RecipesCam/src/utils/toneShader.ts

import { BaseFilter, ColorAdjustments } from '../types';
import { HSL_BANDS, hslBandGaps, isMonochromeBase } from './colorUtils';

// Tone-domain adjustments (Fuji-style Dynamic Range + Highlight/Shadow).
// SkSL runtime effect over a child image shader.
//
// Lightness/chroma split: the curve moves the luma and the colour difference
// (rgb - luma) carries the hue through with most of its chroma. Scaling R,G,B
// by one gain keeps the *ratio* but crushes absolute chroma — that is what
// turned saturated blues black under -SH and bright colours grey under -HL.
//
// Wide, soft knees so the knobs reach like a tone curve instead of biting only
// at the very ends: HL rides only the top (0.65..1.00) so it leaves the greys
// and midtones alone (a 0.45 knee dragged a mid-grey down) while SH rides the
// lower half (0.00..0.55), and the 0.50 midpoint never moves. Earlier narrow
// knees (0.80..1.00 / 0.00..0.30) made both sliders look dead on any photo
// without true whites or blacks.
//
// Both knobs are pure additive shifts of the luma. That keeps the curve
// monotonic (steepest knee slope 4.29/unit * 0.22 = 0.94, and the two knees
// never overlap), so a brighter input can never come out darker. The earlier
// multiplicative form was NOT monotonic: with hl=-1 a grey 0.73 came out
// darker than 0.80.
//
// dr  - DR strength 0..1: lifts shadows slightly and rolls highlights
//       (Fuji extended DR); 0/auto/DR100 = no extra curve.
// hl  - highlight -1..1: + lifts toward white, - rolls the bright side down.
// sh  - shadow    -1..1: + lifts the dark side, - deepens it.
// vib - vibrance -1..1: chroma-masked saturation. It rides along in this shader
//       (rather than the colour matrix) because it needs per-pixel chroma:
//       already-vivid pixels move least, so skins/skies deepen without the neon
//       clip a plain Saturation boost causes.
// hslOn/hslH/hslS/hslL - selective colour mixer: eight hue bands, each with a
//       hue shift, a saturation scale and a lightness offset (-1..1, from the
//       -10..10 knobs). Which band owns which pixel is decided HERE, per pixel
//       from the pixel's hue — so unlike everything above, the eight bands are
//       not one global move and cannot live in a colour matrix. See the band
//       block at the end of TONE_SKSL.
// gh/gs/gl - the mixer's whole-image moves: those same three quantities applied
//       to the WHOLE frame, so they are just the accumulator's seed values and
//       every hue takes them at full weight. Lightness is NOT gated on
//       saturation (unlike the bands), so a frame pulled to grey by -SAT still
//       answers +LUM.
// shT/hlT - split tone (per-channel RGB bias, -1..1 each): a fixed cast applied
//       to the shadows and/or the highlights only. A 4x5 colour matrix cannot do
//       this — it is one linear map, so any cast it applies must also hit the
//       midtones and the opposite end. Classic Neg wants green/cyan shadows with
//       warm highlights at once, so the stock ships these values and the pass
//       stays active for it even when every user knob is 0. All-zero still = no
//       pass.
// The mixer's eight band lines inside TONE_SKSL, generated from HSL_BANDS so the
// anchors and gaps in the shader are the numbers the chips were built from. Each
// line reads its band's three values at a CONSTANT index — SkSL can only index a
// uniform array by a constant, so this block is unrolled rather than looped.
const BAND_BLOCK = hslBandGaps()
  .map(
    (b, i) => `    float w${i} = bandW(hd, ${b.hue.toFixed(1)}, ${b.left.toFixed(1)}, ${b.right.toFixed(1)}) * gate;
    acc += vec3(w${i} * hslH[${i}], w${i} * hslS[${i}], w${i} * hslL[${i}]);\n`
  )
  .join('');

