package s3api

import (
	"context"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"

	"modernc.org/strutil"

	"github.com/seaweedfs/seaweedfs/weed/filer"
	"github.com/seaweedfs/seaweedfs/weed/glog"
	"github.com/seaweedfs/seaweedfs/weed/operation"
	"github.com/seaweedfs/seaweedfs/weed/pb"
	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
	"github.com/seaweedfs/seaweedfs/weed/s3api/s3_constants"
	"github.com/seaweedfs/seaweedfs/weed/s3api/s3err"
	"github.com/seaweedfs/seaweedfs/weed/security"
	"github.com/seaweedfs/seaweedfs/weed/util"
	util_http "github.com/seaweedfs/seaweedfs/weed/util/http"
)

const (
	DirectiveCopy    = "COPY"
	DirectiveReplace = "REPLACE"
)

func (s3a *S3ApiServer) CopyObjectHandler(w http.ResponseWriter, r *http.Request) {

	dstBucket, dstObject := s3_constants.GetBucketAndObject(r)

	// Copy source path.
	cpSrcPath, err := url.QueryUnescape(r.Header.Get("X-Amz-Copy-Source"))
	if err != nil {
		// Save unescaped string as is.
		cpSrcPath = r.Header.Get("X-Amz-Copy-Source")
	}

	srcBucket, srcObject := pathToBucketAndObject(cpSrcPath)

	glog.V(3).Infof("CopyObjectHandler %s %s => %s %s", srcBucket, srcObject, dstBucket, dstObject)

	replaceMeta, replaceTagging := replaceDirective(r.Header)

	if (srcBucket == dstBucket && srcObject == dstObject || cpSrcPath == "") && (replaceMeta || replaceTagging) {
		fullPath := util.FullPath(fmt.Sprintf("%s/%s%s", s3a.option.BucketsPath, dstBucket, dstObject))
		dir, name := fullPath.DirAndName()
		entry, err := s3a.getEntry(dir, name)
		if err != nil || entry.IsDirectory {
			s3err.WriteErrorResponse(w, r, s3err.ErrInvalidCopySource)
			return
		}
		entry.Extended, err = processMetadataBytes(r.Header, entry.Extended, replaceMeta, replaceTagging)
		entry.Attributes.Mtime = time.Now().Unix()
		if err != nil {
			glog.Errorf("CopyObjectHandler ValidateTags error %s: %v", r.URL, err)
			s3err.WriteErrorResponse(w, r, s3err.ErrInvalidTag)
			return
		}
		err = s3a.touch(dir, name, entry)
		if err != nil {
			s3err.WriteErrorResponse(w, r, s3err.ErrInvalidCopySource)
			return
		}
		writeSuccessResponseXML(w, r, CopyObjectResult{
			ETag:         fmt.Sprintf("%x", entry.Attributes.Md5),
			LastModified: time.Now().UTC(),
		})
		return
	}

	// If source object is empty or bucket is empty, reply back invalid copy source.
	if srcObject == "" || srcBucket == "" {
		s3err.WriteErrorResponse(w, r, s3err.ErrInvalidCopySource)
		return
	}
	srcPath := util.FullPath(fmt.Sprintf("%s/%s%s", s3a.option.BucketsPath, srcBucket, srcObject))
	dir, name := srcPath.DirAndName()
	entry, err := s3a.getEntry(dir, name)
	if err != nil || entry.IsDirectory {
		s3err.WriteErrorResponse(w, r, s3err.ErrInvalidCopySource)
		return
	}

	if srcBucket == dstBucket && srcObject == dstObject {
		s3err.WriteErrorResponse(w, r, s3err.ErrInvalidCopyDest)
		return
	}

	// Process metadata and tags
	tagErr := processMetadata(r.Header, nil, replaceMeta, replaceTagging, s3a.getTags, dir, name)
	if tagErr != nil {
		s3err.WriteErrorResponse(w, r, s3err.ErrInvalidCopySource)
		return
	}

	// Create new entry for destination
	dstEntry := &filer_pb.Entry{
		Attributes: &filer_pb.FuseAttributes{
			FileSize: entry.Attributes.FileSize,
			Mtime:    time.Now().Unix(),
			Crtime:   entry.Attributes.Crtime,
			Mime:     entry.Attributes.Mime,
		},
		Extended: make(map[string][]byte),
	}

	// Copy extended attributes
	for k, v := range entry.Extended {
		dstEntry.Extended[k] = v
	}

