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 * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package javafx.scene.control.cell;

import javafx.css.CssMetaData;
import javafx.beans.binding.Bindings;
import javafx.beans.property.BooleanProperty;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.beans.value.ObservableValue;
import javafx.geometry.Pos;
import javafx.scene.control.CheckBox;
import javafx.scene.control.TreeTableCell;
import javafx.scene.control.TreeTableColumn;
import javafx.util.Callback;
import javafx.util.StringConverter;

/**
 * A class containing a {@link TreeTableCell} implementation that draws a 
 * {@link CheckBox} node inside the cell, optionally with a label to indicate 
 * what the checkbox represents.
 * 
 * <p>By default, the CheckBoxTreeTableCell is rendered with a CheckBox centred in 
 * the TreeTableColumn. If a label is required, it is necessary to provide a 
 * non-null StringConverter instance to the 
 * {@link #CheckBoxTreeTableCell(Callback, StringConverter)} constructor.
 * 
 * <p>To construct an instance of this class, it is necessary to provide a 
 * {@link Callback} that, given an object of type T, will return an 
 * {@code ObservableProperty<Boolean>} that represents whether the given item is
 * selected or not. This ObservableValue will be bound bidirectionally (meaning 
 * that the CheckBox in the cell will set/unset this property based on user 
 * interactions, and the CheckBox will reflect the state of the ObservableValue, 
 * if it changes externally).
 * 
 * @param <T> The type of the elements contained within the TreeTableColumn.
 * @since JavaFX 8.0
 */
public class CheckBoxTreeTableCell<S,T> extends TreeTableCell<S,T> {
    
    /***************************************************************************
     *                                                                         *
     * Static cell factories                                                   *
     *                                                                         *
     **************************************************************************/
    
    /**
     * Creates a cell factory for use in a {@link TreeTableColumn} cell factory. 
     * This method requires that the TreeTableColumn be of type {@link Boolean}.
     * 
     * <p>When used in a TreeTableColumn, the CheckBoxCell is rendered with a 
     * CheckBox centered in the column.
     * 
     * <p>The {@code ObservableValue<Boolean>} contained within each cell in the 
     * column will be bound bidirectionally. This means that the  CheckBox in 
     * the cell will set/unset this property based on user interactions, and the 
     * CheckBox will reflect the state of the {@code ObservableValue<Boolean>}, 
     * if it changes externally).
     * 
     * @return A {@link Callback} that will return a {@link TreeTableCell} that is 
     *      able to work on the type of element contained within the TreeTableColumn.
     */
    public static <S> Callback<TreeTableColumn<S,Boolean>, TreeTableCell<S,Boolean>> forTreeTableColumn(
            final TreeTableColumn<S, Boolean> column) {
        return forTreeTableColumn(null, null);
    }
    
    /**
     * Creates a cell factory for use in a {@link TreeTableColumn} cell factory. 
     * This method requires that the TreeTableColumn be of type
     * {@code ObservableValue<Boolean>}.
     * 
     * <p>When used in a TreeTableColumn, the CheckBoxCell is rendered with a 
     * CheckBox centered in the column.
     * 
     * @param <T> The type of the elements contained within the {@link TreeTableColumn} 
     *      instance.
     * @param getSelectedProperty A Callback that, given an object of 
     *      type {@code TreeTableColumn<S,T>}, will return an 
     *      {@code ObservableValue<Boolean>} 
     *      that represents whether the given item is selected or not. This 
     *      {@code ObservableValue<Boolean>} will be bound bidirectionally 
     *      (meaning that the CheckBox in the cell will set/unset this property 
     *      based on user interactions, and the CheckBox will reflect the state of 
     *      the {@code ObservableValue<Boolean>}, if it changes externally).
     * @return A {@link Callback} that will return a {@link TreeTableCell} that is 
     *      able to work on the type of element contained within the TreeTableColumn.
     */
    public static <S,T> Callback<TreeTableColumn<S,T>, TreeTableCell<S,T>> forTreeTableColumn(
            final Callback<Integer, ObservableValue<Boolean>> getSelectedProperty) {
        return forTreeTableColumn(getSelectedProperty, null);
    }
    
