fix: improve alert filtering with time window and deduplication

- Add showAlertsHours config option (default: 12 hours)
- Filter alerts to only show those starting within configured time window
- Remove duplicate alert names when same alert spans multiple days
- Change showAlerts default from false to true
- Update README documentation with new option and examples

This fixes the issue where duplicate alerts were shown (e.g., "Winter Weather Advisory" appearing 3 times for alerts spanning today and tomorrow).

Author: KristjanESPERANTO

MMM-OneCallWeather.js

@@ -42,6 +42,7 @@ Module.register('MMM-OneCallWeather', {
     showCurrent: true,
     showForecast: true,
     showAlerts: true,
+    showAlertsHours: 12,
     forecastLayout: 'columns', // "columns" (days as columns) or "rows" (days as rows)
     arrangement: 'vertical', // "vertical" (forecast below current) or "horizontal" (forecast next to current)
 
@@ -694,13 +695,23 @@ Module.register('MMM-OneCallWeather', {
       currentCell4.colSpan = colspan
       currentCell4.className = 'alert'
 
+      const now = Date.now() / 1000
+      const alertWindow = now + (this.config.showAlertsHours * 3600)
+
       const validAlerts = currentWeather.alerts
-        .filter(alert => alert?.event)
+        .filter(alert =>
+          alert?.event
+          && alert.start < alertWindow  // Starts within the configured time window
+          && alert.end > now,             // Is still active (not expired)
+        )
         .map(alert => alert.event)
 
-      if (validAlerts.length > 0) {
+      // Remove duplicates (e.g., same alert for today and tomorrow)
+      const uniqueAlerts = [...new Set(validAlerts)]
+
+      if (uniqueAlerts.length > 0) {
         const fragment = document.createDocumentFragment()
-        for (const [index, alertEvent] of validAlerts.entries()) {
+        for (const [index, alertEvent] of uniqueAlerts.entries()) {
           if (index > 0) {
             fragment.appendChild(document.createElement('br'))
           }

README.md

@@ -92,7 +92,8 @@ The following properties can be configured:
 | `windUnits`          | The units to use for wind speed.<br><br>**Possible values:** `"mph"` (miles per hour), `"kmph"` (kilometers per hour), `"ms"` (meters per second)<br>**Default value:** `"mph"`<br>This value is optional. By default the weatherforecast module will display wind speed in miles per hour.                                                                                                            |
 | `roundTemp`          | Round temperature values to nearest integer.<br><br>**Possible values:** `true` (round to integer) or `false` (display exact value with decimal point)<br>**Default value:** `false`                                                                                                                                                                                                                   |
 | `showCurrent`        | Show the current weather section.<br><br>**Possible values:** `true` or `false`<br>**Default value:** `true`                                                                                                                                                                                                                                                                                           |
-| `showAlerts`         | Show weather alerts from the OpenWeatherMap API in the current weather section. Displays the alert event names (e.g., "Severe Thunderstorm Warning"). Multiple alerts are shown on separate lines.<br><br>**Possible values:** `true` or `false`<br>**Default value:** `false`<br>**Note:** Alerts are only available with certain OpenWeatherMap API plans and for locations where alerts are issued. |
+| `showAlerts`         | Show weather alerts from the OpenWeatherMap API in the current weather section. Displays the alert event names (e.g., "Severe Thunderstorm Warning"). Multiple alerts are shown on separate lines.<br><br>**Possible values:** `true` or `false`<br>**Default value:** `true`<br>**Note:** Alerts are only available with certain OpenWeatherMap API plans and for locations where alerts are issued. Duplicate alerts are automatically filtered. |
+| `showAlertsHours`    | Time window (in hours) for displaying weather alerts. Only alerts that start within this time window and are still active are shown.<br><br>**Possible values:** Any positive number<br>**Default value:** `12` (shows alerts for the next 12 hours)<br>**Example:** Set to `24` to see alerts for the next day, or `6` for only the next 6 hours. |
 | `showForecast`       | Show the forecast section.<br><br>**Possible values:** `true` or `false`<br>**Default value:** `true`                                                                                                                                                                                                                                                                                                  |
 | `forecastLayout`     | Defines how the forecast is structured internally.<br><br>**Possible values:** `"columns"` (days displayed as table columns), `"rows"` (days displayed as table rows)<br>**Default value:** `"columns"`                                                                                                                                                                                                |
 | `arrangement`        | How current weather and forecast are positioned relative to each other (only relevant when both `showCurrent` and `showForecast` are `true`).<br><br>**Possible values:** `"vertical"` (forecast below current weather), `"horizontal"` (forecast next to current weather)<br>**Default value:** `"vertical"`                                                                                          |