Add download db window with connection checks

download_thread.py

@@ -0,0 +1,43 @@
+from io import BytesIO
+from os import mkdir
+import os.path
+from shutil import rmtree
+import urllib
+from zipfile import ZipFile
+from PyQt5.QtCore import QThread, pyqtSignal
+
+class DownloadThread(QThread):
+    no_connection_error = pyqtSignal()
+    bad_db_download_error = pyqtSignal()
+
+    def __init__(self, db_location, path):
+        super().__init__()
+        self.__db_location = db_location
+        self.__path = path
+        self.regular_execution = True
+        self.reason = 0
+
+    def __del__(self):
+        self.terminate()
+        self.wait()
+
+    def run(self):
+        if os.path.exists(self.__path):
+            rmtree(self.__path)
+        try:
+            db = urllib.request.urlopen(self.__db_location)
+            # raise urllib.error.URLError('Test')
+        except urllib.error.URLError: # No internet connection.
+            self.regular_execution = False
+            self.no_connection_error.emit()
+            return
+        if db.status != 200:
+            self.regular_execution = False
+            self.reason = db.reason
+            self.bad_db_download_error.emit()
+            return
+        try:
+            with ZipFile(BytesIO(db.read())) as zipped:
+                zipped.extractall()
+        except:
+            pass