/*
    * 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.maven.plugin.surefire.util;
  
  import java.io.File;
  import java.util.Collection;
  
  import org.apache.maven.surefire.api.testset.TestFilter;
  
  import static org.apache.maven.surefire.shared.utils.StringUtils.isBlank;
  
  final class FileScanner {
      private final File basedir;
  
      private final String ext;
  
      FileScanner(File basedir, String ext) {
          this.basedir = basedir;
          ext = ext.trim();
          if (isBlank(ext)) {
              throw new IllegalArgumentException("No file extension");
          }
          this.ext = ext.startsWith(".") ? ext : "." + ext;
      }
  
      void scanTo(Collection<String> scannedJavaClassNames, TestFilter<String, String> filter) {
          scan(scannedJavaClassNames, filter, basedir);
      }
  
      private void scan(
              Collection<String> scannedJavaClassNames,
              TestFilter<String, String> filter,
              File basedir,
              String... subDirectories) {
          File[] filesAndDirs = basedir.listFiles();
          if (filesAndDirs != null) {
              final String pAckage = toJavaPackage(subDirectories);
              final String path = toPath(subDirectories);
              final String ext = this.ext;
              final boolean hasExtension = ext != null;
              final int extLength = hasExtension ? ext.length() : 0;
              for (File fileOrDir : filesAndDirs) {
                  String name = fileOrDir.getName();
                  if (!name.isEmpty()) {
                      if (fileOrDir.isFile()) {
                          final int clsLength = name.length() - extLength;
                          if (clsLength > 0
                                  && (!hasExtension || name.regionMatches(true, clsLength, ext, 0, extLength))) {
                              String simpleClassName = hasExtension ? name.substring(0, clsLength) : name;
                              if (filter.shouldRun(toFile(path, simpleClassName), null)) {
                                  String fullyQualifiedClassName =
                                          pAckage.isEmpty() ? simpleClassName : pAckage + '.' + simpleClassName;
                                  scannedJavaClassNames.add(fullyQualifiedClassName);
                              }
                          }
                      } else if (fileOrDir.isDirectory()) {
                          String[] paths = new String[subDirectories.length + 1];
                          System.arraycopy(subDirectories, 0, paths, 0, subDirectories.length);
                          paths[subDirectories.length] = name;
                          scan(scannedJavaClassNames, filter, fileOrDir, paths);
                      }
                  }
              }
          }
      }
  
      private static String toJavaPackage(String... subDirectories) {
          StringBuilder pkg = new StringBuilder();
          for (int i = 0; i < subDirectories.length; i++) {
              if (i > 0 && i < subDirectories.length) {
                  pkg.append('.');
              }
              pkg.append(subDirectories[i]);
          }
          return pkg.toString();
      }
  
      private static String toPath(String... subDirectories) {
          StringBuilder pkg = new StringBuilder();
          for (int i = 0; i < subDirectories.length; i++) {
              if (i > 0 && i < subDirectories.length) {
                  pkg.append('/');
              }
             pkg.append(subDirectories[i]);
         }
         return pkg.toString();
     }
 
     private String toFile(String path, String fileNameWithoutExtension) {
         String pathWithoutExtension = path.isEmpty() ? fileNameWithoutExtension : path + '/' + fileNameWithoutExtension;
         return pathWithoutExtension + ext;
     }
 }