/*
 * Strawberry Music Player
 * This file was part of Clementine.
 * Copyright 2010, David Sansome <me@davidsansome.com>
 *
 * Strawberry 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.
 *
 * Strawberry 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 Strawberry.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "config.h"

#include <QtGlobal>
#include <QObject>
#include <QMutex>
#include <QSet>
#include <QMap>
#include <QByteArray>
#include <QFileInfo>
#include <QDateTime>
#include <QVariant>
#include <QString>
#include <QStringList>
#include <QUrl>
#include <QSqlDatabase>
#include <QSqlQuery>
#include <QtDebug>

#include "core/application.h"
#include "core/database.h"
#include "core/logging.h"
#include "core/scopedtransaction.h"
#include "core/utilities.h"

#include "directory.h"
#include "collectionbackend.h"
#include "collectionquery.h"
#include "sqlrow.h"

const char *CollectionBackend::kSettingsGroup = "Collection";

CollectionBackend::CollectionBackend(QObject *parent) :
    CollectionBackendInterface(parent),
    db_(nullptr) {}

void CollectionBackend::Init(Database *db, const Song::Source source, const QString &songs_table, const QString &dirs_table, const QString &subdirs_table, const QString &fts_table) {
  db_ = db;
  source_ = source;
  songs_table_ = songs_table;
  dirs_table_ = dirs_table;
  subdirs_table_ = subdirs_table;
  fts_table_ = fts_table;
}

void CollectionBackend::LoadDirectoriesAsync() {
  metaObject()->invokeMethod(this, "LoadDirectories", Qt::QueuedConnection);
}

void CollectionBackend::UpdateTotalSongCountAsync() {
  metaObject()->invokeMethod(this, "UpdateTotalSongCount", Qt::QueuedConnection);
}

void CollectionBackend::UpdateTotalArtistCountAsync() {
  metaObject()->invokeMethod(this, "UpdateTotalArtistCount", Qt::QueuedConnection);
}

void CollectionBackend::UpdateTotalAlbumCountAsync() {
  metaObject()->invokeMethod(this, "UpdateTotalAlbumCount", Qt::QueuedConnection);
}

void CollectionBackend::IncrementPlayCountAsync(int id) {
  metaObject()->invokeMethod(this, "IncrementPlayCount", Qt::QueuedConnection, Q_ARG(int, id));
}

void CollectionBackend::IncrementSkipCountAsync(int id, float progress) {
  metaObject()->invokeMethod(this, "IncrementSkipCount", Qt::QueuedConnection, Q_ARG(int, id), Q_ARG(float, progress));
}

void CollectionBackend::ResetStatisticsAsync(int id) {
  metaObject()->invokeMethod(this, "ResetStatistics", Qt::QueuedConnection, Q_ARG(int, id));
}

void CollectionBackend::LoadDirectories() {

  DirectoryList dirs = GetAllDirectories();

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  for (const Directory &dir : dirs) {
    emit DirectoryDiscovered(dir, SubdirsInDirectory(dir.id, db));
  }

}

void CollectionBackend::ChangeDirPath(int id, const QString &old_path, const QString &new_path) {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());
  ScopedTransaction t(&db);

  // Do the dirs table
  {
    QSqlQuery q(db);
    q.prepare(QString("UPDATE %1 SET path=:path WHERE ROWID=:id").arg(dirs_table_));
    q.bindValue(":path", new_path);
    q.bindValue(":id", id);
    q.exec();
    if (db_->CheckErrors(q)) return;
  }

  const QByteArray old_url = QUrl::fromLocalFile(old_path).toEncoded();
  const QByteArray new_url = QUrl::fromLocalFile(new_path).toEncoded();

  const int path_len = old_url.length();

  // Do the subdirs table
  {
    QSqlQuery q(db);
    q.prepare(QString("UPDATE %1 SET path=:path || substr(path, %2) WHERE directory=:id").arg(subdirs_table_).arg(path_len));
    q.bindValue(":path", new_url);
    q.bindValue(":id", id);
    q.exec();
    if (db_->CheckErrors(q)) return;
  }

  // Do the songs table
  {
    QSqlQuery q(db);
    q.prepare(QString("UPDATE %1 SET url=:path || substr(url, %2) WHERE directory=:id").arg(songs_table_).arg(path_len));
    q.bindValue(":path", new_url);
    q.bindValue(":id", id);
    q.exec();
    if (db_->CheckErrors(q)) return;
  }

  t.Commit();

}

DirectoryList CollectionBackend::GetAllDirectories() {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  DirectoryList ret;

