content: /*
   * Copyright 2021 Google LLC
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  // This file is automatically generated. Do not modify it.
  
  package com.google.material.color.hct;
  
  import com.google.material.color.utils.ColorUtils;
  import com.google.material.color.utils.MathUtils;
  
  /**
   * A class that solves the HCT equation.
   */
  public class HctSolver {
      private HctSolver() {
      }
  
      static final double[][] SCALED_DISCOUNT_FROM_LINRGB =
              new double[][]{
                      new double[]{
                              0.001200833568784504, 0.002389694492170889, 0.0002795742885861124,
                      },
                      new double[]{
                              0.0005891086651375999, 0.0029785502573438758, 0.0003270666104008398,
                      },
                      new double[]{
                              0.00010146692491640572, 0.0005364214359186694, 0.0032979401770712076,
                      },
              };
  
      static final double[][] LINRGB_FROM_SCALED_DISCOUNT =
              new double[][]{
                      new double[]{
                              1373.2198709594231, -1100.4251190754821, -7.278681089101213,
                      },
                      new double[]{
                              -271.815969077903, 559.6580465940733, -32.46047482791194,
                      },
                      new double[]{
                              1.9622899599665666, -57.173814538844006, 308.7233197812385,
                      },
              };
  
      static final double[] Y_FROM_LINRGB = new double[]{0.2126, 0.7152, 0.0722};
  
