/*
 * Copyright 2004,2005 The Apache Software Foundation.
 *
 * 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 javax.xml.soap;

/**
 * An exception that signals that a SOAP exception has
 * occurred. A <CODE>SOAPException</CODE> object may contain a
 * <CODE>String</CODE> that gives the reason for the exception, an
 * embedded <CODE>Throwable</CODE> object, or both. This class
 * provides methods for retrieving reason messages and for
 * retrieving the embedded <CODE>Throwable</CODE> object.</P>
 * <p/>
 * <P>Typical reasons for throwing a <CODE>SOAPException</CODE>
 * object are problems such as difficulty setting a header, not
 * being able to send a message, and not being able to get a
 * connection with the provider. Reasons for embedding a <CODE>
 * Throwable</CODE> object include problems such as input/output
 * errors or a parsing problem, such as an error in parsing a
 * header.
 */
public class SOAPException extends Exception {

    private static final long serialVersionUID = 5083961510786058130L;

	/**
     * Constructs a <CODE>SOAPException</CODE> object with no
     * reason or embedded <CODE>Throwable</CODE> object.
     */
    public SOAPException() {
        cause = null;
    }

    /**
     * Constructs a <CODE>SOAPException</CODE> object with the
     * given <CODE>String</CODE> as the reason for the exception
     * being thrown.
     *
     * @param reason a description of what caused
     *               the exception
     */
    public SOAPException(String reason) {

        super(reason);

        cause = null;
    }

    /**
     * Constructs a <CODE>SOAPException</CODE> object with the
     * given <CODE>String</CODE> as the reason for the exception
     * being thrown and the given <CODE>Throwable</CODE> object as
     * an embedded exception.
     *
     * @param reason a description of what caused
     *               the exception
     * @param cause  a <CODE>Throwable</CODE> object
     *               that is to be embedded in this <CODE>SOAPException</CODE>
     *               object
     */
    public SOAPException(String reason, Throwable cause) {

        super(reason);

        initCause(cause);
    }

    /**
     * Constructs a <CODE>SOAPException</CODE> object
     * initialized with the given <CODE>Throwable</CODE>
     * object.
     *
     * @param cause a <CODE>Throwable</CODE> object
     *              that is to be embedded in this <CODE>SOAPException</CODE>
     *              object
     */
    public SOAPException(Throwable cause) {

        super(cause.toString());

        initCause(cause);
    }

    /**
     * Returns the detail message for this <CODE>
     * SOAPException</CODE> object.
     * <p/>
     * <P>If there is an embedded <CODE>Throwable</CODE> object,
     * and if the <CODE>SOAPException</CODE> object has no detail
     * message of its own, this method will return the detail
     * message from the embedded <CODE>Throwable</CODE>
     * object.</P>
     *
     * @return the error or warning message for this <CODE>
     *         SOAPException</CODE> or, if it has none, the message of
     *         the embedded <CODE>Throwable</CODE> object, if there is
     *         one
     */
    public String getMessage() {

        String s = super.getMessage();

        if ((s == null) && (cause != null)) {
            return cause.getMessage();
        } else {
            return s;
        }
    }

    /**
     * Returns the <CODE>Throwable</CODE> object embedded in
     * this <CODE>SOAPException</CODE> if there is one. Otherwise,
     * this method returns <CODE>null</CODE>.
     *
     * @return the embedded <CODE>Throwable</CODE> object or <CODE>
     *         null</CODE> if there is none
     */
    public Throwable getCause() {
        return cause;
    }

    /**
     * Initializes the <CODE>cause</CODE> field of this <CODE>
     * SOAPException</CODE> object with the given <CODE>
     * Throwable</CODE> object.
     * <p/>
     * <P>This method can be called at most once. It is generally
     * called from within the constructor or immediately after the
     * constructor has returned a new <CODE>SOAPException</CODE>
     * object. If this <CODE>SOAPException</CODE> object was
     * created with the constructor {@link #SOAPException(java.lang.Throwable) SOAPException(java.lang.Throwable)}
     * or {@link #SOAPException(java.lang.String, java.lang.Throwable) SOAPException(java.lang.String, java.lang.Throwable)}, meaning
     * that its <CODE>cause</CODE> field already has a value, this
     * method cannot be called even once.
     *
     * @param cause the <CODE>Throwable</CODE>
     *              object that caused this <CODE>SOAPException</CODE> object
     *              to be thrown. The value of this parameter is saved for
     *              later retrieval by the <A href=
     *              "../../../javax/xml/soap/SOAPException.html#getCause()">
     *              <CODE>getCause()</CODE></A> method. A <TT>null</TT> value
     *              is permitted and indicates that the cause is nonexistent
     *              or unknown.
     * @return a reference to this <CODE>SOAPException</CODE>
     *         instance
     * @throws java.lang.IllegalArgumentException
     *          if
     *          <CODE>cause</CODE> is this <CODE>Throwable</CODE> object.
     *          (A <CODE>Throwable</CODE> object cannot be its own
     *          cause.)
     * @throws java.lang.IllegalStateException
     *          if this <CODE>
     *          SOAPException</CODE> object was created with {@link #SOAPException(java.lang.Throwable) SOAPException(java.lang.Throwable)}
     *          or {@link #SOAPException(java.lang.String, java.lang.Throwable) SOAPException(java.lang.String, java.lang.Throwable)}, or this
     *          method has already been called on this <CODE>
     *          SOAPException</CODE> object
     */
    public synchronized Throwable initCause(Throwable cause) {

        if (this.cause != null) {
            throw new IllegalStateException("Can't override cause");
        }

        if (cause == this) {
            throw new IllegalArgumentException("Self-causation not permitted");
        } else {
            this.cause = cause;

            return this;
        }
    }

    private Throwable cause;
}