package s3api

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"
	"testing"
	"time"

	"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/aws/smithy-go"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func versioningCopySource(bucketName, key string) string {
	return fmt.Sprintf("%s/%s", bucketName, url.PathEscape(key))
}

func suspendVersioning(t *testing.T, client *s3.Client, bucketName string) {
	_, err := client.PutBucketVersioning(context.TODO(), &s3.PutBucketVersioningInput{
		Bucket: aws.String(bucketName),
		VersioningConfiguration: &types.VersioningConfiguration{
			Status: types.BucketVersioningStatusSuspended,
		},
	})
	require.NoError(t, err)
}

// vacuumVolumes asks the master to compact away the needles a delete tombstoned.
// Tests that assert a surviving object still has its data need this: deleting an
// entry only tombstones the needles it points at, so a shared chunk list reads
// fine right up until the vacuum makes the loss permanent. A vacuum that does not
// run leaves those tests asserting nothing, so treat every failure as fatal.
func vacuumVolumes(t *testing.T) {
	t.Helper()
	require.NotEmpty(t, defaultConfig.MasterEndpoint, "vacuum needs a master endpoint; set MASTER_ENDPOINT")
	endpoint := strings.TrimRight(defaultConfig.MasterEndpoint, "/") + "/vol/vacuum?garbageThreshold=0.001"
	httpClient := &http.Client{Timeout: 30 * time.Second}
	resp, err := httpClient.Get(endpoint)
	require.NoError(t, err, "vacuum request to %s", endpoint)
	defer resp.Body.Close()
	_, err = io.Copy(io.Discard, resp.Body)
	require.NoError(t, err, "reading the vacuum response")
	require.Equal(t, http.StatusOK, resp.StatusCode, "vacuum request to %s", endpoint)
}

func requireVersionBody(t *testing.T, client *s3.Client, bucketName, objectKey, versionId string, want []byte, msg string) {
	t.Helper()
	getResp, err := client.GetObject(context.TODO(), &s3.GetObjectInput{
		Bucket:    aws.String(bucketName),
		Key:       aws.String(objectKey),
		VersionId: aws.String(versionId),
	})
	require.NoError(t, err, msg)
	defer getResp.Body.Close()
	body, err := io.ReadAll(getResp.Body)
	require.NoError(t, err, msg)
	require.Equal(t, len(want), len(body), msg)
	require.True(t, bytes.Equal(want, body), msg)
}

// chunkedTestContent returns a body large enough to land in volume needles rather
// than inline in the filer entry, so a copy that reuses the source fids is visible
// once those needles are freed.
func chunkedTestContent(size int) []byte {
	content := make([]byte, size)
	for i := range content {
		content[i] = byte(i * 31 % 251)
	}
	return content
}

// TestVersioningSelfCopyMetadataReplaceKeepsChunksIndependent covers the copy that
// only rewrites metadata: it used to hand the source version's chunk fids to the
// new version, so nothing owned those needles and deleting either version freed
// the survivor's data (silently, once a vacuum ran).
func TestVersioningSelfCopyMetadataReplaceKeepsChunksIndependent(t *testing.T) {
	client := getS3Client(t)
	bucketName := getNewBucketName()

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

	enableVersioning(t, client, bucketName)

	objectKey := "self-copy-chunk-ownership.bin"
	content := chunkedTestContent(6 << 20)

	putResp, err := client.PutObject(context.TODO(), &s3.PutObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
		Body:   bytes.NewReader(content),
	})
	require.NoError(t, err)
	require.NotNil(t, putResp.VersionId)

	copyResp, err := client.CopyObject(context.TODO(), &s3.CopyObjectInput{
		Bucket:            aws.String(bucketName),
		Key:               aws.String(objectKey),
		CopySource:        aws.String(versioningCopySource(bucketName, objectKey)),
		Metadata:          map[string]string{"mtime": "1653465360"},
		MetadataDirective: types.MetadataDirectiveReplace,
	})
	require.NoError(t, err)
	require.NotNil(t, copyResp.VersionId)
	require.NotEqual(t, *putResp.VersionId, *copyResp.VersionId)

