package reg

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"net/url"
	"strconv"
	"strings"

	// crypto libraries included for go-digest
	_ "crypto/sha256"
	_ "crypto/sha512"

	"github.com/opencontainers/go-digest"

	"github.com/regclient/regclient/internal/reghttp"
	"github.com/regclient/regclient/internal/reqmeta"
	"github.com/regclient/regclient/types/blob"
	"github.com/regclient/regclient/types/descriptor"
	"github.com/regclient/regclient/types/errs"
	"github.com/regclient/regclient/types/ref"
	"github.com/regclient/regclient/types/warning"
)

var (
	zeroDig = digest.SHA256.FromBytes([]byte{})
)

// BlobDelete removes a blob from the repository
func (reg *Reg) BlobDelete(ctx context.Context, r ref.Ref, d descriptor.Descriptor) error {
	req := &reghttp.Req{
		MetaKind:   reqmeta.Query,
		Host:       r.Registry,
		Method:     "DELETE",
		Repository: r.Repository,
		Path:       "blobs/" + d.Digest.String(),
	}
	resp, err := reg.reghttp.Do(ctx, req)
	if err != nil {
		return fmt.Errorf("failed to delete blob, digest %s, ref %s: %w", d.Digest.String(), r.CommonName(), err)
	}
	if resp.HTTPResponse().StatusCode != 202 {
		return fmt.Errorf("failed to delete blob, digest %s, ref %s: %w", d.Digest.String(), r.CommonName(), reghttp.HTTPError(resp.HTTPResponse().StatusCode))
	}
	return nil
}

// BlobGet retrieves a blob from the repository, returning a blob reader
func (reg *Reg) BlobGet(ctx context.Context, r ref.Ref, d descriptor.Descriptor) (blob.Reader, error) {
	// build/send request
	req := &reghttp.Req{
		MetaKind:   reqmeta.Blob,
		Host:       r.Registry,
		Method:     "GET",
		Repository: r.Repository,
		Path:       "blobs/" + d.Digest.String(),
		ExpectLen:  d.Size,
	}
	resp, err := reg.reghttp.Do(ctx, req)
	if err != nil && len(d.URLs) > 0 {
		for _, curURL := range d.URLs {
			// fallback for external blobs
			var u *url.URL
			u, err = url.Parse(curURL)
			if err != nil {
				return nil, fmt.Errorf("failed to parse external url \"%s\": %w", curURL, err)
			}
			req = &reghttp.Req{
				MetaKind:   reqmeta.Blob,
				Host:       r.Registry,
				Method:     "GET",
				Repository: r.Repository,
				DirectURL:  u,
				NoMirrors:  true,
				ExpectLen:  d.Size,
			}
			resp, err = reg.reghttp.Do(ctx, req)
			if err == nil {
				break
			}
		}
	}
	if err != nil {
		return nil, fmt.Errorf("failed to get blob, digest %s, ref %s: %w", d.Digest.String(), r.CommonName(), err)
	}
	if resp.HTTPResponse().StatusCode != 200 {
		return nil, fmt.Errorf("failed to get blob, digest %s, ref %s: %w", d.Digest.String(), r.CommonName(), reghttp.HTTPError(resp.HTTPResponse().StatusCode))
	}

	b := blob.NewReader(
		blob.WithRef(r),
		blob.WithReader(resp),
		blob.WithDesc(d),
		blob.WithResp(resp.HTTPResponse()),
	)
	return b, nil
}

