refactor: generalize findFirst pattern

Author: Hweinstock

packages/core/src/shared/clients/clientWrapper.ts

@@ -54,6 +54,15 @@ export abstract class ClientWrapper<C extends AwsClient> implements vscode.Dispo
         }
     }
 
+    protected async getFirstResult<CommandInput extends object, CommandOutput extends object, Output extends object>(
+        paginator: SDKPaginator<C, CommandInput, CommandOutput>,
+        input: CommandInput,
+        extractPage: (page: CommandOutput) => Output[] | undefined
+    ): Promise<Output> {
+        const results = await this.makePaginatedRequest(paginator, input, extractPage).flatten().promise()
+        return results[0]
+    }
+
     public dispose() {
         this.client?.destroy()
     }

packages/core/src/shared/clients/ec2.ts

@@ -105,15 +105,13 @@ export class Ec2Client extends ClientWrapper<EC2Client> {
     }
 
     public async getInstanceStatus(instanceId: string): Promise<InstanceStateName> {
-        const instanceStatuses = await this.makePaginatedRequest(
+        const instance = await this.getFirstResult(
             paginateDescribeInstanceStatus,
             { InstanceIds: [instanceId], IncludeAllInstances: true },
             (page) => page.InstanceStatuses
         )
-            .flatten()
-            .promise()
 
-        return instanceStatuses[0].InstanceState!.Name!
+        return instance.InstanceState!.Name!
     }
 
     public async isInstanceRunning(instanceId: string): Promise<boolean> {
@@ -215,17 +213,11 @@ export class Ec2Client extends ClientWrapper<EC2Client> {
      * @returns IAM Association for instance
      */
     private async getIamInstanceProfileAssociation(instanceId: string): Promise<IamInstanceProfileAssociation> {
-        const instanceFilter = this.getInstancesFilter([instanceId])
-
-        const associations = await this.makePaginatedRequest(
+        return await this.getFirstResult(
             paginateDescribeIamInstanceProfileAssociations,
-            { Filters: instanceFilter },
+            { Filters: this.getInstancesFilter([instanceId]) },
             (page) => page.IamInstanceProfileAssociations
         )
-            .flatten()
-            .promise()
-
-        return associations[0]
     }
 
     /**

packages/core/src/shared/clients/ssm.ts

@@ -52,17 +52,13 @@ export class SsmClient extends ClientWrapper<SSMClient> {
     }
 
     public async describeInstance(target: string): Promise<InstanceInformation> {
-        return (
-            await this.makePaginatedRequest(
-                paginateDescribeInstanceInformation,
-                {
-                    InstanceInformationFilterList: [{ key: 'InstanceIds', valueSet: [target] }],
-                } satisfies DescribeInstanceInformationCommandInput,
-                (page) => page.InstanceInformationList
-            )
-                .flatten()
-                .promise()
-        )[0]!
+        return await this.getFirstResult(
+            paginateDescribeInstanceInformation,
+            {
+                InstanceInformationFilterList: [{ key: 'InstanceIds', valueSet: [target] }],
+            } satisfies DescribeInstanceInformationCommandInput,
+            (page) => page.InstanceInformationList
+        )
     }
 
     public async getTargetPlatformName(target: string): Promise<string> {