/*
    * #%L
    * wcm.io
    * %%
    * Copyright (C) 2019 wcm.io
    * %%
    * 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.
   * #L%
   */
  package io.wcm.handler.url.impl.clientlib;
  
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import org.apache.sling.api.resource.ResourceResolverFactory;
  import org.jetbrains.annotations.NotNull;
  import org.osgi.service.component.annotations.Component;
  import org.osgi.service.component.annotations.Deactivate;
  import org.osgi.service.component.annotations.Reference;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Rewrites resource links to client libraries that are in "allowProxy" mode to /etc.clientlibs.
   */
  @Component(service = ClientlibProxyRewriter.class, immediate = true)
  public class ClientlibProxyRewriterImpl implements ClientlibProxyRewriter {
  
    private static final Pattern STATIC_RESOURCE_PATH_PATTERN = Pattern.compile("^(/(apps|libs)/.*)/resources/.*$");
  
    private static final Logger log = LoggerFactory.getLogger(ClientlibProxyRewriterImpl.class);
  
    @Reference
    private ResourceResolverFactory resourceResolverFactory;
  
    @SuppressWarnings("java:S3077") // volatile is ok here
    private volatile ClientlibPathCache clientlibPathCache;
  
    @Deactivate
    private void deactivate() {
      if (clientlibPathCache != null) {
        this.clientlibPathCache.close();
      }
      this.clientlibPathCache = null;
    }
  
    private ClientlibPathCache getClientlibPathCache() {
      if (this.clientlibPathCache == null) {
        // lazy initialization
        synchronized (this) {
          if (this.clientlibPathCache == null) {
            this.clientlibPathCache = new ClientlibPathCache(resourceResolverFactory);
          }
        }
      }
      return this.clientlibPathCache;
    }
  
    @Override
    public @NotNull String rewriteStaticResourcePath(@NotNull String path) {
      Matcher matcher = STATIC_RESOURCE_PATH_PATTERN.matcher(path);
      if (matcher.matches()) {
        String clientlibPath = matcher.group(1);
        boolean clientlibProxyMode = getClientlibPathCache().isClientlibWithAllowProxy(clientlibPath);
        if (clientlibProxyMode) {
          return rewriteClientlibProxyPath(path);
        }
      }
      return path;
    }
  
    private String rewriteClientlibProxyPath(String path) {
      // replace /apps or /libs with /etc.clientlibs
      String rewrittenPath = "/etc.clientlibs" + path.substring(5);
      log.debug("Rewrite {} to {}", path, rewrittenPath);
      return rewrittenPath;
    }
  
  }