WebjarHelperSource.java

/**
 * Copyright (C) 2013-2015 all@code-story.net
 *
 * 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 net.codestory.http.templating.helpers;

import com.github.jknack.handlebars.Options;
import net.codestory.http.misc.Cache;
import net.codestory.http.misc.WebJarUrlFinder;

import java.net.URL;
import java.util.function.Function;

import static net.codestory.http.io.Strings.substringAfter;

public class WebjarHelperSource {
  private final WebJarUrlFinder webJarUrlFinder;
  private final Function<String, String> fullPathForUri;

  public WebjarHelperSource(boolean prodMode) {
    this.webJarUrlFinder = new WebJarUrlFinder(prodMode);
    this.fullPathForUri = prodMode ? new Cache<>(this::fullPathForUri) : this::fullPathForUri;
  }

  // Handler entry point

  public CharSequence webjar(Object context, Options options) {
    String attributes = HelperTools.hashAsString(options);

    return HelperTools.toString(context, value -> singleWebjar(value, attributes));
  }

  // Internal

  private String singleWebjar(Object value, String attributes) {
    String fullPath = fullPathForUri.apply(value.toString());
    return tag(fullPath, attributes);
  }

  private String fullPathForUri(String uri) {
    URL classpathUrl = webJarUrlFinder.url(uri);
    if (classpathUrl == null) {
      return uri; // Not found
    }

    return substringAfter(classpathUrl.toString(), "/META-INF/resources");
  }

  private String tag(String fullPath, String attributes) {
    if (fullPath.endsWith(".css")) {
      return "<link rel=\"stylesheet\" href=\"" + fullPath + "\"" + attributes + ">";
    } else {
      return "<script src=\"" + fullPath + "\"" + attributes + "></script>";
    }
  }
}