import { capitalizeFirstLetter } from "../util/util.js";
import { newProduct as newProduct, getLeft } from "./product.js";
import { newLeft, newRight, match } from "./sum.js";

const eatParameters = (numParams, result) => {
  if (numParams === 0) {
    return result;
  }
  else return () => eatParameters(numParams-1, result);
}

export const makeMatchFn = variants => {
  if (variants.length === 0) {
    return undefined;
  }
  const [_, ...remainingVariants] = variants;
  return sum => handler => {
    return match(sum)
        (leftValue => eatParameters(remainingVariants.length, handler(leftValue)))
        (rightValue => makeMatchFn(remainingVariants)(rightValue));
  };
};

export const makeConstructors = variants => {
  if (variants.length === 0) {
    return [];
  }
  const [variant, ...remainingVariants] = variants;
  const name = getLeft(variant);
  const ctorName = `new${capitalizeFirstLetter(name)}`;
  const constructor = { [ctorName]: val => newLeft(val) }[ctorName];
  return [
    constructor,
    ...makeConstructors(remainingVariants).map(ctor =>
      ({[ctor.name]: val => newRight(ctor(val))}[ctor.name])),
  ];
}