Expose "acknowledge alarm" functionality over MQTT and HTTP

Closes #114

A button is exposed to Home Assistant and a POST /alarm/acknowledge route is exposed via HTTP

app/homeassistant.mjs

@@ -337,12 +337,22 @@ export const configureMqttDiscovery = async (modbusClient, mqttClient) => {
         'defrosting': createDeviceStateConfiguration(configurationBase, 'defrosting', 'Defrosting'),
     }
 
+    // Button for acknowledging alarms
+    const buttonConfigurationMap = {
+        'acknowledgeAlarm': createButtonConfiguration(
+            configurationBase,
+            'acknowledgeAlarm',
+            'Acknowledge newest alarm'
+        ),
+    }
+
     // Final map that describes everything we want to be auto-discovered
     const configurationMap = {
         'sensor': sensorConfigurationMap,
         'number': numberConfigurationMap,
         'switch': switchConfigurationMap,
         'binary_sensor': binarySensorConfigurationMap,
+        'button': buttonConfigurationMap,
     }
 
     // Publish configurations
@@ -476,3 +486,13 @@ const createDeviceStateConfiguration = (configurationBase, stateName, entityName
         'entity_category': 'diagnostic',
     }
 }
+
+const createButtonConfiguration = (configurationBase, buttonName, entityName) => {
+    return {
+        ...configurationBase,
+        'unique_id': `eda-button-${buttonName}`,
+        'name': entityName,
+        'object_id': `eda_button_${buttonName}`,
+        'command_topic': `${TOPIC_PREFIX_ALARM}/acknowledge`,
+    }
+}

app/http.mjs

@@ -6,6 +6,7 @@ import {
     getSettings,
     setMode as modbusSetMode,
     setSetting as modbusSetSetting,
+    acknowledgeAlarm as modbusAcknowledgeAlarm,
     getDeviceState,
     getNewestAlarm,
     getAlarmSummary,
@@ -92,6 +93,16 @@ const setSetting = async (modbusClient, req, res) => {
     }
 }
 
+const acknowledgeAlarm = async (modbusClient, req, res) => {
+    try {
+        logger.info('Acknowledging currently active alarm (if any)')
+
+        await modbusAcknowledgeAlarm(modbusClient)
+    } catch (e) {
+        handleError(e, res)
+    }
+}
+
 export const configureRoutes = (httpServer, modbusClient) => {
     httpServer.get('/', root)
     httpServer.get('/summary', (req, res) => {
@@ -106,6 +117,9 @@ export const configureRoutes = (httpServer, modbusClient) => {
     httpServer.post('/setting/:setting/:value', (req, res) => {
         return setSetting(modbusClient, req, res)
     })
+    httpServer.post('/alarm/acknowledge', (req, res) => {
+        return acknowledgeAlarm(modbusClient, req, res)
+    })
 }
 
 const handleError = (e, res, statusCode = undefined) => {

app/modbus.mjs

@@ -374,6 +374,10 @@ export const getNewestAlarm = async (modbusClient) => {
     }
 }
 
+export const acknowledgeAlarm = async (modbusClient) => {
+    await tryWriteHoldingRegister(modbusClient, 386, 1)
+}
+
 export const getDeviceState = async (modbusClient) => {
     const result = await mutex.runExclusive(async () => tryReadHoldingRegisters(modbusClient, 44, 1))
 

app/mqtt.mjs

@@ -7,6 +7,7 @@ import {
     setMode,
     getAlarmSummary,
     getDeviceState,
+    acknowledgeAlarm,
 } from './modbus.mjs'
 import { createLogger } from './logger.mjs'
 
@@ -121,8 +122,12 @@ const publishTopics = async (mqttClient, topicMap, publishOptions = {}) => {
 }
 
 export const subscribeToChanges = async (modbusClient, mqttClient) => {
-    // Subscribe to settings and mode changes
-    const topicNames = [`${TOPIC_PREFIX_MODE}/+/set`, `${TOPIC_PREFIX_SETTINGS}/+/set`]
+    // Subscribe to writable topics
+    const topicNames = [
+        `${TOPIC_PREFIX_MODE}/+/set`,
+        `${TOPIC_PREFIX_SETTINGS}/+/set`,
+        `${TOPIC_PREFIX_ALARM}/acknowledge`,
+    ]
 
     for (const topicName of topicNames) {
         logger.info(`Subscribing to topic(s) ${topicName}`)
@@ -136,21 +141,27 @@ export const handleMessage = async (modbusClient, mqttClient, topicName, rawPayl
 
     const payload = parsePayload(rawPayload)
 
-    // Handle settings updates
     if (topicName.startsWith(TOPIC_PREFIX_SETTINGS) && topicName.endsWith('/set')) {
+        // Handle settings updates
         const settingName = topicName.substring(TOPIC_PREFIX_SETTINGS.length + 1, topicName.lastIndexOf('/'))
 
         logger.info(`Updating setting ${settingName} to ${payload}`)
 
         await setSetting(modbusClient, settingName, payload)
         await publishSettings(modbusClient, mqttClient)
     } else if (topicName.startsWith(TOPIC_PREFIX_MODE) && topicName.endsWith('/set')) {
+        // Handle mode changes
         const mode = topicName.substring(TOPIC_PREFIX_MODE.length + 1, topicName.lastIndexOf('/'))
 
         logger.info(`Updating mode ${mode} to ${payload}`)
 
         await setMode(modbusClient, mode, payload)
         await publishModeSummary(modbusClient, mqttClient)
+    } else if (topicName.startsWith(TOPIC_PREFIX_ALARM) && topicName.endsWith('/acknowledge')) {
+        // Acknowledge alarm
+        logger.info('Acknowledging currently active alarm (if any)')
+
+        await acknowledgeAlarm(modbusClient)
     }
 }