  QSqlQuery q(db);
  q.prepare(QString("SELECT ROWID, path FROM %1").arg(dirs_table_));
  q.exec();
  if (db_->CheckErrors(q)) return ret;

  while (q.next()) {
    Directory dir;
    dir.id = q.value(0).toInt();
    dir.path = q.value(1).toString();

    ret << dir;
  }
  return ret;

}

SubdirectoryList CollectionBackend::SubdirsInDirectory(int id) {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db = db_->Connect();
  return SubdirsInDirectory(id, db);

}

SubdirectoryList CollectionBackend::SubdirsInDirectory(int id, QSqlDatabase &db) {

  QSqlQuery q(db);
  q.prepare(QString("SELECT path, mtime FROM %1 WHERE directory_id = :dir").arg(subdirs_table_));
  q.bindValue(":dir", id);
  q.exec();
  if (db_->CheckErrors(q)) return SubdirectoryList();

  SubdirectoryList subdirs;
  while (q.next()) {
    Subdirectory subdir;
    subdir.directory_id = id;
    subdir.path = q.value(0).toString();
    subdir.mtime = q.value(1).toUInt();
    subdirs << subdir;
  }

  return subdirs;

}

void CollectionBackend::UpdateTotalSongCount() {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QSqlQuery q(db);
  q.prepare(QString("SELECT COUNT(*) FROM %1 WHERE unavailable = 0").arg(songs_table_));
  q.exec();
  if (db_->CheckErrors(q)) return;
  if (!q.next()) return;

  emit TotalSongCountUpdated(q.value(0).toInt());

}

void CollectionBackend::UpdateTotalArtistCount() {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QSqlQuery q(db);
  q.prepare(QString("select COUNT(distinct artist) from %1 WHERE unavailable = 0").arg(songs_table_));
  q.exec();
  if (db_->CheckErrors(q)) return;
  if (!q.next()) return;

  emit TotalArtistCountUpdated(q.value(0).toInt());

}

void CollectionBackend::UpdateTotalAlbumCount() {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QSqlQuery q(db);
  q.prepare(QString("select COUNT(distinct album) from %1 WHERE unavailable = 0").arg(songs_table_));
  q.exec();
  if (db_->CheckErrors(q)) return;
  if (!q.next()) return;

  emit TotalAlbumCountUpdated(q.value(0).toInt());

}

void CollectionBackend::AddDirectory(const QString &path) {

  QString canonical_path = QFileInfo(path).canonicalFilePath();
  QString db_path = canonical_path;

  if (Application::kIsPortable && Utilities::UrlOnSameDriveAsStrawberry(QUrl::fromLocalFile(canonical_path))) {

    db_path = Utilities::GetRelativePathToStrawberryBin(QUrl::fromLocalFile(db_path)).toLocalFile();
    qLog(Debug) << "db_path" << db_path;
  }

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QSqlQuery q(db);
  q.prepare(QString("INSERT INTO %1 (path, subdirs) VALUES (:path, 1)").arg(dirs_table_));
  q.bindValue(":path", db_path);
  q.exec();
  if (db_->CheckErrors(q)) return;

  Directory dir;
  dir.path = canonical_path;
  dir.id = q.lastInsertId().toInt();

  emit DirectoryDiscovered(dir, SubdirectoryList());

}

void CollectionBackend::RemoveDirectory(const Directory &dir) {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  // Remove songs first
  DeleteSongs(FindSongsInDirectory(dir.id));

  ScopedTransaction transaction(&db);

  // Delete the subdirs that were in this directory
  QSqlQuery q(db);
  q.prepare(QString("DELETE FROM %1 WHERE directory_id = :id").arg(subdirs_table_));
  q.bindValue(":id", dir.id);
  q.exec();
  if (db_->CheckErrors(q)) return;

  // Now remove the directory itself
  q = QSqlQuery(db);
  q.prepare(QString("DELETE FROM %1 WHERE ROWID = :id").arg(dirs_table_));
  q.bindValue(":id", dir.id);
  q.exec();
  if (db_->CheckErrors(q)) return;

  emit DirectoryDeleted(dir);

  transaction.Commit();

}

SongList CollectionBackend::FindSongsInDirectory(int id) {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QSqlQuery q(db);
  q.prepare(QString("SELECT ROWID, " + Song::kColumnSpec + " FROM %1 WHERE directory_id = :directory_id").arg(songs_table_));
  q.bindValue(":directory_id", id);
  q.exec();
  if (db_->CheckErrors(q)) return SongList();

  SongList ret;
  while (q.next()) {
    Song song;
    song.InitFromQuery(q, true);
    ret << song;
  }
  return ret;

}

void CollectionBackend::SongPathChanged(const Song &song, const QFileInfo &new_file) {

