package io.atlassian.fugue.optic.law;
   
   import io.atlassian.fugue.Either;
   import io.atlassian.fugue.Eithers;
   import io.atlassian.fugue.Option;
   import io.atlassian.fugue.Options;
   import io.atlassian.fugue.Pair;
   import io.atlassian.fugue.Suppliers;
   import io.atlassian.fugue.law.IsEq;
  import io.atlassian.fugue.optic.PIso;
  
  import java.util.Collections;
  import java.util.List;
  import java.util.function.Function;
  
  import static io.atlassian.fugue.law.IsEq.isEq;
  import static java.util.Spliterator.ORDERED;
  import static java.util.Spliterators.spliteratorUnknownSize;
  import static java.util.stream.Collectors.toList;
  import static java.util.stream.StreamSupport.stream;
  
  public final class IsoLaws<S, A> {
  
    private final PIso<S, S, A, A> iso;
  
    public IsoLaws(PIso<S, S, A, A> iso) {
      this.iso = iso;
    }
  
    /**
     * get and reverseGet forms an Isomorphism: round trip one way
     */
    public IsEq<S> roundTripOneWay(S s) {
      return isEq(iso.reverseGet(iso.get(s)), s);
    }
  
    /**
     * get and reverseGet forms an Isomorphism: round trip other way
     */
    public IsEq<A> roundTripOtherWay(A a) {
      return isEq(iso.get(iso.reverseGet(a)), a);
    }
  
    /**
     * set is a weaker version of reverseGet
     */
    public IsEq<S> set(S s, A a) {
      return isEq(iso.set(a).apply(s), iso.reverseGet(a));
    }
  
    /**
     * modify id = id
     */
    public IsEq<S> modifyIdentity(S s) {
      return isEq(iso.modify(Function.<A> identity()).apply(s), s);
    }
  
    /**
     * modifyF Applicative.point(_) = Applicative.point(_)
     */
    public IsEq<S> modifySupplierFPoint(S s) {
      return isEq(iso.modifySupplierF(Suppliers::ofInstance).apply(s).get(), s);
    }
  
    /**
     * modifyF Applicative.point(_) = Applicative.point(_)
     */
    public IsEq<Either<String, S>> modifyEitherFPoint(S s) {
      return isEq(iso.<String> modifyEitherF(Eithers.toRight()).apply(s), Either.right(s));
    }
  
    /**
     * modifyF Applicative.point(_) = Applicative.point(_)
     */
    public IsEq<Option<S>> modifyOptionFPoint(S s) {
      return isEq(iso.modifyOptionF(Options.toOption()).apply(s), Option.some(s));
    }
  
    /**
     * modifyF Applicative.point(_) = Applicative.point(_)
     */
    public IsEq<Pair<S, S>> modifyPairFPoint(S s) {
      return isEq(iso.modifyPairF(a -> Pair.pair(a, a)).apply(s), Pair.pair(s, s));
    }
  
    /**
     * modifyF Applicative.point(_) = Applicative.point(_)
     */
    public IsEq<S> modifyFunctionFPoint(S s) {
      return isEq(iso.<String> modifyFunctionF(a -> __ -> a).apply(s).apply(""), s);
    }
  
    /**
     * modifyF Applicative.point(_) = Applicative.point(_)
     */
    public IsEq<List<S>> modifyIterableFPoint(S s) {
      return isEq(stream(spliteratorUnknownSize(iso.modifyIterableF(Collections::singleton).apply(s).iterator(), ORDERED), false).collect(toList()),
        Collections.singletonList(s));
    }
 }