export const TONE_SKSL = `
uniform shader src;
uniform float dr;
uniform float hl;
uniform float sh;
uniform float vib;
uniform float shTr;
uniform float shTg;
uniform float shTb;
uniform float hlTr;
uniform float hlTg;
uniform float hlTb;
uniform float cc;
uniform float ccb;
uniform float hslOn;
uniform float hslH[8];
uniform float hslS[8];
uniform float hslL[8];
uniform float gh;
uniform float gs;
uniform float gl;
// sRGB <-> HSL. The mixer works in HSL because that is the space the knobs are
// named after: a hue shift must not change how light a colour is, and a
// lightness move must not change its hue — exactly what scaling R,G,B gets
// wrong.
vec3 rgb2hsl(vec3 c) {
  float mx = max(max(c.r, c.g), c.b);
  float mn = min(min(c.r, c.g), c.b);
  float l = (mx + mn) * 0.5;
  float d = mx - mn;
  if (d < 0.00001) return vec3(0.0, 0.0, l);
  float s = l > 0.5 ? d / max(0.00001, 2.0 - mx - mn) : d / max(0.00001, mx + mn);
  float h;
  if (mx == c.r) h = (c.g - c.b) / d + (c.g < c.b ? 6.0 : 0.0);
  else if (mx == c.g) h = (c.b - c.r) / d + 2.0;
  else h = (c.r - c.g) / d + 4.0;
  return vec3(h / 6.0, s, l);
}
float hueChannel(float p, float q, float t) {
  t = fract(t);
  if (t < 1.0 / 6.0) return p + (q - p) * 6.0 * t;
  if (t < 0.5) return q;
  if (t < 2.0 / 3.0) return p + (q - p) * (2.0 / 3.0 - t) * 6.0;
  return p;
}
vec3 hsl2rgb(vec3 hsl) {
  if (hsl.y < 0.00001) return vec3(hsl.z);
  float q = hsl.z < 0.5 ? hsl.z * (1.0 + hsl.y) : hsl.z + hsl.y - hsl.z * hsl.y;
  float p = 2.0 * hsl.z - q;
  return vec3(
    hueChannel(p, q, hsl.x + 1.0 / 3.0),
    hueChannel(p, q, hsl.x),
    hueChannel(p, q, hsl.x - 1.0 / 3.0)
  );
}
// How much of a hue one band owns: full at the band's anchor, falling linearly
// to zero at the anchors next door (the gaps are uneven — red is 30 deg from
// orange and 40 deg from magenta). The linearity is the point: two neighbouring
// tents cross at exactly 0.5 at the midpoint, so the eight weights sum to 1 at
// every hue. No pixel is counted twice, no pixel falls in a gap, and a hue
// sitting on an anchor takes its band's full value instead of part of it.
float bandW(float hue, float anchor, float gapL, float gapR) {
  float d = mod(hue - anchor + 180.0, 360.0) - 180.0;
  return d <= 0.0 ? max(0.0, 1.0 + d / gapL) : max(0.0, 1.0 - d / gapR);
}
vec4 main(vec2 xy) {
  vec4 c = src.eval(xy);
  vec3 rgb = clamp(c.rgb, 0.0, 1.0);
  float t = clamp(dot(rgb, vec3(0.2126, 0.7152, 0.0722)), 0.0, 1.0);
  float hlMask = smoothstep(0.65, 1.00, t);
  float shMask = 1.0 - smoothstep(0.00, 0.55, t);
  // NOTE: never name a local 'out' — it is a reserved SkSL qualifier.
  float o = t + hl * 0.22 * hlMask + sh * 0.34 * shMask;
  // Dynamic range: gentle shadow lift + highlight roll (protect brights).
  o += dr * 0.12 * shMask * (1.0 - t);
  o -= dr * 0.18 * hlMask * t;
  o = clamp(o, 0.0, 1.0);
  // Lightness takes the curve, hue stays: the colour difference is gained
  // only part-way so darkening cannot collapse a colour to black and lifting
  // cannot blow a dark saturated colour out to white.
  float cg = clamp(o / max(t, 0.0004), 0.55, 1.35);
  rgb = clamp(vec3(o) + (rgb - vec3(t)) * cg, 0.0, 1.0);
  // Split tone (stock look): the shadows and the highlights may each carry
  // their own tint, so the two ends of the curve can drift opposite ways
  // (Classic Neg: green-cyan darks, warm brights) without touching mid-greys.
  rgb = clamp(rgb + vec3(shTr, shTg, shTb) * shMask + vec3(hlTr, hlTg, hlTb) * hlMask, 0.0, 1.0);
  // Color Chrome / Color Chrome FX Blue: the two stock-dialed colour effects