// BlobHead is used to verify if a blob exists and is accessible
func (reg *Reg) BlobHead(ctx context.Context, r ref.Ref, d descriptor.Descriptor) (blob.Reader, error) {
	// build/send request
	req := &reghttp.Req{
		MetaKind:   reqmeta.Head,
		Host:       r.Registry,
		Method:     "HEAD",
		Repository: r.Repository,
		Path:       "blobs/" + d.Digest.String(),
	}
	resp, err := reg.reghttp.Do(ctx, req)
	if err != nil && len(d.URLs) > 0 {
		for _, curURL := range d.URLs {
			// fallback for external blobs
			var u *url.URL
			u, err = url.Parse(curURL)
			if err != nil {
				return nil, fmt.Errorf("failed to parse external url \"%s\": %w", curURL, err)
			}
			req = &reghttp.Req{
				MetaKind:   reqmeta.Head,
				Host:       r.Registry,
				Method:     "HEAD",
				Repository: r.Repository,
				DirectURL:  u,
				NoMirrors:  true,
			}
			resp, err = reg.reghttp.Do(ctx, req)
			if err == nil {
				break
			}
		}
	}
	if err != nil {
		return nil, fmt.Errorf("failed to request blob head, digest %s, ref %s: %w", d.Digest.String(), r.CommonName(), err)
	}
	defer resp.Close()
	if resp.HTTPResponse().StatusCode != 200 {
		return nil, fmt.Errorf("failed to request blob head, digest %s, ref %s: %w", d.Digest.String(), r.CommonName(), reghttp.HTTPError(resp.HTTPResponse().StatusCode))
	}

	b := blob.NewReader(
		blob.WithRef(r),
		blob.WithDesc(d),
		blob.WithResp(resp.HTTPResponse()),
	)
	return b, nil
}

// BlobMount attempts to perform a server side copy/mount of the blob between repositories
func (reg *Reg) BlobMount(ctx context.Context, rSrc ref.Ref, rTgt ref.Ref, d descriptor.Descriptor) error {
	putURL, _, err := reg.blobMount(ctx, rTgt, d, rSrc)
	// if mount fails and returns an upload location, cancel that upload
	if err != nil {
		_ = reg.blobUploadCancel(ctx, rTgt, putURL)
	}
	return err
}

// BlobPut uploads a blob to a repository.
// Descriptor is optional, leave size and digest to zero value if unknown.
// Reader must also be an [io.Seeker] to support chunked upload fallback.
//
// This will attempt an anonymous blob mount first which some registries may support.
// It will then try doing a full put of the blob without chunking (most widely supported).
// If the full put fails, it will fall back to a chunked upload (useful for flaky networks).
func (reg *Reg) BlobPut(ctx context.Context, r ref.Ref, d descriptor.Descriptor, rdr io.Reader) (descriptor.Descriptor, error) {
	var putURL *url.URL
	var err error
	validDesc := (d.Size > 0 && d.Digest.Validate() == nil) || (d.Size == 0 && d.Digest == zeroDig)
	// dedup warnings
	if w := warning.FromContext(ctx); w == nil {
		ctx = warning.NewContext(ctx, &warning.Warning{Hook: warning.DefaultHook()})
	}

	// attempt an anonymous blob mount
	if validDesc {
		putURL, _, err = reg.blobMount(ctx, r, d, ref.Ref{})
		if err == nil {
			return d, nil
		}
		if err != errs.ErrMountReturnedLocation {
			putURL = nil
		}
	}
	// fallback to requesting upload URL
	if putURL == nil {
		putURL, err = reg.blobGetUploadURL(ctx, r, d)
		if err != nil {
			return d, err
		}
	}
	// send upload as one-chunk
	tryPut := validDesc
	if tryPut {
		host := reg.hostGet(r.Registry)
		maxPut := host.BlobMax
		if maxPut == 0 {
			maxPut = reg.blobMaxPut
		}
		if maxPut > 0 && d.Size > maxPut {
			tryPut = false
		}
	}
	if tryPut {
		err = reg.blobPutUploadFull(ctx, r, d, putURL, rdr)
		if err == nil {
			return d, nil
		}
		// on failure, attempt to seek back to start to perform a chunked upload
		rdrSeek, ok := rdr.(io.ReadSeeker)
		if !ok {
			_ = reg.blobUploadCancel(ctx, r, putURL)
			return d, err
		}
		offset, errR := rdrSeek.Seek(0, io.SeekStart)
		if errR != nil || offset != 0 {
			_ = reg.blobUploadCancel(ctx, r, putURL)
			return d, err
		}
	}
	// send a chunked upload if full upload not possible or too large
	d, err = reg.blobPutUploadChunked(ctx, r, d, putURL, rdr)
	if err != nil {
		_ = reg.blobUploadCancel(ctx, r, putURL)
	}
	return d, err
}