	_, err = client.DeleteObject(context.TODO(), &s3.DeleteObjectInput{
		Bucket:    aws.String(bucketName),
		Key:       aws.String(objectKey),
		VersionId: putResp.VersionId,
	})
	require.NoError(t, err)

	// The filer frees a deleted entry's chunks asynchronously, so re-check across
	// a few vacuum rounds instead of racing a single one.
	for round := 0; round < 4; round++ {
		time.Sleep(time.Second)
		vacuumVolumes(t)
		requireVersionBody(t, client, bucketName, objectKey, *copyResp.VersionId, content,
			"the surviving version must keep its own data after the other version is deleted")
	}
}

// TestSuspendedSelfCopyMetadataReplaceKeepsChunksIndependent is the same defect on
// a suspended bucket: the null version the copy writes sits beside a .versions/
// entry that stays live, so the two must not share needles either.
func TestSuspendedSelfCopyMetadataReplaceKeepsChunksIndependent(t *testing.T) {
	client := getS3Client(t)
	bucketName := getNewBucketName()

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

	enableVersioning(t, client, bucketName)

	objectKey := "suspended-self-copy-chunk-ownership.bin"
	content := chunkedTestContent(6 << 20)

	putResp, err := client.PutObject(context.TODO(), &s3.PutObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
		Body:   bytes.NewReader(content),
	})
	require.NoError(t, err)
	require.NotNil(t, putResp.VersionId)

	suspendVersioning(t, client, bucketName)

	_, err = client.CopyObject(context.TODO(), &s3.CopyObjectInput{
		Bucket:            aws.String(bucketName),
		Key:               aws.String(objectKey),
		CopySource:        aws.String(versioningCopySource(bucketName, objectKey)),
		Metadata:          map[string]string{"mtime": "1653465360"},
		MetadataDirective: types.MetadataDirectiveReplace,
	})
	require.NoError(t, err)

	// Drop the version the copy read from; the null version it wrote must survive.
	_, err = client.DeleteObject(context.TODO(), &s3.DeleteObjectInput{
		Bucket:    aws.String(bucketName),
		Key:       aws.String(objectKey),
		VersionId: putResp.VersionId,
	})
	require.NoError(t, err)

	for round := 0; round < 4; round++ {
		time.Sleep(time.Second)
		vacuumVolumes(t)
		requireVersionBody(t, client, bucketName, objectKey, "null", content,
			"the null version must keep its own data after the version it was copied from is deleted")
	}
}

func TestVersioningSelfCopyMetadataReplaceCreatesNewVersion(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 := "self-copy-versioned.txt"
	initialContent := []byte("copy me without changing the body")

	putResp, err := client.PutObject(context.TODO(), &s3.PutObjectInput{
		Bucket:   aws.String(bucketName),
		Key:      aws.String(objectKey),
		Body:     bytes.NewReader(initialContent),
		Metadata: map[string]string{"stage": "one"},
	})
	require.NoError(t, err)
	require.NotNil(t, putResp.VersionId)

	copyResp, err := client.CopyObject(context.TODO(), &s3.CopyObjectInput{
		Bucket:            aws.String(bucketName),
		Key:               aws.String(objectKey),
		CopySource:        aws.String(versioningCopySource(bucketName, objectKey)),
		Metadata:          map[string]string{"stage": "two"},
		MetadataDirective: types.MetadataDirectiveReplace,
	})
	require.NoError(t, err, "Self-copy with metadata replacement should succeed")
	require.NotNil(t, copyResp.VersionId, "Versioned self-copy should create a new version")
	require.NotEqual(t, *putResp.VersionId, *copyResp.VersionId, "Self-copy should create a distinct version")

	headLatestResp, err := client.HeadObject(context.TODO(), &s3.HeadObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
	})
	require.NoError(t, err)
	assert.Equal(t, "two", headLatestResp.Metadata["stage"], "Latest version should expose replaced metadata")

