From 59eb19224b9aebf3b2f86915ab8e85e4024e9b24 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Robert=20Sch=C3=BCtz?=
 <robert.schuetz@stud.uni-heidelberg.de>
Date: Sun, 4 Feb 2018 01:30:47 +0100
Subject: [PATCH] nixos/home-assistant: support platform=... scheme for
 autoExtraComponents

See https://home-assistant.io/components/sensor.luftdaten/ for an example component using that scheme.
---
 .../modules/services/misc/home-assistant.nix  | 21 ++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/nixos/modules/services/misc/home-assistant.nix b/nixos/modules/services/misc/home-assistant.nix
index 666fa68b01c..cc60a143fa6 100644
--- a/nixos/modules/services/misc/home-assistant.nix
+++ b/nixos/modules/services/misc/home-assistant.nix
@@ -9,8 +9,27 @@ let
 
   availableComponents = pkgs.home-assistant.availableComponents;
 
+  # Given component "parentConfig.platform", returns whether config.parentConfig
+  # is a list containing a set with set.platform == "platform".
+  #
+  # For example, the component sensor.luftdaten is used as follows:
+  # config.sensor = [ {
+  #   platform = "luftdaten";
+  #   ...
+  # } ];
+  useComponentPlatform = component:
+    let
+      path = splitString "." component;
+      parentConfig = attrByPath (init path) null cfg.config;
+      platform = last path;
+    in isList parentConfig && any
+      (item: item.platform or null == platform)
+      parentConfig;
+
   # Returns whether component is used in config
-  useComponent = component: hasAttrByPath (splitString "." component) cfg.config;
+  useComponent = component:
+    hasAttrByPath (splitString "." component) cfg.config
+    || useComponentPlatform component;
 
   # List of components used in config
   extraComponents = filter useComponent availableComponents;