Report Engine Download Status in UI (#64)

* Report downloads in status bar

* Update engine_browser.py UI with any active downloads

src/engines/engine_manager.py

@@ -129,15 +129,6 @@ class EngineManager:
 
     @classmethod
     def download_engine(cls, engine, version, system_os=None, cpu=None, background=False):
-        def download_engine_task(engine, version, system_os=None, cpu=None):
-            existing_download = cls.is_version_downloaded(engine, version, system_os, cpu)
-            if existing_download:
-                logger.info(f"Requested download of {engine} {version}, but local copy already exists")
-                return existing_download
-
-            # Get the appropriate downloader class based on the engine type
-            cls.engine_with_name(engine).downloader().download_engine(version, download_location=cls.engines_path,
-                                                                      system_os=system_os, cpu=cpu, timeout=300)
 
         engine_to_download = cls.engine_with_name(engine)
         existing_task = cls.is_already_downloading(engine, version, system_os, cpu)
@@ -152,8 +143,7 @@ class EngineManager:
         elif not cls.engines_path:
             raise FileNotFoundError("Engines path must be set before requesting downloads")
 
-        thread = threading.Thread(target=download_engine_task, args=(engine, version, system_os, cpu),
-                                  name=f'{engine}-{version}-{system_os}-{cpu}')
+        thread = EngineDownloadWorker(engine, version, system_os, cpu)
         cls.download_tasks.append(thread)
         thread.start()
 
@@ -251,6 +241,29 @@ class EngineManager:
         return undefined_renderer_support[0]
 
 
+class EngineDownloadWorker(threading.Thread):
+    def __init__(self, engine, version, system_os=None, cpu=None):
+        super().__init__()
+        self.engine = engine
+        self.version = version
+        self.system_os = system_os
+        self.cpu = cpu
+
+    def run(self):
+        existing_download = EngineManager.is_version_downloaded(self.engine, self.version, self.system_os, self.cpu)
+        if existing_download:
+            logger.info(f"Requested download of {self.engine} {self.version}, but local copy already exists")
+            return existing_download
+
+        # Get the appropriate downloader class based on the engine type
+        EngineManager.engine_with_name(self.engine).downloader().download_engine(
+            self.version, download_location=EngineManager.engines_path, system_os=self.system_os, cpu=self.cpu,
+            timeout=300)
+
+        # remove itself from the downloader list
+        EngineManager.download_tasks.remove(self)
+
+
 if __name__ == '__main__':
     logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(name)s - %(levelname)s - %(message)s')