  // Take a song and update its path
  Song updated_song = song;
  updated_song.InitFromFilePartial(new_file.absoluteFilePath());
  updated_song.set_source(source_);
  SongList updated_songs;
  updated_songs << updated_song;
  AddOrUpdateSongs(updated_songs);

}

void CollectionBackend::AddOrUpdateSubdirs(const SubdirectoryList &subdirs) {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());
  QSqlQuery find_query(db);
  find_query.prepare(QString("SELECT ROWID FROM %1 WHERE directory_id = :id AND path = :path").arg(subdirs_table_));
  QSqlQuery add_query(db);
  add_query.prepare(QString("INSERT INTO %1 (directory_id, path, mtime) VALUES (:id, :path, :mtime)").arg(subdirs_table_));
  QSqlQuery update_query(db);
  update_query.prepare(QString("UPDATE %1 SET mtime = :mtime WHERE directory_id = :id AND path = :path").arg(subdirs_table_));
  QSqlQuery delete_query(db);
  delete_query.prepare(QString("DELETE FROM %1 WHERE directory_id = :id AND path = :path").arg(subdirs_table_));

  ScopedTransaction transaction(&db);
  for (const Subdirectory &subdir : subdirs) {
    if (subdir.mtime == 0) {
      // Delete the subdirectory
      delete_query.bindValue(":id", subdir.directory_id);
      delete_query.bindValue(":path", subdir.path);
      delete_query.exec();
      db_->CheckErrors(delete_query);
    }
    else {
      // See if this subdirectory already exists in the database
      find_query.bindValue(":id", subdir.directory_id);
      find_query.bindValue(":path", subdir.path);
      find_query.exec();
      if (db_->CheckErrors(find_query)) continue;

      if (find_query.next()) {
        update_query.bindValue(":mtime", subdir.mtime);
        update_query.bindValue(":id", subdir.directory_id);
        update_query.bindValue(":path", subdir.path);
        update_query.exec();
        db_->CheckErrors(update_query);
      }
      else {
        add_query.bindValue(":id", subdir.directory_id);
        add_query.bindValue(":path", subdir.path);
        add_query.bindValue(":mtime", subdir.mtime);
        add_query.exec();
        db_->CheckErrors(add_query);
      }
    }
  }
  transaction.Commit();

}

void CollectionBackend::AddOrUpdateSongs(const SongList &songs) {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QSqlQuery check_dir(db);
  check_dir.prepare(QString("SELECT ROWID FROM %1 WHERE ROWID = :id").arg(dirs_table_));
  QSqlQuery add_song(db);
  add_song.prepare(QString("INSERT INTO %1 (" + Song::kColumnSpec + ") VALUES (" + Song::kBindSpec + ")").arg(songs_table_));
  QSqlQuery update_song(db);
  update_song.prepare(QString("UPDATE %1 SET " + Song::kUpdateSpec + " WHERE ROWID = :id").arg(songs_table_));
  QSqlQuery add_song_fts(db);
  add_song_fts.prepare(QString("INSERT INTO %1 (ROWID, " + Song::kFtsColumnSpec + ") VALUES (:id, " + Song::kFtsBindSpec + ")").arg(fts_table_));
  QSqlQuery update_song_fts(db);
  update_song_fts.prepare(QString("UPDATE %1 SET " + Song::kFtsUpdateSpec + " WHERE ROWID = :id").arg(fts_table_));

  ScopedTransaction transaction(&db);

  SongList added_songs;
  SongList deleted_songs;

  for (const Song &song : songs) {

    // Do a sanity check first - make sure the song's directory still exists
    // This is to fix a possible race condition when a directory is removed while CollectionWatcher is scanning it.
    if (!dirs_table_.isEmpty()) {
      check_dir.bindValue(":id", song.directory_id());
      check_dir.exec();
      if (db_->CheckErrors(check_dir)) continue;

      if (!check_dir.next()) continue;  // Directory didn't exist
    }

    if (song.id() != -1) {  // This song exists in the DB.

      // Get the previous song data first
      Song old_song(GetSongById(song.id()));
      if (!old_song.is_valid()) continue;

      // Update
      song.BindToQuery(&update_song);
      update_song.bindValue(":id", song.id());
      update_song.exec();
      if (db_->CheckErrors(update_song)) continue;

      song.BindToFtsQuery(&update_song_fts);
      update_song_fts.bindValue(":id", song.id());
      update_song_fts.exec();
      if (db_->CheckErrors(update_song_fts)) continue;

      deleted_songs << old_song;
      added_songs << song;

      continue;

    }
    else if (song.song_id() != -1) {  // Song has a unique id, check if the song exists.

