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/*
 * Copyright 2008-2012 Sergey Skladchikov
 *
 * 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 org.gwt.advanced.client.ui.widget.cell;

import com.google.gwt.event.dom.client.BlurEvent;
import com.google.gwt.event.dom.client.BlurHandler;
import com.google.gwt.event.dom.client.FocusEvent;
import com.google.gwt.event.dom.client.FocusHandler;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.Widget;

/**
 * This is an abstract implementation for all numeric cells.
 *
 * @author Sergey Skladchikov
 * @since 1.0.0
 */
public abstract class NumberCell extends TextBoxCell {
    /**
     * integer number pattern
     */
    protected static final String INTEGER_PATTERN = "([+-]?[0-9]+)|([0-9]*)";
    /**
     * real number pattern
     */
    protected static final String REAL_PATTERN = "[+-]?((\\d+(\\.\\d*)?)|\\.\\d+)([eE][+-]?[0-9]+)?";

    /**
     * this is a regular expression to be used for numeric cell content
     */
    private String regExp;
    /**
     * maximum number
     */
    private double max;
    /**
     * minimum number
     */
    private double min;
    /**
     * default numeric cell focus handler
     */
    private FocusHandler focusHandler;
    /** old value of the cell */
    private Object oldValue;

    /**
     * Creates an instance of the class.
     *
     * @param regExp is a regular expresion to be used for check.
     * @param max    is a maximum value.
     * @param min    is a minimum value.
     */
    protected NumberCell(String regExp, double max, double min) {
        this.regExp = regExp;
        this.max = max;
        this.min = min;
    }

    /**
     * {@inheritDoc}
     */
    protected Widget createActive() {
        removeStyleName("numeric-cell");
        return super.createActive();
    }

    /**
     * {@inheritDoc}
     */
    protected Widget createInactive() {
        Widget inactive = super.createInactive();
        removeStyleName("text-cell");
        addStyleName("numeric-cell");
        return inactive;
    }

    /**
     * {@inheritDoc}
     */
    protected void addListeners(Widget widget) {
        if (focusHandler == null) {
            focusHandler = new FocusHandler() {
                public void onFocus(FocusEvent focusEvent) {
                    Widget sender = (Widget) focusEvent.getSource();
                    oldValue = ((NumberCell) sender.getParent()).getValue();
                }
            };
            BlurHandler blurHandler = new BlurHandler() {
                public void onBlur(BlurEvent blurEvent) {
                    TextBox textBox = (TextBox) blurEvent.getSource();
                    String text = textBox.getText();
                    if (
                            text != null
                                    && (
                                    !text.matches(regExp)
                                            || Double.valueOf(text) > max
                                            || Double.valueOf(text) < min
                            )
                            ) {
                        textBox.setText(String.valueOf(oldValue));
                    }
                }
            };
            TextBox box = getTextBox();
            box.addFocusHandler(focusHandler);
            box.addBlurHandler(blurHandler);
            super.addListeners(box);
        }
    }

    /**
     * {@inheritDoc}
     */
    public void setValue(Object value) {
        if (value == null)
            value = convertToNumber("0");
        super.setValue(value);
    }

    /**
     * {@inheritDoc}
     */
    public Object getNewValue() {
        return convertToNumber(String.valueOf(super.getNewValue()));
    }

    /**
     * This method converts abstract number to a concrete number implementation.
     *
     * @param text is a textual representation of the number.
     * @return a concrete number implementation instance.
     */
    protected abstract Number convertToNumber(String text);
}