package de.unisiegen.tpml.graphics.smallstep;

import java.awt.Dimension;
import java.awt.Font;

import javax.swing.JComponent;
import javax.swing.JLabel;

import de.unisiegen.tpml.core.expressions.Expression;

/**
 * Just a simple Component combining two {@link JLabel}s together. One
 * for the name of the rules with a leading <i>(</i> and and a tailing
 * <i>)</i>. And one for a possible exponent, when the rules have been
 * grouped together. When the exponent is <i>1</i> it will not be shown.<br>
 * <br>The following example will display those two possible renderings.<br>
 * <br>
 * <img src="../../../../../../images/rulelabel1.png" /><br>
 * <img src="../../../../../../images/rulelabel2.png" /><br>
 * <br>
 * But no matter if there is an exponent, that should be displayed,
 * the label for the exponent is always there. This way all rule labels
 * have an equal height. Showing here:<br>
 * <img src="../../../../../../images/rulelabel_scheme.png" /><br>
 * <br>
 * The height, this components need, is always containing the exponent
 * even if it isn't shown at all. It is easier to place them if they 
 * have a homogenouse height.
 * 
 * @author marcell
 * @see de.unisiegen.tpml.graphics.smallstep.SmallStepView
 * @see de.unisiegen.tpml.graphics.smallstep.SmallStepComponent
 * @see de.unisiegen.tpml.graphics.smallstep.SmallStepNodeComponent
 * @see de.unisiegen.tpml.graphics.smallstep.SmallStepRulesComponent
 */
public class SmallStepRuleLabel extends JComponent {
	
	/**
	 * 
	 */
	private static final long serialVersionUID = 2850026835245921469L;

	/**
	 * The exponent number
	 */
	private int						ruleCount;
	
	/**
	 * The expression that may be associated with this rule.<br>
	 * <br>
	 * This expression is used to determin the part of the 
	 * current expression of the {@link SmallStepNodeComponent} 
	 * that needs to get underlines.
	 */
	private Expression		stepExpression;
	
	/**
	 * Creates a new SmallStepRuleLabel with a name and a value
	 * for the exponent (the ruleCount).
	 * 
	 * @param ruleName The name of the rule
	 * @param ruleCount The number that should be shown in the exponent.
	 */
	public SmallStepRuleLabel (String ruleName, int ruleCount) {
		super ();
		
		this.ruleCount 	= ruleCount;

		
		setLayout (null);
		
		JLabel ruleLabel = new JLabel ();
		add (ruleLabel);
		ruleLabel.setText("(" + ruleName + ")");
		
		JLabel exponentLabel	= new JLabel ();
		add (exponentLabel);
		exponentLabel.setText("" + ruleCount);
		
		// scale the font down to 0.75
		Font expFont = exponentLabel.getFont();
		expFont = expFont.deriveFont(expFont.getSize2D() * 0.75f);
		exponentLabel.setFont(expFont);
		
		Dimension size = null;
		// the exponen will be placed so that 1/2 of the size of the 
		// exponent label will appear on top of the
		Dimension ruleSize 	= ruleLabel.getPreferredSize();
		Dimension expSize 	= exponentLabel.getPreferredSize();
		int top = expSize.height/2;
		
		ruleLabel.setBounds(0, top, ruleSize.width, ruleSize.height);
		exponentLabel.setBounds(ruleSize.width, 0, expSize.width, expSize.height);
		
		size = new Dimension (ruleSize.width + expSize.width, ruleSize.height + top);
		
		ruleLabel.setVisible(true);
		
		if (ruleCount > 1) {
			exponentLabel.setVisible(true);
		}
		else {
			ruleSize.width -= expSize.width;
			exponentLabel.setVisible(false);
		}
		
		this.stepExpression = null;
		
		// set the size for this component
		setSize (size);
		setMinimumSize (size);
		setMaximumSize (size);
		setPreferredSize (size);
	}
	
	/**
	 * Returns the number of the exponent
	 * @return
	 */
	public int getRuleCount () {
		return this.ruleCount;
	}
	
	/**
	 * Sets a new expression this rule should be associated to.
	 * @param stepExpression
	 * @see #stepExpression
	 */
	public void setStepExpression (Expression stepExpression) {
		this.stepExpression = stepExpression;
	}
	
	/**
	 * Returns the current {@link #stepExpression}
	 * @return
	 */
	public Expression getStepExpression () {
		return this.stepExpression;
	}
	
	/**
	 * Creates a dummy Expression with a placeholder rule name <i>RULE</i>
	 * to determine the height.
	 * 
	 * @return
	 */
	public static int getLabelHeight () {
		
		// just create a label that can calculate the height
		SmallStepRuleLabel l = new SmallStepRuleLabel ("RULE", 1);
		return l.getHeight();
	}
	

}