func (reg *Reg) blobGetUploadURL(ctx context.Context, r ref.Ref, d descriptor.Descriptor) (*url.URL, error) {
	q := url.Values{}
	if d.DigestAlgo() != digest.Canonical {
		// TODO(bmitch): EXPERIMENTAL parameter, registry support and OCI spec change needed
		q.Add(paramBlobDigestAlgo, d.DigestAlgo().String())
	}
	// request an upload location
	req := &reghttp.Req{
		MetaKind:    reqmeta.Blob,
		Host:        r.Registry,
		NoMirrors:   true,
		Method:      "POST",
		Repository:  r.Repository,
		Path:        "blobs/uploads/",
		Query:       q,
		TransactLen: d.Size,
	}
	resp, err := reg.reghttp.Do(ctx, req)
	if err != nil {
		return nil, fmt.Errorf("failed to send blob post, ref %s: %w", r.CommonName(), err)
	}
	defer resp.Close()
	if resp.HTTPResponse().StatusCode != 202 {
		return nil, fmt.Errorf("failed to send blob post, ref %s: %w", r.CommonName(), reghttp.HTTPError(resp.HTTPResponse().StatusCode))
	}

	// if min size header received, check/adjust host settings
	minSizeStr := resp.HTTPResponse().Header.Get(blobChunkMinHeader)
	if minSizeStr != "" {
		minSize, err := strconv.ParseInt(minSizeStr, 10, 64)
		if err != nil {
			reg.slog.Warn("Failed to parse chunk size header",
				slog.String("size", minSizeStr),
				slog.String("err", err.Error()))
		} else {
			host := reg.hostGet(r.Registry)
			reg.muHost.Lock()
			if (host.BlobChunk > 0 && minSize > host.BlobChunk) || (host.BlobChunk <= 0 && minSize > reg.blobChunkSize) {
				host.BlobChunk = min(minSize, reg.blobChunkLimit)
				reg.slog.Debug("Registry requested min chunk size",
					slog.Int64("size", host.BlobChunk),
					slog.String("host", host.Name))
			}
			reg.muHost.Unlock()
		}
	}
	// Extract the location into a new putURL based on whether it's relative, fqdn with a scheme, or without a scheme.
	location := resp.HTTPResponse().Header.Get("Location")
	if location == "" {
		return nil, fmt.Errorf("failed to send blob post, ref %s: %w", r.CommonName(), errs.ErrMissingLocation)
	}
	reg.slog.Debug("Upload location received",
		slog.String("location", location))

	// put url may be relative to the above post URL, so parse in that context
	postURL := resp.HTTPResponse().Request.URL
	putURL, err := postURL.Parse(location)
	if err != nil {
		reg.slog.Warn("Location url failed to parse",
			slog.String("location", location),
			slog.String("err", err.Error()))
		return nil, fmt.Errorf("blob upload url invalid, ref %s: %w", r.CommonName(), err)
	}
	return putURL, nil
}

func (reg *Reg) blobMount(ctx context.Context, rTgt ref.Ref, d descriptor.Descriptor, rSrc ref.Ref) (*url.URL, string, error) {
	// build/send request
	query := url.Values{}
	query.Set("mount", d.Digest.String())
	ignoreErr := true // ignore errors from anonymous blob mount attempts
	if rSrc.Registry == rTgt.Registry && rSrc.Repository != "" {
		query.Set("from", rSrc.Repository)
		ignoreErr = false
	}

	req := &reghttp.Req{
		MetaKind:    reqmeta.Blob,
		Host:        rTgt.Registry,
		NoMirrors:   true,
		Method:      "POST",
		Repository:  rTgt.Repository,
		Path:        "blobs/uploads/",
		Query:       query,
		IgnoreErr:   ignoreErr,
		TransactLen: d.Size,
	}
	resp, err := reg.reghttp.Do(ctx, req)
	if err != nil {
		return nil, "", fmt.Errorf("failed to mount blob, digest %s, ref %s: %w", d.Digest.String(), rTgt.CommonName(), err)
	}
	defer resp.Close()

