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package com.yahoo.maha.parrequest2;

import com.google.common.base.Preconditions;
import scala.Function1;
import scala.Option;
import scala.util.Either;
import scala.util.Right;

import java.util.function.Function;

public class EitherUtils {


    /**
     * Casts the leftEither from  to , meaning it is of type E already and not A or B
     */
    public static  Either castLeft(Either leftEither) {
        Preconditions.checkArgument(leftEither.isLeft());
        return (Either) leftEither;
    }

    /**
     * Maps either by applying function doWithRight if the Either isRight(), otherwise returns the input either with
     * cast to 
     */
    public static  Either flatMap(Function> doWithRight, Either either) {
        if (either.isRight()) {
            return doWithRight.apply(either.right().get());
        } else {
            return ((Either) either);
        }
    }

    /**
     * Converts Either to T by applying the right function or left function depending on if it isRight or isLeft
     */
    public static  T fold(Function doWithLeft, Function doWithRight, Either either) {
        if (either.isLeft()) {
            return doWithLeft.apply(either.left().get());
        } else {
            return doWithRight.apply(either.right().get());
        }
    }

    /**
     * Converts Either to T by applying the right function or left function depending on if it isRight or isLeft
     */
    public static  T fold(Function1 doWithLeft, Function doWithRight, Either either) {
        if (either.isLeft()) {
            return doWithLeft.apply(either.left().get());
        } else {
            return doWithRight.apply(either.right().get());
        }
    }

    /**
     * Maps either by applying function doWithRight if the Either isRight(), otherwise, it passes the Either through
     * with cast to 
     */
    public static  Either map(Function doWithRight, Either either) {
        if (either.isRight()) {
            return new Right<>(doWithRight.apply(either.right().get()));
        } else {
            return ((Either) either);
        }
    }

    /**
     * If option is defined, applies doWithOption function, else returns Option.none()
     */
    final public static  Option map(Function doWithOption, Option option) {
        if (option.isDefined()) {
            T t = option.get();
            return Option.apply(doWithOption.apply(t));
        } else {
            return Option.empty();
        }
    }
}