    /**
     * Creates a cell factory for use in a {@link TreeTableColumn} cell factory. 
     * This method requires that the TreeTableColumn be of type
     * {@code ObservableValue<Boolean>}.
     * 
     * <p>When used in a TreeTableColumn, the CheckBoxCell is rendered with a 
     * CheckBox centered in the column.
     * 
     * @param <T> The type of the elements contained within the {@link TreeTableColumn} 
     *      instance.
     * @param getSelectedProperty A Callback that, given an object of 
     *      type {@code TreeTableColumn<S,T>}, will return an 
     *      {@code ObservableValue<Boolean>} 
     *      that represents whether the given item is selected or not. This 
     *      {@code ObservableValue<Boolean>} will be bound bidirectionally 
     *      (meaning that the CheckBox in the cell will set/unset this property 
     *      based on user interactions, and the CheckBox will reflect the state of 
     *      the {@code ObservableValue<Boolean>}, if it changes externally).
     * @param showLabel In some cases, it may be desirable to show a label in 
     *      the TreeTableCell beside the {@link CheckBox}. By default a label is not 
     *      shown, but by setting this to true the item in the cell will also 
     *      have toString() called on it. If this is not the desired behavior, 
     *      consider using 
     *      {@link #forTreeTableColumn(javafx.util.Callback, javafx.util.StringConverter) }, 
     *      which allows for you to provide a callback that specifies the label for a 
     *      given row item.
     * @return A {@link Callback} that will return a {@link TreeTableCell} that is 
     *      able to work on the type of element contained within the TreeTableColumn.
     */
    public static <S,T> Callback<TreeTableColumn<S,T>, TreeTableCell<S,T>> forTreeTableColumn(
            final Callback<Integer, ObservableValue<Boolean>> getSelectedProperty, 
            final boolean showLabel) {
        StringConverter<T> converter = ! showLabel ? 
                null : CellUtils.<T>defaultStringConverter();
        return forTreeTableColumn(getSelectedProperty, converter);
    }
    
    /**
     * Creates a cell factory for use in a {@link TreeTableColumn} cell factory. 
     * This method requires that the TreeTableColumn be of type
     * {@code ObservableValue<Boolean>}.
     * 
     * <p>When used in a TreeTableColumn, the CheckBoxCell is rendered with a 
     * CheckBox centered in the column.
     * 
     * @param <T> The type of the elements contained within the {@link TreeTableColumn} 
     *      instance.
     * @param getSelectedProperty A Callback that, given an object of type 
     *      {@code TreeTableColumn<S,T>}, will return an 
     *      {@code ObservableValue<Boolean>} that represents whether the given 
     *      item is selected or not. This {@code ObservableValue<Boolean>} will 
     *      be bound bidirectionally (meaning that the CheckBox in the cell will 
     *      set/unset this property based on user interactions, and the CheckBox 
     *      will reflect the state of the {@code ObservableValue<Boolean>}, if 
     *      it changes externally).
     * @param converter A StringConverter that, give an object of type T, will return a 
     *      String that can be used to represent the object visually. The default 
     *      implementation in {@link #forTreeTableColumn(Callback, boolean)} (when 
     *      showLabel is true) is to simply call .toString() on all non-null 
     *      items (and to just return an empty string in cases where the given 
     *      item is null).
     * @return A {@link Callback} that will return a {@link TreeTableCell} that is 
     *      able to work on the type of element contained within the TreeTableColumn.
     */
    public static <S,T> Callback<TreeTableColumn<S,T>, TreeTableCell<S,T>> forTreeTableColumn(
            final Callback<Integer, ObservableValue<Boolean>> getSelectedProperty, 
            final StringConverter<T> converter) {
        return new Callback<TreeTableColumn<S,T>, TreeTableCell<S,T>>() {
            @Override public TreeTableCell<S,T> call(TreeTableColumn<S,T> list) {
                return new CheckBoxTreeTableCell<S,T>(getSelectedProperty, converter);
            }
        };
    }
    
    

    /***************************************************************************
     *                                                                         *
     * Fields                                                                  *
     *                                                                         *
     **************************************************************************/
    private final CheckBox checkBox;
    
    private boolean showLabel;
    
    private ObservableValue<Boolean> booleanProperty;
    
    
    
    /***************************************************************************
     *                                                                         *
     * Constructors                                                            *
     *                                                                         *
     **************************************************************************/
    
    /** 
     * Creates a default CheckBoxTreeTableCell.
     */
    public CheckBoxTreeTableCell() {
        this(null, null);
    }
    
    /**
     * Creates a default CheckBoxTreeTableCell with a custom {@link Callback} to 
     * retrieve an ObservableValue for a given cell index.
     * 
     * @param getSelectedProperty A {@link Callback} that will return an {@link 
     *      ObservableValue} given an index from the TreeTableColumn.
     */
    public CheckBoxTreeTableCell(
            final Callback<Integer, ObservableValue<Boolean>> getSelectedProperty) {
        this(getSelectedProperty, null);
    }

