package javafx.beans.property;

import com.sun.javafx.binding.ListExpressionHelper;
import javafx.beans.InvalidationListener;
import javafx.beans.Observable;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;

import java.lang.ref.WeakReference;

/**
 * The class {@code ListPropertyBase} is the base class for a property
 * wrapping an {@link javafx.collections.ObservableList}.
 *
 * It provides all the functionality required for a property except for the
 * {@link #getBean()} and {@link #getName()} methods, which must be implemented
 * by extending classes.
 *
 * @see javafx.collections.ObservableList
 * @see ListProperty
 *
 * @param <E> the type of the {@code List} elements
 * @since JavaFX 2.1
 */
public abstract class ListPropertyBase<E> extends ListProperty<E> {

    private final ListChangeListener<E> listChangeListener = change -> {
        invalidateProperties();
        invalidated();
        fireValueChangedEvent(change);
    };

    private ObservableList<E> value;
    private ObservableValue<? extends ObservableList<E>> observable = null;
    private InvalidationListener listener = null;
    private boolean valid = true;
    private ListExpressionHelper<E> helper = null;

    private SizeProperty size0;
    private EmptyProperty empty0;

    /**
     * The Constructor of {@code ListPropertyBase}
     */
    public ListPropertyBase() {}

    /**
     * The constructor of the {@code ListPropertyBase}.
     *
     * @param initialValue
     *            the initial value of the wrapped value
     */
    public ListPropertyBase(ObservableList<E> initialValue) {
        this.value = initialValue;
        if (initialValue != null) {
            initialValue.addListener(listChangeListener);
        }
    }

    @Override
    public ReadOnlyIntegerProperty sizeProperty() {
        if (size0 == null) {
            size0 = new SizeProperty();
        }
        return size0;
    }

    private class SizeProperty extends ReadOnlyIntegerPropertyBase {
        @Override
        public int get() {
            return size();
        }

        @Override
        public Object getBean() {
            return ListPropertyBase.this;
        }

        @Override
        public String getName() {
            return "size";
        }

        protected void fireValueChangedEvent() {
            super.fireValueChangedEvent();
        }
    }

    @Override
    public ReadOnlyBooleanProperty emptyProperty() {
        if (empty0 == null) {
            empty0 = new EmptyProperty();
        }
        return empty0;
    }

    private class EmptyProperty extends ReadOnlyBooleanPropertyBase {

        @Override
        public boolean get() {
            return isEmpty();
        }

        @Override
        public Object getBean() {
            return ListPropertyBase.this;
        }

        @Override
        public String getName() {
            return "empty";
        }

        protected void fireValueChangedEvent() {
            super.fireValueChangedEvent();
        }
    }

    @Override
    public void addListener(InvalidationListener listener) {
        helper = ListExpressionHelper.addListener(helper, this, listener);
    }

    @Override
    public void removeListener(InvalidationListener listener) {
        helper = ListExpressionHelper.removeListener(helper, listener);
    }

    @Override
    public void addListener(ChangeListener<? super ObservableList<E>> listener) {
        helper = ListExpressionHelper.addListener(helper, this, listener);
    }

    @Override
    public void removeListener(ChangeListener<? super ObservableList<E>> listener) {
        helper = ListExpressionHelper.removeListener(helper, listener);
    }

    @Override
    public void addListener(ListChangeListener<? super E> listener) {
        helper = ListExpressionHelper.addListener(helper, this, listener);
    }

    @Override
    public void removeListener(ListChangeListener<? super E> listener) {
        helper = ListExpressionHelper.removeListener(helper, listener);
    }

    /**
     * Sends notifications to all attached
     * {@link javafx.beans.InvalidationListener InvalidationListeners},
     * {@link javafx.beans.value.ChangeListener ChangeListeners}, and
     * {@link javafx.collections.ListChangeListener}.
     *
     * This method is called when the value is changed, either manually by
     * calling {@link #set(ObservableList)} or in case of a bound property, if the
     * binding becomes invalid.
     */
    protected void fireValueChangedEvent() {
        ListExpressionHelper.fireValueChangedEvent(helper);
    }

