[tool] Add helper to list all artists in the database

src/tools/CMakeLists.txt

@@ -1 +1,2 @@
+add_subdirectory( database-reader )
 add_subdirectory( tomahawk-test-musicscan )

src/tools/database-reader/CMakeLists.txt

@@ -0,0 +1,20 @@
+set( tomahawk_db_list_artists_src
+    listartists.cpp
+)
+
+include_directories(${CMAKE_CURRENT_BINARY_DIR})
+
+add_executable( tomahawk_db_list_artists_bin WIN32 MACOSX_BUNDLE
+    ${tomahawk_db_list_artists_src} )
+set_target_properties( tomahawk_db_list_artists_bin
+    PROPERTIES
+        AUTOMOC TRUE
+        RUNTIME_OUTPUT_NAME tomahawk-db-list-artists
+)
+target_link_libraries( tomahawk_db_list_artists_bin
+    ${TOMAHAWK_LIBRARIES}
+)
+
+qt5_use_modules(tomahawk_db_list_artists_bin Core)
+install( TARGETS tomahawk_db_list_artists_bin BUNDLE DESTINATION . RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR} )
+

src/tools/database-reader/listartists.cpp

@@ -0,0 +1,83 @@
+#include "database/Database.h"
+#include "database/DatabaseCommand_AllArtists.h"
+#include "utils/TomahawkUtils.h"
+#include "TomahawkVersion.h"
+#include "Typedefs.h"
+
+#include <QCoreApplication>
+#include <QDir>
+
+#include <iostream>
+
+
+class Tasks: public QObject
+{
+Q_OBJECT
+public:
+    Q_INVOKABLE void startDatabase( QString dbpath )
+    {
+        database = QSharedPointer<Tomahawk::Database>( new Tomahawk::Database( dbpath ) );
+        connect( database.data(), SIGNAL( ready() ), SLOT( runDbCmd() ), Qt::QueuedConnection );
+        database->loadIndex();
+    }
+
+    Tomahawk::dbcmd_ptr cmd;
+    QSharedPointer<Tomahawk::Database> database;
+
+public slots:
+    void runDbCmd()
+    {
+        // TODO FIX database so that ready is emitted after the index is loaded and at least one worker runs.
+        database->enqueue( cmd );
+    }
+
+    void dbCmdDone( const QList<Tomahawk::artist_ptr>& artists )
+    {
+        std::cout << "=== ARTISTS - START ===" << std::endl;
+        foreach ( const Tomahawk::artist_ptr& artist, artists )
+        {
+            std::cout << artist->name().toStdString() << std::endl;
+        }
+        std::cout << "=== ARTISTS - END ===" << std::endl;
+        QMetaObject::invokeMethod( thread(), "quit", Qt::QueuedConnection );
+    }
+};
+
+// Include needs to go here as Tasks needs to be defined before.
+#include "listartists.moc"
+
+int main( int argc, char* argv[] )
+{
+    QCoreApplication app( argc, argv );
+    // TODO: Add an argument to change the path
+    app.setOrganizationName( QLatin1String( TOMAHAWK_ORGANIZATION_NAME ) );
+
+    // Helper QObject to connect slots and actions in the correct thread.
+    Tasks tasks;
+
+    // Start a thread so we can actually block main until the end of the DbCmd
+    QThread thread( 0 );
+    thread.start();
+
+    // We need to do this or the finished() signal/quit() SLOT is not called.
+    thread.moveToThread( &thread );
+    tasks.moveToThread( &thread );
+
+    // Load the Database
+    Tomahawk::DatabaseCommand_AllArtists* cmd = new Tomahawk::DatabaseCommand_AllArtists();
+    tasks.cmd = Tomahawk::dbcmd_ptr( cmd );
+    tasks.cmd->moveToThread( &thread );
+    qRegisterMetaType< QList< Tomahawk::artist_ptr > >();
+    QObject::connect( cmd, SIGNAL( artists( QList<Tomahawk::artist_ptr>  ) ),
+                      &tasks, SLOT( dbCmdDone( QList<Tomahawk::artist_ptr> ) ),
+                      Qt::QueuedConnection );
+    QString dbpath = TomahawkUtils::appDataDir().absoluteFilePath( "tomahawk.db" );
+    QMetaObject::invokeMethod( &tasks, "startDatabase", Qt::QueuedConnection, Q_ARG( QString, dbpath ) );
+
+    // Wait until the dbcmd was executed.
+    thread.wait();
+}
+
+#if QT_VERSION < QT_VERSION_CHECK( 5, 0, 0 )
+    Q_DECLARE_METATYPE( QList< Tomahawk::artist_ptr >  )
+#endif