package s3api

import (
	"bytes"
	"context"
	"crypto/md5"
	"fmt"
	"strings"
	"testing"

	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/service/s3"
	"github.com/aws/aws-sdk-go-v2/service/s3/types"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// TestMultipartUploadVersioningListETag tests that multipart uploaded objects
// in versioned buckets have correct ETags when listed.
// This covers a bug where synthetic entries for versioned objects didn't include
// proper ETag handling for multipart uploads (ETags with format "<md5>-<parts>").
func TestMultipartUploadVersioningListETag(t *testing.T) {
	client := getS3Client(t)
	bucketName := getNewBucketName()

	// Create bucket
	createBucket(t, client, bucketName)
	defer deleteBucket(t, client, bucketName)

	// Enable versioning
	_, err := client.PutBucketVersioning(context.TODO(), &s3.PutBucketVersioningInput{
		Bucket: aws.String(bucketName),
		VersioningConfiguration: &types.VersioningConfiguration{
			Status: types.BucketVersioningStatusEnabled,
		},
	})
	require.NoError(t, err, "Failed to enable versioning")

	// Create multipart upload
	objectKey := "multipart-test-object"
	createResp, err := client.CreateMultipartUpload(context.TODO(), &s3.CreateMultipartUploadInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to create multipart upload")

	uploadId := *createResp.UploadId

	// Upload 2 parts (minimum 5MB per part except last)
	partSize := 5 * 1024 * 1024 // 5MB
	part1Data := bytes.Repeat([]byte("a"), partSize)
	part2Data := bytes.Repeat([]byte("b"), partSize)

	// Calculate MD5 for each part
	part1MD5 := md5.Sum(part1Data)
	part2MD5 := md5.Sum(part2Data)

	// Upload part 1
	uploadPart1Resp, err := client.UploadPart(context.TODO(), &s3.UploadPartInput{
		Bucket:     aws.String(bucketName),
		Key:        aws.String(objectKey),
		UploadId:   aws.String(uploadId),
		PartNumber: aws.Int32(1),
		Body:       bytes.NewReader(part1Data),
	})
	require.NoError(t, err, "Failed to upload part 1")

	// Upload part 2
	uploadPart2Resp, err := client.UploadPart(context.TODO(), &s3.UploadPartInput{
		Bucket:     aws.String(bucketName),
		Key:        aws.String(objectKey),
		UploadId:   aws.String(uploadId),
		PartNumber: aws.Int32(2),
		Body:       bytes.NewReader(part2Data),
	})
	require.NoError(t, err, "Failed to upload part 2")

	// Complete multipart upload
	completeResp, err := client.CompleteMultipartUpload(context.TODO(), &s3.CompleteMultipartUploadInput{
		Bucket:   aws.String(bucketName),
		Key:      aws.String(objectKey),
		UploadId: aws.String(uploadId),
		MultipartUpload: &types.CompletedMultipartUpload{
			Parts: []types.CompletedPart{
				{
					ETag:       uploadPart1Resp.ETag,
					PartNumber: aws.Int32(1),
				},
				{
					ETag:       uploadPart2Resp.ETag,
					PartNumber: aws.Int32(2),
				},
			},
		},
	})
	require.NoError(t, err, "Failed to complete multipart upload")

	// Verify the ETag from CompleteMultipartUpload has the multipart format (md5-parts)
	completeETag := strings.Trim(*completeResp.ETag, "\"")
	assert.Contains(t, completeETag, "-", "Multipart ETag should contain '-' (format: md5-parts)")
	assert.True(t, strings.HasSuffix(completeETag, "-2"), "Multipart ETag should end with '-2' for 2 parts")

	t.Logf("CompleteMultipartUpload ETag: %s", completeETag)
	t.Logf("Part 1 MD5: %x", part1MD5)
	t.Logf("Part 2 MD5: %x", part2MD5)

	// HeadObject should return the same ETag
	headResp, err := client.HeadObject(context.TODO(), &s3.HeadObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to head object")

	headETag := strings.Trim(*headResp.ETag, "\"")
	assert.Equal(t, completeETag, headETag, "HeadObject ETag should match CompleteMultipartUpload ETag")