	headOriginalResp, err := client.HeadObject(context.TODO(), &s3.HeadObjectInput{
		Bucket:    aws.String(bucketName),
		Key:       aws.String(objectKey),
		VersionId: putResp.VersionId,
	})
	require.NoError(t, err)
	assert.Equal(t, "one", headOriginalResp.Metadata["stage"], "Previous version metadata should remain intact")

	getResp, err := client.GetObject(context.TODO(), &s3.GetObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
	})
	require.NoError(t, err)
	defer getResp.Body.Close()
	body, err := io.ReadAll(getResp.Body)
	require.NoError(t, err)
	assert.Equal(t, initialContent, body, "Self-copy should not alter the object body")

	versionsResp, err := client.ListObjectVersions(context.TODO(), &s3.ListObjectVersionsInput{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err)
	require.Len(t, versionsResp.Versions, 2, "Self-copy should append a new current version")
	assert.Equal(t, *copyResp.VersionId, *versionsResp.Versions[0].VersionId, "New copy version should be latest")
}

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

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

	enableVersioning(t, client, bucketName)
	suspendVersioning(t, client, bucketName)
	checkVersioningStatus(t, client, bucketName, types.BucketVersioningStatusSuspended)

	objectKey := "self-copy-suspended.txt"
	initialContent := []byte("null version content")

	_, err := client.PutObject(context.TODO(), &s3.PutObjectInput{
		Bucket:   aws.String(bucketName),
		Key:      aws.String(objectKey),
		Body:     bytes.NewReader(initialContent),
		Metadata: map[string]string{"stage": "one"},
	})
	require.NoError(t, err)

	copyResp, err := client.CopyObject(context.TODO(), &s3.CopyObjectInput{
		Bucket:            aws.String(bucketName),
		Key:               aws.String(objectKey),
		CopySource:        aws.String(versioningCopySource(bucketName, objectKey)),
		Metadata:          map[string]string{"stage": "two"},
		MetadataDirective: types.MetadataDirectiveReplace,
	})
	require.NoError(t, err, "Suspended self-copy with metadata replacement should succeed")
	assert.Nil(t, copyResp.VersionId, "Suspended versioning should not return a version header for the current null version")

	headResp, err := client.HeadObject(context.TODO(), &s3.HeadObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
	})
	require.NoError(t, err)
	assert.Equal(t, "two", headResp.Metadata["stage"], "Null current version should be updated in place")

	versionsResp, err := client.ListObjectVersions(context.TODO(), &s3.ListObjectVersionsInput{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err)
	require.Len(t, versionsResp.Versions, 1, "Suspended self-copy should keep a single null current version")
	require.NotNil(t, versionsResp.Versions[0].VersionId)
	assert.Equal(t, "null", *versionsResp.Versions[0].VersionId, "Suspended self-copy should preserve null-version semantics")
	assert.True(t, *versionsResp.Versions[0].IsLatest, "Null version should remain latest")
}

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

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

	enableVersioning(t, client, bucketName)

	objectKey := "self-copy-no-directive.txt"
	firstContent := []byte("first")
	secondContent := []byte("second")

	firstPut, err := client.PutObject(context.TODO(), &s3.PutObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
		Body:   bytes.NewReader(firstContent),
	})
	require.NoError(t, err)
	require.NotNil(t, firstPut.VersionId)

	_, err = client.PutObject(context.TODO(), &s3.PutObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
		Body:   bytes.NewReader(secondContent),
	})
	require.NoError(t, err)

	// Copying an earlier version onto its own key is how AWS restores that version.
	copyResp, err := client.CopyObject(context.TODO(), &s3.CopyObjectInput{
		Bucket:     aws.String(bucketName),
		Key:        aws.String(objectKey),
		CopySource: aws.String(fmt.Sprintf("%s?versionId=%s", versioningCopySource(bucketName, objectKey), *firstPut.VersionId)),
	})
	require.NoError(t, err, "Self-copy of an earlier version should succeed on a versioned bucket")
	require.NotNil(t, copyResp.VersionId)
	assert.NotEqual(t, *firstPut.VersionId, *copyResp.VersionId, "Restore should write a new version")

	getResp, err := client.GetObject(context.TODO(), &s3.GetObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
	})
	require.NoError(t, err)
	defer getResp.Body.Close()
	body, err := io.ReadAll(getResp.Body)
	require.NoError(t, err)
	assert.Equal(t, firstContent, body, "Restored version should serve the earlier body")

	versionsResp, err := client.ListObjectVersions(context.TODO(), &s3.ListObjectVersionsInput{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err)
	assert.Len(t, versionsResp.Versions, 3, "Restore should append to the version history")
}