      // Get the previous song data first
      Song old_song(GetSongBySongId(song.song_id()));

      if (old_song.is_valid() && old_song.id() != -1) {

        Song new_song = song;
        new_song.set_id(old_song.id());
        // Update
        new_song.BindToQuery(&update_song);
        update_song.bindValue(":id", new_song.id());
        update_song.exec();
        if (db_->CheckErrors(update_song)) continue;

        new_song.BindToFtsQuery(&update_song_fts);
        update_song_fts.bindValue(":id", new_song.id());
        update_song_fts.exec();
        if (db_->CheckErrors(update_song_fts)) continue;

        deleted_songs << old_song;
        added_songs << new_song;

        continue;

      }

    }

    // Create new song

    // Insert the row and create a new ID
    song.BindToQuery(&add_song);
    add_song.exec();
    if (db_->CheckErrors(add_song)) continue;

    // Get the new ID
    const int id = add_song.lastInsertId().toInt();

    // Add to the FTS index
    add_song_fts.bindValue(":id", id);
    song.BindToFtsQuery(&add_song_fts);
    add_song_fts.exec();
    if (db_->CheckErrors(add_song_fts)) continue;

    Song copy(song);
    copy.set_id(id);
    added_songs << copy;

  }

  transaction.Commit();

  if (!deleted_songs.isEmpty()) emit SongsDeleted(deleted_songs);

  if (!added_songs.isEmpty()) emit SongsDiscovered(added_songs);

  UpdateTotalSongCountAsync();
  UpdateTotalArtistCountAsync();
  UpdateTotalAlbumCountAsync();

}

void CollectionBackend::UpdateMTimesOnly(const SongList &songs) {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QSqlQuery q(db);
  q.prepare(QString("UPDATE %1 SET mtime = :mtime WHERE ROWID = :id").arg(songs_table_));

  ScopedTransaction transaction(&db);
  for (const Song &song : songs) {
    q.bindValue(":mtime", song.mtime());
    q.bindValue(":id", song.id());
    q.exec();
    db_->CheckErrors(q);
  }
  transaction.Commit();

}

void CollectionBackend::DeleteSongs(const SongList &songs) {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QSqlQuery remove(db);
  remove.prepare(QString("DELETE FROM %1 WHERE ROWID = :id").arg(songs_table_));
  QSqlQuery remove_fts(db);
  remove_fts.prepare(QString("DELETE FROM %1 WHERE ROWID = :id").arg(fts_table_));

  ScopedTransaction transaction(&db);
  for (const Song &song : songs) {
    remove.bindValue(":id", song.id());
    remove.exec();
    db_->CheckErrors(remove);

    remove_fts.bindValue(":id", song.id());
    remove_fts.exec();
    db_->CheckErrors(remove_fts);
  }
  transaction.Commit();

  emit SongsDeleted(songs);

  UpdateTotalSongCountAsync();
  UpdateTotalArtistCountAsync();
  UpdateTotalAlbumCountAsync();

}

void CollectionBackend::MarkSongsUnavailable(const SongList &songs, bool unavailable) {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QSqlQuery remove(db);
  remove.prepare(QString("UPDATE %1 SET unavailable = %2 WHERE ROWID = :id").arg(songs_table_).arg(int(unavailable)));

  ScopedTransaction transaction(&db);
  for (const Song &song : songs) {
    remove.bindValue(":id", song.id());
    remove.exec();
    db_->CheckErrors(remove);
  }
  transaction.Commit();

  emit SongsDeleted(songs);
  UpdateTotalSongCountAsync();
  UpdateTotalArtistCountAsync();
  UpdateTotalAlbumCountAsync();

}

QStringList CollectionBackend::GetAll(const QString &column, const QueryOptions &opt) {

  CollectionQuery query(opt);
  query.SetColumnSpec("DISTINCT " + column);
  query.AddCompilationRequirement(false);

  QMutexLocker l(db_->Mutex());
  if (!ExecQuery(&query)) return QStringList();

  QStringList ret;
  while (query.Next()) {
    ret << query.Value(0).toString();
  }
  return ret;

}

QStringList CollectionBackend::GetAllArtists(const QueryOptions &opt) {

  return GetAll("artist", opt);
}

QStringList CollectionBackend::GetAllArtistsWithAlbums(const QueryOptions &opt) {

  // Albums with 'albumartist' field set:
  CollectionQuery query(opt);
  query.SetColumnSpec("DISTINCT albumartist");
  query.AddCompilationRequirement(false);
  query.AddWhere("album", "", "!=");

  // Albums with no 'albumartist' (extract 'artist'):
  CollectionQuery query2(opt);
  query2.SetColumnSpec("DISTINCT artist");
  query2.AddCompilationRequirement(false);
  query2.AddWhere("album", "", "!=");
  query2.AddWhere("albumartist", "", "=");

