content: /*
   This file is part of Airsonic.
  
   Airsonic is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
  
   Airsonic is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
  
   You should have received a copy of the GNU General Public License
   along with Airsonic.  If not, see <http://www.gnu.org/licenses/>.
  
   Copyright 2016 (C) Airsonic Authors
   Based upon Subsonic, Copyright 2009 (C) Sindre Mehus
   */
  package org.airsonic.player.service;
  
  import org.airsonic.player.domain.*;
  import org.airsonic.player.domain.MusicIndex.SortableArtist;
  import org.airsonic.player.util.FileUtil;
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.stereotype.Service;
  
  import java.io.File;
  import java.io.Serializable;
  import java.text.Collator;
  import java.util.*;
  
  /**
   * Provides services for grouping artists by index.
   *
   * @author Sindre Mehus
   */
  @Service
  public class MusicIndexService {
  
      @Autowired
      private SettingsService settingsService;
      @Autowired
      private MediaFileService mediaFileService;
  
      /**
       * Returns a map from music indexes to sorted lists of artists that are direct children of the given music folders.
       *
       * @param folders The music folders.
       * @param refresh Whether to look for updates by checking the last-modified timestamp of the music folders.
       * @return A map from music indexes to sets of artists that are direct children of this music file.
       */
      public SortedMap<MusicIndex, List<MusicIndex.SortableArtistWithMediaFiles>> getIndexedArtists(List<MusicFolder> folders, boolean refresh) {
          List<MusicIndex.SortableArtistWithMediaFiles> artists = createSortableArtists(folders, refresh);
          return sortArtists(artists);
      }
  
      public SortedMap<MusicIndex, List<MusicIndex.SortableArtistWithArtist>> getIndexedArtists(List<Artist> artists) {
          List<MusicIndex.SortableArtistWithArtist> sortableArtists = createSortableArtists(artists);
          return sortArtists(sortableArtists);
      }
  
      public MusicFolderContent getMusicFolderContent(List<MusicFolder> musicFoldersToUse, boolean refresh) {
          SortedMap<MusicIndex, List<MusicIndex.SortableArtistWithMediaFiles>> indexedArtists = getIndexedArtists(musicFoldersToUse, refresh);
          List<MediaFile> singleSongs = getSingleSongs(musicFoldersToUse, refresh);
          return new MusicFolderContent(indexedArtists, singleSongs);
      }
  
      private List<MediaFile> getSingleSongs(List<MusicFolder> folders, boolean refresh) {
          List<MediaFile> result = new ArrayList<MediaFile>();
          for (MusicFolder folder : folders) {
              MediaFile parent = mediaFileService.getMediaFile(folder.getPath(), !refresh);
              result.addAll(mediaFileService.getChildrenOf(parent, true, false, true, !refresh));
          }
          return result;
      }
  
      public List<MediaFile> getShortcuts(List<MusicFolder> musicFoldersToUse) {
          List<MediaFile> result = new ArrayList<MediaFile>();
          for (String shortcut : settingsService.getShortcutsAsArray()) {
              for (MusicFolder musicFolder : musicFoldersToUse) {
                  File file = new File(musicFolder.getPath(), shortcut);
                  if (FileUtil.exists(file)) {
                      result.add(mediaFileService.getMediaFile(file, true));
                  }
              }
          }
          return result;
      }
  
      private <T extends SortableArtist> SortedMap<MusicIndex, List<T>> sortArtists(List<T> artists) {
          List<MusicIndex> indexes = createIndexesFromExpression(settingsService.getIndexString());
          Comparator<MusicIndex> indexComparator = new MusicIndexComparator(indexes);
  
          SortedMap<MusicIndex, List<T>> result = new TreeMap<MusicIndex, List<T>>(indexComparator);
  
          for (T artist : artists) {
              MusicIndex index = getIndex(artist, indexes);
              List<T> artistSet = result.computeIfAbsent(index, k -> new ArrayList<T>());
              artistSet.add(artist);
          }
  
          for (List<T> artistList : result.values()) {
              Collections.sort(artistList);
          }
  
          return result;
      }
  
      /**
       * Creates a new instance by parsing the given expression.  The expression consists of an index name, followed by
       * an optional list of one-character prefixes. For example:<p/>
       * <p/>
       * The expression <em>"A"</em> will create the index <em>"A" -&gt; ["A"]</em><br/>
       * The expression <em>"The"</em> will create the index <em>"The" -&gt; ["The"]</em><br/>
       * The expression <em>"A(A&Aring;&AElig;)"</em> will create the index <em>"A" -&gt; ["A", "&Aring;", "&AElig;"]</em><br/>
       * The expression <em>"X-Z(XYZ)"</em> will create the index <em>"X-Z" -&gt; ["X", "Y", "Z"]</em>
       *
       * @param expr The expression to parse.
       * @return A new instance.
       */
      protected MusicIndex createIndexFromExpression(String expr) {
          int separatorIndex = expr.indexOf('(');
          if (separatorIndex == -1) {
  
              MusicIndex index = new MusicIndex(expr);
              index.addPrefix(expr);
              return index;
          }
  
