Create service for handling block actions

We'll send all block actions to this service for sorting and handling.
Currently demonstrate that we can react to a template selection action.

src/templatebot/constants.py

@@ -0,0 +1,4 @@
+"""Application constants."""
+
+SELECT_PROJECT_TEMPLATE_ACTION = "templatebot_select_project_template"
+"""Action ID of the static select menu for selecting a project template."""

src/templatebot/factory.py

@@ -6,6 +6,7 @@
 from httpx import AsyncClient
 from structlog.stdlib import BoundLogger
 
+from templatebot.services.slackblockactions import SlackBlockActionsService
 from templatebot.services.slackmessage import SlackMessageService
 from templatebot.storage.slack import SlackWebApiClient
 
@@ -73,3 +74,9 @@ def create_slack_message_service(self) -> SlackMessageService:
         return SlackMessageService(
             logger=self._logger, slack_client=self.create_slack_web_client()
         )
+
+    def create_slack_block_actions_service(self) -> SlackBlockActionsService:
+        """Create a new Slack block actions handling service."""
+        return SlackBlockActionsService(
+            logger=self._logger, slack_client=self.create_slack_web_client()
+        )

src/templatebot/handlers/kafka.py

@@ -81,8 +81,11 @@ async def handle_slack_block_actions(
 ) -> None:
     """Handle a Slack block_actions interaction."""
     logger = context.logger
+    factory = context.factory
 
     logger.debug(
         "Got Slack block_actions",
         actions=payload.actions[0].model_dump(mode="json"),
     )
+    block_actions_service = factory.create_slack_block_actions_service()
+    await block_actions_service.handle_block_actions(payload)

src/templatebot/services/slackblockactions.py

@@ -0,0 +1,54 @@
+"""Slack service for handling block actions."""
+
+from __future__ import annotations
+
+from rubin.squarebot.models.kafka import SquarebotSlackBlockActionsValue
+from rubin.squarebot.models.slack import (
+    SlackBlockActionBase,
+    SlackStaticSelectAction,
+)
+from structlog.stdlib import BoundLogger
+
+from templatebot.constants import SELECT_PROJECT_TEMPLATE_ACTION
+from templatebot.storage.slack import SlackWebApiClient
+
+__all__ = ["SlackBlockActionsService"]
+
+
+class SlackBlockActionsService:
+    """A service for processing Slack block actions."""
+
+    def __init__(
+        self, logger: BoundLogger, slack_client: SlackWebApiClient
+    ) -> None:
+        self._logger = logger
+        self._slack_client = slack_client
+
+    async def handle_block_actions(
+        self, payload: SquarebotSlackBlockActionsValue
+    ) -> None:
+        """Handle a Slack block_actions interaction."""
+        for action in payload.actions:
+            if action.action_id == SELECT_PROJECT_TEMPLATE_ACTION:
+                await self.handle_project_template_selection(
+                    action=action, payload=payload
+                )
+
+    async def handle_project_template_selection(
+        self,
+        *,
+        action: SlackBlockActionBase,
+        payload: SquarebotSlackBlockActionsValue,
+    ) -> None:
+        """Handle a project template selection."""
+        if not isinstance(action, SlackStaticSelectAction):
+            raise TypeError(
+                f"Expected action for {SELECT_PROJECT_TEMPLATE_ACTION} to be "
+                f"a SlackStaticSelectAction, but got {type(action)}"
+            )
+        selected_option = action.selected_option
+        self._logger.debug(
+            "Selected project template",
+            value=selected_option.value,
+            text=selected_option.text.text,
+        )

src/templatebot/services/slackmessage.py

@@ -10,6 +10,7 @@
 )
 from structlog.stdlib import BoundLogger
 
+from templatebot.constants import SELECT_PROJECT_TEMPLATE_ACTION
 from templatebot.storage.slack import (
     SlackChatPostMessageRequest,
     SlackWebApiClient,
@@ -108,7 +109,7 @@ async def _handle_create_project(
         self._logger.info("Creating a project")
         select_element = SlackStaticSelectElement(
             placeholder=SlackPlainTextObject(text="Choose a template…"),
-            action_id="templatebot_select_project_template",
+            action_id=SELECT_PROJECT_TEMPLATE_ACTION,
             option_groups=[
                 SlackOptionGroupObject(
                     label=SlackPlainTextObject(text="SQuaRE"),