      static final double[] CRITICAL_PLANES =
              new double[]{
                      0.015176349177441876,
                      0.045529047532325624,
                      0.07588174588720938,
                      0.10623444424209313,
                      0.13658714259697685,
                      0.16693984095186062,
                      0.19729253930674434,
                      0.2276452376616281,
                      0.2579979360165119,
                      0.28835063437139563,
                      0.3188300904430532,
                      0.350925934958123,
                      0.3848314933096426,
                      0.42057480301049466,
                      0.458183274052838,
                      0.4976837250274023,
                      0.5391024159806381,
                      0.5824650784040898,
                      0.6277969426914107,
                      0.6751227633498623,
                      0.7244668422128921,
                      0.775853049866786,
                      0.829304845476233,
                      0.8848452951698498,
                      0.942497089126609,
                      1.0022825574869039,
                      1.0642236851973577,
                      1.1283421258858297,
                      1.1946592148522128,
                      1.2631959812511864,
                      1.3339731595349034,
                      1.407011200216447,
                      1.4823302800086415,
                      1.5599503113873272,
                      1.6398909516233677,
                      1.7221716113234105,
                      1.8068114625156377,
                      1.8938294463134073,
                      1.9832442801866852,
                      2.075074464868551,
                      2.1693382909216234,
                      2.2660538449872063,
                      2.36523901573795,
                      2.4669114995532007,
                      2.5710888059345764,
                      2.6777882626779785,
                      2.7870270208169257,
                      2.898822059350997,
                      3.0131901897720907,
                      3.1301480604002863,
                      3.2497121605402226,
                      3.3718988244681087,
                      3.4967242352587946,
                      3.624204428461639,
                      3.754355295633311,
                      3.887192587735158,
                      4.022731918402185,
                      4.160988767090289,
                      4.301978482107941,
                      4.445716283538092,
                      4.592217266055746,
                      4.741496401646282,
                      4.893568542229298,
                      5.048448422192488,
                      5.20615066083972,
                      5.3666897647573375,
                      5.5300801301023865,
                      5.696336044816294,
                      5.865471690767354,
                      6.037501145825082,
                      6.212438385869475,
                      6.390297286737924,
                      6.571091626112461,
                      6.7548350853498045,
                      6.941541251256611,
                      7.131223617812143,
                      7.323895587840543,
                      7.5195704746346665,
                      7.7182615035334345,
                      7.919981813454504,
                      8.124744458384042,
                      8.332562408825165,
                      8.543448553206703,
                      8.757415699253682,
                      8.974476575321063,
                      9.194643831691977,
                      9.417930041841839,
                      9.644347703669503,
                      9.873909240696694,
                      10.106627003236781,
                      10.342513269534024,
                      10.58158024687427,
                      10.8238400726681,
                      11.069304815507364,
                      11.317986476196008,
                      11.569896988756009,
                      11.825048221409341,
                      12.083451977536606,
                      12.345119996613247,
                      12.610063955123938,
                      12.878295467455942,
                      13.149826086772048,
                      13.42466730586372,
                      13.702830557985108,
                      13.984327217668513,
                      14.269168601521828,
                      14.55736596900856,
                      14.848930523210871,
                      15.143873411576273,
                      15.44220572664832,
                      15.743938506781891,
                      16.04908273684337,
                      16.35764934889634,
                      16.66964922287304,
                      16.985093187232053,
                      17.30399201960269,
                      17.62635644741625,
                      17.95219714852476,
                      18.281524751807332,
                      18.614349837764564,
                      18.95068293910138,
                      19.290534541298456,
                      19.633915083172692,
                      19.98083495742689,
                      20.331304511189067,
                      20.685334046541502,
                      21.042933821039977,
                      21.404114048223256,
                      21.76888489811322,
                      22.137256497705877,
                      22.50923893145328,
                      22.884842241736916,
                      23.264076429332462,
                      23.6469514538663,
                      24.033477234264016,
                      24.42366364919083,
                      24.817520537484558,
                      25.21505769858089,
                      25.61628489293138,
                      26.021211842414342,
                      26.429848230738664,
                      26.842203703840827,
                      27.258287870275353,
                      27.678110301598522,
                      28.10168053274597,
                      28.529008062403893,
                      28.96010235337422,
                      29.39497283293396,
                      29.83362889318845,
                      30.276079891419332,
                      30.722335150426627,
                      31.172403958865512,
                      31.62629557157785,
                      32.08401920991837,
                      32.54558406207592,
                      33.010999283389665,
                      33.4802739966603,
                      33.953417292456834,
                      34.430438229418264,
                      34.911345834551085,
                      35.39614910352207,
                      35.88485700094671,
                      36.37747846067349,
                      36.87402238606382,
                      37.37449765026789,
                      37.87891309649659,
                      38.38727753828926,
                      38.89959975977785,
                      39.41588851594697,
                      39.93615253289054,
                      40.460400508064545,
                      40.98864111053629,
                      41.520882981230194,
                      42.05713473317016,
                      42.597404951718396,
                      43.141702194811224,
                      43.6900349931913,
                      44.24241185063697,
                      44.798841244188324,
                      45.35933162437017,
                      45.92389141541209,
                      46.49252901546552,
                      47.065252796817916,
                      47.64207110610409,
                      48.22299226451468,
                      48.808024568002054,
                      49.3971762874833,
                      49.9904556690408,
                      50.587870934119984,
                      51.189430279724725,
                      51.79514187861014,
                      52.40501387947288,
                      53.0190544071392,
                      53.637271562750364,
                      54.259673423945976,
                      54.88626804504493,
                      55.517063457223934,
                      56.15206766869424,
                      56.79128866487574,
                      57.43473440856916,
                      58.08241284012621,
                      58.734331877617365,
                      59.39049941699807,
                      60.05092333227251,
                      60.715611475655585,
                      61.38457167773311,
                      62.057811747619894,
                      62.7353394731159,
                      63.417162620860914,
                      64.10328893648692,
                      64.79372614476921,
                      65.48848194977529,
                      66.18756403501224,
                      66.89098006357258,
                      67.59873767827808,
                      68.31084450182222,
                      69.02730813691093,
                      69.74813616640164,
                      70.47333615344107,
                      71.20291564160104,
                      71.93688215501312,
                      72.67524319850172,
                      73.41800625771542,
                      74.16517879925733,
                      74.9167682708136,
                      75.67278210128072,
                      76.43322770089146,
                      77.1981124613393,
                      77.96744375590167,
                      78.74122893956174,
                      79.51947534912904,
                      80.30219030335869,
                      81.08938110306934,
                      81.88105503125999,
                      82.67721935322541,
                      83.4778813166706,
                      84.28304815182372,
                      85.09272707154808,
                      85.90692527145302,
                      86.72564993000343,
                      87.54890820862819,
                      88.3767072518277,
                      89.2090541872801,
                      90.04595612594655,
                      90.88742016217518,
                      91.73345337380438,
                      92.58406282226491,
                      93.43925555268066,
                      94.29903859396902,
                      95.16341895893969,
                      96.03240364439274,
                      96.9059996312159,
                      97.78421388448044,
                      98.6670533535366,
                      99.55452497210776,
              };
  
      /**
       * Sanitizes a small enough angle in radians.
       *
       * @param angle An angle in radians; must not deviate too much from 0.
       * @return A coterminal angle between 0 and 2pi.
       */
      static double sanitizeRadians(double angle) {
          return (angle + Math.PI * 8) % (Math.PI * 2);
      }
  
