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package org.reactfx.collection;

import java.util.List;
import java.util.function.Function;

import javafx.beans.value.ObservableValue;
import javafx.collections.ObservableList;

import org.reactfx.Subscription;
import org.reactfx.util.Lists;
import org.reactfx.value.Val;

class MappedList extends LiveListBase
implements ReadOnlyLiveListImpl {
    private final ObservableList source;
    private final Function mapper;

    public MappedList(
            ObservableList source,
            Function mapper) {
        this.source = source;
        this.mapper = mapper;
    }

    @Override
    public F get(int index) {
        return mapper.apply(source.get(index));
    }

    @Override
    public int size() {
        return source.size();
    }

    @Override
    protected Subscription observeInputs() {
        return LiveList.observeQuasiChanges(source, this::sourceChanged);
    }

    private void sourceChanged(QuasiListChange change) {
        notifyObservers(mappedChangeView(change, mapper));
    }

    static  QuasiListChange mappedChangeView(
            QuasiListChange change,
            Function mapper) {
        return new QuasiListChange() {

            @Override
            public List> getModifications() {
                List> mods = change.getModifications();
                return Lists., QuasiListModification>mappedView(mods, mod -> new QuasiListModification() {

                    @Override
                    public int getFrom() {
                        return mod.getFrom();
                    }

                    @Override
                    public int getAddedSize() {
                        return mod.getAddedSize();
                    }

                    @Override
                    public List getRemoved() {
                        return Lists.mappedView(mod.getRemoved(), mapper);
                    }
                });
            }

        };
    }
}

class DynamicallyMappedList extends LiveListBase
implements ReadOnlyLiveListImpl {
    private final ObservableList source;
    private final Val> mapper;

    public DynamicallyMappedList(
            ObservableList source,
            ObservableValue> mapper) {
        this.source = source;
        this.mapper = Val.wrap(mapper);
    }

    @Override
    public F get(int index) {
        return mapper.getValue().apply(source.get(index));
    }

    @Override
    public int size() {
        return source.size();
    }

    @Override
    protected Subscription observeInputs() {
        return Subscription.multi(
                LiveList.observeQuasiChanges(source, this::sourceChanged),
                mapper.observeInvalidations(this::mapperInvalidated));
    }

    private void sourceChanged(QuasiListChange change) {
        notifyObservers(MappedList.mappedChangeView(change, mapper.getValue()));
    }

    private void mapperInvalidated(Function oldMapper) {
        fireContentReplacement(Lists.mappedView(source, oldMapper));
    }
}