	// if min size header received, check/adjust host settings
	minSizeStr := resp.HTTPResponse().Header.Get(blobChunkMinHeader)
	if minSizeStr != "" {
		minSize, err := strconv.ParseInt(minSizeStr, 10, 64)
		if err != nil {
			reg.slog.Warn("Failed to parse chunk size header",
				slog.String("size", minSizeStr),
				slog.String("err", err.Error()))
		} else {
			host := reg.hostGet(rTgt.Registry)
			reg.muHost.Lock()
			if (host.BlobChunk > 0 && minSize > host.BlobChunk) || (host.BlobChunk <= 0 && minSize > reg.blobChunkSize) {
				host.BlobChunk = min(minSize, reg.blobChunkLimit)
				reg.slog.Debug("Registry requested min chunk size",
					slog.Int64("size", host.BlobChunk),
					slog.String("host", host.Name))
			}
			reg.muHost.Unlock()
		}
	}
	// 201 indicates the blob mount succeeded
	if resp.HTTPResponse().StatusCode == 201 {
		return nil, "", nil
	}
	// 202 indicates blob mount failed but server ready to receive an upload at location
	location := resp.HTTPResponse().Header.Get("Location")
	uuid := resp.HTTPResponse().Header.Get("Docker-Upload-UUID")
	if resp.HTTPResponse().StatusCode == 202 && location != "" {
		postURL := resp.HTTPResponse().Request.URL
		putURL, err := postURL.Parse(location)
		if err != nil {
			reg.slog.Warn("Mount location header failed to parse",
				slog.String("digest", d.Digest.String()),
				slog.String("target", rTgt.CommonName()),
				slog.String("location", location),
				slog.String("err", err.Error()))
		} else {
			return putURL, uuid, errs.ErrMountReturnedLocation
		}
	}
	// all other responses unhandled
	return nil, "", fmt.Errorf("failed to mount blob, digest %s, ref %s: %w", d.Digest.String(), rTgt.CommonName(), reghttp.HTTPError(resp.HTTPResponse().StatusCode))
}

func (reg *Reg) blobPutUploadFull(ctx context.Context, r ref.Ref, d descriptor.Descriptor, putURL *url.URL, rdr io.Reader) error {
	// append digest to request to use the monolithic upload option
	if putURL.RawQuery != "" {
		putURL.RawQuery = putURL.RawQuery + "&digest=" + url.QueryEscape(d.Digest.String())
	} else {
		putURL.RawQuery = "digest=" + url.QueryEscape(d.Digest.String())
	}

	// make a reader function for the blob
	readOnce := false
	bodyFunc := func() (io.ReadCloser, error) {
		// handle attempt to reuse blob reader (e.g. on a connection retry or fallback)
		if readOnce {
			rdrSeek, ok := rdr.(io.ReadSeeker)
			if !ok {
				return nil, fmt.Errorf("blob source is not a seeker%.0w", errs.ErrNotRetryable)
			}
			_, err := rdrSeek.Seek(0, io.SeekStart)
			if err != nil {
				return nil, fmt.Errorf("seek on blob source failed: %w%.0w", err, errs.ErrNotRetryable)
			}
		}
		readOnce = true
		return io.NopCloser(rdr), nil
	}
	// special case for the empty blob
	if d.Size == 0 && d.Digest == zeroDig {
		bodyFunc = nil
	}

	// build/send request
	header := http.Header{
		"Content-Type": {"application/octet-stream"},
	}
	req := &reghttp.Req{
		MetaKind:   reqmeta.Blob,
		Host:       r.Registry,
		Method:     "PUT",
		Repository: r.Repository,
		DirectURL:  putURL,
		BodyFunc:   bodyFunc,
		BodyLen:    d.Size,
		Headers:    header,
		NoMirrors:  true,
	}
	resp, err := reg.reghttp.Do(ctx, req)
	if err != nil {
		return fmt.Errorf("failed to send blob (put), digest %s, ref %s: %w", d.Digest.String(), r.CommonName(), err)
	}
	defer resp.Close()
	// 201 follows distribution-spec, 204 is listed as possible in the Docker registry spec
	if resp.HTTPResponse().StatusCode != 201 && resp.HTTPResponse().StatusCode != 204 {
		return fmt.Errorf("failed to send blob (put), digest %s, ref %s: %w", d.Digest.String(), r.CommonName(), reghttp.HTTPError(resp.HTTPResponse().StatusCode))
	}
	return nil
}