	// Replicate chunks
	dstChunks, err := s3a.copyChunks(entry, r.URL.Path)
	if err != nil {
		glog.Errorf("CopyObjectHandler copy chunks error: %v", err)
		s3err.WriteErrorResponse(w, r, s3err.ErrInternalError)
		return
	}

	dstEntry.Chunks = dstChunks

	// Save the new entry
	dstPath := util.FullPath(fmt.Sprintf("%s/%s%s", s3a.option.BucketsPath, dstBucket, dstObject))
	dstDir, dstName := dstPath.DirAndName()
	if err := s3a.touch(dstDir, dstName, dstEntry); err != nil {
		s3err.WriteErrorResponse(w, r, s3err.ErrInternalError)
		return
	}

	// Convert filer_pb.Entry to filer.Entry for ETag calculation
	filerEntry := &filer.Entry{
		FullPath: dstPath,
		Attr: filer.Attr{
			FileSize: dstEntry.Attributes.FileSize,
			Mtime:    time.Unix(dstEntry.Attributes.Mtime, 0),
			Crtime:   time.Unix(dstEntry.Attributes.Crtime, 0),
			Mime:     dstEntry.Attributes.Mime,
		},
		Chunks: dstEntry.Chunks,
	}

	setEtag(w, filer.ETagEntry(filerEntry))

	response := CopyObjectResult{
		ETag:         filer.ETagEntry(filerEntry),
		LastModified: time.Now().UTC(),
	}

	writeSuccessResponseXML(w, r, response)

}

func pathToBucketAndObject(path string) (bucket, object string) {
	path = strings.TrimPrefix(path, "/")
	parts := strings.SplitN(path, "/", 2)
	if len(parts) == 2 {
		return parts[0], "/" + parts[1]
	}
	return parts[0], "/"
}

type CopyPartResult struct {
	LastModified time.Time `xml:"LastModified"`
	ETag         string    `xml:"ETag"`
}

func (s3a *S3ApiServer) CopyObjectPartHandler(w http.ResponseWriter, r *http.Request) {
	// https://docs.aws.amazon.com/AmazonS3/latest/dev/CopyingObjctsUsingRESTMPUapi.html
	// https://docs.aws.amazon.com/AmazonS3/latest/API/API_UploadPartCopy.html
	dstBucket, dstObject := s3_constants.GetBucketAndObject(r)

	// Copy source path.
	cpSrcPath, err := url.QueryUnescape(r.Header.Get("X-Amz-Copy-Source"))
	if err != nil {
		// Save unescaped string as is.
		cpSrcPath = r.Header.Get("X-Amz-Copy-Source")
	}

	srcBucket, srcObject := pathToBucketAndObject(cpSrcPath)
	// If source object is empty or bucket is empty, reply back invalid copy source.
	if srcObject == "" || srcBucket == "" {
		s3err.WriteErrorResponse(w, r, s3err.ErrInvalidCopySource)
		return
	}

	uploadID := r.URL.Query().Get("uploadId")
	partIDString := r.URL.Query().Get("partNumber")

	partID, err := strconv.Atoi(partIDString)
	if err != nil {
		s3err.WriteErrorResponse(w, r, s3err.ErrInvalidPart)
		return
	}

	glog.V(3).Infof("CopyObjectPartHandler %s %s => %s part %d", srcBucket, srcObject, dstBucket, partID)

	// check partID with maximum part ID for multipart objects
	if partID > globalMaxPartID {
		s3err.WriteErrorResponse(w, r, s3err.ErrInvalidMaxParts)
		return
	}

	rangeHeader := r.Header.Get("x-amz-copy-source-range")

	dstUrl := s3a.genPartUploadUrl(dstBucket, uploadID, partID)
	srcUrl := fmt.Sprintf("http://%s%s/%s%s",
		s3a.option.Filer.ToHttpAddress(), s3a.option.BucketsPath, srcBucket, urlEscapeObject(srcObject))

	resp, dataReader, err := util_http.ReadUrlAsReaderCloser(srcUrl, s3a.maybeGetFilerJwtAuthorizationToken(false), rangeHeader)
	if err != nil {
		s3err.WriteErrorResponse(w, r, s3err.ErrInvalidCopySource)
		return
	}
	defer util_http.CloseResponse(resp)
	defer dataReader.Close()

	glog.V(2).Infof("copy from %s to %s", srcUrl, dstUrl)
	destination := fmt.Sprintf("%s/%s%s", s3a.option.BucketsPath, dstBucket, dstObject)
	etag, errCode := s3a.putToFiler(r, dstUrl, dataReader, destination, dstBucket)

	if errCode != s3err.ErrNone {
		s3err.WriteErrorResponse(w, r, errCode)
		return
	}

	setEtag(w, etag)

	response := CopyPartResult{
		ETag:         etag,
		LastModified: time.Now().UTC(),
	}

	writeSuccessResponseXML(w, r, response)

