package io.atlassian.fugue.optic;
   
   import io.atlassian.fugue.*;
   
   import java.util.Collections;
   import java.util.function.Function;
   import java.util.function.Supplier;
   import java.util.stream.Stream;
   
  /**
   * {@link POptional} restricted to monomorphic update
   */
  public final class Optional<S, A> extends POptional<S, S, A, A> {
  
    final POptional<S, S, A, A> pOptional;
  
    public Optional(final POptional<S, S, A, A> pOptional) {
      this.pOptional = pOptional;
    }
  
    @Override public Function<S, S> set(final A a) {
      return pOptional.set(a);
    }
  
    @Override public Function<S, Supplier<S>> modifySupplierF(final Function<A, Supplier<A>> f) {
      return pOptional.modifySupplierF(f);
    }
  
    @Override public Function<S, Option<S>> modifyOptionF(final Function<A, Option<A>> f) {
      return pOptional.modifyOptionF(f);
    }
  
    @Override public <C> Function<S, Function<C, S>> modifyFunctionF(final Function<A, Function<C, A>> f) {
      return pOptional.modifyFunctionF(f);
    }
  
    @Override public <L> Function<S, Either<L, S>> modifyEitherF(final Function<A, Either<L, A>> f) {
      return pOptional.modifyEitherF(f);
    }
  
    @Override public Function<S, Iterable<S>> modifyIterableF(final Function<A, Iterable<A>> f) {
      return pOptional.modifyIterableF(f);
    }
  
    @Override public Function<S, Pair<S, S>> modifyPairF(final Function<A, Pair<A, A>> f) {
      return pOptional.modifyPairF(f);
    }
  
    @Override public Function<S, S> modify(final Function<A, A> f) {
      return pOptional.modify(f);
    }
  
    @Override public Either<S, A> getOrModify(final S s) {
      return pOptional.getOrModify(s);
    }
  
    @Override public Option<A> getOption(final S s) {
      return pOptional.getOption(s);
    }
  
    /**
     * join two {@link Optional} with the same target
     */
    public final <S1> Optional<Either<S, S1>, A> sum(final Optional<S1, A> other) {
      return new Optional<>(pOptional.sum(other.pOptional));
    }
  
    @Override public final <C> Optional<Pair<S, C>, Pair<A, C>> first() {
      return new Optional<>(pOptional.first());
    }
  
    @Override public final <C> Optional<Pair<C, S>, Pair<C, A>> second() {
      return new Optional<>(pOptional.second());
    }
  
    /**************************************************************/
    /** Compose methods between a {@link Optional} and another Optics */
    /**************************************************************/
  
    /**
     * compose a {@link Optional} with a {@link Setter}
     */
    public final <C> Setter<S, C> composeSetter(final Setter<A, C> other) {
      return new Setter<>(pOptional.composeSetter(other.pSetter));
    }
  
    /**
     * compose a {@link Optional} with a {@link Traversal}
     */
    public final <C> Traversal<S, C> composeTraversal(final Traversal<A, C> other) {
      return new Traversal<>(pOptional.composeTraversal(other.pTraversal));
    }
  
    /**
     * compose a {@link Optional} with a {@link Optional}
     */
    public final <C> Optional<S, C> composeOptional(final Optional<A, C> other) {
      return new Optional<>(pOptional.composeOptional(other.pOptional));
    }
 
   /**
    * compose a {@link Optional} with a {@link Prism}
    */
   public final <C> Optional<S, C> composePrism(final Prism<A, C> other) {
     return new Optional<>(pOptional.composePrism(other.pPrism));
   }
 
   /**
    * compose a {@link Optional} with a {@link Lens}
    */
   public final <C> Optional<S, C> composeLens(final Lens<A, C> other) {
     return new Optional<>(pOptional.composeLens(other.pLens));
   }
 
   /**
    * compose a {@link Optional} with an {@link Iso}
    */
   public final <C> Optional<S, C> composeIso(final Iso<A, C> other) {
     return new Optional<>(pOptional.composeIso(other.pIso));
   }
 
   /********************************************************************/
   /** Transformation methods to view a {@link Optional} as another Optics */
   /********************************************************************/
 
   /**
    * view a {@link Optional} as a {@link Setter}
    */
   @Override public final Setter<S, A> asSetter() {
     return new Setter<>(pOptional.asSetter());
   }
 
   /**
    * view a {@link Optional} as a {@link Traversal}
    */
   @Override public final Traversal<S, A> asTraversal() {
     return new Traversal<>(pOptional.asTraversal());
   }
 
   public static <S> Optional<S, S> id() {
     return new Optional<>(POptional.pId());
   }
 
   public static <S, A> Optional<S, A> optional(final Function<S, Option<A>> getOption, final Function<A, Function<S, S>> set) {
     return new Optional<>(new POptional<S, S, A, A>() {
 
       @Override public Either<S, A> getOrModify(final S s) {
         return getOption.apply(s).fold(() -> Either.<S, A> left(s), Eithers.<S, A> toRight());
       }
 
       @Override public Function<S, S> set(final A a) {
         return set.apply(a);
       }
 
       @Override public Option<A> getOption(final S s) {
         return getOption.apply(s);
       }
 
       @Override public <C> Function<S, Function<C, S>> modifyFunctionF(final Function<A, Function<C, A>> f) {
         return s -> getOption.apply(s).<Function<C, S>> fold(() -> __ -> s, a -> f.apply(a).andThen(b -> set.apply(b).apply(s)));
       }
 
       @Override public <L> Function<S, Either<L, S>> modifyEitherF(final Function<A, Either<L, A>> f) {
         return s -> getOption.apply(s).<Either<L, S>> fold(() -> Either.right(s), t -> f.apply(t).right().map(b -> set.apply(b).apply(s)));
       }
 
       @Override public Function<S, Option<S>> modifyOptionF(final Function<A, Option<A>> f) {
         return s -> getOption.apply(s).fold(() -> Option.some(s), t -> f.apply(t).map(b -> set.apply(b).apply(s)));
       }
 
       @Override public Function<S, Iterable<S>> modifyIterableF(final Function<A, Iterable<A>> f) {
         return s -> getOption.apply(s).<Iterable<S>> fold(() -> Collections.singleton(s), t -> Iterables.map(f.apply(t), b -> set.apply(b).apply(s)));
       }
 
       @Override public Function<S, Supplier<S>> modifySupplierF(final Function<A, Supplier<A>> f) {
         return s -> getOption.apply(s).<Supplier<S>> fold(() -> Suppliers.ofInstance(s),
           t -> Suppliers.compose(b -> set.apply(b).apply(s), f.apply(t)));
       }
 
       @Override public Function<S, Pair<S, S>> modifyPairF(final Function<A, Pair<A, A>> f) {
         return s -> getOption.apply(s).<Pair<S, S>> fold(() -> Pair.pair(s, s), t -> Pair.map(f.apply(t), b -> set.apply(b).apply(s)));
       }
 
       @Override public Function<S, S> modify(final Function<A, A> f) {
         return s -> getOption.apply(s).fold(() -> s, a -> set.apply(f.apply(a)).apply(s));
       }
 
     });
   }
 
 }