func (reg *Reg) blobPutUploadChunked(ctx context.Context, r ref.Ref, d descriptor.Descriptor, putURL *url.URL, rdr io.Reader) (descriptor.Descriptor, error) {
	host := reg.hostGet(r.Registry)
	bufSize := host.BlobChunk
	if bufSize <= 0 {
		bufSize = reg.blobChunkSize
	}
	bufBytes := make([]byte, 0, bufSize)
	bufRdr := bytes.NewReader(bufBytes)
	bufStart := int64(0)
	bufChange := false

	// setup buffer and digest pipe
	digester := d.DigestAlgo().Digester()
	digestRdr := io.TeeReader(rdr, digester.Hash())
	finalChunk := false
	chunkStart := int64(0)
	chunkSize := 0
	bodyFunc := func() (io.ReadCloser, error) {
		// reset to the start on every new read
		_, err := bufRdr.Seek(0, io.SeekStart)
		if err != nil {
			return nil, err
		}
		return io.NopCloser(bufRdr), nil
	}
	chunkURL := *putURL
	retryLimit := 10 // TODO: pull limit from reghttp
	retryCur := 0
	var err error

	for !finalChunk || chunkStart < bufStart+int64(len(bufBytes)) {
		bufChange = false
		for chunkStart >= bufStart+int64(len(bufBytes)) && !finalChunk {
			bufStart += int64(len(bufBytes))
			// reset length if previous read was short
			if cap(bufBytes) != len(bufBytes) {
				bufBytes = bufBytes[:cap(bufBytes)]
				bufChange = true
			}
			// read a chunk into an input buffer, computing the digest
			chunkSize, err = io.ReadFull(digestRdr, bufBytes)
			if err == io.EOF || err == io.ErrUnexpectedEOF {
				finalChunk = true
			} else if err != nil {
				return d, fmt.Errorf("failed to send blob chunk, ref %s: %w", r.CommonName(), err)
			}
			// update length on partial read
			if chunkSize != len(bufBytes) {
				bufBytes = bufBytes[:chunkSize]
				bufChange = true
			}
		}
		if chunkStart > bufStart && chunkStart < bufStart+int64(len(bufBytes)) {
			// next chunk is inside the existing buf
			bufBytes = bufBytes[chunkStart-bufStart:]
			bufStart = chunkStart
			chunkSize = len(bufBytes)
			bufChange = true
		}
		if chunkSize > 0 && chunkStart != bufStart {
			return d, fmt.Errorf("chunkStart (%d) != bufStart (%d)", chunkStart, bufStart)
		}
		if bufChange {
			// need to recreate the reader on a change to the slice length,
			// old reader is looking at the old slice metadata
			bufRdr = bytes.NewReader(bufBytes)
		}

