Add light restore mode

I don't want users to rely on setup priority.

Ref https://github.com/esphome/esphome-docs/pull/248

esphome/components/light/__init__.py

@@ -3,7 +3,7 @@ import esphome.config_validation as cv
 from esphome.components import mqtt, power_supply
 from esphome.const import CONF_COLOR_CORRECT, \
     CONF_DEFAULT_TRANSITION_LENGTH, CONF_EFFECTS, CONF_GAMMA_CORRECT, CONF_ID, \
-    CONF_INTERNAL, CONF_NAME, CONF_MQTT_ID, CONF_POWER_SUPPLY
+    CONF_INTERNAL, CONF_NAME, CONF_MQTT_ID, CONF_POWER_SUPPLY, CONF_RESTORE_MODE
 from esphome.core import coroutine, coroutine_with_priority
 from .automation import light_control_to_code  # noqa
 from .effects import validate_effects, BINARY_EFFECTS, \
@@ -12,9 +12,20 @@ from .types import (  # noqa
     LightState, AddressableLightState, light_ns, LightOutput, AddressableLight)
 
 IS_PLATFORM_COMPONENT = True
+
+LightRestoreMode = light_ns.enum('LightRestoreMode')
+RESTORE_MODES = {
+    'RESTORE_DEFAULT_OFF': LightRestoreMode.LIGHT_RESTORE_DEFAULT_OFF,
+    'RESTORE_DEFAULT_ON': LightRestoreMode.LIGHT_RESTORE_DEFAULT_ON,
+    'ALWAYS_OFF': LightRestoreMode.LIGHT_ALWAYS_OFF,
+    'ALWAYS_ON': LightRestoreMode.LIGHT_ALWAYS_ON,
+}
+
 LIGHT_SCHEMA = cv.MQTT_COMMAND_COMPONENT_SCHEMA.extend({
     cv.GenerateID(): cv.declare_id(LightState),
     cv.OnlyWith(CONF_MQTT_ID, 'mqtt'): cv.declare_id(mqtt.MQTTJSONLightComponent),
+    cv.Optional(CONF_RESTORE_MODE, default='restore_default_off'):
+        cv.enum(RESTORE_MODES, upper=True, space='_'),
 })
 
 BINARY_LIGHT_SCHEMA = LIGHT_SCHEMA.extend({
@@ -41,6 +52,7 @@ ADDRESSABLE_LIGHT_SCHEMA = RGB_LIGHT_SCHEMA.extend({
 
 @coroutine
 def setup_light_core_(light_var, output_var, config):
+    cg.add(light_var.set_restore_mode(config[CONF_RESTORE_MODE]))
     if CONF_INTERNAL in config:
         cg.add(light_var.set_internal(config[CONF_INTERNAL]))
     if CONF_DEFAULT_TRANSITION_LENGTH in config:

esphome/components/light/light_state.cpp

@@ -98,12 +98,25 @@ void LightState::setup() {
     effect->init_internal(this);
   }
 
-  this->rtc_ = global_preferences.make_preference<LightStateRTCState>(this->get_object_id_hash());
-  LightStateRTCState recovered{};
-  // Attempt to load from preferences, else fall back to default values from struct
-  this->rtc_.load(&recovered);
-
   auto call = this->make_call();
+  LightStateRTCState recovered{};
+  switch (this->restore_mode_) {
+    case LIGHT_RESTORE_DEFAULT_OFF:
+    case LIGHT_RESTORE_DEFAULT_ON:
+      this->rtc_ = global_preferences.make_preference<LightStateRTCState>(this->get_object_id_hash());
+      // Attempt to load from preferences, else fall back to default values from struct
+      if (!this->rtc_.load(&recovered)) {
+        recovered.state = this->restore_mode_ == LIGHT_RESTORE_DEFAULT_ON;
+      }
+      break;
+    case LIGHT_ALWAYS_OFF:
+      recovered.state = false;
+      break;
+    case LIGHT_ALWAYS_ON:
+      recovered.state = true;
+      break;
+  }
+
   call.set_state(recovered.state);
   call.set_brightness_if_supported(recovered.brightness);
   call.set_red_if_supported(recovered.red);

esphome/components/light/light_state.h

@@ -160,6 +160,13 @@ class LightCall {
   bool save_{true};
 };
 
+enum LightRestoreMode {
+  LIGHT_RESTORE_DEFAULT_OFF,
+  LIGHT_RESTORE_DEFAULT_ON,
+  LIGHT_ALWAYS_OFF,
+  LIGHT_ALWAYS_ON,
+};
+
 /** This class represents the communication layer between the front-end MQTT layer and the
  * hardware output layer.
  */
@@ -249,6 +256,7 @@ class LightState : public Nameable, public Component {
   /// Set the gamma correction factor
   void set_gamma_correct(float gamma_correct);
   float get_gamma_correct() const { return this->gamma_correct_; }
+  void set_restore_mode(LightRestoreMode restore_mode) { restore_mode_ = restore_mode; }
 
   const std::vector<LightEffect *> &get_effects() const;
 
@@ -292,6 +300,8 @@ class LightState : public Nameable, public Component {
 
   /// Object used to store the persisted values of the light.
   ESPPreferenceObject rtc_;
+  /// Restore mode of the light.
+  LightRestoreMode restore_mode_;
   /// Default transition length for all transitions in ms.
   uint32_t default_transition_length_{};
   /// Value for storing the index of the currently active effect. 0 if no effect is active