package testsupport.matchers;

import com.jnape.palatable.lambda.adt.Either;

import org.hamcrest.Description;

import org.hamcrest.Matcher;

import org.hamcrest.TypeSafeMatcher;

import static com.jnape.palatable.lambda.functions.builtin.fn1.Constantly.constantly;

import static com.jnape.palatable.lambda.io.IO.io;

public final class LeftMatcher<L, R> extends TypeSafeMatcher<Either<L, R>> {

private final Matcher<L> lMatcher;

private LeftMatcher(Matcher<L> lMatcher) {

this.lMatcher = lMatcher;

}

@Override

protected boolean matchesSafely(Either<L, R> actual) {

return actual.match(lMatcher::matches, constantly(false));

}

@Override

public void describeTo(Description description) {

description.appendText("Left value of ");

lMatcher.describeTo(description);

}

@Override

protected void describeMismatchSafely(Either<L, R> item, Description mismatchDescription) {

mismatchDescription.appendText("was ");

item.peek(l -> io(() -> {

mismatchDescription.appendText("Left value of ");

lMatcher.describeMismatch(l, mismatchDescription);

}),

r -> io(() -> mismatchDescription.appendValue(item)));

}

public static <L, R> LeftMatcher<L, R> isLeftThat(Matcher<L> lMatcher) {

return new LeftMatcher<>(lMatcher);

}

}