  // DEEPEN what is already chromatic and leave neutrals exactly where they are
  // (Fuji: "deeper tone in highly saturated colour"; FX Blue does it for the
  // blue/cyan side only). Both therefore need per-pixel chroma — a 4x5 colour
  // matrix is one linear map, so any gain it applies also moves greys, and a
  // blue-only gain drags the whole white point.
  float mxc = max(max(rgb.r, rgb.g), rgb.b);
  float mnc = min(min(rgb.r, rgb.g), rgb.b);
  // Chroma ratio with a small floor: a near-black pixel with a hair of cast
  // has ratio 1.0 but no colour to deepen, and must stay put.
  float ccChroma = (mxc - mnc) / max(mxc, 0.10);
  // Color Chrome rides the chroma itself: a muted colour barely moves, a vivid
  // one gains density. The 0.25 knee keeps skin, haze and pastels untouched.
  float ccMask = cc * smoothstep(0.25, 0.85, ccChroma);
  // FX Blue: only where blue clearly leads red AND green (so magenta/purple
  // stay out), and richest in a bright blue — a dark blue has no tonality left
  // to deepen.
  float ccbBlue = clamp((rgb.b - rgb.r) * 2.0, 0.0, 1.0) * clamp((rgb.b - 0.5 * (rgb.r + rgb.g) + 0.05) * 3.0, 0.0, 1.0);
  float ccbMask = ccb * ccbBlue * smoothstep(0.15, 0.60, ccChroma) * smoothstep(0.20, 0.70, t);
  float deep = clamp(ccMask + ccbMask, 0.0, 1.0);
  // Density = lightness down with the colour difference riding along, so hue is
  // preserved and the colour cannot collapse toward black (same reason the tone
  // curve above keeps chroma). A touch of chroma is given up as it deepens.
  float l3 = dot(rgb, vec3(0.2126, 0.7152, 0.0722));
  rgb = clamp(vec3(l3 * (1.0 - 0.28 * deep)) + (rgb - vec3(l3)) * (1.0 - 0.10 * deep), 0.0, 1.0);
  // Vibrance: push the LESS-saturated pixels harder than the vivid ones.
  float l2 = dot(rgb, vec3(0.2126, 0.7152, 0.0722));
  float mx = max(max(rgb.r, rgb.g), rgb.b);
  float mn = min(min(rgb.r, rgb.g), rgb.b);
  float chroma = mx > 0.0001 ? (mx - mn) / mx : 0.0;
  float kv = 1.0 + vib * 0.75 * (1.0 - chroma);
  rgb = clamp(mix(vec3(l2), rgb, kv), 0.0, 1.0);
  // Selective colour by hue band — the LAST move, so a band edit is judged on
  // the colour the user actually sampled from the render.
  //
  // Grey pixels are dropped before any weight is read: rgb2hsl hands them hue 0,
  // so without the gate EVERY neutral pixel in the frame would be taken for pure
  // red and drift with the red band. Below 8% saturation there is also no hue
  // worth moving.
  //
  // The three accumulators are band values scaled by how much of the hue each
  // band owns, so a hue halfway between two anchors takes a proportional mix of
  // both edits — the blend the weights already add up to. Hue is a turn (plus or
  // minus 30 deg at full), saturation a scale (0 = grey at -10) and lightness an
  // additive offset (plus or minus 0.25 at full), which is why the ramp cannot
  // invert.
  if (hslOn > 0.5) {
    vec3 hsl = rgb2hsl(rgb);
    float gate = smoothstep(0.0, 0.08, hsl.y);
    float hd = hsl.x * 360.0;
    // The whole-image moves are the seed: every hue takes the hue turn and the
    // saturation scale at full weight, and the bands add their share on top.
    // Lightness is added below OUTSIDE the gate, so it still lifts a colour that
    // -SAT has already pulled to grey.
    vec3 acc = vec3(gh, gs, 0.0) * gate;
${BAND_BLOCK}    hsl.x = fract(hsl.x + acc.x * (30.0 / 360.0));
    hsl.y = clamp(hsl.y * (1.0 + acc.y), 0.0, 1.0);
    hsl.z = clamp(hsl.z + (acc.z + gl) * 0.25, 0.0, 1.0);
    rgb = hsl2rgb(hsl);
  }
  return vec4(clamp(rgb, 0.0, 1.0), c.a);
}
`;

