From 4b766f54aeedccdc97f676f65d12e3603f91f5dd Mon Sep 17 00:00:00 2001
From: Travis Shears <t@travisshears.com>
Date: Tue, 24 Mar 2026 11:35:21 +0100
Subject: [PATCH 1/2] add sensor module that defines some basic sensor metadata

---
 src/mqtt_dummy.gleam     |  8 ++++++--
 src/sensors.gleam        | 38 ++++++++++++++++++++++++++++++++++++++
 src/weather_portal.gleam |  6 +++---
 3 files changed, 47 insertions(+), 5 deletions(-)
 create mode 100644 src/sensors.gleam

diff --git a/src/mqtt_dummy.gleam b/src/mqtt_dummy.gleam
index 5a3fdd7..0713e4c 100644
--- a/src/mqtt_dummy.gleam
+++ b/src/mqtt_dummy.gleam
@@ -1,9 +1,10 @@
 import gleam/erlang/process
 import gleam/list
 import gleam/otp/actor
+import sensors
 
 pub type Subscriber =
-  process.Subject(String)
+  process.Subject(sensors.SensorReading)
 
 pub type Message {
   Subscribe(subscriber: Subscriber)
@@ -24,7 +25,10 @@ fn handle_message(
     }
     Proc -> {
       list.each(subscribers, fn(subscriber) {
-        process.send(subscriber, "Hello from dummy mqtt action")
+        process.send(
+          subscriber,
+          sensors.SensorReading(sensors.Temperature, 26.6),
+        )
       })
       actor.continue(subscribers)
     }
diff --git a/src/sensors.gleam b/src/sensors.gleam
new file mode 100644
index 0000000..caf2db9
--- /dev/null
+++ b/src/sensors.gleam
@@ -0,0 +1,38 @@
+import gleam/float
+import gleam/io
+
+pub type Sensor {
+  Temperature
+  Humidity
+  Pressure
+  ParticalMatterOne
+  ParticalMatterTwoPointFive
+  ParticalMatterTen
+}
+
+pub type SensorReading {
+  SensorReading(sensor: Sensor, value: Float)
+}
+
+pub fn print_sensor_reading(reading: SensorReading) -> Nil {
+  let sensor_name = case reading.sensor {
+    Temperature -> "Temperature"
+    Humidity -> "Humidity"
+    Pressure -> "Pressure"
+    ParticalMatterOne -> "Partical matter 1 micron or less"
+    ParticalMatterTwoPointFive -> "Partical matter 2.5 micros or less"
+    ParticalMatterTen -> "Partical matter 10 microns or less"
+  }
+  io.println(sensor_name <> ": " <> float.to_string(reading.value))
+}
+
+pub fn sensor_unit(sensor: Sensor) -> String {
+  case sensor {
+    Temperature -> "°C"
+    Humidity -> "%"
+    Pressure -> "hPa"
+    ParticalMatterOne -> "µg/m³"
+    ParticalMatterTwoPointFive -> "µg/m³"
+    ParticalMatterTen -> "µg/m³"
+  }
+}
diff --git a/src/weather_portal.gleam b/src/weather_portal.gleam
index 1627003..2888f43 100644
--- a/src/weather_portal.gleam
+++ b/src/weather_portal.gleam
@@ -2,6 +2,7 @@ import config
 import gleam/erlang/process
 import gleam/io
 import mqtt_dummy
+import sensors
 
 pub fn main() -> Nil {
   case config.load_config() {
@@ -37,13 +38,12 @@ pub fn main() -> Nil {
 }
 
 fn receive_and_reschedule(
-  mailbox: process.Subject(String),
+  mailbox: process.Subject(sensors.SensorReading),
   subject: process.Subject(mqtt_dummy.Message),
 ) -> Nil {
   case process.receive(mailbox, 2000) {
     Ok(msg) -> {
-      io.println("Got message: " <> msg)
-      // Reschedule the next Proc message
+      sensors.print_sensor_reading(msg)
       process.send_after(subject, 1000, mqtt_dummy.Proc)
       receive_and_reschedule(mailbox, subject)
     }

From 113384b6ce84e63028076f917e1dde4870fa5497 Mon Sep 17 00:00:00 2001
From: Travis Shears <t@travisshears.com>
Date: Tue, 24 Mar 2026 11:48:46 +0100
Subject: [PATCH 2/2] add test for sensor_name and sensor_unit

---
 src/sensors.gleam       |  8 ++++++--
 test/sensors_test.gleam | 19 +++++++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)
 create mode 100644 test/sensors_test.gleam

diff --git a/src/sensors.gleam b/src/sensors.gleam
index caf2db9..0cc1df2 100644
--- a/src/sensors.gleam
+++ b/src/sensors.gleam
@@ -14,8 +14,8 @@ pub type SensorReading {
   SensorReading(sensor: Sensor, value: Float)
 }
 
-pub fn print_sensor_reading(reading: SensorReading) -> Nil {
-  let sensor_name = case reading.sensor {
+pub fn sensor_name(sensor: Sensor) -> String {
+  case sensor {
     Temperature -> "Temperature"
     Humidity -> "Humidity"
     Pressure -> "Pressure"
@@ -23,6 +23,10 @@ pub fn print_sensor_reading(reading: SensorReading) -> Nil {
     ParticalMatterTwoPointFive -> "Partical matter 2.5 micros or less"
     ParticalMatterTen -> "Partical matter 10 microns or less"
   }
+}
+
+pub fn print_sensor_reading(reading: SensorReading) -> Nil {
+  let sensor_name = sensor_name(reading.sensor)
   io.println(sensor_name <> ": " <> float.to_string(reading.value))
 }
 
diff --git a/test/sensors_test.gleam b/test/sensors_test.gleam
new file mode 100644
index 0000000..fd4ce0e
--- /dev/null
+++ b/test/sensors_test.gleam
@@ -0,0 +1,19 @@
+import gleeunit
+import gleeunit/should
+import sensors
+
+pub fn main() -> Nil {
+  gleeunit.main()
+}
+
+// gleeunit test functions end in `_test`
+pub fn file_read_test() {
+  let reading =
+    sensors.sensor_name(sensors.Temperature)
+    <> " "
+    <> "20.5"
+    <> " "
+    <> sensors.sensor_unit(sensors.Temperature)
+  reading
+  |> should.equal("Temperature 20.5 °C")
+}