From 89a8c599c71e34e70786f06401521e7316d290fd Mon Sep 17 00:00:00 2001
From: Sven van Heugten <sven@memcmp.org>
Date: Mon, 5 Jan 2026 17:51:57 +0100
Subject: [PATCH] Strongly type the device FriendlyName

---
 NightLight.Core.Tests/FakeHome.fs |  8 ++++++--
 NightLight.Core/Models.fs         | 19 +++++++++++++------
 NightLight.Core/ZigbeeCommands.fs |  4 ++--
 NightLight.Core/ZigbeeEvents.fs   |  4 ++--
 4 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/NightLight.Core.Tests/FakeHome.fs b/NightLight.Core.Tests/FakeHome.fs
index 6413cbd..3facd72 100644
--- a/NightLight.Core.Tests/FakeHome.fs
+++ b/NightLight.Core.Tests/FakeHome.fs
@@ -59,7 +59,11 @@ type FakeHome() =
         option {
             let! friendlyName =
                 let m = Regex.Match(command.Topic, "^zigbee2mqtt/(.+)/set$")
-                if m.Success then Some m.Groups.[1].Value else None
+
+                if m.Success then
+                    Some(DeviceFriendlyName m.Groups.[1].Value)
+                else
+                    None
 
             let! fakeLight = Map.tryFind friendlyName friendlyNameToFakeLight
 
@@ -94,7 +98,7 @@ type FakeHome() =
               Payload =
                 $@"{{
                     ""type"": ""device_announce"",
-                    ""data"": {{ ""friendly_name"": ""{light.FriendlyName}"" }}
+                    ""data"": {{ ""friendly_name"": ""{light.FriendlyName.Get}"" }}
                   }}" }
             |> ReceivedZigbeeEvent
             |> onEventPublished.Trigger
diff --git a/NightLight.Core/Models.fs b/NightLight.Core/Models.fs
index 7452f6e..b9fa8db 100644
--- a/NightLight.Core/Models.fs
+++ b/NightLight.Core/Models.fs
@@ -30,24 +30,31 @@ type Bulb =
     | IkeaBulb
     | PaulmannBulb
 
+type DeviceFriendlyName =
+    | DeviceFriendlyName of string
+
+    member this.Get =
+        match this with
+        | DeviceFriendlyName deviceFriendlyName -> deviceFriendlyName
+
 type Light =
-    { FriendlyName: string
+    { FriendlyName: DeviceFriendlyName
       Room: Room
       Bulb: Bulb }
 
 let lights =
-    [ { FriendlyName = "Vardagsrum - Fönsterlampa"
+    [ { FriendlyName = DeviceFriendlyName "Vardagsrum - Fönsterlampa"
         Room = LivingRoom
         Bulb = IkeaBulb }
-      { FriendlyName = "Vardagsrum - Vägglampa"
+      { FriendlyName = DeviceFriendlyName "Vardagsrum - Vägglampa"
         Room = LivingRoom
         Bulb = PaulmannBulb }
-      { FriendlyName = "Vardagsrum - Golvlampa"
+      { FriendlyName = DeviceFriendlyName "Vardagsrum - Golvlampa"
         Room = LivingRoom
         Bulb = PaulmannBulb }
-      { FriendlyName = "Badrum - Taklampa"
+      { FriendlyName = DeviceFriendlyName "Badrum - Taklampa"
         Room = Bathroom
         Bulb = IkeaBulb }
-      { FriendlyName = "Sovrum - Nattduksbordlampa"
+      { FriendlyName = DeviceFriendlyName "Sovrum - Nattduksbordlampa"
         Room = Bedroom
         Bulb = IkeaBulb } ]
diff --git a/NightLight.Core/ZigbeeCommands.fs b/NightLight.Core/ZigbeeCommands.fs
index 6df6e85..2d25c04 100644
--- a/NightLight.Core/ZigbeeCommands.fs
+++ b/NightLight.Core/ZigbeeCommands.fs
@@ -4,7 +4,7 @@ open System.Text.Json.Nodes
 open NightLight.Core.Models
 open NightLight.Core.Moods
 
-let generateZigbeeCommand friendlyName targetColor targetBrightness =
+let generateZigbeeCommand (friendlyName: DeviceFriendlyName) targetColor targetBrightness =
     let commandObj = JsonObject()
 
     match targetColor with
@@ -19,7 +19,7 @@ let generateZigbeeCommand friendlyName targetColor targetBrightness =
         match targetBrightness with
         | Brightness b -> b
 
-    let topic = $"zigbee2mqtt/{friendlyName}/set"
+    let topic = $"zigbee2mqtt/{friendlyName.Get}/set"
     let payload = commandObj.ToJsonString()
 
     { Topic = topic; Payload = payload }
diff --git a/NightLight.Core/ZigbeeEvents.fs b/NightLight.Core/ZigbeeEvents.fs
index b435698..e6a9769 100644
--- a/NightLight.Core/ZigbeeEvents.fs
+++ b/NightLight.Core/ZigbeeEvents.fs
@@ -4,7 +4,7 @@ open NightLight.Core.Models
 open FsToolkit.ErrorHandling
 open FSharp.Data
 
-type ZigbeeEvent = DeviceAnnounce of FriendlyName: string
+type ZigbeeEvent = DeviceAnnounce of DeviceFriendlyName
 
 let parseZigbeeEvent (message: Message) =
     result {
@@ -17,7 +17,7 @@ let parseZigbeeEvent (message: Message) =
             match messageType with
             | JsonValue.String "device_announce" ->
                 match messageData.TryGetProperty "friendly_name" with
-                | Some(JsonValue.String friendlyName) -> Ok(DeviceAnnounce friendlyName)
+                | Some(JsonValue.String friendlyName) -> Ok <| DeviceAnnounce(DeviceFriendlyName friendlyName)
                 | Some _ -> Error InvalidFriendlyNameField
                 | None -> Error MissingFriendlyNameField
             | JsonValue.String _ -> Error UnknownType