	// ListObjectsV2 should return the same ETag
	listResp, err := client.ListObjectsV2(context.TODO(), &s3.ListObjectsV2Input{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to list objects")
	require.Len(t, listResp.Contents, 1, "Should have exactly one object")

	listETag := strings.Trim(*listResp.Contents[0].ETag, "\"")
	assert.Equal(t, completeETag, listETag, "ListObjectsV2 ETag should match CompleteMultipartUpload ETag")
	assert.NotEmpty(t, listETag, "ListObjectsV2 ETag should not be empty")

	t.Logf("ListObjectsV2 ETag: %s", listETag)

	// ListObjectVersions should also return the correct ETag
	versionsResp, err := client.ListObjectVersions(context.TODO(), &s3.ListObjectVersionsInput{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to list object versions")
	require.Len(t, versionsResp.Versions, 1, "Should have exactly one version")

	versionETag := strings.Trim(*versionsResp.Versions[0].ETag, "\"")
	assert.Equal(t, completeETag, versionETag, "ListObjectVersions ETag should match CompleteMultipartUpload ETag")
	assert.NotEmpty(t, versionETag, "ListObjectVersions ETag should not be empty")

	t.Logf("ListObjectVersions ETag: %s", versionETag)
}

// TestMultipartUploadMultipleVersionsListETag tests that multiple versions
// of multipart uploaded objects all have correct ETags when listed.
func TestMultipartUploadMultipleVersionsListETag(t *testing.T) {
	client := getS3Client(t)
	bucketName := getNewBucketName()

	// Create bucket
	createBucket(t, client, bucketName)
	defer deleteBucket(t, client, bucketName)

	// Enable versioning
	_, err := client.PutBucketVersioning(context.TODO(), &s3.PutBucketVersioningInput{
		Bucket: aws.String(bucketName),
		VersioningConfiguration: &types.VersioningConfiguration{
			Status: types.BucketVersioningStatusEnabled,
		},
	})
	require.NoError(t, err, "Failed to enable versioning")

	objectKey := "multipart-multi-version-object"
	partSize := 5 * 1024 * 1024 // 5MB
	var expectedETags []string

	// Create 3 versions using multipart upload
	for version := 1; version <= 3; version++ {
		// Create multipart upload
		createResp, err := client.CreateMultipartUpload(context.TODO(), &s3.CreateMultipartUploadInput{
			Bucket: aws.String(bucketName),
			Key:    aws.String(objectKey),
		})
		require.NoError(t, err, "Failed to create multipart upload for version %d", version)

		uploadId := *createResp.UploadId

		// Create unique data for each version
		partData := bytes.Repeat([]byte(fmt.Sprintf("%d", version)), partSize)

		// Upload single part (still results in multipart ETag format)
		uploadPartResp, err := client.UploadPart(context.TODO(), &s3.UploadPartInput{
			Bucket:     aws.String(bucketName),
			Key:        aws.String(objectKey),
			UploadId:   aws.String(uploadId),
			PartNumber: aws.Int32(1),
			Body:       bytes.NewReader(partData),
		})
		require.NoError(t, err, "Failed to upload part for version %d", version)

		// Complete multipart upload
		completeResp, err := client.CompleteMultipartUpload(context.TODO(), &s3.CompleteMultipartUploadInput{
			Bucket:   aws.String(bucketName),
			Key:      aws.String(objectKey),
			UploadId: aws.String(uploadId),
			MultipartUpload: &types.CompletedMultipartUpload{
				Parts: []types.CompletedPart{
					{
						ETag:       uploadPartResp.ETag,
						PartNumber: aws.Int32(1),
					},
				},
			},
		})
		require.NoError(t, err, "Failed to complete multipart upload for version %d", version)

		etag := strings.Trim(*completeResp.ETag, "\"")
		expectedETags = append(expectedETags, etag)
		t.Logf("Version %d ETag: %s", version, etag)
	}

	// ListObjectVersions should return all versions with correct ETags
	versionsResp, err := client.ListObjectVersions(context.TODO(), &s3.ListObjectVersionsInput{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to list object versions")
	require.Len(t, versionsResp.Versions, 3, "Should have exactly 3 versions")