}

func replaceDirective(reqHeader http.Header) (replaceMeta, replaceTagging bool) {
	return reqHeader.Get(s3_constants.AmzUserMetaDirective) == DirectiveReplace, reqHeader.Get(s3_constants.AmzObjectTaggingDirective) == DirectiveReplace
}

func processMetadata(reqHeader, existing http.Header, replaceMeta, replaceTagging bool, getTags func(parentDirectoryPath string, entryName string) (tags map[string]string, err error), dir, name string) (err error) {
	if sc := reqHeader.Get(s3_constants.AmzStorageClass); len(sc) == 0 {
		if sc := existing[s3_constants.AmzStorageClass]; len(sc) > 0 {
			reqHeader[s3_constants.AmzStorageClass] = sc
		}
	}

	if !replaceMeta {
		for header, _ := range reqHeader {
			if strings.HasPrefix(header, s3_constants.AmzUserMetaPrefix) {
				delete(reqHeader, header)
			}
		}
		for k, v := range existing {
			if strings.HasPrefix(k, s3_constants.AmzUserMetaPrefix) {
				reqHeader[k] = v
			}
		}
	}

	if !replaceTagging {
		for header, _ := range reqHeader {
			if strings.HasPrefix(header, s3_constants.AmzObjectTagging) {
				delete(reqHeader, header)
			}
		}

		found := false
		for k, _ := range existing {
			if strings.HasPrefix(k, s3_constants.AmzObjectTaggingPrefix) {
				found = true
				break
			}
		}

		if found {
			tags, err := getTags(dir, name)
			if err != nil {
				return err
			}

			var tagArr []string
			for k, v := range tags {
				tagArr = append(tagArr, fmt.Sprintf("%s=%s", k, v))
			}
			tagStr := strutil.JoinFields(tagArr, "&")
			reqHeader.Set(s3_constants.AmzObjectTagging, tagStr)
		}
	}
	return
}

func processMetadataBytes(reqHeader http.Header, existing map[string][]byte, replaceMeta, replaceTagging bool) (metadata map[string][]byte, err error) {
	metadata = make(map[string][]byte)

	if sc := existing[s3_constants.AmzStorageClass]; len(sc) > 0 {
		metadata[s3_constants.AmzStorageClass] = sc
	}
	if sc := reqHeader.Get(s3_constants.AmzStorageClass); len(sc) > 0 {
		metadata[s3_constants.AmzStorageClass] = []byte(sc)
	}

	if replaceMeta {
		for header, values := range reqHeader {
			if strings.HasPrefix(header, s3_constants.AmzUserMetaPrefix) {
				for _, value := range values {
					metadata[header] = []byte(value)
				}
			}
		}
	} else {
		for k, v := range existing {
			if strings.HasPrefix(k, s3_constants.AmzUserMetaPrefix) {
				metadata[k] = v
			}
		}
	}
	if replaceTagging {
		if tags := reqHeader.Get(s3_constants.AmzObjectTagging); tags != "" {
			parsedTags, err := parseTagsHeader(tags)
			if err != nil {
				return nil, err
			}
			err = ValidateTags(parsedTags)
			if err != nil {
				return nil, err
			}
			for k, v := range parsedTags {
				metadata[s3_constants.AmzObjectTagging+"-"+k] = []byte(v)
			}
		}
	} else {
		for k, v := range existing {
			if strings.HasPrefix(k, s3_constants.AmzObjectTagging) {
				metadata[k] = v
			}
		}
		delete(metadata, s3_constants.AmzTagCount)
	}

	return
}

// copyChunks replicates chunks from source entry to destination entry
func (s3a *S3ApiServer) copyChunks(entry *filer_pb.Entry, dstPath string) ([]*filer_pb.FileChunk, error) {
	dstChunks := make([]*filer_pb.FileChunk, len(entry.GetChunks()))
	executor := util.NewLimitedConcurrentExecutor(4) // Limit to 4 concurrent operations
	errChan := make(chan error, len(entry.GetChunks()))

	for i, chunk := range entry.GetChunks() {
		chunkIndex := i
		executor.Execute(func() {
			dstChunk, err := s3a.copySingleChunk(chunk, dstPath)
			if err != nil {
				errChan <- fmt.Errorf("chunk %d: %v", chunkIndex, err)
				return
			}
			dstChunks[chunkIndex] = dstChunk
			errChan <- nil
		})
	}

