// Copyright 2005-2007 onetsoft.com
//
// 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 com.onetsoft.fastjsp;

import com.onetsoft.fastjsp.util.Constants;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;


/**
 * 抽象錯誤處理類
 * 自定義錯誤處理應繼承此類
 *
 * @author <a href="mailto:hgw@onetsoft.com">hgw</a>
 * @since 2.0
 */
public abstract class AbstractExceptionHandler implements ExceptionHandler {
    public void handle(Exception exception, Servicer servicer) throws IOException, ServletException {
        if (exception instanceof RedirectException) {
            handleRedirectException((RedirectException) exception, servicer);
        } else if (exception instanceof PageRedirectException) {
            handlePageRedirectException((PageRedirectException) exception, servicer);
        } else {
            handleException(exception, servicer);
        }
    }

    private void handleRedirectException(RedirectException e, Servicer servicer) throws IOException {
        HttpServletResponse response = servicer.getResponse();
        response.sendRedirect(response.encodeRedirectURL(e.getUrl()));
    }

    private void handlePageRedirectException(PageRedirectException e, Servicer servicer) throws IOException, ServletException {
        servicer.getRequest().setAttribute(Constants.EXCEPTION_ATTRIBUTE, e);
        ((AbstractServicer) servicer).forward(e.getPage());
    }

    /**
     * 處理系統拋出的各類錯誤
     *
     * @param exception
     * @param servicer
     */
    protected abstract void handleException(Exception exception, Servicer servicer) throws IOException, ServletException;
}