Target.java

/*
 * Copyright 2013 Netflix, 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 feign;

import static feign.Util.checkNotNull;
import static feign.Util.emptyToNull;

/**
 * <br><br><b>relationship to JAXRS 2.0</b><br> <br> Similar to {@code
 * javax.ws.rs.client.WebTarget}, as it produces requests. However, {@link RequestTemplate} is a
 * closer match to {@code WebTarget}.
 *
 * @param <T> type of the interface this target applies to.
 */
public interface Target<T> {

  /* The type of the interface this target applies to. ex. {@code Route53}. */
  Class<T> type();

  /* configuration key associated with this target. For example, {@code route53}. */
  String name();

  /* base HTTP URL of the target. For example, {@code https://api/v2}. */
  String url();

  /**
   * Targets a template to this target, adding the {@link #url() base url} and any target-specific
   * headers or query parameters. <br> <br> For example: <br>
   * <pre>
   * public Request apply(RequestTemplate input) {
   *     input.insert(0, url());
   *     input.replaceHeader("X-Auth", currentToken);
   *     return input.asRequest();
   * }
   * </pre>
   * <br> <br><br><b>relationship to JAXRS 2.0</b><br> <br> This call is similar to {@code
   * javax.ws.rs.client.WebTarget.request()}, except that we expect transient, but necessary
   * decoration to be applied on invocation.
   */
  public Request apply(RequestTemplate input);

  public static class HardCodedTarget<T> implements Target<T> {

    private final Class<T> type;
    private final String name;
    private final String url;

    public HardCodedTarget(Class<T> type, String url) {
      this(type, url, url);
    }

    public HardCodedTarget(Class<T> type, String name, String url) {
      this.type = checkNotNull(type, "type");
      this.name = checkNotNull(emptyToNull(name), "name");
      this.url = checkNotNull(emptyToNull(url), "url");
    }

    @Override
    public Class<T> type() {
      return type;
    }

    @Override
    public String name() {
      return name;
    }

    @Override
    public String url() {
      return url;
    }

    /* no authentication or other special activity. just insert the url. */
    @Override
    public Request apply(RequestTemplate input) {
      if (input.url().indexOf("http") != 0) {
        input.insert(0, url());
      }
      return input.request();
    }

    @Override
    public boolean equals(Object obj) {
      if (obj instanceof HardCodedTarget) {
        HardCodedTarget<?> other = (HardCodedTarget) obj;
        return type.equals(other.type)
               && name.equals(other.name)
               && url.equals(other.url);
      }
      return false;
    }

    @Override
    public int hashCode() {
      int result = 17;
      result = 31 * result + type.hashCode();
      result = 31 * result + name.hashCode();
      result = 31 * result + url.hashCode();
      return result;
    }

    @Override
    public String toString() {
      if (name.equals(url)) {
        return "HardCodedTarget(type=" + type.getSimpleName() + ", url=" + url + ")";
      }
      return "HardCodedTarget(type=" + type.getSimpleName() + ", name=" + name + ", url=" + url
             + ")";
    }
  }

  public static final class EmptyTarget<T> implements Target<T> {

    private final Class<T> type;
    private final String name;

    EmptyTarget(Class<T> type, String name) {
      this.type = checkNotNull(type, "type");
      this.name = checkNotNull(emptyToNull(name), "name");
    }

    public static <T> EmptyTarget<T> create(Class<T> type) {
      return new EmptyTarget<T>(type, "empty:" + type.getSimpleName());
    }

    public static <T> EmptyTarget<T> create(Class<T> type, String name) {
      return new EmptyTarget<T>(type, name);
    }

    @Override
    public Class<T> type() {
      return type;
    }

    @Override
    public String name() {
      return name;
    }

    @Override
    public String url() {
      throw new UnsupportedOperationException("Empty targets don't have URLs");
    }

    @Override
    public Request apply(RequestTemplate input) {
      if (input.url().indexOf("http") != 0) {
        throw new UnsupportedOperationException(
            "Request with non-absolute URL not supported with empty target");
      }
      return input.request();
    }

    @Override
    public boolean equals(Object obj) {
      if (obj instanceof EmptyTarget) {
        EmptyTarget<?> other = (EmptyTarget) obj;
        return type.equals(other.type)
               && name.equals(other.name);
      }
      return false;
    }

    @Override
    public int hashCode() {
      int result = 17;
      result = 31 * result + type.hashCode();
      result = 31 * result + name.hashCode();
      return result;
    }

    @Override
    public String toString() {
      if (name.equals("empty:" + type.getSimpleName())) {
        return "EmptyTarget(type=" + type.getSimpleName() + ")";
      }
      return "EmptyTarget(type=" + type.getSimpleName() + ", name=" + name + ")";
    }
  }
}