/**
 *#########################################################################
 * FedoraGS3Exception.java - works with the demo-client for Greenstone 3, 
 * of the Greenstone digital library suite from the New Zealand Digital 
 * Library Project at the  * University of Waikato, New Zealand.
 * <BR><BR>
 * Copyright (C) 2008 New Zealand Digital Library Project
 * <BR><BR>
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * <BR><BR>
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *########################################################################
 */

package org.greenstone.fedora.services;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.rmi.RemoteException;

import org.apache.log4j.Logger;
import org.greenstone.gsdl3.util.GSXML;
import org.xml.sax.SAXException;

/**
 * The exceptions that can be thrown by FedoraGS3. This class
 * represents a general FedoraGS3 exception. It will LOG the 
 * exceptions for all the (static inner) subclasses. And, through 
 * the Cause object, also for the static inner Exception classes 
 * that do not inherit but are encapsulated in subclass 
 * FedoraGS3RunException when its constructor is called with the
 * particular Exception type. The 'Cause' Exception classes therefore
 * indicate the root causes for why a FedoraGS3RunException was thrown.
 * @author ak19
*/
public class FedoraGS3Exception extends Exception {
	/** Constant string message to display when a connection is refused */
	public static final String connectionRefusedMessage 
		= "\nUnable to connect. Either the host" 
	    + " and/or port contain invalid values\nOR the fedora" 
	    + " server at that location is down/not yet running." 
	    + "\nTry once more by changing the values for host or port.";
	/** Constant string message to display if the sslHandshake fails
	 * when trying to connect to Fedora using https */
	public static final String sslHandshakeExceptionMessage
		= "SSLHandshakeException.\nThe protocol 'https' might be"
		+ "incorrect.\nTry once more. Perhaps with 'http' instead.";
	/** Constant string message to check against if "AXIS engine  
	 * could not find a target service to invoke" message is the cause 
	 * for an AxisFault exception embedded in a RemoteException */
	public static final String missingTargetService
		= "could not find a target service to invoke";
	/** The logging instance for this class */
	private static final Logger LOG = Logger.getLogger(
			FedoraGS3Exception.class.getName());
		
	/** No argument constructor merely sets the message to 
	 * this class' name. */
	public FedoraGS3Exception(){ 
		super("FedoraGS3Exception");
		if(this.getMessage() != null) {
			LOG.error("Message: " + this.getMessage());
		}
		if(this.getCause() != null) {
			LOG.error("Cause: " + this.getCause().getMessage());
		}
		LOG.debug(this); // stacktrace
	}
	
	/** Constructs a FedoraGS3Exception with the given message.
	 * @param message is an information String of what went wrong. */
	public FedoraGS3Exception(String message){ 
		super(message);
		if(this.getMessage() != null) {
			LOG.error("Message: " + this.getMessage());
		}
		if(this.getCause() != null) {
			LOG.error("Cause: " + this.getCause().getMessage());
		}
		LOG.debug(this); // stacktrace
	}
	
	/** Constructs a FedoraGS3Exception with the given message and cause.
	 * @param message is an information String of what went wrong. 
	 * @param cause is a Throwable object (perhaps another Exception) 
	 * of what caused this exception to occur. */
	public FedoraGS3Exception(String message, Throwable cause) { 
		super(message, cause);
		if(this.getMessage() != null) {
			LOG.error("Message: " + this.getMessage());
		}
		if(this.getCause() != null) {
			LOG.error("Cause: " + this.getCause().getMessage());
		}
		LOG.debug(this); // stacktrace
	}
	
	/** Constructs a FedoraGS3Exception with the given cause.
	 * @param cause is a Throwable object (perhaps another Exception) 
	 * of what caused this exception to occur. */
	public FedoraGS3Exception(Throwable cause) { 
		super("FedoraGS3Exception", cause);
		if(this.getMessage() != null) {
			LOG.error("Message: " + this.getMessage());
		}
		if(this.getCause() != null) {
			LOG.error("Cause: " + this.getCause().getMessage());
		}
		LOG.debug(this); // stacktrace
	}

