io.helidon.integrations.oci.sdk.cdi.CascadingAdpSupplier Maven / Gradle / Ivy
/*
* Copyright (c) 2024 Oracle and/or its affiliates.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.helidon.integrations.oci.sdk.cdi;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Optional;
import com.oracle.bmc.auth.BasicAuthenticationDetailsProvider;
import static java.util.function.UnaryOperator.identity;
import static java.util.stream.Stream.iterate;
/**
* An {@link AdpSupplier} that tries a series of other {@link AdpSupplier}s until a suitable one is found.
*
* @see #get()
*/
class CascadingAdpSupplier implements AdpSupplier {
private final List> adps;
/**
* A convenience constructor that creates a new {@link CascadingAdpSupplier} using an {@link AdpSupplierSelector}
* and a sequence of {@linkplain AdpStrategyDescriptors OCI authentication strategy descriptors}.
*
* @param the type of the {@linkplain AdpStrategyDescriptors OCI authentication strategy descriptors} used by
* the supplied {@link AdpSupplierSelector}; most commonly {@link String}
*
* @param s an {@link AdpSupplierSelector}; must not be {@code null}
*
* @param i an {@link Iterable} of strategy descriptors; must not be {@code null}
*
* @exception NullPointerException if either argument is {@code null}
*
* @see #CascadingAdpSupplier(Iterable)
*
* @see AdpSupplierSelector#select(Iterable)
*
* @see AdpStrategyDescriptors
*/
CascadingAdpSupplier(AdpSupplierSelector s,
Iterable i) {
this(s.select(i));
}
/**
* Creates a new {@link CascadingAdpSupplier}.
*
* @param adps an {@link Iterable} of {@link BasicAuthenticationDetailsProvider}s; must not be {@code null}
*
* @exception NullPointerException if {@code adps} is {@code null}
*/
CascadingAdpSupplier(Iterable> adps) {
super();
this.adps = list(adps);
}
/**
* Calls the {@link AdpSupplier#get()} method on each of the {@linkplain #CascadingAdpSupplier(Iterable)
* AdpSuppliers supplied at construction time}, in order, until a non-{@linkplain Optional#isEmpty()
* empty} {@link Optional} {@linkplain Optional#get() housing} a {@link BasicAuthenticationDetailsProvider} is
* found, and returns it.
*
* If no non-{@linkplain Optional#isEmpty() empty} {@link Optional} can be found, then the result of invoking
* {@link Optional#empty()} is returned.
*
* @return an {@link Optional} {@linkplain Optional#get() housing} a {@link BasicAuthenticationDetailsProvider}, or
* an {@linkplain Optional#isEmpty() empty} {@link Optional}; never {@code null}
*
* @see #CascadingAdpSupplier(Iterable)
*/
@Override
@SuppressWarnings("unchecked")
public final Optional get() {
return (Optional) this.adps.stream()
.map(AdpSupplier::get)
.dropWhile(Optional::isEmpty)
.findFirst()
.orElseGet(Optional::empty);
}
private static List list(Iterable i) {
return i instanceof Collection c
? List.copyOf(c)
: iterate(i.iterator(), Iterator::hasNext, identity()).map(Iterator::next).toList();
}
}