Various patches for database importing (#344)

* Implement page enums for import wizard, pages now have explicit nextId page

* Ensure no db import can take place before biosphere (biosphere3) exists

* Speedup 7zip extract by not printing 'Extracted ...' lines.

* Force cleanup of DatabaseImportWizard on creation and project change

* Subclass BW2Package to allow check for required dependencies

* Move tempdir creation and handling together, feed correct paths to methods

* Rename 'import failed' signal for clarity

* Possible fix for #333

activity_browser/app/controller.py

@@ -28,10 +28,10 @@ class Controller(object):
     It is different from bwutils in that it also contains Qt elements such as dialogs.
     - """
     def __init__(self):
+        self.db_wizard = None
         self.connect_signals()
         signals.project_selected.emit()
         self.load_settings()
-        self.db_wizard = None
         print('Brightway2 data directory: {}'.format(bw.projects._base_data_dir))
         print('Brightway2 active project: {}'.format(bw.projects.current))
 
@@ -77,18 +77,21 @@ def load_settings(self):
             self.switch_brightway2_dir_path(dirpath=ab_settings.custom_bw_dir)
             self.change_project(ab_settings.startup_project)
 
+    def clear_database_wizard(self):
+        """ Separate cleanup method, used to clear out existing import wizard
+        when switching projects.
+        """
+        if self.db_wizard is None:
+            return
+        self.db_wizard.deleteLater()
+        self.db_wizard = None
+
     def import_database_wizard(self):
-        try:
-            if self.db_wizard is None:
-                self.db_wizard = DatabaseImportWizard()
-            else:
-                self.db_wizard.show()
-                self.db_wizard.activateWindow()
-        except:
-            QtWidgets.QMessageBox.warning(None,
-                                              "Error during importing.",
-                                              "Oops. Something went wrong with the data import. "
-                                              "Please check the console for details.")
+        """ Create a database import wizard, if it already exists, set the
+        previous one to delete and recreate it.
+        """
+        self.clear_database_wizard()
+        self.db_wizard = DatabaseImportWizard()
 
     def switch_brightway2_dir_path(self, dirpath):
         if dirpath == bw.projects._base_data_dir:
@@ -128,6 +131,7 @@ def change_project_dialog(self):
 
     def change_project(self, name=None, reload=False):
         # TODO: what should happen if a new project is opened? (all activities, etc. closed?)
+        self.clear_database_wizard()
         if not name:
             print("No project name given.")
             return

activity_browser/app/ui/menu_bar.py

@@ -19,6 +19,9 @@ def __init__(self, window):
             "&Update biosphere...", None
         )
         self.biosphere_updater = None
+        self.import_db_action = QtWidgets.QAction(
+            qicons.import_db, '&Import database...', None
+        )
 
         self.menubar = QtWidgets.QMenuBar()
         self.menubar.addMenu(self.setup_file_menu())
@@ -35,15 +38,12 @@ def connect_signals(self):
         signals.project_selected.connect(self.biosphere_exists)
         signals.databases_changed.connect(self.biosphere_exists)
         self.update_biosphere_action.triggered.connect(self.update_biosphere)
+        self.import_db_action.triggered.connect(signals.import_database.emit)
 
     # FILE
     def setup_file_menu(self):
         menu = QtWidgets.QMenu('&File', self.window)
-        menu.addAction(
-            qicons.import_db,
-            '&Import database...',
-            signals.import_database.emit
-        )
+        menu.addAction(self.import_db_action)
         menu.addAction(
             self.window.style().standardIcon(QtWidgets.QStyle.SP_DriveHDIcon),
             "&Export database...",
@@ -153,6 +153,7 @@ def biosphere_exists(self) -> None:
         """
         exists = True if bw.config.biosphere in bw.databases else False
         self.update_biosphere_action.setEnabled(exists)
+        self.import_db_action.setEnabled(exists)
 
     def update_biosphere(self):
         """ Open a popup with progression bar and run through the different