  {
    QMutexLocker l(db_->Mutex());
    if (!ExecQuery(&query) || !ExecQuery(&query2)) {
      return QStringList();
    }
  }

  QSet<QString> artists;
  while (query.Next()) {
    artists << query.Value(0).toString();
  }

  while (query2.Next()) {
    artists << query2.Value(0).toString();
  }

  return QStringList(artists.toList());

}

CollectionBackend::AlbumList CollectionBackend::GetAllAlbums(const QueryOptions &opt) {
  return GetAlbums(QString(), false, opt);
}

CollectionBackend::AlbumList CollectionBackend::GetAlbumsByArtist(const QString &artist, const QueryOptions &opt) {
  return GetAlbums(artist, false, opt);
}

SongList CollectionBackend::GetSongsByAlbum(const QString &album, const QueryOptions &opt) {
  CollectionQuery query(opt);
  query.AddCompilationRequirement(false);
  query.AddWhere("album", album);
  return ExecCollectionQuery(&query);
}

SongList CollectionBackend::GetSongs(const QString &artist, const QString &album, const QueryOptions &opt) {
  CollectionQuery query(opt);
  query.AddCompilationRequirement(false);
  query.AddWhere("artist", artist);
  query.AddWhere("album", album);
  return ExecCollectionQuery(&query);
}

SongList CollectionBackend::ExecCollectionQuery(CollectionQuery *query) {

  query->SetColumnSpec("%songs_table.ROWID, " + Song::kColumnSpec);
  QMutexLocker l(db_->Mutex());
  if (!ExecQuery(query)) return SongList();

  SongList ret;
  while (query->Next()) {
    Song song;
    song.InitFromQuery(*query, true);
    ret << song;
  }
  return ret;

}

Song CollectionBackend::GetSongById(int id) {
  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());
  return GetSongById(id, db);
}

SongList CollectionBackend::GetSongsById(const QList<int> &ids) {
  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QStringList str_ids;
  for (int id : ids) {
    str_ids << QString::number(id);
  }

  return GetSongsById(str_ids, db);
}

SongList CollectionBackend::GetSongsById(const QStringList &ids) {
  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  return GetSongsById(ids, db);
}

SongList CollectionBackend::GetSongsByForeignId(const QStringList &ids, const QString &table, const QString &column) {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QString in = ids.join(",");

  QSqlQuery q(db);
  q.prepare(QString("SELECT %2.ROWID, " + Song::kColumnSpec + ", %2.%3 FROM %2, %1 WHERE %2.%3 IN (%4) AND %1.ROWID = %2.ROWID AND unavailable = 0").arg(songs_table_, table, column, in));
  q.exec();
  if (db_->CheckErrors(q)) return SongList();

  QVector<Song> ret(ids.count());
  while (q.next()) {
    const QString foreign_id = q.value(Song::kColumns.count() + 1).toString();
    const int index = ids.indexOf(foreign_id);
    if (index == -1) continue;

    ret[index].InitFromQuery(q, true);
  }
  return ret.toList();

}

Song CollectionBackend::GetSongById(int id, QSqlDatabase &db) {
  SongList list = GetSongsById(QStringList() << QString::number(id), db);
  if (list.isEmpty()) return Song();
  return list.first();
}

SongList CollectionBackend::GetSongsById(const QStringList &ids, QSqlDatabase &db) {

  QString in = ids.join(",");

  QSqlQuery q(db);
  q.prepare(QString("SELECT ROWID, " + Song::kColumnSpec + " FROM %1 WHERE ROWID IN (%2)").arg(songs_table_, in));
  q.exec();
  if (db_->CheckErrors(q)) return SongList();

  SongList ret;
  while (q.next()) {
    Song song;
    song.InitFromQuery(q, true);
    ret << song;
  }
  return ret;

}

Song CollectionBackend::GetSongByUrl(const QUrl &url, qint64 beginning) {

  CollectionQuery query;
  query.SetColumnSpec("%songs_table.ROWID, " + Song::kColumnSpec);
  query.AddWhere("url", url.toString());
  query.AddWhere("beginning", beginning);

  Song song;
  if (ExecQuery(&query) && query.Next()) {
    song.InitFromQuery(query, true);
  }
  return song;

}

SongList CollectionBackend::GetSongsByUrl(const QUrl &url) {

  CollectionQuery query;
  query.SetColumnSpec("%songs_table.ROWID, " + Song::kColumnSpec);
  query.AddWhere("url", url.toString());

  SongList songlist;
  if (ExecQuery(&query)) {
    while (query.Next()) {
      Song song;
      song.InitFromQuery(query, true);
      songlist << song;
    }
  }
  return songlist;

}


Song CollectionBackend::GetSongBySongId(int song_id) {
  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());
  return GetSongBySongId(song_id, db);
}

