package com.github.mikkoi.maven.plugins.enforcer.rule.propertyusage.configuration;
   
   import org.apache.maven.plugin.logging.Log;
   import org.codehaus.plexus.util.DirectoryScanner;
   import org.codehaus.plexus.util.StringUtils;
   
   import javax.annotation.Nonnull;
   import java.io.File;
   import java.nio.file.Path;
  import java.nio.file.Paths;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.HashSet;
  import java.util.stream.Collectors;
  
  /**
   * Handle FileSpecs.
   */
  public class FileSpecs {
  
  	private FileSpecs() {
  		// This class cannot be instantiated.
  		throw new AssertionError();
  	}
  
      public static String absoluteCwdAndFile(@Nonnull final String filename) {
          return Paths.get(System.getProperty("user.dir"), filename).toAbsolutePath().normalize().toString();
      }
  
      /**
       * Process collection of file names.
       * If file name is a file, get its absolute path.
       * If not, assume it is either a directory or a wildcard name, and
       * scan it with DirectoryScanner.
       *
       * @param files A Collection of Strings
       * @return A Collection of Strings
       */
      @Nonnull
      public static Collection<String> getAbsoluteFilenames(
              @Nonnull final Collection<String> files,
              @Nonnull final Path basedir,
              @Nonnull final Log log
              ) {
          Collection<String> allFilenames = new HashSet<>();
          if(!files.isEmpty()) {
              // We have to process away files with an absolute path because
              // DirectoryScanner can't handle them (as they may not be in basedir)
              // So we take away all files that exist.
              for (String fileSpec : files) {
              	if (StringUtils.isBlank(fileSpec)) {
                      log.error(logFileIterationMsg(fileSpec, "is blank. Error in configuration") + "!");
                      continue;
                  }
              	File file = new File(fileSpec);
                  if (file.exists() && file.isFile()) {
                      log.debug(logFileIterationMsg(fileSpec, "is a file") + ".");
                      allFilenames.add(file.getAbsolutePath()); // If item is already in Set, discarded automatically.
                  } else if (file.exists() && file.isDirectory()) {
                      log.debug(logFileIterationMsg(fileSpec, "is a directory") + ".");
                      DirectoryScanner ds = initializeDS(Paths.get(fileSpec));
                      ds.scan();
                      allFilenames.addAll(Arrays.stream(ds.getIncludedFiles()).map(includedFile -> new File(includedFile).getAbsolutePath()).collect(Collectors.toSet()));
                  } else if (file.exists()) {
                      log.error(logFileIterationMsg(fileSpec, "is not a file or directory. Do not know what to do") + "!");
                  } else {
                      log.debug(logFileIterationMsg(fileSpec, "does not exist. Assume wildcards") + ".");
                      DirectoryScanner ds = initializeDS(basedir);
                      ds.setIncludes(new String[]{fileSpec});
                      ds.scan();
                      Collection<String> foundFiles = Arrays.stream(ds.getIncludedFiles()).map(includedFile -> Paths.get(basedir.toString(), includedFile).toString()).collect(Collectors.toSet());
                      log.debug("    Found files:[");
                      for (final String foundFile : foundFiles) {
                          log.debug("        " + foundFile);
                      }
                      log.debug("    ]");
                      allFilenames.addAll(foundFiles);
                  }
              }
          }
          return allFilenames;
      }
  
      private static DirectoryScanner initializeDS(@Nonnull final Path path) {
          DirectoryScanner ds = new DirectoryScanner();
          ds.setCaseSensitive(true);
          ds.setFollowSymlinks(true);
          ds.addDefaultExcludes();
          ds.setBasedir(path.toAbsolutePath().toString());
          return ds;
      }
  
      @Nonnull
      private static String logFileIterationMsg(@Nonnull final String filename, @Nonnull final String comment) {
          return "File spec '" + filename + "' " + comment;
      }
  
  
  }