	// Wait for all operations to complete and check for errors
	for i := 0; i < len(entry.GetChunks()); i++ {
		if err := <-errChan; err != nil {
			return nil, err
		}
	}

	return dstChunks, nil
}

// copySingleChunk copies a single chunk from source to destination
func (s3a *S3ApiServer) copySingleChunk(chunk *filer_pb.FileChunk, dstPath string) (*filer_pb.FileChunk, error) {
	// Create a new chunk with same properties but new file ID
	dstChunk := &filer_pb.FileChunk{
		Offset:       chunk.Offset,
		Size:         chunk.Size,
		ModifiedTsNs: time.Now().UnixNano(),
		ETag:         chunk.ETag,
		IsCompressed: chunk.IsCompressed,
		CipherKey:    chunk.CipherKey,
	}

	// Get new file ID using filer's AssignVolume
	assignResult, err := s3a.assignNewVolume(dstPath)
	if err != nil {
		return nil, fmt.Errorf("assign volume: %v", err)
	}

	dstChunk.FileId = assignResult.FileId
	fid, err := filer_pb.ToFileIdObject(assignResult.FileId)
	if err != nil {
		return nil, fmt.Errorf("parse file ID: %v", err)
	}
	dstChunk.Fid = fid

	// Get source URL using LookupFileId
	srcUrl, _, err := operation.LookupFileId(func(_ context.Context) pb.ServerAddress {
		return pb.ServerAddress(s3a.option.Filer.ToGrpcAddress())
	}, s3a.option.GrpcDialOption, chunk.GetFileIdString())
	if err != nil {
		return nil, fmt.Errorf("lookup source file ID: %v", err)
	}

	// Download and upload the chunk
	if err := s3a.transferChunkData(srcUrl, assignResult); err != nil {
		return nil, fmt.Errorf("transfer chunk data: %v", err)
	}

	return dstChunk, nil
}

// assignNewVolume assigns a new volume for the chunk
func (s3a *S3ApiServer) assignNewVolume(dstPath string) (*filer_pb.AssignVolumeResponse, error) {
	var assignResult *filer_pb.AssignVolumeResponse
	err := s3a.WithFilerClient(false, func(client filer_pb.SeaweedFilerClient) error {
		resp, err := client.AssignVolume(context.Background(), &filer_pb.AssignVolumeRequest{
			Count:       1,
			Replication: "",
			Collection:  "",
			DiskType:    "",
			DataCenter:  s3a.option.DataCenter,
			Path:        dstPath,
		})
		if err != nil {
			return fmt.Errorf("assign volume: %v", err)
		}
		if resp.Error != "" {
			return fmt.Errorf("assign volume: %v", resp.Error)
		}
		assignResult = resp
		return nil
	})
	if err != nil {
		return nil, err
	}
	return assignResult, nil
}

// transferChunkData downloads the chunk from source and uploads it to destination
func (s3a *S3ApiServer) transferChunkData(srcUrl string, assignResult *filer_pb.AssignVolumeResponse) error {
	dstUrl := fmt.Sprintf("http://%s/%s", assignResult.Location.Url, assignResult.FileId)

	_, _, resp, err := util_http.DownloadFile(srcUrl, s3a.maybeGetFilerJwtAuthorizationToken(false))
	if err != nil {
		return fmt.Errorf("download chunk: %v", err)
	}

	// Read response body into byte slice
	chunkData, err := io.ReadAll(resp.Body)
	util_http.CloseResponse(resp)
	if err != nil {
		return fmt.Errorf("read chunk data: %v", err)
	}

	// Upload chunk to new location
	uploadOption := &operation.UploadOption{
		UploadUrl:         dstUrl,
		Cipher:            false,
		IsInputCompressed: false,
		MimeType:          "",
		PairMap:           nil,
		Jwt:               security.EncodedJwt(assignResult.Auth),
	}
	uploader, err := operation.NewUploader()
	if err != nil {
		return fmt.Errorf("create uploader: %v", err)
	}
	_, err = uploader.UploadData(chunkData, uploadOption)
	if err != nil {
		return fmt.Errorf("upload chunk: %v", err)
	}

	return nil
}