Show some suggested queries in the global search widget

src/globalsearch/digitallyimportedsearchprovider.cpp

@@ -25,7 +25,7 @@ DigitallyImportedSearchProvider::DigitallyImportedSearchProvider(
       service_(service)
 {
   Init(service_->name(), service->api_service_name(), service_->icon(),
-       ArtIsInSongMetadata);
+       ArtIsInSongMetadata | CanGiveSuggestions);
 
   set_safe_words(QStringList() << "sky.fm" << "skyfm" << "di.fm" << "difm"
                                << "digitallyimported");

src/globalsearch/globalsearch.cpp

@@ -318,3 +318,23 @@ void GlobalSearch::SaveProvidersSettings() {
     s.setValue("enabled_" + provider->id(), providers_[provider].enabled_);
   }
 }
+
+QStringList GlobalSearch::GetSuggestions(int max) {
+  QStringList ret;
+  QList<SearchProvider*> eligible_providers;
+
+  foreach (SearchProvider* provider, providers_.keys()) {
+    if (is_provider_enabled(provider) && provider->can_give_suggestions()) {
+      eligible_providers << provider;
+    }
+  }
+
+  while (ret.count() < max && !eligible_providers.isEmpty()) {
+    SearchProvider* provider = eligible_providers.takeAt(qrand() % eligible_providers.count());
+    QString suggestion = provider->GetSuggestion().trimmed();
+    if (!suggestion.isEmpty())
+      ret << suggestion;
+  }
+
+  return ret;
+}

src/globalsearch/globalsearch.h

@@ -44,6 +44,7 @@ public:
   int SearchAsync(const QString& query);
   int LoadArtAsync(const SearchProvider::Result& result);
   int LoadTracksAsync(const SearchProvider::Result& result);
+  QStringList GetSuggestions(int max);
 
   void CancelSearch(int id);
   void CancelArt(int id);

src/globalsearch/globalsearchwidget.cpp

@@ -44,6 +44,8 @@
 const int GlobalSearchWidget::kMinVisibleItems = 3;
 const int GlobalSearchWidget::kMaxVisibleItems = 25;
 const int GlobalSearchWidget::kSwapModelsTimeoutMsec = 250;
+const int GlobalSearchWidget::kSuggestionTimeoutMsec = 60000; // 1 minute
+const int GlobalSearchWidget::kSuggestionCount = 3;
 
 
 GlobalSearchWidget::GlobalSearchWidget(QWidget* parent)
@@ -64,7 +66,8 @@ GlobalSearchWidget::GlobalSearchWidget(QWidget* parent)
     background_(":allthethings.png"),
     desktop_(qApp->desktop()),
     show_tooltip_(true),
-    combine_identical_results_(true)
+    combine_identical_results_(true),
+    next_suggestion_timer_(new QTimer(this))
 {
   ui_->setupUi(this);
   ReloadSettings();
@@ -124,12 +127,16 @@ GlobalSearchWidget::GlobalSearchWidget(QWidget* parent)
   swap_models_timer_->setSingleShot(true);
   swap_models_timer_->setInterval(kSwapModelsTimeoutMsec);
 
+  next_suggestion_timer_->setInterval(kSuggestionTimeoutMsec);
+  hint_text_ = ui_->search->hint();
+
   connect(ui_->search, SIGNAL(textEdited(QString)), SLOT(TextEdited(QString)));
   connect(view_, SIGNAL(doubleClicked(QModelIndex)), SLOT(ResultDoubleClicked()));
   connect(view_->selectionModel(), SIGNAL(currentChanged(QModelIndex,QModelIndex)),
           SLOT(UpdateTooltip()));
   connect(swap_models_timer_, SIGNAL(timeout()), SLOT(SwapModels()));
   connect(ui_->settings, SIGNAL(clicked()), SLOT(SettingsClicked()));
+  connect(next_suggestion_timer_, SIGNAL(timeout()), SLOT(NextSuggestion()));
 }
 
 GlobalSearchWidget::~GlobalSearchWidget() {
@@ -196,6 +203,19 @@ void GlobalSearchWidget::paintEvent(QPaintEvent* e) {
   p.drawLine(total_rect.bottomLeft(), total_rect.bottomRight());
 }
 