	// Collect ETags from the listing
	var listedETags []string
	for _, v := range versionsResp.Versions {
		etag := strings.Trim(*v.ETag, "\"")
		listedETags = append(listedETags, etag)
		assert.NotEmpty(t, etag, "Version ETag should not be empty")
		assert.Contains(t, etag, "-", "Multipart ETag should contain '-'")
	}

	t.Logf("Expected ETags: %v", expectedETags)
	t.Logf("Listed ETags: %v", listedETags)

	// Verify all expected ETags are present (order may differ due to version ordering)
	assert.ElementsMatch(t, expectedETags, listedETags, "Listed ETags should match all expected ETags")

	// Regular ListObjectsV2 should return only the latest version with correct ETag
	listResp, err := client.ListObjectsV2(context.TODO(), &s3.ListObjectsV2Input{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to list objects")
	require.Len(t, listResp.Contents, 1, "Should have exactly one object in regular listing")

	listETag := strings.Trim(*listResp.Contents[0].ETag, "\"")
	// The latest version (version 3) should be the one shown
	assert.Equal(t, expectedETags[2], listETag, "ListObjectsV2 should show latest version's ETag")
}

// TestMixedSingleAndMultipartVersionsListETag tests that a mix of
// single-part and multipart uploaded versions all have correct ETags.
func TestMixedSingleAndMultipartVersionsListETag(t *testing.T) {
	client := getS3Client(t)
	bucketName := getNewBucketName()

	// Create bucket
	createBucket(t, client, bucketName)
	defer deleteBucket(t, client, bucketName)

	// Enable versioning
	_, err := client.PutBucketVersioning(context.TODO(), &s3.PutBucketVersioningInput{
		Bucket: aws.String(bucketName),
		VersioningConfiguration: &types.VersioningConfiguration{
			Status: types.BucketVersioningStatusEnabled,
		},
	})
	require.NoError(t, err, "Failed to enable versioning")

	objectKey := "mixed-upload-versions"

	// Version 1: Regular PutObject (single-part, pure MD5 ETag)
	content1 := []byte("This is version 1 content - single part upload")
	putResp1, err := client.PutObject(context.TODO(), &s3.PutObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
		Body:   bytes.NewReader(content1),
	})
	require.NoError(t, err, "Failed to put version 1")
	etag1 := strings.Trim(*putResp1.ETag, "\"")
	assert.NotContains(t, etag1, "-", "Single-part ETag should not contain '-'")
	t.Logf("Version 1 (PutObject) ETag: %s", etag1)

	// Version 2: Multipart upload
	partSize := 5 * 1024 * 1024
	partData := bytes.Repeat([]byte("x"), partSize)

	createResp, err := client.CreateMultipartUpload(context.TODO(), &s3.CreateMultipartUploadInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to create multipart upload")

	uploadPartResp, err := client.UploadPart(context.TODO(), &s3.UploadPartInput{
		Bucket:     aws.String(bucketName),
		Key:        aws.String(objectKey),
		UploadId:   createResp.UploadId,
		PartNumber: aws.Int32(1),
		Body:       bytes.NewReader(partData),
	})
	require.NoError(t, err, "Failed to upload part")

	completeResp, err := client.CompleteMultipartUpload(context.TODO(), &s3.CompleteMultipartUploadInput{
		Bucket:   aws.String(bucketName),
		Key:      aws.String(objectKey),
		UploadId: createResp.UploadId,
		MultipartUpload: &types.CompletedMultipartUpload{
			Parts: []types.CompletedPart{
				{
					ETag:       uploadPartResp.ETag,
					PartNumber: aws.Int32(1),
				},
			},
		},
	})
	require.NoError(t, err, "Failed to complete multipart upload")
	etag2 := strings.Trim(*completeResp.ETag, "\"")
	assert.Contains(t, etag2, "-", "Multipart ETag should contain '-'")
	t.Logf("Version 2 (Multipart) ETag: %s", etag2)

