/*-
 * ============LICENSE_START=======================================================
 * ONAP - SO
 * ================================================================================
 * Copyright (C) 2017 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * 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.
 * ============LICENSE_END=========================================================
 */

package org.onap.so.cloudify.connector.http;

import java.net.URI;
import org.apache.http.HttpRequest;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.ProtocolException;
import org.apache.http.annotation.Immutable;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpHead;
import org.apache.http.client.methods.HttpDelete;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.client.methods.RequestBuilder;
import org.apache.http.impl.client.DefaultRedirectStrategy;
import org.apache.http.protocol.HttpContext;

/**
 * Custom {@link org.apache.http.client.RedirectStrategy} implementation that automatically redirects all HEAD, GET and
 * DELETE requests. The {@link org.apache.http.client.DefaultRedirectStrategy} only redirects GET and HEAD
 * automatically, per the HTTP specification (POST and PUT typically have bodies and thus cannot be redirected).
 * 
 * A custom strategy is needed for the Openstack API, which can also send 302 on a DELETE (by name) request, expecting
 * the client to follow the redirect to perform the actual deletion.
 */
@Immutable
public class HttpClientRedirectStrategy extends DefaultRedirectStrategy {

    /**
     * Redirectable methods.
     */
    private static final String[] REDIRECT_METHODS =
            new String[] {HttpGet.METHOD_NAME, HttpDelete.METHOD_NAME, HttpHead.METHOD_NAME};

    /**
     * Determine if the request should be redirected. This may not actually be needed, since the REDIRECT_METHODS array
     * has been updated with the DELETE.
     */
    @Override
    protected boolean isRedirectable(final String method) {
        for (final String m : REDIRECT_METHODS) {
            if (m.equalsIgnoreCase(method)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Override the default redirect handling method. As implemented in HttpClient, it does not preserve the method on
     * 301 or 302 responses, always redirecting to a GET.
     */
    @Override
    public HttpUriRequest getRedirect(final HttpRequest request, final HttpResponse response, final HttpContext context)
            throws ProtocolException {

        final URI uri = getLocationURI(request, response, context);
        final String method = request.getRequestLine().getMethod();
        if (method.equalsIgnoreCase(HttpHead.METHOD_NAME)) {
            return new HttpHead(uri);
        } else if (method.equalsIgnoreCase(HttpGet.METHOD_NAME)) {
            return new HttpGet(uri);
        } else {

            final int status = response.getStatusLine().getStatusCode();

            HttpUriRequest newRequest = null;
            if (status == HttpStatus.SC_TEMPORARY_REDIRECT || status == HttpStatus.SC_MOVED_TEMPORARILY) {
                newRequest = RequestBuilder.copy(request).setUri(uri).build();
            } else {
                newRequest = new HttpGet(uri);
            }
            return newRequest;
        }
    }
}