import { TInput, Irgba, TFormat, Iluva } from "../types";
import { adjustAlpha, clamp } from "../utils/numeric";
import { isLUVObject } from "../utils/typeGuards";
import { LUVtoRGB } from "../conversions/luv";

/**
 * color(luv[a] <number | percentage>{3} [ / <alpha-value> ]? )
 * @note For typical images, u and v range is ±100%. By definition, 0 ≤ L ≤ 100%.
 * @see https://en.wikipedia.org/wiki/CIELUV#Cylindrical_representation_.28CIELCH.29
 */
const LUVA_RE =
  /color\s*\(\s*luva?\s*(\d*\.?\d+%?)\s*,?\s*([+-]?\d*\.?\d+%?)\s*,?\s*([+-]?\d*\.?\d+%?)\s*,?\s*\/?\s*?(\d*\.?\d+%?)?\s*\)/gi;

function createReturnArr({ l, u, v, a }: Iluva): [Irgba, TFormat] {
  return [LUVtoRGB({ l: clamp(0, l, 100), u: clamp(-100, u, 100), v: clamp(-100, v, 100), a: adjustAlpha(a) }), "luv"];
}

export function luvaParser(color: TInput): [Irgba, TFormat] {
  if (color.constructor.name.toLowerCase() === "object" && isLUVObject(color)) {
    return createReturnArr(color as Iluva);
  } else if (typeof color === "string") {
    LUVA_RE.lastIndex = 0;

    const matches = LUVA_RE.exec(color);
    if (matches) {
      const [l, u, v, a] = matches
        .filter((val) => val !== undefined)
        .slice(1)
        .map((elem, i) => (elem.includes("%") ? +elem.slice(0, -1) * (i < 3 ? 1 : 0.01) : +elem));
      return createReturnArr({ l, u, v, a });
    }
  }

  return [{ r: 0, g: 0, b: 0, a: 1 }, "invalid"];
}