Refactor entity service calls to reduce complexity (#99783)

* Refactor entity service calls to reduce complexity

gets rid of the noqa C901

* Refactor entity service calls to reduce complexity

gets rid of the noqa C901

* short

homeassistant/helpers/service.py

@@ -732,8 +732,59 @@ def async_set_service_schema(
     descriptions_cache[(domain, service)] = description
 
 
+def _get_permissible_entity_candidates(
+    call: ServiceCall,
+    platforms: Iterable[EntityPlatform],
+    entity_perms: None | (Callable[[str, str], bool]),
+    target_all_entities: bool,
+    all_referenced: set[str] | None,
+) -> list[Entity]:
+    """Get entity candidates that the user is allowed to access."""
+    if entity_perms is not None:
+        # Check the permissions since entity_perms is set
+        if target_all_entities:
+            # If we target all entities, we will select all entities the user
+            # is allowed to control.
+            return [
+                entity
+                for platform in platforms
+                for entity in platform.entities.values()
+                if entity_perms(entity.entity_id, POLICY_CONTROL)
+            ]
+
+        assert all_referenced is not None
+        # If they reference specific entities, we will check if they are all
+        # allowed to be controlled.
+        for entity_id in all_referenced:
+            if not entity_perms(entity_id, POLICY_CONTROL):
+                raise Unauthorized(
+                    context=call.context,
+                    entity_id=entity_id,
+                    permission=POLICY_CONTROL,
+                )
+
+    elif target_all_entities:
+        return [
+            entity for platform in platforms for entity in platform.entities.values()
+        ]
+
+    # We have already validated they have permissions to control all_referenced
+    # entities so we do not need to check again.
+    assert all_referenced is not None
+    if single_entity := len(all_referenced) == 1 and list(all_referenced)[0]:
+        for platform in platforms:
+            if (entity := platform.entities.get(single_entity)) is not None:
+                return [entity]
+
+    return [
+        platform.entities[entity_id]
+        for platform in platforms
+        for entity_id in all_referenced.intersection(platform.entities)
+    ]
+
+
 @bind_hass
-async def entity_service_call(  # noqa: C901
+async def entity_service_call(
     hass: HomeAssistant,
     platforms: Iterable[EntityPlatform],
     func: str | Callable[..., Coroutine[Any, Any, ServiceResponse]],
@@ -771,69 +822,24 @@ async def entity_service_call(  # noqa: C901
     else:
         data = call
 
-    # Check the permissions
-
     # A list with entities to call the service on.
-    entity_candidates: list[Entity] = []
-
-    if entity_perms is None:
-        for platform in platforms:
-            platform_entities = platform.entities
-            if target_all_entities:
-                entity_candidates.extend(platform_entities.values())
-            else:
-                assert all_referenced is not None
-                entity_candidates.extend(
-                    [
-                        platform_entities[entity_id]
-                        for entity_id in all_referenced.intersection(platform_entities)
-                    ]
-                )
-
-    elif target_all_entities:
-        # If we target all entities, we will select all entities the user
-        # is allowed to control.
-        for platform in platforms:
-            entity_candidates.extend(
-                [
-                    entity
-                    for entity in platform.entities.values()
-                    if entity_perms(entity.entity_id, POLICY_CONTROL)
-                ]
-            )
-
-    else:
-        assert all_referenced is not None
-
-        for platform in platforms:
-            platform_entities = platform.entities
-            platform_entity_candidates = []
-            entity_id_matches = all_referenced.intersection(platform_entities)
-            for entity_id in entity_id_matches:
-                if not entity_perms(entity_id, POLICY_CONTROL):
-                    raise Unauthorized(
-                        context=call.context,
-                        entity_id=entity_id,
-                        permission=POLICY_CONTROL,
-                    )
-
-                platform_entity_candidates.append(platform_entities[entity_id])
-
-            entity_candidates.extend(platform_entity_candidates)
+    entity_candidates = _get_permissible_entity_candidates(
+        call,
+        platforms,
+        entity_perms,
+        target_all_entities,
+        all_referenced,
+    )
 
     if not target_all_entities:
         assert referenced is not None
-
         # Only report on explicit referenced entities
-        missing = set(referenced.referenced)
-
+        missing = referenced.referenced.copy()
         for entity in entity_candidates:
             missing.discard(entity.entity_id)
-
         referenced.log_missing(missing)
 
     entities: list[Entity] = []
-
     for entity in entity_candidates:
         if not entity.available:
             continue