          MusicIndex index = new MusicIndex(expr.substring(0, separatorIndex));
          String prefixString = expr.substring(separatorIndex + 1, expr.length() - 1);
          for (int i = 0; i < prefixString.length(); i++) {
              index.addPrefix(prefixString.substring(i, i + 1));
          }
          return index;
      }
  
      /**
       * Creates a list of music indexes by parsing the given expression.  The expression is a space-separated list of
       * sub-expressions, for which the rules described in {@link #createIndexFromExpression} apply.
       *
       * @param expr The expression to parse.
       * @return A list of music indexes.
       */
      protected List<MusicIndex> createIndexesFromExpression(String expr) {
          List<MusicIndex> result = new ArrayList<MusicIndex>();
  
          StringTokenizer tokenizer = new StringTokenizer(expr, " ");
          while (tokenizer.hasMoreTokens()) {
              MusicIndex index = createIndexFromExpression(tokenizer.nextToken());
              result.add(index);
          }
  
          return result;
      }
  
      private List<MusicIndex.SortableArtistWithMediaFiles> createSortableArtists(List<MusicFolder> folders, boolean refresh) {
          String[] ignoredArticles = settingsService.getIgnoredArticlesAsArray();
          String[] shortcuts = settingsService.getShortcutsAsArray();
          SortedMap<String, MusicIndex.SortableArtistWithMediaFiles> artistMap = new TreeMap<String, MusicIndex.SortableArtistWithMediaFiles>();
          Set<String> shortcutSet = new HashSet<String>(Arrays.asList(shortcuts));
          Collator collator = createCollator();
  
          for (MusicFolder folder : folders) {
  
              MediaFile root = mediaFileService.getMediaFile(folder.getPath(), !refresh);
              List<MediaFile> children = mediaFileService.getChildrenOf(root, false, true, true, !refresh);
              for (MediaFile child : children) {
                  if (shortcutSet.contains(child.getName())) {
                      continue;
                  }
  
                  String sortableName = createSortableName(child.getName(), ignoredArticles);
                  MusicIndex.SortableArtistWithMediaFiles artist = artistMap.get(sortableName);
                  if (artist == null) {
                      artist = new MusicIndex.SortableArtistWithMediaFiles(child.getName(), sortableName, collator);
                      artistMap.put(sortableName, artist);
                  }
                  artist.addMediaFile(child);
              }
          }
  
          return new ArrayList<MusicIndex.SortableArtistWithMediaFiles>(artistMap.values());
      }
  
      private List<MusicIndex.SortableArtistWithArtist> createSortableArtists(List<Artist> artists) {
          List<MusicIndex.SortableArtistWithArtist> result = new ArrayList<MusicIndex.SortableArtistWithArtist>();
          String[] ignoredArticles = settingsService.getIgnoredArticlesAsArray();
          Collator collator = createCollator();
          for (Artist artist : artists) {
              String sortableName = createSortableName(artist.getName(), ignoredArticles);
              result.add(new MusicIndex.SortableArtistWithArtist(artist.getName(), sortableName, artist, collator));
          }
  
          return result;
      }
  
      /**
       * Returns a collator to be used when sorting artists.
       */
      private Collator createCollator() {
          return Collator.getInstance(settingsService.getLocale());
      }
  
      private String createSortableName(String name, String[] ignoredArticles) {
          String uppercaseName = name.toUpperCase();
          for (String article : ignoredArticles) {
              if (uppercaseName.startsWith(article.toUpperCase() + " ")) {
                  return name.substring(article.length() + 1) + ", " + article;
              }
          }
          return name;
      }
  
      /**
       * Returns the music index to which the given artist belongs.
       *
       * @param artist  The artist in question.
       * @param indexes List of available indexes.
       * @return The music index to which this music file belongs, or {@link MusicIndex#OTHER} if no index applies.
       */
      private MusicIndex getIndex(SortableArtist artist, List<MusicIndex> indexes) {
          String sortableName = artist.getSortableName().toUpperCase();
          for (MusicIndex index : indexes) {
              for (String prefix : index.getPrefixes()) {
                  if (sortableName.startsWith(prefix.toUpperCase())) {
                      return index;
                  }
              }
          }
          return MusicIndex.OTHER;
      }
  
      public void setSettingsService(SettingsService settingsService) {
          this.settingsService = settingsService;
      }
  
      public void setMediaFileService(MediaFileService mediaFileService) {
          this.mediaFileService = mediaFileService;
      }
  
      private static class MusicIndexComparator implements Comparator<MusicIndex>, Serializable {
  
          private List<MusicIndex> indexes;
  
          public MusicIndexComparator(List<MusicIndex> indexes) {
              this.indexes = indexes;
          }
  
          public int compare(MusicIndex a, MusicIndex b) {
              int indexA = indexes.indexOf(a);
              int indexB = indexes.indexOf(b);
  
              if (indexA == -1) {
                  indexA = Integer.MAX_VALUE;
              }
              if (indexB == -1) {
                  indexB = Integer.MAX_VALUE;
              }
  
              return Integer.compare(indexA, indexB);
          }
      }
  }