package de.unisiegen.tpml.core ;


import java.text.MessageFormat ;


/**
 * This exception is thrown when an attempt to apply a rule that cannot be
 * applied to a node.
 * 
 * @author Benedikt Meurer
 * @version $Rev:415 $
 * @see de.unisiegen.tpml.core.ProofGuessException
 */
public final class ProofRuleException extends Exception
{
  //
  // Constants
  //
  /**
   * The serial version id.
   */
  private static final long serialVersionUID = - 765882201403684253L ;


  //
  // Attributes
  //
  /**
   * The node to which the rule was about to be applied.
   * 
   * @see #getNode()
   */
  private ProofNode node ;


  /**
   * The rule that turned out to be invalid.
   * 
   * @see #getRule()
   */
  private ProofRule rule ;


  //
  // Constructor
  //
  /**
   * Allocates a new {@link ProofRuleException} telling that the specified
   * <code>rule</code> could not be applied to the given <code>node</code>.
   * 
   * @param pNode the {@link ProofNode}.
   * @param pRule the {@link ProofRule} that could not be applied to the
   *          <code>node</code>.
   * @throws NullPointerException if <code>node</code> or <code>rule</code>
   *           is <code>null</code>.
   * @see #ProofRuleException(ProofNode, ProofRule, Throwable)
   */
  public ProofRuleException ( ProofNode pNode , ProofRule pRule )
  {
    this ( pNode , pRule , null ) ;
  }


  /**
   * Allocates a new {@link ProofRuleException} telling that the specified
   * <code>rule</code> could not be applied to the given <code>node</code>.
   * 
   * @param pNode the {@link ProofNode}.
   * @param pRule the {@link ProofRule} that could not be applied to the
   *          <code>node</code>.
   * @param cause the cause, which is saved for later retrieval by the
   *          {@link Throwable#getCause()} method. A <code>null</code> value
   *          is permitted, and indicates that the cause is nonexistent or
   *          unknown.
   * @throws NullPointerException if <code>node</code> or <code>rule</code>
   *           is <code>null</code>.
   * @see #ProofRuleException(String, ProofNode, ProofRule, Throwable)
   */
  public ProofRuleException ( ProofNode pNode , ProofRule pRule ,
      Throwable cause )
  {
    this (
        MessageFormat.format (
            Messages.getString ( "ProofRuleException.0" ) , pRule , pNode ) , pNode , //$NON-NLS-1$
        pRule , cause ) ;
  }


  /**
   * Allocates a new {@link ProofRuleException} telling that the specified
   * <code>rule</code> could not be applied to the given <code>node</code>.
   * The <code>message</code> gives detailed information about the cause of
   * the problem.
   * 
   * @param message detailed information about the cause.
   * @param pNode the {@link ProofNode}.
   * @param pRule the {@link ProofRule} that could not be applied to the
   *          <code>node</code>.
   * @param cause the cause, which is saved for later retrieval by the
   *          {@link Throwable#getCause()} method. A <code>null</code> value
   *          is permitted, and indicates that the cause is nonexistent or
   *          unknown.
   * @throws NullPointerException if <code>message</code>, <code>node</code>
   *           or <code>rule</code> is <code>null</code>.
   */
  public ProofRuleException ( String message , ProofNode pNode ,
      ProofRule pRule , Throwable cause )
  {
    super ( message , cause ) ;
    if ( message == null )
    {
      throw new NullPointerException ( "message is null" ) ; //$NON-NLS-1$
    }
    if ( pNode == null )
    {
      throw new NullPointerException ( "node is null" ) ; //$NON-NLS-1$
    }
    if ( pRule == null )
    {
      throw new NullPointerException ( "rule is null" ) ; //$NON-NLS-1$
    }
    this.node = pNode ;
    this.rule = pRule ;
  }


  //
  // Accessors
  //
  /**
   * Returns the node on which a rule application failed.
   * 
   * @return the node on which a rule application failed.
   */
  public ProofNode getNode ( )
  {
    return this.node ;
  }


  /**
   * Returns the rule that failed to apply.
   * 
   * @return the rule that failed to apply.
   */
  public ProofRule getRule ( )
  {
    return this.rule ;
  }
}