	/** Represents an exception that occurs when FedoraGS3 is running 
	 * A subclass of FedoraGS3Exception */
	public static class FedoraGS3RunException extends FedoraGS3Exception {
		/** If a problem occurs converting the error message into XML
		 * this string is created in the format of XML stating the 
		 * problem that occurred when trying to convert XML to String. */
		protected static String xmlToStringConversionFailureResponseMsg; 
		/** Some extra information as to what when wrong */
		protected String specifics = "";
		
		static {
			StringBuffer buf = new StringBuffer("<" + GSXML.MESSAGE_ELEM + ">");
			buf.append("<" + GSXML.RESPONSE_ELEM + " " 
					+ GSXML.FROM_ATT + "=\"" + "FedoraGS3\"" + ">");
			buf.append("<" + GSXML.ERROR_ELEM + " " 
				+ GSXML.ERROR_TYPE_ATT + "=\""+ GSXML.ERROR_TYPE_OTHER + "\"" + ">");
			buf.append("(TransformerException): trouble converting original XML " 
					+ "response message into String.");
			buf.append("</" + GSXML.ERROR_ELEM + ">");
			buf.append("</" + GSXML.RESPONSE_ELEM + ">");
			buf.append("</" + GSXML.MESSAGE_ELEM + ">");
			xmlToStringConversionFailureResponseMsg = buf.toString();
			//System.err.println(xmlToStringConversionFailureResponseMsg);
		}
		
		public FedoraGS3RunException() { 
			super("FedoraGS3RunException"); 
		}
		
		public FedoraGS3RunException(String message){ 
			super(message); 
		}
		
		public FedoraGS3RunException(String message, Throwable cause) { 
			super("FedoraGS3RunException " + message, cause); 
		}
		
		public FedoraGS3RunException(Throwable cause) { 
			super("Caused by " 
				+ cause.getClass() + ":\n" + cause.getMessage(), cause);
		}
		
		public void setSpecifics(String specifics) {
			this.specifics = specifics;
		}
		
	        /** Overloading getMessage() to return some details as to what
		 * exactly went wrong. */
		public String getMessage() {
			String msg = "";
			Throwable cause = this.getCause();
			
			if(cause == null)
				return super.getMessage();
			
			if(cause instanceof RemoteException) {
				// specifically indicate it's a RemoteException (as it encapsulates
				// different exception classes) 
				msg = "(RemoteException): problem invoking web service";
				if(specifics != null && !specifics.equals("")) {
					msg += ", possibly trouble finding " + specifics;
				}
				// Some info on what caused the Remote Exception:
				msg += ".\nCause: " + cause.getMessage();
			} else { // Other kind of cause to exception:
				if(cause instanceof UnsupportedEncodingException) {
				msg = "(UnsupportedEncodingException): trouble converting " 
					+ specifics + "returned " 
					+ "from Fedora web services to " + FedoraConnection.UTF8;
				} else if(cause instanceof SAXException) {
					msg = "(SAXException): trouble parsing " 
						+ specifics + " returned from web service";
				} else if(cause instanceof IOException) {
					msg = "(IOException): trouble parsing " 
						+ specifics + " returned from web service";
				} /*else if(cause instanceof TransformerException) {
					msg = msg + "(TransformerException) - trouble converting original XML " 
					+ "response into String"; 
				}*/ 
				// else (other Exception, including FedoraVersionNotSupportedException) 
				// in those cases, just return it as it is.
				// else msg = "";
				if(!msg.equals(""))
					msg = " " + msg + ". ";
			}
			return this.getClass().getCanonicalName() 
				+ msg + super.getMessage();
		} 
	}
	