	// Version 3: Another regular PutObject
	content3 := []byte("This is version 3 content - another single part upload")
	putResp3, err := client.PutObject(context.TODO(), &s3.PutObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
		Body:   bytes.NewReader(content3),
	})
	require.NoError(t, err, "Failed to put version 3")
	etag3 := strings.Trim(*putResp3.ETag, "\"")
	assert.NotContains(t, etag3, "-", "Single-part ETag should not contain '-'")
	t.Logf("Version 3 (PutObject) ETag: %s", etag3)

	// ListObjectVersions should return all 3 versions with correct ETags
	versionsResp, err := client.ListObjectVersions(context.TODO(), &s3.ListObjectVersionsInput{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to list object versions")
	require.Len(t, versionsResp.Versions, 3, "Should have exactly 3 versions")

	var listedETags []string
	for _, v := range versionsResp.Versions {
		etag := strings.Trim(*v.ETag, "\"")
		assert.NotEmpty(t, etag, "Version ETag should not be empty")
		listedETags = append(listedETags, etag)
		t.Logf("Listed version %s ETag: %s, IsLatest: %v", *v.VersionId, etag, *v.IsLatest)
	}

	// Verify all ETags were found
	assert.ElementsMatch(t, []string{etag1, etag2, etag3}, listedETags, "Listed ETags should match all expected ETags")

	// Regular ListObjectsV2 should return only the latest (version 3)
	listResp, err := client.ListObjectsV2(context.TODO(), &s3.ListObjectsV2Input{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to list objects")
	require.Len(t, listResp.Contents, 1, "Should have exactly one object")

	listETag := strings.Trim(*listResp.Contents[0].ETag, "\"")
	assert.Equal(t, etag3, listETag, "ListObjectsV2 should show latest version's ETag (version 3)")
}

// TestMultipartUploadDeleteMarkerListBehavior tests that delete markers work correctly
// with multipart uploaded objects in versioned buckets.
func TestMultipartUploadDeleteMarkerListBehavior(t *testing.T) {
	client := getS3Client(t)
	bucketName := getNewBucketName()

	// Create bucket
	createBucket(t, client, bucketName)
	defer deleteBucket(t, client, bucketName)

	// Enable versioning
	_, err := client.PutBucketVersioning(context.TODO(), &s3.PutBucketVersioningInput{
		Bucket: aws.String(bucketName),
		VersioningConfiguration: &types.VersioningConfiguration{
			Status: types.BucketVersioningStatusEnabled,
		},
	})
	require.NoError(t, err, "Failed to enable versioning")

	objectKey := "multipart-delete-marker-test"
	partSize := 5 * 1024 * 1024 // 5MB

	// Create multipart upload
	createResp, err := client.CreateMultipartUpload(context.TODO(), &s3.CreateMultipartUploadInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to create multipart upload")

	// Upload 2 parts
	part1Data := bytes.Repeat([]byte("a"), partSize)
	part2Data := bytes.Repeat([]byte("b"), partSize)

	uploadPart1Resp, err := client.UploadPart(context.TODO(), &s3.UploadPartInput{
		Bucket:     aws.String(bucketName),
		Key:        aws.String(objectKey),
		UploadId:   createResp.UploadId,
		PartNumber: aws.Int32(1),
		Body:       bytes.NewReader(part1Data),
	})
	require.NoError(t, err, "Failed to upload part 1")

	uploadPart2Resp, err := client.UploadPart(context.TODO(), &s3.UploadPartInput{
		Bucket:     aws.String(bucketName),
		Key:        aws.String(objectKey),
		UploadId:   createResp.UploadId,
		PartNumber: aws.Int32(2),
		Body:       bytes.NewReader(part2Data),
	})
	require.NoError(t, err, "Failed to upload part 2")

	// Complete multipart upload
	completeResp, err := client.CompleteMultipartUpload(context.TODO(), &s3.CompleteMultipartUploadInput{
		Bucket:   aws.String(bucketName),
		Key:      aws.String(objectKey),
		UploadId: createResp.UploadId,
		MultipartUpload: &types.CompletedMultipartUpload{
			Parts: []types.CompletedPart{
				{ETag: uploadPart1Resp.ETag, PartNumber: aws.Int32(1)},
				{ETag: uploadPart2Resp.ETag, PartNumber: aws.Int32(2)},
			},
		},
	})
	require.NoError(t, err, "Failed to complete multipart upload")

	multipartETag := strings.Trim(*completeResp.ETag, "\"")
	multipartVersionId := *completeResp.VersionId
	t.Logf("Multipart upload completed: ETag=%s, VersionId=%s", multipartETag, multipartVersionId)

