Populate headline post actions with @headline_post_action (#92)

* Populate headline post actions with @headline_post_action

Adds a decorator that allows easily populating actions in headline
posts, so that we can add custom integrations there (e.g. PagerDuty).

Also adds a post_to_thread method in HeadlinePost

* Add docs + logging for @headline_post_action

docs/development.md

@@ -65,4 +65,32 @@ def handle_close_incident(action_context: ActionContext):
     incident = action_context.incident
     incident.end_time = datetime.now()
     incident.save()
-```
+```
+
+### Headline Post Actions
+
+When a new incident is created, we create a "headline post" message in the central incidents channel. We add action buttons here - by default allowing creating an incident channel, editing the incident or closing. There is a decorator that allows you to add custom action buttons here - `@headline_post_action`.
+
+For example:
+```
+from response.slack import block_kit
+from response.slack.decorators import headline_post_action
+
+@headline_post_action(order=150)
+def my_cool_headline_action(headline_post):
+    return block_kit.Button(":sparkles: My cool action", "my-cool-action", value=headline_post.incident.pk)
+```
+
+You should provide a function which takes a `headline_post` parameter, and either returns `None` (a button won't be created) or an action, e.g. `block_kit.Button`. You can also specify an `order` parameter, which will determine the order in which actions appear. The default buttons have orders of 100, 200 and 300, so the above example would appear second:
+
+![](https://www.dropbox.com/s/ummtglal8xmw2rj/Screenshot%202019-08-08%2014.55.20.png?raw=1)
+
+Check the logs to see which actions have been registered, and what order they're registered in.
+
+```
+INFO  - headline_post_a - Registering headline post action create_comms_channel_action with order 100
+INFO  - headline_post_a - Registering headline post action edit_incident_button with order 200
+INFO  - headline_post_a - Registering headline post action close_incident_button with order 300
+INFO  - headline_post_a - Registering headline post action my_cool_headline_action with order 150
+```
+

response/slack/decorators/__init__.py

@@ -1,5 +1,6 @@
 from .action_handler import *
 from .event_handler import *
+from .headline_post_action import *
 from .incident_command import *
 from .keyword_handler import *
 from .incident_notification import *

response/slack/decorators/action_handler.py

@@ -1,7 +1,7 @@
 import after_response
 
 from response.core.models.incident import Incident
-from response.slack.models import CommsChannel
+from response.slack.models.comms_channel import CommsChannel
 
 import logging
 logger = logging.getLogger(__name__)

response/slack/decorators/event_handler.py

@@ -4,7 +4,7 @@
 from django.core.exceptions import ObjectDoesNotExist, MultipleObjectsReturned
 
 from response.core.models.incident import Incident
-from response.slack.models import CommsChannel
+from response.slack.models.comms_channel import CommsChannel
 
 
 logger = logging.getLogger(__name__)

response/slack/decorators/headline_post_action.py

@@ -0,0 +1,38 @@
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+SLACK_HEADLINE_POST_ACTION_MAPPINGS = {}
+
+
+def headline_post_action(order=0, func=None):
+    """headline_post_action
+
+    Decorator that allows adding a button/action into the headline post. Should be attached
+    to functions that take a HeadlinePost and return a Slack Action type (e.g. Button).
+
+    Actions can be conditional - returning None means that no Action will be added.
+
+    The order parameter determines the relative position the action appears in the post -
+    actions will be ordered low-high from left to right. Actions with the same order number
+    will be added in the order the decorator is executed, which depends on the order of file imports.
+
+    Usage:
+    @headline_post_action(100)
+    def edit_incident(headline_post):
+        return slack.block_kit.Button(":pencil2: Edit", EDIT_INCIDENT_BUTTON, value=headline_post.incident.pk)
+
+    """
+
+    def _wrapper(fn):
+        SLACK_HEADLINE_POST_ACTION_MAPPINGS[
+            order
+        ] = SLACK_HEADLINE_POST_ACTION_MAPPINGS.get(order, []) + [fn]
+        logger.info(f"Registering headline post action {fn.__name__} with order {order}")
+        return fn
+
+    if func:
+        return _wrapper(func)
+
+    return _wrapper

