/*
    *  Copyright 2012 Christopher Pheby
    *
    *  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.jadira.cdt.exception;
  
  /**
   * Class for constructing checked Exceptions with a given root cause.
   */
  public abstract class WrappedCheckedException extends Exception {
  
  	private static final long serialVersionUID = 615855181745250021L;
  
  	/**
  	 * Construct a WrappedCheckedException with the specified 
  	 * message.
  	 * @param message the specific message
  	 */
  	public WrappedCheckedException(String message) {
  		super(message);
  	}
  
  	/**
  	 * Construct a WrappedCheckedException with the specified 
  	 * message and wrapped exception.
  	 * @param message the specific message
  	 * @param cause the wrapped exception
  	 */
  	public WrappedCheckedException(String message, Throwable cause) {
  		super(message, cause);
  	}
  
  	/**
  	 * Return the detail message, including the message from the Wrapped
  	 * exception if there is one.
  	 */
  	@Override
  	public String getMessage() {
  		return constructMessage(super.getMessage(), getCause());
  	}
  
  	/**
  	 * Constructs an exception String with the given message and incorporating the
  	 * causing exception
  	 * @param message The specific message
  	 * @param cause The causing exception
  	 * @return The exception String
  	 */
  	protected String constructMessage(String message, Throwable cause) {
  		
  		if (cause != null) {
  		
  			StringBuilder strBuilder = new StringBuilder();
  			
  			if (message != null) {
  				strBuilder.append(message).append(": ");
  			}
  			
  			strBuilder.append("Wrapped exception is {").append(cause);
  			strBuilder.append("}");
  			
  			return strBuilder.toString();
  			
  		} else {
  			return message;
  		}
  	}
  
  	/**
  	 * Retrieves the ultimate root cause for this exception, or null
  	 * @return The root cause
  	 */
  	public Throwable getRootCause() {
  		
  		Throwable rootCause = null;
  		Throwable nextCause = getCause();
  		
  		while (nextCause != null && !nextCause.equals(rootCause)) {
  			rootCause = nextCause;
  			nextCause = nextCause.getCause();
  		}
  		
  		return rootCause;
  	}
  
  	/**
  	 * Returns the next parent exception of the given type, or null
  	 * @param exceptionType the exception type to match
 	 * @param <E> The Exception type
 	 * @return The matched exception of the target type, or null
 	 */
 	public <E extends Exception> E findWrapped(Class<E> exceptionType) {
 		
 		if (exceptionType == null) {
 			return null;
 		}
 		
 		Throwable cause = getCause();
 		
 		while (true) {
 			
 			if (cause == null) {
 				return null;
 			}
 			
 			if (exceptionType.isInstance(cause)) {
 				
 				@SuppressWarnings("unchecked") E matchedCause = (E) cause;
 				return matchedCause;
 			}
 
 			if (cause.getCause() == cause) {
 				return null;
 			}
 			
 			if (cause instanceof WrappedRuntimeException) {
 				return ((WrappedRuntimeException) cause).findWrapped(exceptionType);
 			}
 			if (cause instanceof WrappedCheckedException) {
 				return ((WrappedCheckedException) cause).findWrapped(exceptionType);
 			}			
 			
 			cause = cause.getCause();
 		}
 	}
 }