	// Verify object is visible in ListObjectsV2
	listBeforeDelete, err := client.ListObjectsV2(context.TODO(), &s3.ListObjectsV2Input{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to list objects before delete")
	require.Len(t, listBeforeDelete.Contents, 1, "Object should be visible before delete")
	assert.Equal(t, multipartETag, strings.Trim(*listBeforeDelete.Contents[0].ETag, "\""),
		"Listed ETag should match multipart ETag before delete")

	// Delete object (creates delete marker)
	deleteResp, err := client.DeleteObject(context.TODO(), &s3.DeleteObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to delete object")
	require.NotNil(t, deleteResp.DeleteMarker, "Should create delete marker")
	assert.True(t, *deleteResp.DeleteMarker, "DeleteMarker should be true")
	require.NotNil(t, deleteResp.VersionId, "Delete marker should have version ID")

	deleteMarkerVersionId := *deleteResp.VersionId
	t.Logf("Delete marker created: VersionId=%s", deleteMarkerVersionId)

	// ListObjectsV2 should NOT show the object anymore
	listAfterDelete, err := client.ListObjectsV2(context.TODO(), &s3.ListObjectsV2Input{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to list objects after delete")
	assert.Empty(t, listAfterDelete.Contents, "Object should NOT be visible after delete marker")

	// ListObjectVersions should show both the original version AND the delete marker
	versionsResp, err := client.ListObjectVersions(context.TODO(), &s3.ListObjectVersionsInput{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to list object versions")

	// Should have 1 version (the multipart object)
	require.Len(t, versionsResp.Versions, 1, "Should have exactly 1 version (the multipart object)")
	version := versionsResp.Versions[0]
	assert.Equal(t, multipartVersionId, *version.VersionId, "Version ID should match")
	assert.Equal(t, multipartETag, strings.Trim(*version.ETag, "\""), "Version ETag should match multipart ETag")
	assert.False(t, *version.IsLatest, "Multipart version should NOT be latest (delete marker is latest)")

	// Should have 1 delete marker
	require.Len(t, versionsResp.DeleteMarkers, 1, "Should have exactly 1 delete marker")
	deleteMarker := versionsResp.DeleteMarkers[0]
	assert.Equal(t, deleteMarkerVersionId, *deleteMarker.VersionId, "Delete marker version ID should match")
	assert.True(t, *deleteMarker.IsLatest, "Delete marker should be latest")

	t.Logf("ListObjectVersions: 1 version (ETag=%s), 1 delete marker", multipartETag)

	// Access the specific version by version ID - should still work
	getResp, err := client.GetObject(context.TODO(), &s3.GetObjectInput{
		Bucket:    aws.String(bucketName),
		Key:       aws.String(objectKey),
		VersionId: aws.String(multipartVersionId),
	})
	require.NoError(t, err, "Should be able to get object by version ID after delete marker")
	defer getResp.Body.Close()

	assert.Equal(t, multipartETag, strings.Trim(*getResp.ETag, "\""),
		"GetObject with version ID should return correct ETag")
	assert.Equal(t, int64(partSize*2), *getResp.ContentLength,
		"GetObject with version ID should return correct size")

	t.Logf("Successfully retrieved version %s after delete marker", multipartVersionId)

	// Delete the delete marker to "undelete" the object
	undeleteResp, err := client.DeleteObject(context.TODO(), &s3.DeleteObjectInput{
		Bucket:    aws.String(bucketName),
		Key:       aws.String(objectKey),
		VersionId: aws.String(deleteMarkerVersionId),
	})
	require.NoError(t, err, "Failed to delete the delete marker")
	require.NotNil(t, undeleteResp.DeleteMarker, "Deleting a delete marker version should report DeleteMarker=true")
	assert.True(t, *undeleteResp.DeleteMarker, "Deleting a delete marker version should report DeleteMarker=true")
	require.NotNil(t, undeleteResp.VersionId, "Deleting a delete marker version should echo the version ID")
	assert.Equal(t, deleteMarkerVersionId, *undeleteResp.VersionId, "DeleteObject should report the deleted delete-marker version ID")