SongList CollectionBackend::GetSongsBySongId(const QList<int> &song_ids) {
  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QStringList str_song_ids;
  for (int song_id : song_ids) {
    str_song_ids << QString::number(song_id);
  }

  return GetSongsBySongId(str_song_ids, db);
}

SongList CollectionBackend::GetSongsBySongId(const QStringList &song_ids) {
  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  return GetSongsBySongId(song_ids, db);
}

Song CollectionBackend::GetSongBySongId(int song_id, QSqlDatabase &db) {
  SongList list = GetSongsBySongId(QStringList() << QString::number(song_id), db);
  if (list.isEmpty()) return Song();
  return list.first();
}

SongList CollectionBackend::GetSongsBySongId(const QStringList &song_ids, QSqlDatabase &db) {

  QString in = song_ids.join(",");

  QSqlQuery q(db);
  q.prepare(QString("SELECT ROWID, " + Song::kColumnSpec + " FROM %1 WHERE SONG_ID IN (%2)").arg(songs_table_, in));
  q.exec();
  if (db_->CheckErrors(q)) return SongList();

  SongList ret;
  while (q.next()) {
    Song song;
    song.InitFromQuery(q, true);
    ret << song;
  }
  return ret;

}

CollectionBackend::AlbumList CollectionBackend::GetCompilationAlbums(const QueryOptions &opt) {
  return GetAlbums(QString(), true, opt);
}

SongList CollectionBackend::GetCompilationSongs(const QString &album, const QueryOptions &opt) {

  CollectionQuery query(opt);
  query.SetColumnSpec("%songs_table.ROWID, " + Song::kColumnSpec);
  query.AddCompilationRequirement(true);
  query.AddWhere("album", album);

  QMutexLocker l(db_->Mutex());
  if (!ExecQuery(&query)) return SongList();

  SongList ret;
  while (query.Next()) {
    Song song;
    song.InitFromQuery(query, true);
    ret << song;
  }
  return ret;

}

void CollectionBackend::UpdateCompilations() {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  // Look for albums that have songs by more than one 'effective album artist' in the same directory

  QSqlQuery q(db);
  q.prepare(QString("SELECT effective_albumartist, album, url, compilation_detected FROM %1 WHERE unavailable = 0 ORDER BY album").arg(songs_table_));
  q.exec();
  if (db_->CheckErrors(q)) return;

  QMap<QString, CompilationInfo> compilation_info;
  while (q.next()) {
    QString artist = q.value(0).toString();
    QString album = q.value(1).toString();
    QString filename = q.value(2).toString();
    bool compilation_detected = q.value(3).toBool();

    // Ignore songs that don't have an album field set
    if (album.isEmpty()) continue;

    // Find the directory the song is in
    int last_separator = filename.lastIndexOf('/');
    if (last_separator == -1) continue;

    CompilationInfo &info = compilation_info[album];
    info.artists.insert(artist);
    info.directories.insert(filename.left(last_separator));
    if (compilation_detected) info.has_compilation_detected = true;
    else info.has_not_compilation_detected = true;
  }

  // Now mark the songs that we think are in compilations
  QSqlQuery update(db);
  update.prepare(QString("UPDATE %1 SET compilation_detected = :compilation_detected, compilation_effective = ((compilation OR :compilation_detected OR compilation_on) AND NOT compilation_off) + 0 WHERE album = :album AND unavailable = 0").arg(songs_table_));
  QSqlQuery find_songs(db);
  find_songs.prepare(QString("SELECT ROWID, " + Song::kColumnSpec + " FROM %1 WHERE album = :album AND compilation_detected = :compilation_detected AND unavailable = 0").arg(songs_table_));

  SongList deleted_songs;
  SongList added_songs;

  ScopedTransaction transaction(&db);

  QMap<QString, CompilationInfo>::const_iterator it = compilation_info.constBegin();
  for (; it != compilation_info.constEnd(); ++it) {
    const CompilationInfo &info = it.value();
    QString album(it.key());

    // If there were more 'effective album artists' than there were directories for this album then it's a compilation.

    if (info.artists.count() > info.directories.count()) {
      if (info.has_not_compilation_detected)
        UpdateCompilations(find_songs, update, deleted_songs, added_songs, album, 1);
    }
    else {
      if (info.has_compilation_detected)
        UpdateCompilations(find_songs, update, deleted_songs, added_songs, album, 0);
    }
  }

  transaction.Commit();

  if (!deleted_songs.isEmpty()) {
    emit SongsDeleted(deleted_songs);
    emit SongsDiscovered(added_songs);
  }
}

void CollectionBackend::UpdateCompilations(QSqlQuery &find_songs, QSqlQuery &update, SongList &deleted_songs, SongList &added_songs, const QString &album, int compilation_detected) {