// Bright Pass Filter for the HDF EFFECT pass (HDF), SkSL over a child image
// shader — the pattern TONE_SKSL above already proved on device.
//
// Per channel the old 2.5*in-1.5 curve only zeroed a channel that was dark
// *itself*: a saturated blue (B = 1.0) came out of it fully lit, so a dark blue
// shadow bloomed and a dark saturated colour smeared its hue into the darks.
// Photoshop's Bright Pass filters on the LUMINANCE instead: one knee decides how
// much light a pixel carries, and one gain scales all three channels, so below
// the knee the output is exactly 0.0 (Screen against black = no-op, the shadows
// are untouched) and above it every channel keeps its ratio — the hue cannot
// drift, only the brightness blooms.
//
// Knee t0..t1 = 0.55..0.85: the soft end of the old hard 0.6 cut (2.5*0.6-1.5 =
// 0), wide enough that a specular ramps in instead of clipping on/off.
export const GLOW_T0 = 0.55;
export const GLOW_T1 = 0.85;

export const GLOW_SKSL = `
uniform shader src;
uniform float t0;
uniform float t1;
vec4 main(vec2 xy) {
  vec4 c = src.eval(xy);
  float luma = dot(clamp(c.rgb, 0.0, 1.0), vec3(0.2126, 0.7152, 0.0722));
  return vec4(c.rgb * smoothstep(t0, t1, luma), c.a);
}
`;

// Flat uniform buffer for `makeShaderWithChildren` — same order as GLOW_SKSL's
// declarations (t0, t1).
export function glowUniformArray(): number[] {
  'worklet';
  return [GLOW_T0, GLOW_T1];
}

// Same values for the declarative <Shader> path, which indexes uniforms by
// NAME (a flat array is only valid for the JS makeShaderWithChildren API).
export const GLOW_UNIFORMS = { t0: GLOW_T0, t1: GLOW_T1 };

// CLARITY (positive): unsharp 3x3 with epsilon 0 — the kernel export pass 4
// builds with MakeMatrixConvolution, re-expressed as a plain shader because RN
// Skia 2.6 exposes no convolution image filter to the declarative JSX writer.
// `px` is one ORIGINAL image pixel expressed in the caller's canvas units, so
// the preview, the camera worklet and the file all sharpen at the same radius.
export const CLARITY_SKSL = `
uniform shader src;
uniform float a;
uniform float2 px;
vec4 main(vec2 xy) {
  vec4 c = src.eval(xy);
  vec4 s = src.eval(xy + float2(0.0, -px.y))
         + src.eval(xy + float2(0.0,  px.y))
         + src.eval(xy + float2(-px.x, 0.0))
         + src.eval(xy + float2( px.x, 0.0));
  return vec4(clamp(c.rgb * (1.0 + 4.0 * a) - a * s.rgb, 0.0, 1.0), c.a);
}
`;

