import { RgbaColor } from "@noya-app/noya-color";
import { interpolate } from "@noya-app/noya-utils";

export interface GradientStopRgba {
  color: RgbaColor;
  position: number;
}

const RGBA_COMPONENTS = ["r", "g", "b", "a"] as const;

export function interpolateRgba(
  stops: GradientStopRgba[],
  pos: number
): RgbaColor {
  const color: RgbaColor = { r: 0, g: 0, b: 0, a: 1 };

  if (stops.length === 0) return color;

  const sorted = [...stops].sort((a, b) => a.position - b.position);

  RGBA_COMPONENTS.forEach((component) => {
    const inputRange = sorted.map((stop) => stop.position);
    const outputRange = sorted.map((stop) => stop.color[component]);

    color[component] = interpolate(pos, { inputRange, outputRange });
  });

  return color;
}