	/** Static inner class FedoraGS3InitFailureException is an Exception
	 * that is thrown when no connection can be made to the Fedora server
	 * and therefore the FedoraGS3 object construction failed.
	 * Its constructor allows other exceptions to be encapsulated within
	 * it, via the cause object (a Throwable, superclass of Exception) 
	 * parameter. This (the actual exception that caused the 
	 * FedoraGS3InitFailureException) can be queried by interested parties
	 * via the getCause() method. */
	public static class FedoraGS3InitFailureException extends FedoraGS3Exception {
		public static final String MESSAGE = 
			"Unable to instantiate FedoraToGS3Interface"; 
		public FedoraGS3InitFailureException(){ super(MESSAGE); }
		public FedoraGS3InitFailureException(String message){ super(message); }
		public FedoraGS3InitFailureException(String message, Throwable cause) { 
			super(message, cause); 
		}
		public FedoraGS3InitFailureException(Throwable cause) { 
			super(MESSAGE+ " due to exception " 
				+ cause.getClass() + ":\n" + cause.getMessage(), cause);
		}
	}
	
	//***************** FEDORA CONNECTION EXCEPTIONS**********************/
	/** 
	 * When the user chooses to cancel out of the FedoraConnection dialog of
	 * the constructor (where they have to enter authentication information), 
	 * this exception is thrown, so that classes making use of FedoraConnection 
	 * may choose whether to exit their program or deal with it differently. 
	 * */
	public static class CancelledException extends Exception {
		public CancelledException() {
    		super("User cancelled out of connecting to Fedora.\n"
    			+ "Cannot instantiate FedoraConnection.\n");
    	}
    }
	
	/** 
	 * This AuthenticationFailedException can be thrown when the user enters 
	 * an invalid username and password into the FedoraConnection Authentication 
	 * popup dialog (displayed upon FedoraConnection object construction). 
	*/
	public static class AuthenticationFailedException extends Exception {
		public AuthenticationFailedException() {
    		super("(401) Incorrect username and/or password. " 
    				+ "Please re-enter values.");
    	}
    }
	
	/** 
	 * This ServerNotFoundException can be thrown when the user enters 
	 * there is no (Fedora) server listening at a given host and port.
	 * Thrown when a 404 Not Found occurs.
	*/
	public static class ServerNotFoundException extends Exception {
		public ServerNotFoundException(String message) {
    		super(message);
    	}
    }
	
	/** 
	 * This AuthenticationFailedException can be thrown when there is some
	 * server listening at the host and port values entered by the user, but
	 * when this server is (most likely) not a Fedora Server. 
	 * The IOException message received in such cases is:
	 * "Unable to instantiate FedoraConnection
	 * java.io.IOException: Request failed [404 /fedora/describe]"
	 * And in such cases, we can throw this NotAFedoraServerException
	 * to deal with it more particularly than more general IOExceptions. 
	*/
	public static class NotAFedoraServerException extends Exception {
		public static final String MESSAGE =
			"There is a server listening at the given host and port," 
			+ "\nbut it does not seem to be a Fedora server." 
			+ "\nTry changing the host and/or port values.";
		
		public NotAFedoraServerException() {
    		super(MESSAGE);
    	}
		
		public NotAFedoraServerException(String message) {
    		super(MESSAGE + ":\n(" + message + ")");
    	}
    }

	/**
	 * Certain functionality in Fedora - in particular fielded search - is
	 * implemented differently or uses slightly different Fedora types in older
	 * versions of Fedora (fielded search in 2.0 uses a different Condition class). 
	 * In that case, the fielded search web service cannot be performed, and
	 * this FedoraVersionNotSupportedException is thrown.
	 */
	public static class FedoraVersionNotSupportedException extends Exception {
		
		public FedoraVersionNotSupportedException(String fedoraVersion) {
			super("Fedora repository version is " + fedoraVersion 
				+ "\nHowever, browsing/searching by field only works "
				+ "from version " + FedoraConnection.SUPPORTED_VERSION + " onwards.");
		}
	}
}