/*
 * Copyright (c) nosqlbench
 *
 * 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.nosqlbench.virtdata.library.basics.shared.functionadapters;

import io.nosqlbench.virtdata.api.annotations.Categories;
import io.nosqlbench.virtdata.api.annotations.Category;
import io.nosqlbench.virtdata.api.annotations.ThreadSafeMapper;

import java.util.function.*;

/**
 * Adapts any compatible {@link FunctionalInterface} type to a LongFunction,
 * for use with higher-order functions, when they require a
 * LongFunction as an argument. Some of the higher-order functions within
 * this library specifically require a LongFunction as an argument, while
 * some of the other functions are provided in semantically equivalent
 * forms with compatible types which can't be converted directly or
 * automatically by Java.
 *
 * In such cases, those types of functions can be wrapped with the forms
 * described here in order to allow the inner and outer functions to work together.
 */
@ThreadSafeMapper
@Categories({Category.diagnostics})
public class ToLongFunction implements LongFunction<Object> {

    private final LongFunction<?> function;

    public ToLongFunction(LongUnaryOperator op) {
        this.function = op::applyAsLong;
    }
    public ToLongFunction(Function<Long,Long> op) {
        this.function = op::apply;
    }
    public ToLongFunction(LongToIntFunction op) {
        this.function = op::applyAsInt;
    }
    public ToLongFunction(LongToDoubleFunction op) {
        this.function = op::applyAsDouble;
    }
    public ToLongFunction(LongFunction<?> func) {
        this.function = func;
    }


    @Override
    public Object apply(long value) {
        return function.apply(value);
    }
}
