Collapse two unenroll functions into one (elastic#94848)

## Summary

Refactoring in progress towards elastic#90437 

Collapse `forceUninstallAgents` into `uninstallAgents` into one function with an option. The pseudocode diff is

```diff
- function uninstallAgents() {
-   // filtering logic A
-   // side effects A
- }
- function forceUninstallAgents() {
-   // filtering logic A
-   // side effects B
- }

+ function uninstallAgents({ flag: boolean}) {
+   // filtering logic A
+   // if flag: side effects B
+   // else: side effects A
+ }
```

actually, there is [_one difference_](https://github.com/elastic/kibana/pull/94848/files/5564f253831a8a94e2b2bbb808afe6d2019016d7#diff-ecc3c625f2366949f1723e56b8477f6afb552ccfbcf3a71e0c28b2062fd05195) in the filtering logic
 
### Checklist
- [x] [Unit or functional tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html) were updated or added to match the most common scenarios

x-pack/plugins/fleet/server/routes/agent/unenroll_handler.ts

@@ -52,19 +52,20 @@ export const postBulkAgentsUnenrollHandler: RequestHandler<
       body: { message: 'Requires Gold license' },
     });
   }
+
   const soClient = context.core.savedObjects.client;
   const esClient = context.core.elasticsearch.client.asInternalUser;
-  const unenrollAgents =
-    request.body?.force === true ? AgentService.forceUnenrollAgents : AgentService.unenrollAgents;
+  const agentOptions = Array.isArray(request.body.agents)
+    ? { agentIds: request.body.agents }
+    : { kuery: request.body.agents };
 
   try {
-    if (Array.isArray(request.body.agents)) {
-      await unenrollAgents(soClient, esClient, { agentIds: request.body.agents });
-    } else {
-      await unenrollAgents(soClient, esClient, { kuery: request.body.agents });
-    }
-
+    await AgentService.unenrollAgents(soClient, esClient, {
+      ...agentOptions,
+      force: request.body?.force,
+    });
     const body: PostBulkAgentUnenrollResponse = {};
+
     return response.ok({ body });
   } catch (error) {
     return defaultIngestErrorHandler({ error, response });

x-pack/plugins/fleet/server/services/agents/unenroll.ts

@@ -56,45 +56,78 @@ export async function unenrollAgent(
 export async function unenrollAgents(
   soClient: SavedObjectsClientContract,
   esClient: ElasticsearchClient,
-  options: GetAgentsOptions
+  options: GetAgentsOptions & { force?: boolean }
 ) {
+  // start with all agents specified
   const agents = await getAgents(esClient, options);
 
-  // Filter to agents that are not already unenrolled, or unenrolling
-  const agentsEnrolled = agents.filter(
-    (agent) => !agent.unenrollment_started_at && !agent.unenrolled_at
-  );
+  // Filter to those not already unenrolled, or unenrolling
+  const agentsEnrolled = agents.filter((agent) => {
+    if (options.force) {
+      return !agent.unenrolled_at;
+    }
+    return !agent.unenrollment_started_at && !agent.unenrolled_at;
+  });
   // And which are allowed to unenroll
   const settled = await Promise.allSettled(
     agentsEnrolled.map((agent) =>
       unenrollAgentIsAllowed(soClient, esClient, agent.id).then((_) => agent)
     )
   );
   const agentsToUpdate = agentsEnrolled.filter((_, index) => settled[index].status === 'fulfilled');
-
   const now = new Date().toISOString();
 
-  // Create unenroll action for each agent
-  await bulkCreateAgentActions(
-    soClient,
-    esClient,
-    agentsToUpdate.map((agent) => ({
-      agent_id: agent.id,
-      created_at: now,
-      type: 'UNENROLL',
-    }))
-  );
+  if (options.force) {
+    // Get all API keys that need to be invalidated
+    const apiKeys = agentsToUpdate.reduce<string[]>((keys, agent) => {
+      if (agent.access_api_key_id) {
+        keys.push(agent.access_api_key_id);
+      }
+      if (agent.default_api_key_id) {
+        keys.push(agent.default_api_key_id);
+      }
+
+      return keys;
+    }, []);
+
+    // Invalidate all API keys
+    if (apiKeys.length) {
+      await APIKeyService.invalidateAPIKeys(soClient, apiKeys);
+    }
+    // Update the necessary agents
+    return bulkUpdateAgents(
+      esClient,
+      agentsToUpdate.map((agent) => ({
+        agentId: agent.id,
+        data: {
+          active: false,
+          unenrolled_at: now,
+        },
+      }))
+    );
+  } else {
+    // Create unenroll action for each agent
+    await bulkCreateAgentActions(
+      soClient,
+      esClient,
+      agentsToUpdate.map((agent) => ({
+        agent_id: agent.id,
+        created_at: now,
+        type: 'UNENROLL',
+      }))
+    );
 
-  // Update the necessary agents
-  return bulkUpdateAgents(
-    esClient,
-    agentsToUpdate.map((agent) => ({
-      agentId: agent.id,
-      data: {
-        unenrollment_started_at: now,
-      },
-    }))
-  );
+    // Update the necessary agents
+    return bulkUpdateAgents(
+      esClient,
+      agentsToUpdate.map((agent) => ({
+        agentId: agent.id,
+        data: {
+          unenrollment_started_at: now,
+        },
+      }))
+    );
+  }
 }
 
 export async function forceUnenrollAgent(
@@ -118,41 +151,3 @@ export async function forceUnenrollAgent(
     unenrolled_at: new Date().toISOString(),
   });
 }
-
-export async function forceUnenrollAgents(
-  soClient: SavedObjectsClientContract,
-  esClient: ElasticsearchClient,
-  options: GetAgentsOptions
-) {
-  // Filter to agents that are not already unenrolled
-  const agents = await getAgents(esClient, options);
-  const agentsToUpdate = agents.filter((agent) => !agent.unenrolled_at);
-  const now = new Date().toISOString();
-  const apiKeys: string[] = [];
-
-  // Get all API keys that need to be invalidated
-  agentsToUpdate.forEach((agent) => {
-    if (agent.access_api_key_id) {
-      apiKeys.push(agent.access_api_key_id);
-    }
-    if (agent.default_api_key_id) {
-      apiKeys.push(agent.default_api_key_id);
-    }
-  });
-
-  // Invalidate all API keys
-  if (apiKeys.length) {
-    APIKeyService.invalidateAPIKeys(soClient, apiKeys);
-  }
-  // Update the necessary agents
-  return bulkUpdateAgents(
-    esClient,
-    agentsToUpdate.map((agent) => ({
-      agentId: agent.id,
-      data: {
-        active: false,
-        unenrolled_at: now,
-      },
-    }))
-  );
-}