bootstrap script preps DI'd handlers and start orm [bootstrap_script]

Author: hjwp

src/allocation/bootstrap.py

@@ -0,0 +1,44 @@
+import inspect
+from typing import Callable
+from allocation.adapters import email, orm, redis_eventpublisher
+from allocation.service_layer import handlers, messagebus, unit_of_work
+
+
+def bootstrap(
+    start_orm: bool = True,
+    uow: unit_of_work.AbstractUnitOfWork = unit_of_work.SqlAlchemyUnitOfWork(),
+    send_mail: Callable = email.send,
+    publish: Callable = redis_eventpublisher.publish,
+) -> messagebus.MessageBus:
+
+    if start_orm:
+        orm.start_mappers()
+
+    dependencies = {'uow': uow, 'send_mail': send_mail, 'publish': publish}
+    injected_event_handlers = {
+        event_type: [
+            inject_dependencies(handler, dependencies)
+            for handler in event_handlers
+        ]
+        for event_type, event_handlers in handlers.EVENT_HANDLERS.items()
+    }
+    injected_command_handlers = {
+        command_type: inject_dependencies(handler, dependencies)
+        for command_type, handler in handlers.COMMAND_HANDLERS.items()
+    }
+
+    return messagebus.MessageBus(
+        uow=uow,
+        event_handlers=injected_event_handlers,
+        command_handlers=injected_command_handlers,
+    )
+
+
+def inject_dependencies(handler, dependencies):
+    params = inspect.signature(handler).parameters
+    deps = {
+        name: dependency
+        for name, dependency in dependencies.items()
+        if name in params
+    }
+    return lambda message: handler(message, **deps)