package VASSAL.configure;

import VASSAL.build.BadDataReport;
import VASSAL.build.module.properties.PropertySource;
import VASSAL.counters.GamePiece;
import VASSAL.counters.PieceFilter;
import VASSAL.i18n.Resources;
import VASSAL.script.expression.Expression;
import VASSAL.script.expression.ExpressionException;
import VASSAL.script.expression.NullExpression;
import VASSAL.tools.ErrorDialog;

/*
 * Class encapsulating a Property Match Expression
 * A PropertyExpression is it's own PieceFilter.
 */
public class PropertyExpression implements PieceFilter {

  protected Expression expression = new NullExpression();

  public PropertyExpression() {

  }

  public PropertyExpression(String s) {
    setExpression(s);
  }

  public void setExpression(String s) {
    expression = Expression.createPropertyExpression(s);
  }

  public String getExpression() {
    return expression.getExpression();
  }

  public boolean isNull() {
    return expression == null || expression instanceof NullExpression;
  }

  public PieceFilter getFilter(PropertySource source) {
    return expression.getFilter(source);
  }

  public PieceFilter getFilter() {
    return expression.getFilter();
  }

  public boolean accept(GamePiece piece) {
    return accept(piece, piece);
  }

  public boolean accept(GamePiece source, GamePiece piece) {
    return getFilter(source).accept(piece);
  }

  public boolean equals(Object o) {
    if (o instanceof PropertyExpression) {
      return getExpression().equals(((PropertyExpression) o).getExpression());
    }
    return false;
  }

  /**
   * Evaluate the Property Expression as true/false using
   * a supplied property source
   *
   * @param ps Property Source   *
   * @return boolean result
   */
  public boolean isTrue(PropertySource ps) {
    String result = null;
    try {
      result = expression.evaluate(ps);
    }
    catch (ExpressionException e) {
      ErrorDialog.dataError(new BadDataReport(Resources.getString("Error.expression_error"), "Expression="+getExpression()+", Error="+e.getError(), e));
    }
    return "true".equals(result);
  }

}