    /**
     * Sends notifications to all attached
     * {@link javafx.beans.InvalidationListener InvalidationListeners},
     * {@link javafx.beans.value.ChangeListener ChangeListeners}, and
     * {@link javafx.collections.ListChangeListener}.
     *
     * This method is called when the content of the list changes.
     *
     * @param change the change that needs to be propagated
     */
    protected void fireValueChangedEvent(ListChangeListener.Change<? extends E> change) {
        ListExpressionHelper.fireValueChangedEvent(helper, change);
    }

    private void invalidateProperties() {
        if (size0 != null) {
            size0.fireValueChangedEvent();
        }
        if (empty0 != null) {
            empty0.fireValueChangedEvent();
        }
    }

    private void markInvalid(ObservableList<E> oldValue) {
        if (valid) {
            if (oldValue != null) {
                oldValue.removeListener(listChangeListener);
            }
            valid = false;
            invalidateProperties();
            invalidated();
            fireValueChangedEvent();
        }
    }



    /**
     * The method {@code invalidated()} can be overridden to receive
     * invalidation notifications. This is the preferred option in
     * {@code Objects} defining the property, because it requires less memory.
     *
     * The default implementation is empty.
     */
    protected void invalidated() {
    }

    @Override
    public ObservableList<E> get() {
        if (!valid) {
            value = observable == null ? value : observable.getValue();
            valid = true;
            if (value != null) {
                value.addListener(listChangeListener);
            }
        }
        return value;
    }

    @Override
    public void set(ObservableList<E> newValue) {
        if (isBound()) {
            throw new java.lang.RuntimeException((getBean() != null && getName() != null ?
                    getBean().getClass().getSimpleName() + "." + getName() + " : ": "") + "A bound value cannot be set.");
        }
        if (value != newValue) {
            final ObservableList<E> oldValue = value;
            value = newValue;
            markInvalid(oldValue);
        }
    }

    @Override
    public boolean isBound() {
        return observable != null;
    }

    @Override
    public void bind(final ObservableValue<? extends ObservableList<E>> newObservable) {
        if (newObservable == null) {
            throw new NullPointerException("Cannot bind to null");
        }

        if (!newObservable.equals(observable)) {
            unbind();
            observable = newObservable;
            if (listener == null) {
                listener = new Listener<>(this);
            }
            observable.addListener(listener);
            markInvalid(value);
        }
    }

    @Override
    public void unbind() {
        if (observable != null) {
            value = observable.getValue();
            observable.removeListener(listener);
            observable = null;
        }
    }

    /**
     * Returns a string representation of this {@code ListPropertyBase} object.
     * @return a string representation of this {@code ListPropertyBase} object.
     */
    @Override
    public String toString() {
        final Object bean = getBean();
        final String name = getName();
        final StringBuilder result = new StringBuilder("ListProperty [");
        if (bean != null) {
            result.append("bean: ").append(bean).append(", ");
        }
        if ((name != null) && (!name.equals(""))) {
            result.append("name: ").append(name).append(", ");
        }
        if (isBound()) {
            result.append("bound, ");
            if (valid) {
                result.append("value: ").append(get());
            } else {
                result.append("invalid");
            }
        } else {
            result.append("value: ").append(get());
        }
        result.append("]");
        return result.toString();
    }

    private static class Listener<E> implements InvalidationListener {

        private final WeakReference<ListPropertyBase<E>> wref;

        public Listener(ListPropertyBase<E> ref) {
            this.wref = new WeakReference<ListPropertyBase<E>>(ref);
        }

        @Override
        public void invalidated(Observable observable) {
            ListPropertyBase<E> ref = wref.get();
            if (ref == null) {
                observable.removeListener(this);
            } else {
                ref.markInvalid(ref.value);
            }
        }
    }

}