From 5fd14eade570eeaf004609d9ea996b1a9ef4a9f8 Mon Sep 17 00:00:00 2001
From: Russell Cloran <rcloran@gmail.com>
Date: Sat, 2 Sep 2023 01:20:36 -0700
Subject: [PATCH] Handle timestamp sensors in Prometheus integration (#98001)

---
 homeassistant/components/prometheus/__init__.py | 16 +++++++++++++++-
 tests/components/prometheus/test_init.py        | 16 ++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/homeassistant/components/prometheus/__init__.py b/homeassistant/components/prometheus/__init__.py
index e5d7f6cb060..adc5225b286 100644
--- a/homeassistant/components/prometheus/__init__.py
+++ b/homeassistant/components/prometheus/__init__.py
@@ -19,6 +19,7 @@ from homeassistant.components.climate import (
 from homeassistant.components.cover import ATTR_POSITION, ATTR_TILT_POSITION
 from homeassistant.components.http import HomeAssistantView
 from homeassistant.components.humidifier import ATTR_AVAILABLE_MODES, ATTR_HUMIDITY
+from homeassistant.components.sensor import SensorDeviceClass
 from homeassistant.const import (
     ATTR_BATTERY_LEVEL,
     ATTR_DEVICE_CLASS,
@@ -44,6 +45,7 @@ import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.entity_registry import EVENT_ENTITY_REGISTRY_UPDATED
 from homeassistant.helpers.entity_values import EntityValues
 from homeassistant.helpers.typing import ConfigType
+from homeassistant.util.dt import as_timestamp
 from homeassistant.util.unit_conversion import TemperatureConverter
 
 _LOGGER = logging.getLogger(__name__)
@@ -147,6 +149,7 @@ class PrometheusMetrics:
         self._sensor_metric_handlers = [
             self._sensor_override_component_metric,
             self._sensor_override_metric,
+            self._sensor_timestamp_metric,
             self._sensor_attribute_metric,
             self._sensor_default_metric,
             self._sensor_fallback_metric,
@@ -292,7 +295,10 @@ class PrometheusMetrics:
     def state_as_number(state):
         """Return a state casted to a float."""
         try:
-            value = state_helper.state_as_number(state)
+            if state.attributes.get(ATTR_DEVICE_CLASS) == SensorDeviceClass.TIMESTAMP:
+                value = as_timestamp(state.state)
+            else:
+                value = state_helper.state_as_number(state)
         except ValueError:
             _LOGGER.debug("Could not convert %s to float", state)
             value = 0
@@ -576,6 +582,14 @@ class PrometheusMetrics:
             return f"sensor_{metric}_{unit}"
         return None
 
+    @staticmethod
+    def _sensor_timestamp_metric(state, unit):
+        """Get metric for timestamp sensors, which have no unit of measurement attribute."""
+        metric = state.attributes.get(ATTR_DEVICE_CLASS)
+        if metric == SensorDeviceClass.TIMESTAMP:
+            return f"sensor_{metric}_seconds"
+        return None
+
     def _sensor_override_metric(self, state, unit):
         """Get metric from override in configuration."""
         if self._override_metric:
diff --git a/tests/components/prometheus/test_init.py b/tests/components/prometheus/test_init.py
index 446666c4a6a..82a205eb259 100644
--- a/tests/components/prometheus/test_init.py
+++ b/tests/components/prometheus/test_init.py
@@ -232,6 +232,12 @@ async def test_sensor_device_class(client, sensor_entities) -> None:
         'friendly_name="Radio Energy"} 14.0' in body
     )
 
+    assert (
+        'sensor_timestamp_seconds{domain="sensor",'
+        'entity="sensor.timestamp",'
+        'friendly_name="Timestamp"} 1.691445808136036e+09' in body
+    )
+
 
 @pytest.mark.parametrize("namespace", [""])
 async def test_input_number(client, input_number_entities) -> None:
@@ -1049,6 +1055,16 @@ async def sensor_fixture(
     set_state_with_entry(hass, sensor_11, 50)
     data["sensor_11"] = sensor_11
 
+    sensor_12 = entity_registry.async_get_or_create(
+        domain=sensor.DOMAIN,
+        platform="test",
+        unique_id="sensor_12",
+        original_device_class=SensorDeviceClass.TIMESTAMP,
+        suggested_object_id="Timestamp",
+        original_name="Timestamp",
+    )
+    set_state_with_entry(hass, sensor_12, "2023-08-07T15:03:28.136036-0700")
+    data["sensor_12"] = sensor_12
     await hass.async_block_till_done()
     return data