// Named uniforms for <Shader uniforms>, same names as CLARITY_SKSL declares.
export function clarityUniforms(a: number, pxX: number, pxY: number) {
  return { a, px: [pxX, pxY] };
}

export interface ToneUniforms {
  // All zero → no tone adjustment needed (caller can skip the shader pass).
  dr: number; // 0..1
  hl: number; // -1..1 (adjustments.highlight / 10)
  sh: number; // -1..1 (adjustments.shadow / 10)
  vib: number; // -1..1 (adjustments.vibrance / 10)
  shT: [number, number, number]; // shadow split-tone RGB bias, -1..1
  hlT: [number, number, number]; // highlight split-tone RGB bias, -1..1
  cc: number; // 0..1 Color Chrome depth (0 = 'none')
  ccb: number; // 0..1 Color Chrome FX Blue depth (0 = 'none')
  hslOn: number; // 1 when a band or a whole-image move is set (0 = skip the mixer)
  hslH: number[]; // 8 x -1..1 in HSL_BANDS order (+/-30 deg hue at full)
  hslS: number[]; // 8 x -1..1 (saturation scale, -1 = grey)
  hslL: number[]; // 8 x -1..1 (additive lightness, +/-0.25 at full)
  gh: number; // -1..1 whole-image hue turn (+/-30 deg at full)
  gs: number; // -1..1 whole-image saturation scale
  gl: number; // -1..1 whole-image lightness offset (+/-0.25 at full, ungated)
}

// Per-stock tone pass. Fuji's Classic stocks are not a plain colour matrix:
// Classic Neg splits its tone (green-cyan darks / warm brights) and Classic
// Chrome crushes the shadows hard while muting colour. Those two parts live
// here instead of in the 4x5 matrix, which cannot move one end of the curve
// without also moving the other.
const FILM_TONE: Partial<Record<BaseFilter, Partial<ToneUniforms>>> = {
  'classic-chrome': { sh: -0.28 },
  // Classic Vivid keeps Chrome's dived shadow: the shadow pull belongs to the
  // stock, not to the matrix rows it borrows from Velvia.
  'classic-vivid': { sh: -0.28 },
  'classic-neg': { shT: [-0.018, 0.009, 0.013], hlT: [0.024, 0.008, -0.012] },
  // Acros. A black-and-white stock IS its grey ramp, so this entry only shapes
  // the two ENDS and leaves the middle an identity: a smooth shadow toe that
  // reaches a true black (no film-base lift, no flat grey wash) and a highlight
  // shoulder that stops just short of white instead of clipping a cloud to
  // paper. Mid-tones see neither mask, so the ramp keeps every step the matrix
  // handed over — which is what 'deep black' costs in a colour stock and does
  // not have to cost here.
  // Gains are TONE_SKSL's own (sh * 0.34, hl * 0.22), so -0.12 puts the toe at
  // ~5% and -0.05 trims the top ~1%.
  monochrome: { sh: -0.12, hl: -0.05 },
  // B&W HIGH CONTRAST. Acros' ramp with both ends pushed hard: a deeper toe
  // (-0.32 against Acros' -0.12) so the darks reach true black, and a shoulder
  // that LIFTS instead of rolling (-0.05 becomes +0.26), which is the whites
  // step of the brief. Midtones see neither mask, so the long smooth stretch
  // between the two ends survives — that is what keeps a hard push off the
  // posterised look, and the slope this stock needs on the greys is its matrix
  // gain (STOCK_BIAS in colorUtils), not another mask here.
  'mono-high-contrast': { sh: -0.32, hl: 0.26 },
};