      /**
       * Delinearizes an RGB component, returning a floating-point number.
       *
       * @param rgbComponent 0.0 <= rgb_component <= 100.0, represents linear R/G/B channel
       * @return 0.0 <= output <= 255.0, color channel converted to regular RGB space
       */
      static double trueDelinearized(double rgbComponent) {
          double normalized = rgbComponent / 100.0;
          double delinearized = 0.0;
          if (normalized <= 0.0031308) {
              delinearized = normalized * 12.92;
          } else {
              delinearized = 1.055 * Math.pow(normalized, 1.0 / 2.4) - 0.055;
          }
          return delinearized * 255.0;
      }
  
      static double chromaticAdaptation(double component) {
          double af = Math.pow(Math.abs(component), 0.42);
          return MathUtils.signum(component) * 400.0 * af / (af + 27.13);
      }
  
      /**
       * Returns the hue of a linear RGB color in CAM16.
       *
       * @param linrgb The linear RGB coordinates of a color.
       * @return The hue of the color in CAM16, in radians.
       */
      static double hueOf(double[] linrgb) {
          double[] scaledDiscount = MathUtils.matrixMultiply(linrgb, SCALED_DISCOUNT_FROM_LINRGB);
          double rA = chromaticAdaptation(scaledDiscount[0]);
          double gA = chromaticAdaptation(scaledDiscount[1]);
          double bA = chromaticAdaptation(scaledDiscount[2]);
          // redness-greenness
          double a = (11.0 * rA + -12.0 * gA + bA) / 11.0;
          // yellowness-blueness
          double b = (rA + gA - 2.0 * bA) / 9.0;
          return Math.atan2(b, a);
      }
  
      static boolean areInCyclicOrder(double a, double b, double c) {
          double deltaAB = sanitizeRadians(b - a);
          double deltaAC = sanitizeRadians(c - a);
          return deltaAB < deltaAC;
      }
  
      /**
       * Solves the lerp equation.
       *
       * @param source The starting number.
       * @param mid    The number in the middle.
       * @param target The ending number.
       * @return A number t such that lerp(source, target, t) = mid.
       */
      static double intercept(double source, double mid, double target) {
          return (mid - source) / (target - source);
      }
  
      static double[] lerpPoint(double[] source, double t, double[] target) {
          return new double[]{
                  source[0] + (target[0] - source[0]) * t,
                  source[1] + (target[1] - source[1]) * t,
                  source[2] + (target[2] - source[2]) * t,
          };
      }
  
      /**
       * Intersects a segment with a plane.
       *
       * @param source     The coordinates of point A.
       * @param coordinate The R-, G-, or B-coordinate of the plane.
       * @param target     The coordinates of point B.
       * @param axis       The axis the plane is perpendicular with. (0: R, 1: G, 2: B)
       * @return The intersection point of the segment AB with the plane R=coordinate, G=coordinate, or
       * B=coordinate
       */
      static double[] setCoordinate(double[] source, double coordinate, double[] target, int axis) {
          double t = intercept(source[axis], coordinate, target[axis]);
          return lerpPoint(source, t, target);
      }
  
      static boolean isBounded(double x) {
          return 0.0 <= x && x <= 100.0;
      }
  
      /**
       * Returns the nth possible vertex of the polygonal intersection.
       *
       * @param y The Y value of the plane.
       * @param n The zero-based index of the point. 0 <= n <= 11.
       * @return The nth possible vertex of the polygonal intersection of the y plane and the RGB cube,
       * in linear RGB coordinates, if it exists. If this possible vertex lies outside of the cube,
       * [-1.0, -1.0, -1.0] is returned.
       */
      static double[] nthVertex(double y, int n) {
          double kR = Y_FROM_LINRGB[0];
          double kG = Y_FROM_LINRGB[1];
          double kB = Y_FROM_LINRGB[2];
          double coordA = n % 4 <= 1 ? 0.0 : 100.0;
          double coordB = n % 2 == 0 ? 0.0 : 100.0;
          if (n < 4) {
              double g = coordA;
              double b = coordB;
              double r = (y - g * kG - b * kB) / kR;
              if (isBounded(r)) {
                  return new double[]{r, g, b};
              } else {
                  return new double[]{-1.0, -1.0, -1.0};
              }
          } else if (n < 8) {
              double b = coordA;
              double r = coordB;
              double g = (y - r * kR - b * kB) / kG;
              if (isBounded(g)) {
                  return new double[]{r, g, b};
              } else {
                  return new double[]{-1.0, -1.0, -1.0};
              }
          } else {
              double r = coordA;
              double g = coordB;
              double b = (y - r * kR - g * kG) / kB;
              if (isBounded(b)) {
                  return new double[]{r, g, b};
              } else {
                  return new double[]{-1.0, -1.0, -1.0};
              }
          }
      }
  
