/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.beam.runners.core.construction.resources;

import io.github.classgraph.ClassGraph;
import java.io.File;
import java.util.List;
import java.util.stream.Collectors;

/**
 * Attempts to detect all the resources to be staged using classgraph library.
 *
 * <p>See <a
 * href="https://github.com/classgraph/classgraph">https://github.com/classgraph/classgraph</a>
 */
public class ClasspathScanningResourcesDetector implements PipelineResourcesDetector {

  private transient ClassGraph classGraph;

  public ClasspathScanningResourcesDetector(ClassGraph classGraph) {
    this.classGraph = classGraph;
  }

  /**
   * Detects classpath resources and returns a list of absolute paths to them.
   *
   * @param classLoader The classloader to use to detect resources to stage (optional).
   * @return A list of absolute paths to the resources the class loader uses.
   */
  @Override
  public List<String> detect(ClassLoader classLoader) {
    List<File> classpathContents =
        classGraph
            .disableNestedJarScanning()
            .addClassLoader(classLoader)
            .scan(1)
            .getClasspathFiles();

    return classpathContents.stream().map(File::getAbsolutePath).collect(Collectors.toList());
  }
}