response/slack/decorators/incident_command.py

@@ -2,7 +2,7 @@
 import logging
 
 from response.core.models import Incident
-from response.slack.models import CommsChannel
+from response.slack.models.comms_channel import CommsChannel
 from response.slack.client import SlackError
 
 logger = logging.getLogger(__name__)

response/slack/decorators/incident_notification.py

@@ -5,7 +5,8 @@
 from datetime import datetime
 
 from response.core.models import Incident
-from response.slack.models import CommsChannel, Notification
+from response.slack.models.comms_channel import CommsChannel
+from response.slack.models.notification import Notification
 
 logger = logging.getLogger(__name__)
 

response/slack/decorators/keyword_handler.py

@@ -1,5 +1,5 @@
 from response.core.models.incident import Incident
-from response.slack.models import CommsChannel
+from response.slack.models.comms_channel import CommsChannel
 
 import logging
 logger = logging.getLogger(__name__)

response/slack/models/headline_post.py

@@ -7,6 +7,7 @@
 
 from response import errors
 from response.core.models.incident import Incident
+from response.slack.decorators.headline_post_action import SLACK_HEADLINE_POST_ACTION_MAPPINGS, headline_post_action
 from response.slack.models.comms_channel import CommsChannel
 
 from response.slack.block_kit import *
@@ -71,12 +72,13 @@ def update_in_slack(self):
             msg.add_block(Section(text=Text("Need something else?")))
             actions = Actions(block_id="actions")
 
-            if not self.comms_channel:
-                actions.add_element(Button(":speaking_head_in_silhouette: Create Comms Channel", self.CREATE_COMMS_CHANNEL_BUTTON, value=self.incident.pk))
-
-            actions.add_element(Button(":pencil2: Edit", self.EDIT_INCIDENT_BUTTON, value=self.incident.pk))
-
-            actions.add_element(Button(":white_check_mark: Close", self.CLOSE_INCIDENT_BUTTON, value=self.incident.pk))
+            # Add all actions mapped by @headline_post_action decorators
+            for key in sorted(SLACK_HEADLINE_POST_ACTION_MAPPINGS.keys()):
+                funclist = SLACK_HEADLINE_POST_ACTION_MAPPINGS[key]
+                for f in funclist:
+                    action = f(self)
+                    if action:
+                        actions.add_element(action)
 
             msg.add_block(actions)
 
@@ -89,3 +91,25 @@ def update_in_slack(self):
         if not self.message_ts:
             self.message_ts = response['ts']
             self.save()
+
+    def post_to_thread(self, message):
+        settings.SLACK_CLIENT.send_message(settings.INCIDENT_CHANNEL_ID, message,
+                           thread_ts=self.message_ts)
+
+# Default/core actions to display on headline post. In order to allow inserting actions between these ones we increment the order by 100
+
+@headline_post_action(order=100)
+def create_comms_channel_action(headline_post):
+    if headline_post.comms_channel:
+        # No need to create an action, channel already exists
+        return None
+    return Button(":speaking_head_in_silhouette: Create Comms Channel", HeadlinePost.CREATE_COMMS_CHANNEL_BUTTON, value=headline_post.incident.pk)
+
+@headline_post_action(order=200)
+def edit_incident_button(headline_post):
+    return Button(":pencil2: Edit", HeadlinePost.EDIT_INCIDENT_BUTTON, value=headline_post.incident.pk)
+
+@headline_post_action(order=300)
+def close_incident_button(headline_post):
+    return Button(":white_check_mark: Close", HeadlinePost.CLOSE_INCIDENT_BUTTON, value=headline_post.incident.pk)
+