      /**
       * Finds the segment containing the desired color.
       *
       * @param y         The Y value of the color.
       * @param targetHue The hue of the color.
       * @return A list of two sets of linear RGB coordinates, each corresponding to an endpoint of the
       * segment containing the desired color.
       */
      static double[][] bisectToSegment(double y, double targetHue) {
          double[] left = new double[]{-1.0, -1.0, -1.0};
          double[] right = left;
          double leftHue = 0.0;
          double rightHue = 0.0;
          boolean initialized = false;
          boolean uncut = true;
          for (int n = 0; n < 12; n++) {
              double[] mid = nthVertex(y, n);
              if (mid[0] < 0) {
                  continue;
              }
              double midHue = hueOf(mid);
              if (!initialized) {
                  left = mid;
                  right = mid;
                  leftHue = midHue;
                  rightHue = midHue;
                  initialized = true;
                  continue;
              }
              if (uncut || areInCyclicOrder(leftHue, midHue, rightHue)) {
                  uncut = false;
                  if (areInCyclicOrder(leftHue, targetHue, midHue)) {
                      right = mid;
                      rightHue = midHue;
                  } else {
                      left = mid;
                      leftHue = midHue;
                  }
              }
          }
          return new double[][]{left, right};
      }
  
      static double[] midpoint(double[] a, double[] b) {
          return new double[]{
                  (a[0] + b[0]) / 2, (a[1] + b[1]) / 2, (a[2] + b[2]) / 2,
          };
      }
  
      static int criticalPlaneBelow(double x) {
          return (int) Math.floor(x - 0.5);
      }
  
      static int criticalPlaneAbove(double x) {
          return (int) Math.ceil(x - 0.5);
      }
  
      /**
       * Finds a color with the given Y and hue on the boundary of the cube.
       *
       * @param y         The Y value of the color.
       * @param targetHue The hue of the color.
       * @return The desired color, in linear RGB coordinates.
       */
      static double[] bisectToLimit(double y, double targetHue) {
          double[][] segment = bisectToSegment(y, targetHue);
          double[] left = segment[0];
          double leftHue = hueOf(left);
          double[] right = segment[1];
          for (int axis = 0; axis < 3; axis++) {
              if (left[axis] != right[axis]) {
                  int lPlane = -1;
                  int rPlane = 255;
                  if (left[axis] < right[axis]) {
                      lPlane = criticalPlaneBelow(trueDelinearized(left[axis]));
                      rPlane = criticalPlaneAbove(trueDelinearized(right[axis]));
                  } else {
                      lPlane = criticalPlaneAbove(trueDelinearized(left[axis]));
                      rPlane = criticalPlaneBelow(trueDelinearized(right[axis]));
                  }
                  for (int i = 0; i < 8; i++) {
                      if (Math.abs(rPlane - lPlane) <= 1) {
                          break;
                      } else {
                          int mPlane = (int) Math.floor((lPlane + rPlane) / 2.0);
                          double midPlaneCoordinate = CRITICAL_PLANES[mPlane];
                          double[] mid = setCoordinate(left, midPlaneCoordinate, right, axis);
                          double midHue = hueOf(mid);
                          if (areInCyclicOrder(leftHue, targetHue, midHue)) {
                              right = mid;
                              rPlane = mPlane;
                          } else {
                              left = mid;
                              leftHue = midHue;
                              lPlane = mPlane;
                          }
                      }
                  }
              }
          }
          return midpoint(left, right);
      }
  
      static double inverseChromaticAdaptation(double adapted) {
          double adaptedAbs = Math.abs(adapted);
          double base = Math.max(0, 27.13 * adaptedAbs / (400.0 - adaptedAbs));
          return MathUtils.signum(adapted) * Math.pow(base, 1.0 / 0.42);
      }
  
