/**
 * Noir Style — Desaturation + High Contrast + Vignette
 * Classic film noir / detective movie look
 */
export const noirShader = {
  name: 'noir',
  uniforms: {
    contrastAmt: { default: 1.2, min: 0, max: 2, label: 'Contrast' },
    grainAmt: { default: 0.5, min: 0, max: 1, label: 'Grain' },
    vignetteAmt: { default: 0.5, min: 0, max: 1, label: 'Vignette' },
  },
  fragmentShader: /* glsl */ `
    uniform sampler2D colorTexture;
    uniform vec2 colorTextureDimensions;
    uniform float intensity;
    uniform float contrastAmt;
    uniform float grainAmt;
    uniform float vignetteAmt;
    in vec2 v_textureCoordinates;

    void main() {
      vec2 uv = v_textureCoordinates;
      vec4 color = texture(colorTexture, uv);

      // Desaturate
      float luma = dot(color.rgb, vec3(0.299, 0.587, 0.114));
      vec3 gray = vec3(luma);
      vec3 desaturated = mix(color.rgb, gray, intensity);

      // High contrast with S-curve (driven by contrastAmt uniform)
      float contrast = 1.0 + contrastAmt * intensity;
      vec3 contrasted = (desaturated - 0.5) * contrast + 0.5;
      contrasted = clamp(contrasted, 0.0, 1.0);

      // Film grain (driven by grainAmt uniform)
      float grain = fract(sin(dot(uv * colorTextureDimensions, vec2(12.9898, 78.233))) * 43758.5453);
      grain = (grain - 0.5) * 0.08 * grainAmt * intensity;
      contrasted += grain;

      // Vignette (driven by vignetteAmt uniform)
      vec2 vigUV = uv * (1.0 - uv);
      float vig = vigUV.x * vigUV.y * 16.0;
      vig = pow(vig, 0.3 + 0.4 * vignetteAmt * intensity);

      // Slight sepia tint for warmth
      vec3 sepia = vec3(
        dot(contrasted, vec3(0.393, 0.769, 0.189)),
        dot(contrasted, vec3(0.349, 0.686, 0.168)),
        dot(contrasted, vec3(0.272, 0.534, 0.131))
      );
      vec3 tinted = mix(contrasted, sepia, 0.15 * intensity);

      vec3 result = tinted * vig;
      out_FragColor = vec4(mix(color.rgb, result, intensity), color.a);
    }
  `,
};