export function getToneUniforms(adj: ColorAdjustments, baseFilter?: BaseFilter): ToneUniforms {
  const drRaw = adj.dynamicRange ?? 'auto';
  const dr = drRaw === 'auto' || drRaw === 100 ? 0 : (drRaw - 100) / 300;
  const hl = Math.max(-1, Math.min(1, (adj.highlight ?? 0) / 10));
  const sh = Math.max(-1, Math.min(1, (adj.shadow ?? 0) / 10));
  const vib = Math.max(-1, Math.min(1, (adj.vibrance ?? 0) / 10));
  const film = (baseFilter && FILM_TONE[baseFilter]) || {};
  const shT: [number, number, number] = film.shT ?? [0, 0, 0];
  const hlT: [number, number, number] = film.hlT ?? [0, 0, 0];
  // Color Chrome depth per stop of the UI's none/weak/strong. A chrome set is a
  // monochrome look, so both are forced off there: the effect is colour-only
  // (the preview/export matrix skips them for monochrome for the same reason).
  const colour = !isMonochromeBase(baseFilter);
  const chromeDepth = (v: ColorAdjustments['colorChrome'] | undefined) =>
    !colour || v === 'none' || v == null ? 0 : v === 'strong' ? 0.9 : 0.45;
  const blueDepth = (v: ColorAdjustments['colorChromeBlue'] | undefined) =>
    !colour || v === 'none' || v == null ? 0 : v === 'strong' ? 1.0 : 0.5;
  // Selective colour: one slot per band, in HSL_BANDS order, so the flat buffer
  // lines up with the shader's arrays. A band the user has not moved keeps three
  // zeroes and only costs its own slots.
  const bands = adj.hslBands ?? {};
  const tenth = (v: unknown) =>
    typeof v === 'number' && Number.isFinite(v) ? Math.max(-1, Math.min(1, v / 10)) : 0;
  const hslH: number[] = [];
  const hslS: number[] = [];
  const hslL: number[] = [];
  let hslOn = 0;
  for (const band of HSL_BANDS) {
    const v = bands[band.id];
    const [h, s, l] = v ? [tenth(v[0]), tenth(v[1]), tenth(v[2])] : [0, 0, 0];
    hslH.push(h);
    hslS.push(s);
    hslL.push(l);
    if (h || s || l) hslOn = 1;
  }
  // A stock black-and-white has no hue to select on.
  if (!colour) hslOn = 0;
  // The mixer's whole-image move: every hue takes it at full weight.
  const gh = tenth(adj.hslHue);
  const gs = tenth(adj.hslSat);
  const gl = tenth(adj.hslLum);
  if (colour && (gh || gs || gl)) hslOn = 1;
  return {
    dr,
    hl: hl + (film.hl ?? 0),
    sh: sh + (film.sh ?? 0),
    vib,
    shT,
    hlT,
    cc: chromeDepth(adj.colorChrome),
    ccb: blueDepth(adj.colorChromeBlue),
    hslOn,
    hslH,
    hslS,
    hslL,
    gh,
    gs,
    gl,
  };
}

// Flat uniform buffer for `makeShaderWithChildren` / `<Shader uniforms>` — the
// order must match TONE_SKSL's declarations.
export function toneUniformArray(u: ToneUniforms): number[] {
  return [
    u.dr, u.hl, u.sh, u.vib,
    u.shT[0], u.shT[1], u.shT[2], u.hlT[0], u.hlT[1], u.hlT[2], u.cc, u.ccb,
    u.hslOn, ...u.hslH, ...u.hslS, ...u.hslL, u.gh, u.gs, u.gl,
  ];
}

export function toneIsActive(u: ToneUniforms): boolean {
  return (
    u.hslOn !== 0 ||
    u.dr !== 0 ||
    u.hl !== 0 ||
    u.sh !== 0 ||
    u.vib !== 0 ||
    u.shT[0] !== 0 ||
    u.shT[1] !== 0 ||
    u.shT[2] !== 0 ||
    u.hlT[0] !== 0 ||
    u.hlT[1] !== 0 ||
    u.hlT[2] !== 0 ||
    u.cc !== 0 ||
    u.ccb !== 0
  );
}