/**
 * Copyright 2010 Google 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 org.waveprotocol.wave.client.doodad.experimental.htmltemplate;

import com.google.gwt.core.client.JavaScriptObject;

/**
 * Exposes a public http cajoling service as a {@link CajoleService}.
 */
public final class HttpCajoleService implements CajoleService {

  /** Public cajoling service. */
  private static final String SERVICE_URL = "http://caja.appspot.com/cajole";

  /** String to prepend to page URLs to form the cajoling request. */
  private static final String URL_PREFIX = SERVICE_URL //
      + "?input-mime-type=text/html" //
      + "&output-mime-type=application/javascript" //
      + "&alt=json-in-script" //
      + "&url=";

  /**
   * Exposes the JSO response as a {@link CajoleService.CajolerResponse}.
   */
  private static final class CajolerResponseJsoImpl extends JavaScriptObject
      implements CajolerResponse {

    // GWT requires JSO constructor visibility to be exactly protected
    @SuppressWarnings("unused")
    protected CajolerResponseJsoImpl() {
    }

    @Override
    public native String getHtml() /*-{
      return this.html;
    }-*/;

    @Override
    public native String getJs() /*-{
      return this.js;
    }-*/;
  }

  /** RPC processo for cajoler request/responses. */
  private final JsonpRouter<CajolerResponseJsoImpl> router = JsonpRouter.create();

  @Override
  public void cajole(String scriptUrl, Callback<? super CajolerResponse> callback) {
    router.request(URL_PREFIX + scriptUrl, callback);
  }
}