Move manual configuration of MQTT fan and light to the integration key (#71676)

* Processing yaml config through entry setup

* Setup all platforms

* Update homeassistant/components/mqtt/__init__.py

Co-authored-by: Martin Hjelmare <marhje52@gmail.com>

* adjust mock_mqtt - reference config from cache

* Fix test config entry override

* Add tests yaml setup

* additional tests

* Introduce PLATFORM_SCHEMA_MODERN

* recover temporary MQTT_BASE_PLATFORM_SCHEMA

* Allow extra key in light base schema, restore test

* Fix test for exception on platform key

* One deprecation message per platform

* Remove deprecation checks from modern schema

* Update homeassistant/components/mqtt/fan.py

Co-authored-by: Erik Montnemery <erik@montnemery.com>

* Update homeassistant/components/mqtt/fan.py

Co-authored-by: Erik Montnemery <erik@montnemery.com>

* Update homeassistant/components/mqtt/light/__init__.py

Co-authored-by: Erik Montnemery <erik@montnemery.com>

* Update homeassistant/components/mqtt/light/__init__.py

Co-authored-by: Erik Montnemery <erik@montnemery.com>

* Update homeassistant/components/mqtt/light/schema_json.py

Co-authored-by: Erik Montnemery <erik@montnemery.com>

* Update homeassistant/components/mqtt/light/schema_template.py

Co-authored-by: Erik Montnemery <erik@montnemery.com>

* Update homeassistant/components/mqtt/mixins.py

Co-authored-by: Erik Montnemery <erik@montnemery.com>

* rename validate_modern_schema

* Do not fail platform if a single config is broken

* Update homeassistant/components/mqtt/__init__.py

Co-authored-by: Erik Montnemery <erik@montnemery.com>

* Fix tests on asserting log

* Update log. Make helper transparant, remove patch

* Perform parallel processing

* Update tests/components/mqtt/test_init.py

Co-authored-by: Martin Hjelmare <marhje52@gmail.com>

* Apply suggestions from code review

Co-authored-by: Martin Hjelmare <marhje52@gmail.com>

* Update homeassistant/components/mqtt/mixins.py

Co-authored-by: Martin Hjelmare <marhje52@gmail.com>

* black

* Fix tests and add #new_format anchor

Co-authored-by: Martin Hjelmare <marhje52@gmail.com>
Co-authored-by: Erik Montnemery <erik@montnemery.com>

homeassistant/components/mqtt/mixins.py

@@ -9,6 +9,7 @@ from typing import Any, Protocol, cast, final
 
 import voluptuous as vol
 
+from homeassistant.config import async_log_exception
 from homeassistant.config_entries import ConfigEntry
 from homeassistant.const import (
     ATTR_CONFIGURATION_URL,
@@ -64,6 +65,7 @@ from .const import (
     CONF_ENCODING,
     CONF_QOS,
     CONF_TOPIC,
+    DATA_MQTT_CONFIG,
     DATA_MQTT_RELOAD_NEEDED,
     DEFAULT_ENCODING,
     DEFAULT_PAYLOAD_AVAILABLE,
@@ -223,6 +225,31 @@ MQTT_ENTITY_COMMON_SCHEMA = MQTT_AVAILABILITY_SCHEMA.extend(
 )
 
 
+def warn_for_legacy_schema(domain: str) -> Callable:
+    """Warn once when a legacy platform schema is used."""
+    warned = set()
+
+    def validator(config: ConfigType) -> ConfigType:
+        """Return a validator."""
+        nonlocal warned
+
+        if domain in warned:
+            return config
+
+        _LOGGER.warning(
+            "Manually configured MQTT %s(s) found under platform key '%s', "
+            "please move to the mqtt integration key, see "
+            "https://www.home-assistant.io/integrations/%s.mqtt/#new_format",
+            domain,
+            domain,
+            domain,
+        )
+        warned.add(domain)
+        return config
+
+    return validator
+
+
 class SetupEntity(Protocol):
     """Protocol type for async_setup_entities."""
 
@@ -237,6 +264,31 @@ class SetupEntity(Protocol):
         """Define setup_entities type."""
 
 
+async def async_get_platform_config_from_yaml(
+    hass: HomeAssistant, domain: str, schema: vol.Schema
+) -> list[ConfigType]:
+    """Return a list of validated configurations for the domain."""
+
+    def async_validate_config(
+        hass: HomeAssistant,
+        config: list[ConfigType],
+    ) -> list[ConfigType]:
+        """Validate config."""
+        validated_config = []
+        for config_item in config:
+            try:
+                validated_config.append(schema(config_item))
+            except vol.MultipleInvalid as err:
+                async_log_exception(err, domain, config_item, hass)
+
+        return validated_config
+
+    config_yaml: ConfigType = hass.data.get(DATA_MQTT_CONFIG, {})
+    if not (platform_configs := config_yaml.get(domain)):
+        return []
+    return async_validate_config(hass, platform_configs)
+
+
 async def async_setup_entry_helper(hass, domain, async_setup, schema):
     """Set up entity, automation or tag creation dynamically through MQTT discovery."""