  // Get songs that were already in that album, so we can tell the model they've been updated
  find_songs.bindValue(":album", album);
  find_songs.bindValue(":compilation_detected", int(!compilation_detected));
  find_songs.exec();
  while (find_songs.next()) {
    Song song;
    song.InitFromQuery(find_songs, true);
    deleted_songs << song;
    song.set_compilation_detected(true);
    added_songs << song;
  }

  // Mark this album
  update.bindValue(":compilation_detected", compilation_detected);
  update.bindValue(":album", album);
  update.exec();
  db_->CheckErrors(update);

}

CollectionBackend::AlbumList CollectionBackend::GetAlbums(const QString &artist, bool compilation, const QueryOptions &opt) {

  AlbumList ret;

  CollectionQuery query(opt);
  query.SetColumnSpec("album, artist, albumartist, compilation, compilation_detected, art_automatic, art_manual, url");
  query.SetOrderBy("album");

  if (compilation) {
    query.AddCompilationRequirement(true);
  }
  else if (!artist.isEmpty()) {
    query.AddCompilationRequirement(false);
    query.AddWhereArtist(artist);
  }

  {
    QMutexLocker l(db_->Mutex());
    if (!ExecQuery(&query)) return ret;
  }

  QString last_album;
  QString last_artist;
  QString last_album_artist;
  while (query.Next()) {
    bool compilation = query.Value(3).toBool() | query.Value(4).toBool();

    Album info;
    info.artist = compilation ? QString() : query.Value(1).toString();
    info.album_artist = compilation ? QString() : query.Value(2).toString();
    info.album_name = query.Value(0).toString();
    info.art_automatic = query.Value(5).toUrl();
    info.art_manual = query.Value(6).toUrl();
    info.first_url = QUrl::fromEncoded(query.Value(7).toByteArray());

    if ((info.artist == last_artist || info.album_artist == last_album_artist) && info.album_name == last_album)
      continue;

    ret << info;

    last_album = info.album_name;
    last_artist = info.artist;
    last_album_artist = info.album_artist;
  }

  return ret;

}

CollectionBackend::Album CollectionBackend::GetAlbumArt(const QString &artist, const QString &albumartist, const QString &album) {

  Album ret;
  ret.album_name = album;
  ret.artist = artist;
  ret.album_artist = albumartist;

  CollectionQuery query = CollectionQuery(QueryOptions());
  query.SetColumnSpec("art_automatic, art_manual, url");
  if (!albumartist.isEmpty()) {
    query.AddWhere("albumartist", albumartist);
  }
  else if (!artist.isEmpty()) {
    query.AddWhere("artist", artist);
  }
  query.AddWhere("album", album);

  QMutexLocker l(db_->Mutex());
  if (!ExecQuery(&query)) return ret;

  if (query.Next()) {
    ret.art_automatic = query.Value(0).toUrl();
    ret.art_manual = query.Value(1).toUrl();
    ret.first_url = QUrl::fromEncoded(query.Value(2).toByteArray());
  }

  return ret;

}

void CollectionBackend::UpdateManualAlbumArtAsync(const QString &artist, const QString &albumartist, const QString &album, const QUrl &cover_url) {

  metaObject()->invokeMethod(this, "UpdateManualAlbumArt", Qt::QueuedConnection, Q_ARG(QString, artist), Q_ARG(QString, albumartist), Q_ARG(QString, album), Q_ARG(QUrl, cover_url));

}

void CollectionBackend::UpdateManualAlbumArt(const QString &artist, const QString &albumartist, const QString &album, const QUrl &cover_url) {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  // Get the songs before they're updated
  CollectionQuery query;
  query.SetColumnSpec("ROWID, " + Song::kColumnSpec);
  query.AddWhere("album", album);

  if (!albumartist.isEmpty()) {
    query.AddWhere("albumartist", albumartist);
  }
  else if (!artist.isEmpty()) {
    query.AddWhere("artist", artist);
  }

  if (!ExecQuery(&query)) return;

  SongList deleted_songs;
  while (query.Next()) {
    Song song;
    song.InitFromQuery(query, true);
    deleted_songs << song;
  }

  // Update the songs
  QString sql(QString("UPDATE %1 SET art_manual = :cover WHERE album = :album AND unavailable = 0").arg(songs_table_));

  if (!albumartist.isNull() && !albumartist.isEmpty()) {
    sql += " AND albumartist = :albumartist";
  }
  else if (!artist.isNull()) {
    sql += " AND artist = :artist";
  }

