BCDA-8208: Fix S3 path parsing (#960)

## 🎫 Ticket

https://jira.cms.gov/browse/BCDA-8208

## 🛠 Changes

- Fix S3 path parsing

## ℹ️ Context

I observed failures with the lambdas attempting to list files in S3
within the bfdeft01 prefix. This is not the correct prefix — the
team-specific IAM roles can only access specific subfolders (i.e.
bfdeft01/bcda, bfdeft01/dpc, etc.) so the lambdas _should_ be trying to
list files within those subfolders.

When parsing the S3 prefix from the SQS event, it needs to split from
the last separator instead of the first separator.

## 🧪 Validation

Deployed to Dev and verified successful import by uploading a file (I
basically did this part of the integration test manually:
https://github.com/CMSgov/bcda-app/blob/fabde15cb4f460d7398dcdfcf61205840258afcd/.github/workflows/opt-out-import-test-integration.yml#L47-L48
but fixed the filename since it's using the DPC filename)

**Successful lambda logs**


![](https://github.com/CMSgov/bcda-app/assets/2308368/c13a4d4c-58da-466e-9df2-38a6e9b1903a)

bcda/aws/parsers.go

@@ -2,6 +2,8 @@ package bcdaaws
 
 import (
 	"encoding/json"
+	"fmt"
+	"strings"
 
 	"github.com/aws/aws-lambda-go/events"
 	"github.com/pkg/errors"
@@ -34,3 +36,13 @@ func ParseSQSEvent(event events.SQSEvent) (*events.S3Event, error) {
 
 	return &s3Event, nil
 }
+
+func ParseS3Directory(bucket, key string) string {
+	lastSeparatorIdx := strings.LastIndex(key, "/")
+
+	if lastSeparatorIdx == -1 {
+		return bucket
+	} else {
+		return fmt.Sprintf("%s/%s", bucket, key[:lastSeparatorIdx])
+	}
+}

bcda/aws/parsers_test.go

@@ -47,3 +47,9 @@ func TestParseSQSEvent(t *testing.T) {
 	assert.NotNil(t, s3Event)
 	assert.Equal(t, "demo-bucket", s3Event.Records[0].S3.Bucket.Name)
 }
+
+func TestParseS3Directory(t *testing.T) {
+	assert.Equal(t, "my-bucket", ParseS3Directory("my-bucket", "some-file"))
+	assert.Equal(t, "my-bucket/my-dir", ParseS3Directory("my-bucket", "my-dir/some-file"))
+	assert.Equal(t, "my-bucket/my-dir/nested", ParseS3Directory("my-bucket", "my-dir/nested/some-file"))
+}

bcda/lambda/cclf/main.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 	"fmt"
 	"os"
-	"strings"
 	"time"
 
 	"github.com/aws/aws-lambda-go/events"
@@ -56,14 +55,8 @@ func cclfImportHandler(ctx context.Context, sqsEvent events.SQSEvent) (string, e
 				return "", err
 			}
 
-			parts := strings.Split(e.S3.Object.Key, "/")
-
-			if len(parts) == 1 {
-				return handleCclfImport(s3AssumeRoleArn, e.S3.Bucket.Name)
-			} else {
-				directory := fmt.Sprintf("%s/%s", e.S3.Bucket.Name, parts[0])
-				return handleCclfImport(s3AssumeRoleArn, directory)
-			}
+			dir := bcdaaws.ParseS3Directory(e.S3.Bucket.Name, e.S3.Object.Key)
+			return handleCclfImport(s3AssumeRoleArn, dir)
 		}
 	}
 

bcda/lambda/optout/main.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"fmt"
 	"os"
-	"strings"
 	"time"
 
 	"github.com/aws/aws-lambda-go/events"
@@ -58,14 +57,8 @@ func optOutImportHandler(ctx context.Context, sqsEvent events.SQSEvent) (string,
 				return "", err
 			}
 
-			parts := strings.Split(e.S3.Object.Key, "/")
-
-			if len(parts) == 1 {
-				return handleOptOutImport(s3AssumeRoleArn, e.S3.Bucket.Name)
-			} else {
-				directory := fmt.Sprintf("%s/%s", e.S3.Bucket.Name, parts[0])
-				return handleOptOutImport(s3AssumeRoleArn, directory)
-			}
+			dir := bcdaaws.ParseS3Directory(e.S3.Bucket.Name, e.S3.Object.Key)
+			return handleOptOutImport(s3AssumeRoleArn, dir)
 		}
 	}