package ca.uhn.fhir.jaxrs.server.interceptor;

/*
 * #%L
 * HAPI FHIR JAX-RS Server
 * %%
 * Copyright (C) 2014 - 2017 University Health Network
 * %%
 * 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.
 * #L%
 */

import java.io.IOException;

import javax.interceptor.AroundInvoke;
import javax.interceptor.InvocationContext;
import javax.servlet.ServletException;
import javax.ws.rs.core.Response;

import ca.uhn.fhir.jaxrs.server.AbstractJaxRsProvider;
import ca.uhn.fhir.jaxrs.server.util.JaxRsRequest;
import ca.uhn.fhir.rest.server.exceptions.BaseServerResponseException;
import ca.uhn.fhir.rest.server.exceptions.InternalErrorException;
import ca.uhn.fhir.rest.server.interceptor.ExceptionHandlingInterceptor;

/**
 * An interceptor that catches the jax-rs exceptions
 *
 * @author Peter Van Houte | peter.vanhoute@agfa.com | Agfa Healthcare
 */
public class JaxRsExceptionInterceptor {

    /** the existing exception handler which is able to convert exception into responses*/
    private final ExceptionHandlingInterceptor exceptionHandler;

    /**
     * The default constructor
     */
    public JaxRsExceptionInterceptor() {
        this.exceptionHandler = new ExceptionHandlingInterceptor();
    }

    /**
     * A utility constructor for unit testing
     * @param exceptionHandler the handler for the exception conversion
     */
    JaxRsExceptionInterceptor(final ExceptionHandlingInterceptor exceptionHandler) {
        this.exceptionHandler = exceptionHandler;
    }

    /**
     * This interceptor will catch all exception and convert them using the exceptionhandler
     * @param ctx the invocation context
     * @return the result
     * @throws JaxRsResponseException an exception that can be handled by a jee container
     */
    @AroundInvoke
    public Object intercept(final InvocationContext ctx)
            throws JaxRsResponseException {
        try {
            return ctx.proceed();
        }
        catch (final Exception theException) {
            final AbstractJaxRsProvider theServer = (AbstractJaxRsProvider) ctx.getTarget();
            throw convertException(theServer, theException);
        }
    }

    /**
     * This method convert an exception to a JaxRsResponseException
     * @param theServer the provider
     * @param theException the exception to convert
     * @return JaxRsResponseException
     */
    public JaxRsResponseException convertException(final AbstractJaxRsProvider theServer, final Throwable theException) {
        if (theServer.withStackTrace()) {
            exceptionHandler.setReturnStackTracesForExceptionTypes(Throwable.class);
        }
        final JaxRsRequest requestDetails = theServer.getRequest(null, null).build();
        final BaseServerResponseException convertedException = preprocessException(theException, requestDetails);
        return new JaxRsResponseException(convertedException);
    }

    /**
     * This method converts an exception into a response
     * @param theRequest the request
     * @param theException the thrown exception
     * @return the response describing the error
     * @throws IOException
     */
    public Response convertExceptionIntoResponse(final JaxRsRequest theRequest, final JaxRsResponseException theException)
            throws IOException {
        return handleExceptionWithoutServletError(theRequest, theException);
    }

    private BaseServerResponseException preprocessException(final Throwable theException, final JaxRsRequest requestDetails) {
        try {
            Throwable theExceptionToConvert = theException;
            if (!(theException instanceof BaseServerResponseException) && (theException.getCause() instanceof BaseServerResponseException)) {
                theExceptionToConvert = theException.getCause();
            }
            return exceptionHandler.preProcessOutgoingException(requestDetails, theExceptionToConvert, null);
        }
        catch (final ServletException e) {
            return new InternalErrorException(e);
        }
    }

    private Response handleExceptionWithoutServletError(final JaxRsRequest theRequest, final BaseServerResponseException theException)
            throws IOException {
        try {
            return (Response) exceptionHandler.handleException(theRequest, theException);
        }
        catch (final ServletException e) {
            final BaseServerResponseException newException = preprocessException(new InternalErrorException(e), theRequest);
            return handleExceptionWithoutServletError(theRequest, newException);
        }
    }
}