Add SmartThings component and switch platform (#20148)

* Added SmartThings component and switch platform

* Corrected comment typos.

* Embedded switch platform.

* Replaced custom view usage with webhook component.

* Replaced urls with tokens in strings.

* Fixed line length.

* Use generated webhook id instead of static one.

* Reuse core constant instead of defining again.

* Optimizations in anticipation of future platforms.

* Use async_generate_path instead of hard-coded path.

* Fixed line length.

* Updates per review feedback.

* Updates per latest review feedback.

homeassistant/components/smartthings/switch.py

@@ -0,0 +1,70 @@
+"""
+Support for switches through the SmartThings cloud API.
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/smartthings.switch/
+"""
+from homeassistant.components.switch import SwitchDevice
+
+from . import SmartThingsEntity
+from .const import DATA_BROKERS, DOMAIN
+
+DEPENDENCIES = ['smartthings']
+
+
+async def async_setup_platform(hass, config, async_add_entities,
+                               discovery_info=None):
+    """Platform uses config entry setup."""
+    pass
+
+
+async def async_setup_entry(hass, config_entry, async_add_entities):
+    """Add switches for a config entry."""
+    broker = hass.data[DOMAIN][DATA_BROKERS][config_entry.entry_id]
+    async_add_entities(
+        [SmartThingsSwitch(device) for device in broker.devices.values()
+         if is_switch(device)])
+
+
+def is_switch(device):
+    """Determine if the device should be represented as a switch."""
+    from pysmartthings import Capability
+
+    # Must be able to be turned on/off.
+    if Capability.switch not in device.capabilities:
+        return False
+    # Must not have a capability represented by other types.
+    non_switch_capabilities = [
+        Capability.color_control,
+        Capability.color_temperature,
+        Capability.fan_speed,
+        Capability.switch_level
+    ]
+    if any(capability in device.capabilities
+           for capability in non_switch_capabilities):
+        return False
+
+    return True
+
+
+class SmartThingsSwitch(SmartThingsEntity, SwitchDevice):
+    """Define a SmartThings switch."""
+
+    async def async_turn_off(self, **kwargs) -> None:
+        """Turn the switch off."""
+        await self._device.switch_off(set_status=True)
+        # State is set optimistically in the command above, therefore update
+        # the entity state ahead of receiving the confirming push updates
+        self.async_schedule_update_ha_state()
+
+    async def async_turn_on(self, **kwargs) -> None:
+        """Turn the switch on."""
+        await self._device.switch_on(set_status=True)
+        # State is set optimistically in the command above, therefore update
+        # the entity state ahead of receiving the confirming push updates
+        self.async_schedule_update_ha_state()
+
+    @property
+    def is_on(self) -> bool:
+        """Return true if light is on."""
+        return self._device.status.switch