	// ListObjectsV2 should show the object again
	listAfterUndelete, err := client.ListObjectsV2(context.TODO(), &s3.ListObjectsV2Input{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to list objects after undelete")
	require.Len(t, listAfterUndelete.Contents, 1, "Object should be visible again after removing delete marker")
	assert.Equal(t, multipartETag, strings.Trim(*listAfterUndelete.Contents[0].ETag, "\""),
		"Undeleted object should have correct multipart ETag")

	t.Logf("Object restored after delete marker removal, ETag=%s", multipartETag)
}

func TestVersioningCompleteMultipartUploadIsIdempotent(t *testing.T) {
	client := getS3Client(t)
	bucketName := getNewBucketName()

	createBucket(t, client, bucketName)
	defer deleteBucket(t, client, bucketName)

	enableVersioning(t, client, bucketName)
	checkVersioningStatus(t, client, bucketName, types.BucketVersioningStatusEnabled)

	objectKey := "multipart-idempotent-object"
	createResp, err := client.CreateMultipartUpload(context.TODO(), &s3.CreateMultipartUploadInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to create multipart upload")

	partSize := 5 * 1024 * 1024
	part1Data := bytes.Repeat([]byte("i"), partSize)
	part2Data := bytes.Repeat([]byte("j"), partSize)

	uploadPart1Resp, err := client.UploadPart(context.TODO(), &s3.UploadPartInput{
		Bucket:     aws.String(bucketName),
		Key:        aws.String(objectKey),
		UploadId:   createResp.UploadId,
		PartNumber: aws.Int32(1),
		Body:       bytes.NewReader(part1Data),
	})
	require.NoError(t, err, "Failed to upload first part")

	uploadPart2Resp, err := client.UploadPart(context.TODO(), &s3.UploadPartInput{
		Bucket:     aws.String(bucketName),
		Key:        aws.String(objectKey),
		UploadId:   createResp.UploadId,
		PartNumber: aws.Int32(2),
		Body:       bytes.NewReader(part2Data),
	})
	require.NoError(t, err, "Failed to upload second part")

	completeInput := &s3.CompleteMultipartUploadInput{
		Bucket:   aws.String(bucketName),
		Key:      aws.String(objectKey),
		UploadId: createResp.UploadId,
		MultipartUpload: &types.CompletedMultipartUpload{
			Parts: []types.CompletedPart{
				{ETag: uploadPart1Resp.ETag, PartNumber: aws.Int32(1)},
				{ETag: uploadPart2Resp.ETag, PartNumber: aws.Int32(2)},
			},
		},
	}

	firstCompleteResp, err := client.CompleteMultipartUpload(context.TODO(), completeInput)
	require.NoError(t, err, "First CompleteMultipartUpload should succeed")
	require.NotNil(t, firstCompleteResp.ETag)
	require.NotNil(t, firstCompleteResp.VersionId)

	secondCompleteResp, err := client.CompleteMultipartUpload(context.TODO(), completeInput)
	require.NoError(t, err, "Repeated CompleteMultipartUpload should return the existing object instead of creating a second version")
	require.NotNil(t, secondCompleteResp.ETag)
	require.NotNil(t, secondCompleteResp.VersionId, "Repeated complete should report the existing version ID")
	assert.Equal(t, *firstCompleteResp.ETag, *secondCompleteResp.ETag, "Repeated complete should report the same ETag")
	assert.Equal(t, *firstCompleteResp.VersionId, *secondCompleteResp.VersionId, "Repeated complete should report the same version ID")

	versionsResp, err := client.ListObjectVersions(context.TODO(), &s3.ListObjectVersionsInput{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err, "Failed to list object versions")
	require.Len(t, versionsResp.Versions, 1, "Repeated completion must not create a duplicate version")
	assert.Equal(t, *firstCompleteResp.VersionId, *versionsResp.Versions[0].VersionId, "The original multipart version should remain current")
	assert.Empty(t, versionsResp.DeleteMarkers, "Repeated completion should not create delete markers")
}