import type { RoiKind } from '../../getRois.js';
import { hsvToRgb } from '../hsvToRgb.js';
import { rgbToNumber } from '../rgbToNumber.js';

export interface GetSaturationMapOptions {
  /**
   * Number of black ROIs.
   */
  nbNegative: number;
  /**
   * Number of white ID ROIs.
   */
  nbPositive: number;
  /**
   * Specify which ROIs to color.
   * @default `'bw'`
   */
  roiKind?: RoiKind;
  /**
   * Hue of white ROIs.
   *  @default `0`
   */
  whiteHue?: number;
  /**
   * Hue of black ROIs.
   * @default `240`
   */
  blackHue?: number;
}

/**
 * Return a map where ROIs are different shades of red (positive) or blue (negative) depending on the ROI index. It it the saturation of the HSV color model that is varied.
 * @param options - Get temperature map options.
 * @returns The colored map.
 */
export function getSaturationMap(
  options: GetSaturationMapOptions,
): Uint32Array {
  const {
    nbNegative,
    nbPositive,
    roiKind = 'bw',
    whiteHue = 0,
    blackHue = 240,
  } = options;

  const colorMap = new Uint32Array(nbNegative + nbPositive + 1);

  const range = 255 - 63; // saturation range for good contrast
  const negativeStep = range / nbNegative;
  const positiveStep = range / nbPositive;

  // negative values
  let counter = 0;
  if (roiKind === 'bw' || roiKind === 'black') {
    for (let i = -nbNegative; i < 0; i++) {
      const hsv = [blackHue, 255 - counter++ * negativeStep, 255];
      colorMap[i + nbNegative] = rgbToNumber(hsvToRgb(hsv));
    }
  }
  // positive values
  counter = 0;
  if (roiKind === 'bw' || roiKind === 'white') {
    for (let i = 1; i <= nbPositive; i++) {
      const hsv = [whiteHue, 255 - counter++ * positiveStep, 255];
      colorMap[i + nbNegative] = rgbToNumber(hsvToRgb(hsv));
    }
  }
  return colorMap;
}