+void GlobalSearchWidget::hideEvent(QHideEvent* e) {
+  QWidget::hideEvent(e);
+
+  next_suggestion_timer_->stop();
+}
+
+void GlobalSearchWidget::showEvent(QShowEvent* e) {
+  QWidget::showEvent(e);
+
+  next_suggestion_timer_->start();
+  NextSuggestion();
+}
+
 void GlobalSearchWidget::TextEdited(const QString& text) {
   const QString trimmed_text = text.trimmed();
 
@@ -670,3 +690,14 @@ void GlobalSearchWidget::UpdateTooltip() {
 void GlobalSearchWidget::SettingsClicked() {
   emit OpenSettingsAtPage(SettingsDialog::Page_GlobalSearch);
 }
+
+void GlobalSearchWidget::NextSuggestion() {
+  const QStringList suggestions = engine_->GetSuggestions(kSuggestionCount);
+  QString hint = hint_text_;
+
+  if (!suggestions.isEmpty()) {
+    hint += ", e.g. " + suggestions.join(", ");
+  }
+
+  ui_->search->set_hint(hint);
+}

src/globalsearch/globalsearchwidget.h

@@ -50,6 +50,8 @@ public:
   static const int kMinVisibleItems;
   static const int kMaxVisibleItems;
   static const int kSwapModelsTimeoutMsec;
+  static const int kSuggestionTimeoutMsec;
+  static const int kSuggestionCount;
 
   enum Role {
     Role_PrimaryResult = Qt::UserRole + 1,
@@ -63,7 +65,7 @@ public:
   // Called by the delegate
   void LazyLoadArt(const QModelIndex& index);
 
-  // QWidget
+  // QObject
   bool eventFilter(QObject* o, QEvent* e);
 
 public slots:
@@ -76,6 +78,8 @@ signals:
 protected:
   void resizeEvent(QResizeEvent* e);
   void paintEvent(QPaintEvent* e);
+  void showEvent(QShowEvent* e);
+  void hideEvent(QHideEvent* e);
 
 private slots:
   void TextEdited(const QString& text);
@@ -98,6 +102,8 @@ private slots:
 
   void SwapModels();
 
+  void NextSuggestion();
+
 private:
   // Return values from CanCombineResults
   enum CombineAction {
@@ -159,6 +165,9 @@ private:
   QAction* replace_;
   QAction* replace_and_play_;
   QList<QAction*> actions_;
+
+  QString hint_text_;
+  QTimer* next_suggestion_timer_;
 };
 
 #endif // GLOBALSEARCHWIDGET_H

src/globalsearch/globalsearchwidget.ui

@@ -17,7 +17,7 @@
    <item>
     <widget class="LineEdit" name="search">
      <property name="hint" stdset="0">
-      <string>Global search</string>
+      <string>Search for anything</string>
      </property>
     </widget>
    </item>

src/globalsearch/lastfmsearchprovider.cpp

@@ -23,7 +23,8 @@
 LastFMSearchProvider::LastFMSearchProvider(LastFMService* service, QObject* parent)
   : SimpleSearchProvider(parent),
     service_(service) {
-  Init("Last.fm", "lastfm", QIcon(":last.fm/as.png"), CanShowConfig);
+  Init("Last.fm", "lastfm", QIcon(":last.fm/as.png"),
+       CanShowConfig | CanGiveSuggestions);
   icon_ = ScaleAndPad(QImage(":last.fm/as.png"));
 
   set_safe_words(QStringList() << "lastfm" << "last.fm");

src/globalsearch/librarysearchprovider.cpp

@@ -32,7 +32,8 @@ LibrarySearchProvider::LibrarySearchProvider(LibraryBackendInterface* backend,
   : BlockingSearchProvider(parent),
     backend_(backend)
 {
-  Init(name, id, icon, WantsSerialisedArtQueries | ArtIsInSongMetadata);
+  Init(name, id, icon, WantsSerialisedArtQueries | ArtIsInSongMetadata |
+                       CanGiveSuggestions);
 }
 
