From 490243638b9923d0d2604e5380b9fc7aa5696df9 Mon Sep 17 00:00:00 2001
From: Daniel Raper <me@danr.uk>
Date: Sun, 31 Dec 2023 00:31:57 +0000
Subject: [PATCH] Added experimental charge state monitoring

---
 custom_components/ohme/binary_sensor.py | 74 +++++++++++++++++++++++--
 1 file changed, 69 insertions(+), 5 deletions(-)

diff --git a/custom_components/ohme/binary_sensor.py b/custom_components/ohme/binary_sensor.py
index d8bad2b..92af83d 100644
--- a/custom_components/ohme/binary_sensor.py
+++ b/custom_components/ohme/binary_sensor.py
@@ -1,6 +1,6 @@
 """Platform for sensor integration."""
 from __future__ import annotations
-
+import logging
 from homeassistant.components.binary_sensor import (
     BinarySensorDeviceClass,
     BinarySensorEntity
@@ -12,7 +12,9 @@
 from .const import DOMAIN, DATA_COORDINATORS, COORDINATOR_CHARGESESSIONS, DATA_CLIENT
 from .coordinator import OhmeChargeSessionsCoordinator
 from .utils import charge_graph_in_slot
+from time import time
 
+_LOGGER = logging.getLogger(__name__)
 
 async def async_setup_entry(
     hass: core.HomeAssistant,
@@ -97,6 +99,13 @@ def __init__(
         self._state = False
         self._client = client
 
+        # Cache the last power readings
+        self._last_reading = None
+        self._last_reading_in_slot = False
+
+        # Allow a state override
+        self._override_until = None
+
         self.entity_id = generate_entity_id(
             "binary_sensor.{}", "ohme_car_charging", hass=hass)
 
@@ -115,13 +124,68 @@ def unique_id(self) -> str:
 
     @property
     def is_on(self) -> bool:
-        if self.coordinator.data and self.coordinator.data["power"]:
-            # Assume the car is actively charging if drawing over 0 watts
-            self._state = self.coordinator.data["power"]["watt"] > 0
+        return self._state
+
+    def _calculate_state(self) -> bool:
+        """Some trickery to get the charge state to update quickly."""
+        # If we have overriden the state, return the current value until that time
+        if self._override_until and time() < self._override_until:
+            _LOGGER.debug("State overridden to False for 310s")
+            return self._state
+
+        # We have passed override check, reset it
+        self._override_until = None
+
+        power = self.coordinator.data["power"]["watt"]
+
+        # No last reading to go off, use power draw based state only - this lags
+        if not self._last_reading:
+            _LOGGER.debug("Last reading not found, default to power > 0")
+            return power > 0
+
+        # Get power from last reading
+        lr_power = self._last_reading["power"]["watt"]
+
+        # See if we are in a charge slot now and if we were for the last reading
+        in_charge_slot = charge_graph_in_slot(
+            self.coordinator.data['startTime'], self.coordinator.data['chargeGraph']['points'])
+        lr_in_charge_slot = self._last_reading_in_slot
+
+        # Store this for next time
+        self._last_reading_in_slot = in_charge_slot
+
+        # If:
+        # - Power has dropped by 40% since the last reading
+        # - Last reading we were in a charge slot
+        # - Now we are not in a charge slot
+        # The charge has stopped but the power reading is lagging.
+        if lr_power > 0 and power / lr_power < 0.6 and not in_charge_slot and lr_in_charge_slot:
+            _LOGGER.debug("Charge stop behaviour seen - overriding to False for 310 seconds")
+            self._override_until = time() + 310  # Override for 5 mins (and a bit)
+            return False
+
+        # Its possible that this is the 'transitionary' reading - slots updated but not power
+        # Override _last_reading_in_slot and see what happens next time around
+        elif lr_power > 0 and not in_charge_slot and lr_in_charge_slot:
+            _LOGGER.debug("Possible transitionary reading. Treating as slot boundary in next tick.")
+            self._last_reading_in_slot = True
+
+        # Fallback to the old way
+        return power > 0
+
+    @callback
+    def _handle_coordinator_update(self) -> None:
+        """Update data."""
+        # If we have power info and the car is plugged in, calculate state. Otherwise, false
+        if self.coordinator.data and self.coordinator.data["power"] and self.coordinator.data['mode'] != "DISCONNECTED":
+            self._state = self._calculate_state()
         else:
             self._state = False
 
-        return self._state
+        self._last_reading = self.coordinator.data
+        self._last_updated = utcnow()
+
+        self.async_write_ha_state()
 
 
 class PendingApprovalBinarySensor(