function getScaleInputs()

in packages/charts/src/chart_types/bullet_graph/utils/color.ts [139:230]
75 lines of code
17 McCabe index (conditional complexity)

function getScaleInputs(baseDomain: ContinuousDomain, config: BulletColorConfig, backgroundColor: Color): ScaleInputs {
  if (!Array.isArray(config) || !isComplexConfig(config)) {
    const { colors: rawColors, steps }: { colors: string[]; steps?: number | number[] } = !Array.isArray(config)
      ? config
      : {
          colors: config,
        };

    // TODO - fix thrown error for RGBA colors from storybook
    const colors = rawColors.map((c) => c.toLowerCase());
    if (colors.length === 1) {
      // Adds second color
      const [color] = colors;
      // should always have color
      if (color) {
        const secondary = getChromaColor(color).alpha(0.7).hex();
        const blendedSecondary = combineColors(colorToRgba(secondary), colorToRgba(backgroundColor));
        colors.push(RGBATupleToString(blendedSecondary));
      }
    }

    return {
      colors,
      steps,
    };
  }

  if (!isComplexConfig(config)) {
    return {
      colors: config,
    };
  }

  const getDomainPair = getDomainPairFn(baseDomain);
  const { colors, boundedDomains } = config.reduce<{
    boundedDomains: [number | null, number | null][];
    colors: string[];
  }>(
    (acc, colorConfig) => {
      if (typeof colorConfig === 'string') {
        acc.colors.push(colorConfig);
      } else {
        acc.colors.push(colorConfig.color);
        const domainPair = getDomainPair(colorConfig);
        acc.boundedDomains.push(domainPair);
      }

      return acc;
    },
    {
      boundedDomains: [],
      colors: [],
    },
  );

  let prevMax = -Infinity;
  return boundedDomains.reduce<Required<ScaleInputs, 'colorBandDomain'>>(
    (acc, [min, max], i) => {
      // TODO: Add better error handling around this logic, the complex config right now assumes the following:
      // - All ranges are ordered from min to max
      // - All ranges are compatible with each other such that there is no overlapping or excluded ranges
      // Ideally we validate the config and fix it the best we can based on what is provided, filling or clamping as needed
      const testMinValue = isFiniteNumber(min) ? min : isFiniteNumber(max) ? max : null;
      if (testMinValue === null || testMinValue < prevMax) {
        Logger.warn(`Error with ColorBandComplexConfig:

Ranges are incompatible with each other such that there is either overlapping or excluded range pairs`);
        return acc;
      }
      const newMaxValue = isFiniteNumber(max) ? max : isFiniteNumber(min) ? min : null;
      if (newMaxValue === null) return acc;

      prevMax = newMaxValue;
      const color = colors[i] ?? Colors.Transparent.keyword;

      if (isFiniteNumber(min)) {
        acc.colorBandDomain.push(min);
        acc.colors.push(color);
      }
      if (isFiniteNumber(max)) {
        acc.colorBandDomain.push(max);
        acc.colors.push(color);
      }

      return acc;
    },
    {
      colorBandDomain: [],
      colors: [],
    },
  );
}