 SearchProvider::ResultList LibrarySearchProvider::Search(int id, const QString& query) {
@@ -146,3 +147,45 @@ void LibrarySearchProvider::LoadTracksAsync(int id, const Result& result) {
 
   emit TracksLoaded(id, mime_data);
 }
+
+QString LibrarySearchProvider::GetSuggestion() {
+  // We'd like to use order by random(), but that's O(n) in sqlite, so instead
+  // get the largest ROWID and pick a couple of random numbers within that
+  // range.
+
+  LibraryQuery q;
+  q.SetColumnSpec("ROWID");
+  q.SetOrderBy("ROWID DESC");
+  q.SetIncludeUnavailable(true);
+  q.SetLimit(1);
+
+  if (!backend_->ExecQuery(&q) || !q.Next()) {
+    return QString();
+  }
+
+  const int largest_rowid = q.Value(0).toInt();
+
+  for (int attempt=0 ; attempt<10 ; ++attempt) {
+    LibraryQuery q;
+    q.SetColumnSpec("artist, album");
+    q.SetIncludeUnavailable(true);
+    q.AddWhere("ROWID", qrand() % largest_rowid);
+    q.SetLimit(1);
+
+    if (!backend_->ExecQuery(&q) || !q.Next()) {
+      continue;
+    }
+
+    const QString artist = q.Value(0).toString();
+    const QString album  = q.Value(1).toString();
+
+    if (!artist.isEmpty() && !album.isEmpty())
+      return (qrand() % 2 == 0) ? artist : album;
+    else if (!artist.isEmpty())
+      return artist;
+    else if (!album.isEmpty())
+      return album;
+  }
+
+  return QString();
+}

src/globalsearch/librarysearchprovider.h

@@ -30,6 +30,7 @@ public:
 
   ResultList Search(int id, const QString& query);
   void LoadTracksAsync(int id, const Result& result);
+  QString GetSuggestion();
 
 private:
   LibraryBackendInterface* backend_;

src/globalsearch/searchprovider.h

@@ -86,7 +86,11 @@ public:
     // Indicates this provider has a config dialog that can be shown by calling
     // CanShowConfig.  If this is not set then the button will be greyed out
     // in the GUI.
-    CanShowConfig = 0x10
+    CanShowConfig = 0x10,
+
+    // This provider can provide some example search strings to display in the
+    // UI.
+    CanGiveSuggestions = 0x20
   };
   Q_DECLARE_FLAGS(Hints, Hint)
 
@@ -100,6 +104,7 @@ public:
   bool art_is_probably_remote() const { return hints() & ArtIsProbablyRemote; }
   bool art_is_in_song_metadata() const { return hints() & ArtIsInSongMetadata; }
   bool can_show_config() const { return hints() & CanShowConfig; }
+  bool can_give_suggestions() const { return hints() & CanGiveSuggestions; }
 
   // Starts a search.  Must emit ResultsAvailable zero or more times and then
   // SearchFinished exactly once, using this ID.
@@ -113,6 +118,11 @@ public:
   // ResultsAvailable.  Must emit TracksLoaded exactly once with this ID.
   virtual void LoadTracksAsync(int id, const Result& result);
 
+  // Returns an example search string to display in the UI.  The provider should
+  // pick one of its items at random.  Remember to set the CanGiveSuggestions
+  // hint.
+  virtual QString GetSuggestion() { return QString(); }
+
   // If provider needs user login to search and play songs, this method should
   // be reimplemented
   virtual bool IsLoggedIn() { return true; }

src/globalsearch/simplesearchprovider.cpp

@@ -124,3 +124,18 @@ void SimpleSearchProvider::SetItems(const ItemList& items) {
   QMutexLocker l(&items_mutex_);
   items_ = items;
 }
+
+QString SimpleSearchProvider::GetSuggestion() {
+  QMutexLocker l(&items_mutex_);
+
+  if (items_.isEmpty())
+    return QString();
+
+  for (int attempt=0 ; attempt<10 ; ++attempt) {
+    const Item& item = items_[qrand() % items_.count()];
+    if (!item.keyword_.isEmpty())
+      return item.keyword_;
+  }
+
+  return QString();
+}

src/globalsearch/simplesearchprovider.h

@@ -33,6 +33,7 @@ public:
 
   // SearchProvider
   void LoadTracksAsync(int id, const Result& result);
+  QString GetSuggestion();
 
 protected slots:
   // Calls RecreateItems now if the user has done a global search with this

src/globalsearch/somafmsearchprovider.cpp

@@ -22,7 +22,7 @@ SomaFMSearchProvider::SomaFMSearchProvider(SomaFMService* service, QObject* pare
   : SimpleSearchProvider(parent),
     service_(service)
 {
-  Init("SomaFM", "somafm", QIcon(":/providers/somafm.png"));
+  Init("SomaFM", "somafm", QIcon(":/providers/somafm.png"), CanGiveSuggestions);
   set_result_limit(3);
   icon_ = ScaleAndPad(QImage(":/providers/somafm.png"));