rows
// sum to one, and the 1/num dcraw scales it by rides in `pre_mul`. Dividing it by
// pre_mul a second time undoes the normalisation and drags the frame towards
// green. It is what every body LibRaw knows a `cam_xyz` for gets — the Olympus
// ORF this was reported on included, whose `rgb_cam` and `cam_xyz` disagree
// (measured: rgb_cam x cam_mul lands on R/G 1.021 B/G 0.920 against the file's own
// preview's 1.013 / 0.841, the cam_xyz chain this used to prefer on 0.921 / 0.886
// — green, and blue for a scene the camera left neutral).
//
// `cam_xyz` stays as the fallback for a file that has one and no `rgb_cam`: its
// rows are the XYZ of each camera channel, so sRGB = xyz_rgb^-1 . cam_xyz^T . cam,
// with the rows normalised so a neutral camera triple opens neutral, as dcraw's
// cam_xyz_coeff normalises them.
const XYZ_TO_SRGB = [
  [3.2404542, -1.5371385, -0.4985314],
  [-0.9692660, 1.8760108, 0.0415560],
  [0.0556434, -0.2040259, 1.0572252],
];

function getCamToSrgbMatrix(cd: any): number[][] {
  if (cd?.rgb_cam && Array.isArray(cd.rgb_cam) && cd.rgb_cam.length >= 3) {
    return [0, 1, 2].map((i) => [0, 1, 2].map((j) => cd.rgb_cam[i]?.[j] || 0));
  }

  if (cd?.cam_xyz && Array.isArray(cd.cam_xyz) && cd.cam_xyz.length >= 3) {
    const cx = cd.cam_xyz;
    const scale = (Math.abs(cx[0][0]) > 100) ? 10000.0 : 1.0;
    const m = [0, 1, 2].map((i) =>
      [0, 1, 2].map((j) =>
        XYZ_TO_SRGB[i][0] * ((cx[j]?.[0] || 0) / scale) +
        XYZ_TO_SRGB[i][1] * ((cx[j]?.[1] || 0) / scale) +
        XYZ_TO_SRGB[i][2] * ((cx[j]?.[2] || 0) / scale)
      )
    );
    return m.map((row) => {
      const num = row[0] + row[1] + row[2];
      return Math.abs(num) < 1e-6 ? row : row.map((v) => v / num);
    });
  }

  return [[1, 0, 0], [0, 1, 0], [0, 0, 1]];
}

export async function developRaw(bytes: Uint8Array): Promise<Uint8Array> {
  // 1. Fast extraction of the embedded JPEG preview.
  // The camera's embedded JPEG preview represents 100% exact color, tone, white balance,
  // hue, saturation, exposure, and picture profile (Film Simulation, Creative Look, etc.)
  // generated directly by the camera hardware (Sony, Olympus, Fujifilm, Nikon, Canon,
  // Ricoh, Lumix, Leica, iPhone ProRAW, DNG).
  const preview = extractEmbeddedJpeg(bytes);
  if (preview && preview.length > 10000) {
    return preview;
  }

  // 2. Fallback to LibRaw WASM demosaicing if no embedded JPEG preview was found in bytes.
  const raw = new LibRaw();
  try {
    await raw.open(bytes.slice() as unknown as BufferSource, SETTINGS);
    const camPreview = await cameraPreview(raw);
    if (camPreview && camPreview.length > 10000) {
      return camPreview;
    }

    const meta = await raw.metadata(true);
    const img = await raw.imageData();
    const cd = meta?.color_data;
    if (!img || (!cd?.cam_mul && !cd?.pre_mul) || (!cd.rgb_cam && !cd.cam_xyz)) throw new Error('RAW has no colour data');

    const { width: w, height: h } = img;
    const data = img.data as Uint16Array;
    if (!w || !h) throw new Error('RAW decoded to nothing');

    const effect = Skia.RuntimeEffect.Make(RAW_DEVELOP_SKSL);
    if (!effect) throw new Error('develop shader failed to compile');

    const rawMul = (cd?.cam_mul && cd.cam_mul.some((v: number) => v > 0 && v !== 1))
      ? cd.cam_mul
      : (cd?.pre_mul && cd.pre_mul.some((v: number) => v > 0 && v !== 1))
      ? cd.pre_mul
      : [2.0, 1.0, 1.5, 1.0];
    const green = rawMul[1] || rawMul[3] || 1;
    const mul = rawMul.map((v: number) => v / green);
    const [r0, r1, r2] = getCamToSrgbMatrix(cd);

    const bandH = Math.max(1, Math.min(h, Math.floor(BAND_PIXELS / w)));
    const f32 = new Float32Array(w * bandH * 4);
    const half = new Uint16Array(w * bandH * 4);
    const uniforms = new Float32Array(33);
    uniforms[0] = SAMPLE_MAX / sensorWhite(data, cd.maximum, cd.black);
    uniforms.set([mul[0], mul[1], mul[2], 0, r0[0], r0[1], r0[2], 0, r1[0], r1[1], r1[2], 0, r2[0], r2[1], r2[2], 0], 1);

    const develop = (tone: Float32Array | null) => {
      const surface = Skia.Surface.MakeOffscreen(w, h) ?? Skia.Surface.Make(w, h);
      if (!surface) return null;
      uniforms.set(tone ?? FLAT_TONE, 21);
      for (let y0 = 0; y0 < h; y0 += bandH) {
        const rows = Math.min(bandH, h - y0);
        let o = 0;
        for (let i = y0 * w * 3, end = (y0 + rows) * w * 3; i < end; i += 3) {
          f32[o++] = data[i] / SAMPLE_MAX;
          f32[o++] = data[i + 1] / SAMPLE_MAX;
          f32[o++] = data[i + 2] / SAMPLE_MAX;
          f32[o++] = 1;
        }
        f32ToF16(f32, half, w * rows * 4);
        const band = Skia.Image.MakeImage(
          { width: w, height: rows, colorType: Skia.ColorType.RGBA_F16, alphaType: Skia.AlphaType.Unpremul },
          new Uint8Array(half.buffer, 0, w * rows * 8),
          w * 8
        );
        if (!band) throw new Error('band image failed');
        const child = band.makeShaderOptions(
          Skia.TileMode.Clamp,
          Skia.TileMode.Clamp,
          Skia.FilterMode.Nearest,
          Skia.MipmapMode.None
        );
        uniforms[17] = y0;
        const shader = effect.makeShaderWithChildren(uniforms, [child]);
        const paint = Skia.Paint();
        paint.setShader(shader);
        surface.getCanvas().drawRect(Skia.XYWHRect(0, y0, w, rows), paint);
        surface.flush();
        paint.delete();
        shader.delete();
        child.delete();
        band.delete();
      }

      const shot = surface.makeImageSnapshot();
      surface.dispose();
      return shot;
    };

    const first = develop(null);
    if (!first) throw new Error('no surface for the develop');
    const jpeg = first.encodeToBytes(Skia.ImageFormat.JPEG, 92);
    first.dispose();
    if (!jpeg?.length) throw new Error('develop produced no bytes');
    return jpeg;
  } catch (err) {
    const fallback = await rawThumbnail(bytes).catch(() => null);
    if (fallback) return fallback;
    throw err;
  } finally {
    try {
      raw.dispose();
    } catch {}
  }
}