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/*
 * Copyright (c) 2022 vitasystems GmbH and Hannover Medical School.
 *
 * This file is part of project EHRbase
 *
 * 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
 *
 *     https://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 org.ehrbase.dao.access.support;

import java.util.function.BiFunction;
import java.util.function.Function;

public class SafeNav {
    public static  SafeNav of(T1 obj) {
        return new SafeNav(obj);
    }

    private final T obj;

    private SafeNav(T obj) {
        this.obj = obj;
    }

    public  SafeNav get(Function accessor) {
        if (obj == null) return new SafeNav(null);
        try {
            return new SafeNav(accessor.apply(obj));
        } catch (NullPointerException e) {
            return new SafeNav(null);
        }
    }

    public T get() {
        return obj;
    }

    public boolean isSafe() {
        return obj != null;
    }

    public  CombineSafeNav use(SafeNav s) {
        return new CombineSafeNav<>(s);
    }

    public class CombineSafeNav {
        private final SafeNav safe;

        private CombineSafeNav(SafeNav safe) {
            this.safe = safe;
        }

        public SafeNav get(BiFunction accessor) {
            if (!SafeNav.this.isSafe()) return null;
            try {
                return SafeNav.of(accessor.apply(safe.get(), SafeNav.this.obj));
            } catch (NullPointerException e) {
                return new SafeNav(null);
            }
        }
    }
}