Windows path fixes (#129)

* Change uses of os.path to use Pathlib

* Add return types and type hints

* Add more docstrings

* Add missing import to api_server

src/render_queue.py

@@ -1,34 +1,35 @@
 import logging
-import os
 from datetime import datetime
+from pathlib import Path
+from typing import List, Dict, Any, Optional
 
 from pubsub import pub
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
 from sqlalchemy.orm.exc import DetachedInstanceError
 
-from src.engines.core.base_worker import Base
+from src.engines.core.base_worker import Base, BaseRenderWorker
 from src.utilities.status_utils import RenderStatus
 
 logger = logging.getLogger()
 
 
 class JobNotFoundError(Exception):
-    def __init__(self, job_id, *args):
+    def __init__(self, job_id: str, *args: Any) -> None:
         super().__init__(args)
         self.job_id = job_id
 
-    def __str__(self):
+    def __str__(self) -> str:
         return f"Cannot find job with ID: {self.job_id}"
 
 
 class RenderQueue:
-    engine = None
-    session = None
-    job_queue = []
-    maximum_renderer_instances = {'blender': 1, 'aerender': 1, 'ffmpeg': 4}
-    last_saved_counts = {}
-    is_running = False
+    engine: Optional[create_engine] = None
+    session: Optional[sessionmaker] = None
+    job_queue: List[BaseRenderWorker] = []
+    maximum_renderer_instances: Dict[str, int] = {'blender': 1, 'aerender': 1, 'ffmpeg': 4}
+    last_saved_counts: Dict[str, int] = {}
+    is_running: bool = False
 
     # --------------------------------------------
     # Render Queue Evaluation:
@@ -116,9 +117,9 @@ class RenderQueue:
     # --------------------------------------------
 
     @classmethod
-    def load_state(cls, database_directory):
+    def load_state(cls, database_directory: Path):
         if not cls.engine:
-            cls.engine = create_engine(f"sqlite:///{os.path.join(database_directory, 'database.db')}")
+            cls.engine = create_engine(f"sqlite:///{database_directory / 'database.db'}")
             Base.metadata.create_all(cls.engine)
             cls.session = sessionmaker(bind=cls.engine)()
         from src.engines.core.base_worker import BaseRenderWorker