Improved validation for Addressable Light Partition Segments (#2439)

Co-authored-by: Otto Winter <otto@otto-winter.com>

esphome/components/partition/light.py

@@ -1,11 +1,13 @@
 import esphome.codegen as cg
 import esphome.config_validation as cv
+import esphome.final_validate as fv
 from esphome.components import light
 from esphome.const import (
     CONF_ADDRESSABLE_LIGHT_ID,
     CONF_FROM,
     CONF_ID,
     CONF_LIGHT_ID,
+    CONF_NUM_LEDS,
     CONF_SEGMENTS,
     CONF_SINGLE_LIGHT_ID,
     CONF_TO,
@@ -31,6 +33,27 @@ def validate_from_to(value):
     return value
 
 
+def validate_segment(config):
+    fconf = fv.full_config.get()
+
+    if CONF_ID in config:  # only validate addressable segments
+        path = fconf.get_path_for_id(config[CONF_ID])[:-1]
+        segment_light_config = fconf.get_config_for_path(path)
+
+        if CONF_NUM_LEDS in segment_light_config:
+            segment_len = segment_light_config[CONF_NUM_LEDS]
+            if config[CONF_FROM] >= segment_len:
+                raise cv.Invalid(
+                    f"FROM ({config[CONF_FROM]}) must be less than the number of LEDs in light '{config[CONF_ID]}' ({segment_len})",
+                    [CONF_FROM],
+                )
+            if config[CONF_TO] >= segment_len:
+                raise cv.Invalid(
+                    f"TO ({config[CONF_TO]}) must be less than the number of LEDs in light '{config[CONF_ID]}' ({segment_len})",
+                    [CONF_TO],
+                )
+
+
 ADDRESSABLE_SEGMENT_SCHEMA = cv.Schema(
     {
         cv.Required(CONF_ID): cv.use_id(light.AddressableLightState),
@@ -63,6 +86,13 @@ CONFIG_SCHEMA = light.ADDRESSABLE_LIGHT_SCHEMA.extend(
     }
 )
 
+FINAL_VALIDATE_SCHEMA = cv.Schema(
+    {
+        cv.Required(CONF_SEGMENTS): [validate_segment],
+    },
+    extra=cv.ALLOW_EXTRA,
+)
+
 
 async def to_code(config):
     segments = []