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/*
 * Copyright 2015 the original author or authors.
 *
 * 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 pl.touk.tscreload;

import javaslang.*;
import lombok.extern.slf4j.Slf4j;
import pl.touk.tscreload.impl.*;

import java.util.Optional;

@Slf4j
public abstract class Reloadable extends Observable {

    private T current;

    protected Reloadable(T current) {
        this.current = current;
    }

    public  Reloadable map(Function1 f) {
        return map((t, prev) -> f.apply(t));
    }

    public  Reloadable map(Function2, U> f) {
        Reloadable1 child = new Reloadable1<>(currentValue(), f);
        addWeakObserver(child);
        return child;
    }

    protected synchronized void updateCurrentValue(Function1, T> transform) {
        try {
            T newValue = transform.apply(Optional.of(current));
            if (!current.equals(newValue)) {
                current = newValue;
                notifyObservers(newValue);
            }
        } catch (Exception ex) {
            log.error("Exception while computing reloaded value. Propagation of changes for child nodes will be discarded.", ex);
        }
    }

    public synchronized T currentValue() {
        return current;
    }


    public static  Reloadable compose(Reloadable r1,
                                                    Reloadable r2,
                                                    Function2 f) {
        return compose(r1, r2, (p1, p2, prev) -> f.apply(p1, p2));
    }

    public static  Reloadable compose(Reloadable r1,
                                                    Reloadable r2,
                                                    Function3, U> f) {
        Reloadable2 reloadable = new Reloadable2<>(
                r1.currentValue(),
                r2.currentValue(),
                f);
        r1.addWeakObserver(reloadable.observer1);
        r2.addWeakObserver(reloadable.observer2);
        return reloadable;
    }

    public static  Reloadable compose(Reloadable r1,
                                                        Reloadable r2,
                                                        Reloadable r3,
                                                        Function3 f) {
        return compose(r1, r2, r3, (p1, p2, p3, prev) -> f.apply(p1, p2, p3));
    }

    public static  Reloadable compose(Reloadable r1,
                                                        Reloadable r2,
                                                        Reloadable r3,
                                                        Function4, U> f) {
        Reloadable3 reloadable = new Reloadable3<>(
                r1.currentValue(),
                r2.currentValue(),
                r3.currentValue(),
                f);
        r1.addWeakObserver(reloadable.observer1);
        r2.addWeakObserver(reloadable.observer2);
        r3.addWeakObserver(reloadable.observer3);
        return reloadable;
    }


    public static  Reloadable compose(Reloadable r1,
                                                            Reloadable r2,
                                                            Reloadable r3,
                                                            Reloadable r4,
                                                            Function4 f) {
        return compose(r1, r2, r3, r4, (p1, p2, p3, p4, prev) -> f.apply(p1, p2, p3, p4));
    }

    public static  Reloadable compose(Reloadable r1,
                                                            Reloadable r2,
                                                            Reloadable r3,
                                                            Reloadable r4,
                                                            Function5, U> f) {
        Reloadable4 reloadable = new Reloadable4<>(
                r1.currentValue(),
                r2.currentValue(),
                r3.currentValue(),
                r4.currentValue(),
                f);
        r1.addWeakObserver(reloadable.observer1);
        r2.addWeakObserver(reloadable.observer2);
        r3.addWeakObserver(reloadable.observer3);
        r4.addWeakObserver(reloadable.observer4);
        return reloadable;
    }

    public static  Reloadable compose(Reloadable r1,
                                                                Reloadable r2,
                                                                Reloadable r3,
                                                                Reloadable r4,
                                                                Reloadable r5,
                                                                Function5 f) {
        return compose(r1, r2, r3, r4, r5, (p1, p2, p3, p4, p5, prev) -> f.apply(p1, p2, p3, p4, p5));
    }

    public static  Reloadable compose(Reloadable r1,
                                                                Reloadable r2,
                                                                Reloadable r3,
                                                                Reloadable r4,
                                                                Reloadable r5,
                                                                Function6, U> f) {
        Reloadable5 reloadable = new Reloadable5<>(
                r1.currentValue(),
                r2.currentValue(),
                r3.currentValue(),
                r4.currentValue(),
                r5.currentValue(),
                f);
        r1.addWeakObserver(reloadable.observer1);
        r2.addWeakObserver(reloadable.observer2);
        r3.addWeakObserver(reloadable.observer3);
        r4.addWeakObserver(reloadable.observer4);
        r5.addWeakObserver(reloadable.observer5);
        return reloadable;
    }

}