com.hotels.styx.client.RewriteRuleset Maven / Gradle / Ivy

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/**
 * Copyright (C) 2013-2017 Expedia Inc.
 *
 * 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.hotels.styx.client;

import com.google.common.collect.ImmutableList;
import com.hotels.styx.api.HttpRequest;
import com.hotels.styx.api.Url;

import java.util.List;
import java.util.Objects;
import java.util.Optional;

/**
 * A list of rules that defines how to rewrite the URL in HTTP requests. The rules are tested in order, until a matching
 * rule is found. When the match is found, a rewrite is performed. If no match is found, the original URL is retained.
 */
public class RewriteRuleset {
    private final List rewriteRules;

    /**
     * Constructs an instance with a list of rewrite rules.
     *
     * @param rewriteRules rewrite rules
     */
    public RewriteRuleset(List rewriteRules) {
        this.rewriteRules = ImmutableList.copyOf(rewriteRules);
    }

    /**
     * Rewrites the URL of the request according to the rewrite rules.
     *
     * @param request a request
     * @return a rewritten request
     */
    public HttpRequest rewrite(HttpRequest request) {
        String path = request.path();
        String newPath = newPath(path);

        if (!Objects.equals(newPath, path)) {
            Url newUrl = request.url().newBuilder().path(newPath).build();
            return request.newBuilder()
                    .url(newUrl)
                    .build();
        }

        return request;
    }

    private String newPath(String requestUri) {
        return rewriteRules.stream()
                .map(rewriteRule -> rewriteRule.rewrite(requestUri))
                .filter(Optional::isPresent)
                .map(Optional::get)
                .findFirst()
                .orElse(requestUri);
    }
}