    /**
     * Creates a CheckBoxTreeTableCell with a custom string converter.
     * 
     * @param getSelectedProperty A {@link Callback} that will return a {@link 
     *      ObservableValue} given an index from the TreeTableColumn.
     * @param converter A StringConverter that, given an object of type T, will return a 
     *      String that can be used to represent the object visually.
     */
    public CheckBoxTreeTableCell(
            final Callback<Integer, ObservableValue<Boolean>> getSelectedProperty, 
            final StringConverter<T> converter) {
        // we let getSelectedProperty be null here, as we can always defer to the
        // TreeTableColumn
        this.getStyleClass().add("check-box-tree-table-cell");
        
        this.checkBox = new CheckBox();

        // by default the graphic is null until the cell stops being empty
        setGraphic(null);
        
        setSelectedStateCallback(getSelectedProperty);
        setConverter(converter);
        
//        // alignment is styleable through css. Calling setAlignment
//        // makes it look to css like the user set the value and css will not 
//        // override. Initializing alignment by calling set on the 
//        // CssMetaData ensures that css will be able to override the value.
//        final CssMetaData prop = CssMetaData.getCssMetaData(alignmentProperty());
//        prop.set(this, Pos.CENTER);
    }
    
    
    /***************************************************************************
     *                                                                         *
     * Properties                                                              *
     *                                                                         *
     **************************************************************************/
    
    // --- converter
    private ObjectProperty<StringConverter<T>> converter = 
            new SimpleObjectProperty<StringConverter<T>>(this, "converter") {
        protected void invalidated() {
            updateShowLabel();
        }
    };

    /**
     * The {@link StringConverter} property.
     */
    public final ObjectProperty<StringConverter<T>> converterProperty() { 
        return converter; 
    }
    
    /** 
     * Sets the {@link StringConverter} to be used in this cell.
     */
    public final void setConverter(StringConverter<T> value) { 
        converterProperty().set(value); 
    }
    
    /**
     * Returns the {@link StringConverter} used in this cell.
     */
    public final StringConverter<T> getConverter() { 
        return converterProperty().get(); 
    }
    
    
    
    // --- selected state callback property
    private ObjectProperty<Callback<Integer, ObservableValue<Boolean>>> 
            selectedStateCallback = 
            new SimpleObjectProperty<Callback<Integer, ObservableValue<Boolean>>>(
            this, "selectedStateCallback");

    /**
     * Property representing the {@link Callback} that is bound to by the 
     * CheckBox shown on screen.
     */
    public final ObjectProperty<Callback<Integer, ObservableValue<Boolean>>> selectedStateCallbackProperty() { 
        return selectedStateCallback; 
    }
    
    /** 
     * Sets the {@link Callback} that is bound to by the CheckBox shown on screen.
     */
    public final void setSelectedStateCallback(Callback<Integer, ObservableValue<Boolean>> value) { 
        selectedStateCallbackProperty().set(value); 
    }
    
    /**
     * Returns the {@link Callback} that is bound to by the CheckBox shown on screen.
     */
    public final Callback<Integer, ObservableValue<Boolean>> getSelectedStateCallback() { 
        return selectedStateCallbackProperty().get(); 
    }
    
    
    
    /***************************************************************************
     *                                                                         *
     * Public API                                                              *
     *                                                                         *
     **************************************************************************/
    
    /** {@inheritDoc} */
    @Override public void updateItem(T item, boolean empty) {
        super.updateItem(item, empty);
        
        if (empty) {
            setText(null);
            setGraphic(null);
        } else {
            StringConverter c = getConverter();
            
            if (showLabel) {
                setText(c.toString(item));
            }
            setGraphic(checkBox);
            
            if (booleanProperty instanceof BooleanProperty) {
                checkBox.selectedProperty().unbindBidirectional((BooleanProperty)booleanProperty);
            }
            ObservableValue obsValue = getSelectedProperty();
            if (obsValue instanceof BooleanProperty) {
                booleanProperty = obsValue;
                checkBox.selectedProperty().bindBidirectional((BooleanProperty)booleanProperty);
            }
            
            checkBox.disableProperty().bind(Bindings.not(
                    getTreeTableView().editableProperty().and(
                    getTableColumn().editableProperty()).and(
                    editableProperty())
                ));
        }
    }
    
    
    
    /***************************************************************************
     *                                                                         *
     * Private implementation                                                  *
     *                                                                         *
     **************************************************************************/
    
    private void updateShowLabel() {
        this.showLabel = converter != null;
        this.checkBox.setAlignment(showLabel ? Pos.CENTER_LEFT : Pos.CENTER);
    }
    
    private ObservableValue getSelectedProperty() {
        return getSelectedStateCallback() != null ?
                getSelectedStateCallback().call(getIndex()) :
                getTableColumn().getCellObservableValue(getIndex());
    }
}