  QSqlQuery q(db);
  q.prepare(sql);
  q.bindValue(":cover", cover_url);
  q.bindValue(":album", album);
  if (!albumartist.isEmpty()) {
    q.bindValue(":albumartist", albumartist);
  }
  else if (!artist.isEmpty()) {
    q.bindValue(":artist", artist);
  }

  q.exec();
  db_->CheckErrors(q);

  // Now get the updated songs
  if (!ExecQuery(&query)) return;

  SongList added_songs;
  while (query.Next()) {
    Song song;
    song.InitFromQuery(query, true);
    added_songs << song;
  }

  if (!added_songs.isEmpty() || !deleted_songs.isEmpty()) {
    emit SongsDeleted(deleted_songs);
    emit SongsDiscovered(added_songs);
  }

}

void CollectionBackend::ForceCompilation(const QString &album, const QList<QString> &artists, bool on) {

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());
  SongList deleted_songs, added_songs;

  for (const QString &artist : artists) {
    // Get the songs before they're updated
    CollectionQuery query;
    query.SetColumnSpec("ROWID, " + Song::kColumnSpec);
    query.AddWhere("album", album);
    if (!artist.isNull() && !artist.isEmpty()) query.AddWhere("artist", artist);

    if (!ExecQuery(&query)) return;

    while (query.Next()) {
      Song song;
      song.InitFromQuery(query, true);
      deleted_songs << song;
    }

    // Update the songs
    QString sql(QString("UPDATE %1 SET compilation_on = :compilation_on, compilation_off = :compilation_off, compilation_effective = ((compilation OR compilation_detected OR :compilation_on) AND NOT :compilation_off) + 0 WHERE album = :album AND unavailable = 0").arg(songs_table_));
    if (!artist.isEmpty()) sql += " AND artist = :artist";

    QSqlQuery q(db);
    q.prepare(sql);
    q.bindValue(":compilation_on", on ? 1 : 0);
    q.bindValue(":compilation_off", on ? 0 : 1);
    q.bindValue(":album", album);
    if (!artist.isEmpty()) q.bindValue(":artist", artist);

    q.exec();
    db_->CheckErrors(q);

    // Now get the updated songs
    if (!ExecQuery(&query)) return;

    while (query.Next()) {
      Song song;
      song.InitFromQuery(query, true);
      added_songs << song;
    }
  }

  if (!added_songs.isEmpty() || !deleted_songs.isEmpty()) {
    emit SongsDeleted(deleted_songs);
    emit SongsDiscovered(added_songs);
  }

}

bool CollectionBackend::ExecQuery(CollectionQuery *q) {
  return !db_->CheckErrors(q->Exec(db_->Connect(), songs_table_, fts_table_));
}

void CollectionBackend::IncrementPlayCount(int id) {

  if (id == -1) return;

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QSqlQuery q(db);
  q.prepare(QString("UPDATE %1 SET playcount = playcount + 1, lastplayed = :now WHERE ROWID = :id").arg(songs_table_));
  q.bindValue(":now", QDateTime::currentDateTime().toTime_t());
  q.bindValue(":id", id);
  q.exec();
  if (db_->CheckErrors(q)) return;

  Song new_song = GetSongById(id, db);
  emit SongsStatisticsChanged(SongList() << new_song);

}

void CollectionBackend::IncrementSkipCount(int id, float progress) {

  if (id == -1) return;

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QSqlQuery q(db);
  q.prepare(QString("UPDATE %1 SET skipcount = skipcount + 1 WHERE ROWID = :id").arg(songs_table_));
  q.bindValue(":id", id);
  q.exec();
  if (db_->CheckErrors(q)) return;

  Song new_song = GetSongById(id, db);
  emit SongsStatisticsChanged(SongList() << new_song);

}

void CollectionBackend::ResetStatistics(int id) {

  if (id == -1) return;

  QMutexLocker l(db_->Mutex());
  QSqlDatabase db(db_->Connect());

  QSqlQuery q(db);
  q.prepare(QString("UPDATE %1 SET playcount = 0, skipcount = 0, lastplayed = -1 WHERE ROWID = :id").arg(songs_table_));
  q.bindValue(":id", id);
  q.exec();
  if (db_->CheckErrors(q)) return;

  Song new_song = GetSongById(id, db);
  emit SongsStatisticsChanged(SongList() << new_song);

}

void CollectionBackend::DeleteAll() {

  {
    QMutexLocker l(db_->Mutex());
    QSqlDatabase db(db_->Connect());
    ScopedTransaction t(&db);

    QSqlQuery q("DELETE FROM " + songs_table_, db);
    q.exec();
    if (db_->CheckErrors(q)) return;

    q = QSqlQuery("DELETE FROM " + fts_table_, db);
    q.exec();
    if (db_->CheckErrors(q)) return;

    t.Commit();
  }

  emit DatabaseReset();

}