      /**
       * Finds a color with the given hue, chroma, and Y.
       *
       * @param hueRadians The desired hue in radians.
       * @param chroma     The desired chroma.
       * @param y          The desired Y.
       * @return The desired color as a hexadecimal integer, if found; 0 otherwise.
       */
      static int findResultByJ(double hueRadians, double chroma, double y) {
          // Initial estimate of j.
          double j = Math.sqrt(y) * 11.0;
          // ===========================================================
          // Operations inlined from Cam16 to avoid repeated calculation
          // ===========================================================
          ViewingConditions viewingConditions = ViewingConditions.DEFAULT;
          double tInnerCoeff = 1 / Math.pow(1.64 - Math.pow(0.29, viewingConditions.getN()), 0.73);
          double eHue = 0.25 * (Math.cos(hueRadians + 2.0) + 3.8);
          double p1 = eHue * (50000.0 / 13.0) * viewingConditions.getNc() * viewingConditions.getNcb();
          double hSin = Math.sin(hueRadians);
          double hCos = Math.cos(hueRadians);
          for (int iterationRound = 0; iterationRound < 5; iterationRound++) {
              // ===========================================================
              // Operations inlined from Cam16 to avoid repeated calculation
              // ===========================================================
              double jNormalized = j / 100.0;
              double alpha = chroma == 0.0 || j == 0.0 ? 0.0 : chroma / Math.sqrt(jNormalized);
              double t = Math.pow(alpha * tInnerCoeff, 1.0 / 0.9);
              double ac =
                      viewingConditions.getAw()
                              * Math.pow(jNormalized, 1.0 / viewingConditions.getC() / viewingConditions.getZ());
              double p2 = ac / viewingConditions.getNbb();
              double gamma = 23.0 * (p2 + 0.305) * t / (23.0 * p1 + 11 * t * hCos + 108.0 * t * hSin);
              double a = gamma * hCos;
              double b = gamma * hSin;
              double rA = (460.0 * p2 + 451.0 * a + 288.0 * b) / 1403.0;
              double gA = (460.0 * p2 - 891.0 * a - 261.0 * b) / 1403.0;
              double bA = (460.0 * p2 - 220.0 * a - 6300.0 * b) / 1403.0;
              double rCScaled = inverseChromaticAdaptation(rA);
              double gCScaled = inverseChromaticAdaptation(gA);
              double bCScaled = inverseChromaticAdaptation(bA);
              double[] linrgb =
                      MathUtils.matrixMultiply(
                              new double[]{rCScaled, gCScaled, bCScaled}, LINRGB_FROM_SCALED_DISCOUNT);
              // ===========================================================
              // Operations inlined from Cam16 to avoid repeated calculation
              // ===========================================================
              if (linrgb[0] < 0 || linrgb[1] < 0 || linrgb[2] < 0) {
                  return 0;
              }
              double kR = Y_FROM_LINRGB[0];
              double kG = Y_FROM_LINRGB[1];
              double kB = Y_FROM_LINRGB[2];
              double fnj = kR * linrgb[0] + kG * linrgb[1] + kB * linrgb[2];
              if (fnj <= 0) {
                  return 0;
              }
              if (iterationRound == 4 || Math.abs(fnj - y) < 0.002) {
                  if (linrgb[0] > 100.01 || linrgb[1] > 100.01 || linrgb[2] > 100.01) {
                      return 0;
                  }
                  return ColorUtils.argbFromLinrgb(linrgb);
              }
              // Iterates with Newton method,
              // Using 2 * fn(j) / j as the approximation of fn'(j)
              j = j - (fnj - y) * j / (2 * fnj);
          }
          return 0;
      }
  
      /**
       * Finds an sRGB color with the given hue, chroma, and L*, if possible.
       *
       * @param hueDegrees The desired hue, in degrees.
       * @param chroma     The desired chroma.
       * @param lstar      The desired L*.
       * @return A hexadecimal representing the sRGB color. The color has sufficiently close hue,
       * chroma, and L* to the desired values, if possible; otherwise, the hue and L* will be
       * sufficiently close, and chroma will be maximized.
       */
      public static int solveToInt(double hueDegrees, double chroma, double lstar) {
          if (chroma < 0.0001 || lstar < 0.0001 || lstar > 99.9999) {
              return ColorUtils.argbFromLstar(lstar);
          }
          hueDegrees = MathUtils.sanitizeDegreesDouble(hueDegrees);
          double hueRadians = hueDegrees / 180 * Math.PI;
          double y = ColorUtils.yFromLstar(lstar);
          int exactAnswer = findResultByJ(hueRadians, chroma, y);
          if (exactAnswer != 0) {
              return exactAnswer;
          }
          double[] linrgb = bisectToLimit(y, hueRadians);
          return ColorUtils.argbFromLinrgb(linrgb);
      }
  
      /**
       * Finds an sRGB color with the given hue, chroma, and L*, if possible.
       *
       * @param hueDegrees The desired hue, in degrees.
       * @param chroma The desired chroma.
       * @param lstar The desired L*.
       * @return A CAM16 object representing the sRGB color. The color has sufficiently close hue,
       *     chroma, and L* to the desired values, if possible; otherwise, the hue and L* will be
       *     sufficiently close, and chroma will be maximized.
     */
    public static Cam16 solveToCam(double hueDegrees, double chroma, double lstar) {
      return Cam16.fromInt(solveToInt(hueDegrees, chroma, lstar));
    }
  }
  
  