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/*
 * This file is part of SpongeAPI, licensed under the MIT License (MIT).
 *
 * Copyright (c) SpongePowered 
 * Copyright (c) contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package org.spongepowered.api.util;

import com.google.common.collect.ImmutableSet;

import java.util.Arrays;
import java.util.Collection;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.Callable;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Executor;
import java.util.function.BiPredicate;
import java.util.function.Predicate;

/**
 * Utility methods to help with function work.
 */
public class Functional {

    private Functional() {
    }

    /**
     * Perform an AND using an array of predicates.
     *
     * @param predicates The predicates to AND
     * @param  The type to accept
     * @return The combined predicate
     */
    @SafeVarargs
    @SuppressWarnings("varargs")
    public static  Predicate predicateAnd(Predicate... predicates) {
        return Functional.predicateAnd(Arrays.asList(predicates));
    }

    /**
     * Perform an AND using an iterable of predicates.
     *
     * @param predicates The predicates to and
     * @param  The type to accept
     * @return The combined predicate
     */
    public static  Predicate predicateAnd(Iterable> predicates) {
        return e -> {
            for (Predicate pred : predicates) {
                if (!pred.test(e)) {
                    return false;
                }
            }
            return true;
        };
    }

    /**
     * Perform an AND using an array of bi-predicates.
     *
     * @param predicates The bi-predicates to AND
     * @param  The left type to accept
     * @param  The right type to accept
     * @return The combined bi-predicate
     */
    @SafeVarargs
    @SuppressWarnings("varargs")
    public static  BiPredicate biPredicateAnd(BiPredicate... predicates) {
        return Functional.biPredicateAnd(Arrays.asList(predicates));
    }

    /**
     * Perform an AND using an iterable of bi-predicates.
     *
     * @param predicates The bi-predicates to and
     * @param  The left type to accept
     * @param  The right type to accept
     * @return The combined bi-predicate
     */
    public static  BiPredicate biPredicateAnd(Iterable> predicates) {
        return (l, r) -> {
            for (BiPredicate pred : predicates) {
                if (!pred.test(l, r)) {
                    return false;
                }
            }
            return true;
        };
    }

    /**
     * Creates a new {@link Predicate} defining whether an {@link Object}
     * is contained within the provided {@link Collection}.
     *
     * @param collection The collection
     * @param  The type of object
     * @return The predicate
     */
    public static  Predicate predicateIn(Collection collection) {
        return collection::contains;
    }

    /**
     * Creates a {@link com.google.common.base.Predicate} based on the provided {@link Predicate}, used
     * to transform between Java 8 specific code to those from the guava
     * library.
     *
     * @param predicate The predicate
     * @param  The type of object
     * @return The guava predicate
     */
    public static  com.google.common.base.Predicate java8ToGuava(Predicate predicate) {
        return predicate::test;
    }

    /**
     * Gets the value of an {@link Optional} as either a zero- or one-element immutable set.
     *
     * @param value The value to get as a set
     * @param  The type
     * @return The immutable set containing any value the optional has
     */
    public static  Set optionalAsSet(Optional value) {
        return value.isPresent() ? ImmutableSet.of(value.get()) : ImmutableSet.of();
    }

    /**
     * Execute a callable on the current thread, capturing the result or any exceptions that may be thrown into a {@link
     * CompletableFuture}.
     *
     * @param call The callable to execute
     * @param  The type of value returned
     * @return The future holding the result
     */
    public static  CompletableFuture failableFuture(Callable call) {
        final CompletableFuture ret = new CompletableFuture<>();
        try {
            ret.complete(call.call());
        } catch (Throwable e) {
            ret.completeExceptionally(e);
        }
        return ret;
    }

    /**
     * Execute a callable on the provided executor, capturing the result or any exceptions that may be thrown into a {@link
     * CompletableFuture}.
     *
     * @param call The callable to execute
     * @param exec The executor to execute this task on
     * @param  The type of value returned
     * @return The future holding the result
     */
    public static  CompletableFuture asyncFailableFuture(Callable call, Executor exec) {
        final CompletableFuture ret = new CompletableFuture<>();
        exec.execute(() -> {
            try {
                ret.complete(call.call());
            } catch (Throwable e) {
                ret.completeExceptionally(e);
            }
        });
        return ret;
    }

}