Add ClickSend notify service. (home-assistant#8135)

* Add ClickSend notify service.

* PR home-assistant#8135 changes.

- Some code spacing fixes.
- Add timeout to requests.
- Change doc url.
- Use const.py as much as possible.
- Check credentials to determine if setup fails or not.
- Add docstrings.
- Use string formatting.

* PR home-assistant#8135 changes.

- Remove unused variables.
- Continuation line under-indented for visual indent.

* PR home-assistant#8135 changes.

- Format code based on PEP8.

* PR home-assistant#8135 changes.

- Remove unused base64 dependency.

* PR home-assistant#8135 changes.

- Fix: D205: 1 blank line required between summary line and description (found 0)
- Fix: standard import "import json" comes before "import requests"

* PR home-assistant#8135 changes.

- Add files to .coveragerc

* Remove obvious comments and set constant

.coveragerc

@@ -342,6 +342,7 @@ omit =
     homeassistant/components/notify/aws_sns.py
     homeassistant/components/notify/aws_sqs.py
     homeassistant/components/notify/ciscospark.py
+    homeassistant/components/notify/clicksend.py
     homeassistant/components/notify/discord.py
     homeassistant/components/notify/facebook.py
     homeassistant/components/notify/free_mobile.py

homeassistant/components/notify/clicksend.py

@@ -0,0 +1,80 @@
+"""
+Clicksend platform for notify component.
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/notify.clicksend/
+"""
+import json
+import logging
+import requests
+
+import voluptuous as vol
+
+import homeassistant.helpers.config_validation as cv
+from homeassistant.const import (
+    CONF_USERNAME, CONF_API_KEY, CONF_RECIPIENT, HTTP_HEADER_CONTENT_TYPE,
+    CONTENT_TYPE_JSON)
+from homeassistant.components.notify import (
+    PLATFORM_SCHEMA, BaseNotificationService)
+
+_LOGGER = logging.getLogger(__name__)
+
+BASE_API_URL = 'https://rest.clicksend.com/v3'
+
+HEADERS = {HTTP_HEADER_CONTENT_TYPE: CONTENT_TYPE_JSON}
+
+PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
+    vol.Required(CONF_USERNAME): cv.string,
+    vol.Required(CONF_API_KEY): cv.string,
+    vol.Required(CONF_RECIPIENT): cv.string,
+})
+
+
+def get_service(hass, config, discovery_info=None):
+    """Get the ClickSend notification service."""
+    if _authenticate(config) is False:
+        _LOGGER.exception("You are not authorized to access ClickSend")
+        return None
+
+    return ClicksendNotificationService(config)
+
+
+class ClicksendNotificationService(BaseNotificationService):
+    """Implementation of a notification service for the ClickSend service."""
+
+    def __init__(self, config):
+        """Initialize the service."""
+        self.username = config.get(CONF_USERNAME)
+        self.api_key = config.get(CONF_API_KEY)
+        self.recipient = config.get(CONF_RECIPIENT)
+
+    def send_message(self, message="", **kwargs):
+        """Send a message to a user."""
+        data = ({'messages': [{'source': 'hass.notify', 'from': self.recipient,
+                               'to': self.recipient, 'body': message}]})
+
+        api_url = "{}/sms/send".format(BASE_API_URL)
+
+        resp = requests.post(api_url, data=json.dumps(data), headers=HEADERS,
+                             auth=(self.username, self.api_key), timeout=5)
+
+        obj = json.loads(resp.text)
+        response_msg = obj['response_msg']
+        response_code = obj['response_code']
+
+        if resp.status_code != 200:
+            _LOGGER.error("Error %s : %s (Code %s)", resp.status_code,
+                          response_msg, response_code)
+
+
+def _authenticate(config):
+    """Authenticate with ClickSend."""
+    api_url = '{}/account'.format(BASE_API_URL)
+    resp = requests.get(api_url, headers=HEADERS,
+                        auth=(config.get(CONF_USERNAME),
+                              config.get(CONF_API_KEY)), timeout=5)
+
+    if resp.status_code != 200:
+        return False
+
+    return True