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

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

	objectKey := "self-copy-unversioned.txt"
	putObject(t, client, bucketName, objectKey, "content")

	_, err := client.CopyObject(context.TODO(), &s3.CopyObjectInput{
		Bucket:     aws.String(bucketName),
		Key:        aws.String(objectKey),
		CopySource: aws.String(versioningCopySource(bucketName, objectKey)),
	})
	require.Error(t, err, "Self-copy without a metadata change is a no-op on an unversioned bucket")
	var apiErr smithy.APIError
	if assert.True(t, errors.As(err, &apiErr), "Expected a smithy.APIError, but got %T", err) {
		assert.Equal(t, "InvalidRequest", apiErr.ErrorCode())
	}
}

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

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

	enableVersioning(t, client, bucketName)
	suspendVersioning(t, client, bucketName)

	objectKey := "self-copy-suspended-no-directive.txt"
	putObject(t, client, bucketName, objectKey, "content")

	_, err := client.CopyObject(context.TODO(), &s3.CopyObjectInput{
		Bucket:     aws.String(bucketName),
		Key:        aws.String(objectKey),
		CopySource: aws.String(versioningCopySource(bucketName, objectKey)),
	})
	require.Error(t, err, "Suspended versioning overwrites the null version in place, so the copy changes nothing")
	var apiErr smithy.APIError
	if assert.True(t, errors.As(err, &apiErr), "Expected a smithy.APIError, but got %T", err) {
		assert.Equal(t, "InvalidRequest", apiErr.ErrorCode())
	}
}

// A suspended-versioning CopyObject writes the null version at the regular path, so
// like PutObject and multipart completion it has to retire the null delete marker a
// preceding DELETE left in .versions. While the regular-path object owns the null
// slot the leftover marker is shadowed, but it resurfaces as a phantom delete the
// moment that null version goes away.
func TestSuspendedCopyRetiresDeleteMarker(t *testing.T) {
	client := getS3Client(t)
	bucketName := getNewBucketName()

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

	sourceKey := "suspended-copy-source.txt"
	objectKey := "suspended-copy-dest.txt"

	enableVersioning(t, client, bucketName)
	putObject(t, client, bucketName, objectKey, "pre-suspension-content")
	suspendVersioning(t, client, bucketName)

	putObject(t, client, bucketName, sourceKey, "source-content")
	putObject(t, client, bucketName, objectKey, "null-version-content")
	deleteKey(t, client, bucketName, objectKey)

	_, err := client.CopyObject(context.TODO(), &s3.CopyObjectInput{
		Bucket:     aws.String(bucketName),
		Key:        aws.String(objectKey),
		CopySource: aws.String(versioningCopySource(bucketName, sourceKey)),
	})
	require.NoError(t, err)

	getResp, err := client.GetObject(context.TODO(), &s3.GetObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
	})
	require.NoError(t, err)
	defer getResp.Body.Close()
	body, err := io.ReadAll(getResp.Body)
	require.NoError(t, err)
	assert.Equal(t, "source-content", string(body))

	// Drop the null version the copy just wrote; a retired marker leaves nothing behind.
	_, err = client.DeleteObject(context.TODO(), &s3.DeleteObjectInput{
		Bucket:    aws.String(bucketName),
		Key:       aws.String(objectKey),
		VersionId: aws.String("null"),
	})
	require.NoError(t, err)

	listResp, err := client.ListObjectVersions(context.TODO(), &s3.ListObjectVersionsInput{
		Bucket: aws.String(bucketName),
		Prefix: aws.String(objectKey),
	})
	require.NoError(t, err)
	assert.Empty(t, listResp.DeleteMarkers, "the copy should have retired the null delete marker")
}