RecipesCam/src/utils/cinemaShader.ts

import { CinemaSeason } from '../types';

// Cinematic seasonal atmosphere grade. Deliberately NOT a fake re-light: a
// still photo has no depth, so "moving the sun" would look plastic. Instead
// this reads the photo's EXISTING exposure and pushes it a certain way:
//   - lit areas get the season's warm/golden tint + a soft sun glow (halation)
//   - shadow side gets a complementary cool tint
//   - a seasonal haze/fog veil blends toward a fog color (strongest in winter)
// That reads as "sunlight / morning mist" without inventing new light.
//
// Uniforms are 16 flat floats (scalar form keeps the JSX <Shader> uniforms
// object and the worklet/export flat arrays in the exact same order):
//   strength, contrast, saturation, haze,
//   warmR, warmG, warmB, warmAmt,
//   coolR, coolG, coolB, coolAmt,
//   fogR, fogG, fogB, fogAmt
export const CINEMA_SKSL = `
uniform shader src;
uniform float strength;
uniform float contrast;
uniform float saturation;
uniform float haze;
uniform float warmR;
uniform float warmG;
uniform float warmB;
uniform float warmAmt;
uniform float coolR;
uniform float coolG;
uniform float coolB;
uniform float coolAmt;
uniform float fogR;
uniform float fogG;
uniform float fogB;
uniform float fogAmt;
vec4 main(vec2 xy) {
  vec4 c = src.eval(xy);
  float t = clamp(dot(c.rgb, vec3(0.2126, 0.7152, 0.0722)), 0.0, 1.0);
  vec3 r = c.rgb;
  // Filmic-ish gentle contrast on the luma (keeps hue).
  r = mix(r, clamp((r - 0.5) * (1.0 + contrast * strength) + 0.5, 0.0, 1.0), strength);
  // Saturation.
  float l = dot(r, vec3(0.2126, 0.7152, 0.0722));
  r = mix(vec3(l), r, mix(1.0, saturation, strength));
  // Season tints follow the EXISTING light: warm on lit areas, cool in shade.
  float lit = smoothstep(0.30, 1.0, t);
  float shad = 1.0 - smoothstep(0.0, 0.45, t);
  vec3 warm = vec3(warmR, warmG, warmB);
  vec3 cool = vec3(coolR, coolG, coolB);
  r *= 1.0 + (warm - 1.0) * lit * warmAmt * strength;
  r *= 1.0 + (cool - 1.0) * shad * coolAmt * strength;
  // Soft sun glow at the brightest points (halation of existing highlights).
  float glow = smoothstep(0.65, 1.0, t);
  r += warm * glow * warmAmt * 0.45 * strength;
  // Atmospheric haze/fog veil (lightest shadow side => misty air).
  vec3 fog = vec3(fogR, fogG, fogB);
  r = mix(r, fog, fogAmt * strength * (0.3 + 0.7 * shad));
  return vec4(clamp(r, 0.0, 1.0), c.a);
}
`;

export interface CinemaUniformSet {
  season: CinemaSeason;
  // 16 flat floats — order matches CINEMA_SKSL declaration order above.
  flat: number[];
  // Name-keyed, for the JSX <Shader uniforms={...}> form.
  uniforms: Record<string, number>;
}

const ZERO: Record<string, number> = {};

const SEASONS: Record<CinemaSeason, { name: string; values: number[] }> = {
  // Soft fresh light, gentle warm haze, barely-there cool in shade.
  spring: {
    name: 'CINEMA SPRING',
    values: [
      0.6, 0.08, 1.04, 0.18,
      1.02, 0.998, 0.95, 0.3,
      0.97, 0.995, 1.03, 0.12,
      0.95, 0.96, 0.98, 0.16,
    ],
  },
  // Golden hour-ish high sun: strong warm on lit, bluish shade, crisp.
  summer: {
    name: 'CINEMA SUMMER',
    values: [
      0.75, 0.2, 1.12, 0.1,
      1.08, 1.04, 0.88, 0.4,
      0.93, 0.97, 1.06, 0.2,
      1.0, 0.97, 0.88, 0.05,
    ],
  },
  // Amber low sun + warm atmospheric haze.
  autumn: {
    name: 'CINEMA AUTUMN',
    values: [
      0.8, 0.16, 1.1, 0.24,
      1.12, 1.02, 0.78, 0.42,
      1.02, 0.98, 0.88, 0.16,
      1.0, 0.93, 0.75, 0.18,
    ],
  },
  // Cold winter fog: desaturated, blue-grey, heavy mist, no warm sun.
  winter: {
    name: 'CINEMA WINTER',
    values: [
      0.65, -0.02, 0.88, 0.38,
      0.99, 0.995, 1.02, 0.06,
      0.94, 0.97, 1.08, 0.3,
      0.9, 0.93, 0.97, 0.45,
    ],
  },
};

const KEYS = [
  'strength', 'contrast', 'saturation', 'haze',
  'warmR', 'warmG', 'warmB', 'warmAmt',
  'coolR', 'coolG', 'coolB', 'coolAmt',
  'fogR', 'fogG', 'fogB', 'fogAmt',
] as const;

export function getCinemaUniforms(season: CinemaSeason | null | undefined): CinemaUniformSet | null {
  if (!season) return null;
  const s = SEASONS[season];
  if (!s) return null;
  const uniforms: Record<string, number> = {};
  KEYS.forEach((k, i) => (uniforms[k] = s.values[i]));
  return { season, flat: s.values, uniforms };
}

// Zeroed 16-float block — used to turn the cinema pass OFF in the worklet
// synchronizable (strength === 0 means inactive there).
export function cinemaOffFlat(): number[] {
  return [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
}

export function cinemaIsActive(flat: number[] | null | undefined): boolean {
  return !!flat && flat.length === 16 && flat[0] > 0;
}