/**
 * This file is part of Graylog.
 *
 * Graylog 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 3 of the License, or
 * (at your option) any later version.
 *
 * Graylog 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with Graylog.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.graylog2.shared.security;

import org.apache.shiro.authz.AuthorizationException;
import org.apache.shiro.authz.annotation.RequiresPermissions;
import org.graylog2.rest.RestTools;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.annotation.Priority;
import javax.ws.rs.ForbiddenException;
import javax.ws.rs.Priorities;
import javax.ws.rs.container.ContainerRequestContext;
import javax.ws.rs.container.ContainerRequestFilter;
import javax.ws.rs.core.SecurityContext;
import java.io.IOException;
import java.util.Locale;

@Priority(Priorities.AUTHORIZATION)
public class ShiroAuthorizationFilter implements ContainerRequestFilter {
    private static final Logger LOG = LoggerFactory.getLogger(ShiroAuthorizationFilter.class);
    private final RequiresPermissions annotation;

    public ShiroAuthorizationFilter(RequiresPermissions annotation) {
        this.annotation = annotation;
    }

    @Override
    public void filter(ContainerRequestContext requestContext) throws IOException {
        final SecurityContext securityContext = requestContext.getSecurityContext();
        if (securityContext instanceof ShiroSecurityContext) {
            final ShiroSecurityContext context = (ShiroSecurityContext) securityContext;
            final String userName = RestTools.getUserNameFromRequest(requestContext);
            final ContextAwarePermissionAnnotationHandler annotationHandler = new ContextAwarePermissionAnnotationHandler(context);
            try {
                LOG.debug("Checking authorization for user [{}], needs permissions: {}", userName, annotation.value());
                annotationHandler.assertAuthorized(annotation);
            } catch (AuthorizationException e) {
                final String msg = String.format(Locale.US, "User [%s] not authorized. (%s %s)", userName,
                        requestContext.getMethod(), requestContext.getUriInfo().getPath());
                LOG.info(msg);
                throw new ForbiddenException(msg);
            }
        } else {
            throw new ForbiddenException();
        }
    }
}