package converter;
 
 
import java.text.NumberFormat;
import java.text.ParseException;
import javafx.beans.InvalidationListener;                          
 
import javafx.beans.property.DoubleProperty;
import javafx.collections.ObservableList;
import javafx.scene.control.ComboBox;
 
import javafx.scene.control.Slider;
 
import javafx.scene.control.TextField;
 
import javafx.scene.control.TitledPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
 
import javafx.util.StringConverter;
 
 
public class ConversionPanel extends TitledPane {
    
    final static int MAX = 10000;
    
    private ComboBox<Unit> comboBox;
    private Slider slider;
    private TextField textField;
    private DoubleProperty meters;
    private NumberFormat numberFormat;  
    
    private InvalidationListener fromMeters = t -> {
        if (!textField.isFocused()) {
            textField.setText(numberFormat.format(meters.get() / getMultiplier()));
        }
    };
 
    private InvalidationListener toMeters = t -> {
        if (!textField.isFocused()) {
            return;
        }
        try {
            meters.set(numberFormat.parse(textField.getText()).doubleValue() * getMultiplier());
            } catch (ParseException | Error | RuntimeException ignored) {
            }
    };
 
    public ConversionPanel(String title, ObservableList<Unit> units, DoubleProperty meters) {
        setText(title);
        setCollapsible(false);
        
        numberFormat = NumberFormat.getNumberInstance();
        numberFormat.setMaximumFractionDigits(2);
 
        textField = new TextField();
        slider = new Slider(0, MAX, 0);
        comboBox = new ComboBox(units);
        comboBox.setConverter(new StringConverter<Unit>() {                      
                            
            @Override
            public String toString(Unit t) {
                return t.description;
            }
 
            @Override
            public Unit fromString(String string) {
                throw new UnsupportedOperationException("Not supported yet.");
            }
        });
        VBox vbox = new VBox(textField, slider);
        HBox hbox = new HBox(vbox, comboBox);
        setContent(hbox);
        this.meters = meters;
        
        comboBox.getSelectionModel().select(0);
        meters.addListener(fromMeters);
        comboBox.valueProperty().addListener(fromMeters);
        textField.textProperty().addListener(toMeters);
        fromMeters.invalidated(null);
        
        slider.valueProperty().bindBidirectional(meters);
    }
    
    /**
     * 返回当前选择的计量单位的乘数（单位/米）。
     * @return 
     */
    public double getMultiplier() {
        return comboBox.getValue().multiplier;
    }    
}