FFMPEG downloader (#36)

* Add ffmpeg_downloader.py

* Move shared download logic to downloader_core.py

* Added Windows support and some misc cleanup

* Fix issue with copying contents of .dmg files

* Add FFMPEGDownloader to engine_manager.py

src/engines/engine_manager.py

@@ -2,6 +2,8 @@ import os
 import logging
 import platform
 import shutil
+from .downloaders.blender_downloader import BlenderDownloader
+from .downloaders.ffmpeg_downloader import FFMPEGDownloader
 
 try:
     from .blender_engine import Blender
@@ -41,7 +43,7 @@ class EngineManager:
                 # Create a dictionary with named keys
                 executable_names = {'linux': 'blender', 'windows': 'blender.exe', 'macos': 'Blender.app'}
                 result_dict = {keys[i]: segments[i] for i in range(min(len(keys), len(segments)))}
-                result_dict['path'] = os.path.join(cls.engines_path, directory, executable_names[result_dict['system_os']])
+                result_dict['path'] = os.path.join(cls.engines_path, directory, executable_names.get(result_dict['system_os'], 'unknown'))
                 result_dict['type'] = 'managed'
                 results.append(result_dict)
         except FileNotFoundError:
@@ -98,15 +100,24 @@ class EngineManager:
             logger.info(f"Requested download of {engine} {version}, but local copy already exists")
             return existing_download
 
-        if engine == "blender":
-            from .scripts.blender.blender_downloader import BlenderDownloader
-            logger.info(f"Requesting download of {engine} {version}")
-            if BlenderDownloader.download_engine(version, download_location=cls.engines_path, system_os=system_os, cpu=cpu):
-                return cls.has_engine_version(engine, version, system_os, cpu)
-            else:
-                logger.error("Error downloading Engine")
+        logger.info(f"Requesting download of {engine} {version}")
+        downloader_classes = {
+            "blender": BlenderDownloader,
+            "ffmpeg": FFMPEGDownloader,
+            # Add more engine types and corresponding downloader classes as needed
+        }
 
-        return None  # Return None to indicate an error
+        # Check if the provided engine type is valid
+        if engine not in downloader_classes:
+            logger.error("No valid engine found")
+            return
+
+        # Get the appropriate downloader class based on the engine type
+        downloader = downloader_classes[engine]
+        if downloader.download_engine(version, download_location=cls.engines_path, system_os=system_os, cpu=cpu):
+            return cls.has_engine_version(engine, version, system_os, cpu)
+        else:
+            logger.error(f"Error downloading {engine}")
 
     @classmethod
     def delete_engine_download(cls, engine, version, system_os=None, cpu=None):
@@ -125,4 +136,4 @@ if __name__ == '__main__':
     logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(name)s - %(levelname)s - %(message)s')
 
     # print(EngineManager.newest_engine_version('blender', 'macos', 'arm64'))
-    EngineManager.delete_engine_download('blender', '3.2.1', 'windows', 'x64')
+    EngineManager.delete_engine_download('blender', '3.2.1', 'macos', 'a')