Implement task API with input validation; implement error handling; refactoring

tofu_api/dependencies.py

@@ -1,6 +1,26 @@
+from typing import TypeVar
+
 from sqlalchemy.orm import Session
 
+from tofu_api.api.tasks import TaskHandler
 from tofu_api.common.database import SQLAlchemy
+from tofu_api.repositories import TaskRepository
+
+T_Dep_Callable = TypeVar('T_Dep_Callable')
+
+
+def cache_dependency(func: T_Dep_Callable) -> T_Dep_Callable:
+    """
+    Decorator to be used in `Dependencies` to cache dependencies inside the Dependencies instance.
+    """
+    dep_name = func.__name__
+
+    def wrapped_func(self: 'Dependencies'):
+        if dep_name not in self._dependency_cache:
+            self._dependency_cache[dep_name] = func(self)
+        return self._dependency_cache.get(dep_name)
+
+    return wrapped_func
 
 
 class Dependencies:
@@ -15,10 +35,22 @@ class Dependencies:
 
     # Database dependencies
 
+    @cache_dependency
     def get_sqlalchemy(self) -> SQLAlchemy:
-        if SQLAlchemy not in self._dependency_cache:
-            self._dependency_cache[SQLAlchemy] = SQLAlchemy()
-        return self._dependency_cache[SQLAlchemy]
+        return SQLAlchemy()
 
+    # No caching necessary here
     def get_db_session(self) -> Session:
         return self.get_sqlalchemy().session
+
+    # Repository classes
+
+    @cache_dependency
+    def get_task_repository(self) -> TaskRepository:
+        return TaskRepository(session=self.get_db_session())
+
+    # API Handler classes
+
+    @cache_dependency
+    def get_task_handler(self) -> TaskHandler:
+        return TaskHandler(task_repository=self.get_task_repository())