		if chunkSize > 0 {
			// write chunk
			header := http.Header{
				"Content-Type":  {"application/octet-stream"},
				"Content-Range": {fmt.Sprintf("%d-%d", chunkStart, chunkStart+int64(chunkSize)-1)},
			}
			req := &reghttp.Req{
				MetaKind:    reqmeta.Blob,
				Host:        r.Registry,
				Method:      "PATCH",
				Repository:  r.Repository,
				DirectURL:   &chunkURL,
				BodyFunc:    bodyFunc,
				BodyLen:     int64(chunkSize),
				Headers:     header,
				NoMirrors:   true,
				TransactLen: d.Size - int64(chunkSize),
			}
			resp, err := reg.reghttp.Do(ctx, req)
			if err != nil && !errors.Is(err, errs.ErrHTTPStatus) && !errors.Is(err, errs.ErrNotFound) {
				return d, fmt.Errorf("failed to send blob (chunk), ref %s: http do: %w", r.CommonName(), err)
			}
			err = resp.Close()
			if err != nil {
				return d, fmt.Errorf("failed to close request: %w", err)
			}
			httpResp := resp.HTTPResponse()
			// distribution-spec is 202, AWS ECR returns a 201 and rejects the put
			if resp.HTTPResponse().StatusCode == 201 {
				reg.slog.Debug("Early accept of chunk in PATCH before PUT request",
					slog.String("ref", r.CommonName()),
					slog.Int64("chunkStart", chunkStart),
					slog.Int("chunkSize", chunkSize))
			} else if resp.HTTPResponse().StatusCode >= 400 && resp.HTTPResponse().StatusCode < 500 &&
				resp.HTTPResponse().Header.Get("Location") != "" &&
				resp.HTTPResponse().Header.Get("Range") != "" {
				retryCur++
				reg.slog.Debug("Recoverable chunk upload error",
					slog.String("ref", r.CommonName()),
					slog.Int64("chunkStart", chunkStart),
					slog.Int("chunkSize", chunkSize),
					slog.String("range", resp.HTTPResponse().Header.Get("Range")))
			} else if resp.HTTPResponse().StatusCode != 202 {
				retryCur++
				statusResp, statusErr := reg.blobUploadStatus(ctx, r, &chunkURL)
				if retryCur > retryLimit || statusErr != nil {
					return d, fmt.Errorf("failed to send blob (chunk), ref %s: http status: %w", r.CommonName(), reghttp.HTTPError(resp.HTTPResponse().StatusCode))
				}
				httpResp = statusResp
			} else {
				// successful request
				if retryCur > 0 {
					retryCur--
				}
			}
			rangeEnd, err := blobUploadCurBytes(httpResp)
			if err == nil {
				chunkStart = rangeEnd + 1
			} else {
				chunkStart += int64(chunkSize)
			}
			location := httpResp.Header.Get("Location")
			if location != "" {
				reg.slog.Debug("Next chunk upload location received",
					slog.String("location", location))
				prevURL := httpResp.Request.URL
				parseURL, err := prevURL.Parse(location)
				if err != nil {
					return d, fmt.Errorf("failed to send blob (parse next chunk location), ref %s: %w", r.CommonName(), err)
				}
				chunkURL = *parseURL
			}
		}
	}

	// compute digest
	dOut := digester.Digest()
	if d.Digest.Validate() == nil && dOut != d.Digest {
		return d, fmt.Errorf("%w, expected %s, computed %s", errs.ErrDigestMismatch, d.Digest.String(), dOut.String())
	}
	if d.Size != 0 && chunkStart != d.Size {
		return d, fmt.Errorf("blob content size does not match descriptor, expected %d, received %d%.0w", d.Size, chunkStart, errs.ErrMismatch)
	}
	d.Digest = dOut
	d.Size = chunkStart

	// send the final put
	// append digest to request to use the monolithic upload option
	if chunkURL.RawQuery != "" {
		chunkURL.RawQuery = chunkURL.RawQuery + "&digest=" + url.QueryEscape(dOut.String())
	} else {
		chunkURL.RawQuery = "digest=" + url.QueryEscape(dOut.String())
	}

	header := http.Header{
		"Content-Type": {"application/octet-stream"},
	}
	req := &reghttp.Req{
		MetaKind:   reqmeta.Query,
		Host:       r.Registry,
		Method:     "PUT",
		Repository: r.Repository,
		DirectURL:  &chunkURL,
		BodyLen:    int64(0),
		Headers:    header,
		NoMirrors:  true,
	}
	resp, err := reg.reghttp.Do(ctx, req)
	if err != nil {
		return d, fmt.Errorf("failed to send blob (chunk digest), digest %s, ref %s: %w", dOut, r.CommonName(), err)
	}
	defer resp.Close()
	// 201 follows distribution-spec, 204 is listed as possible in the Docker registry spec
	if resp.HTTPResponse().StatusCode != 201 && resp.HTTPResponse().StatusCode != 204 {
		return d, fmt.Errorf("failed to send blob (chunk digest), digest %s, ref %s: %w", dOut, r.CommonName(), reghttp.HTTPError(resp.HTTPResponse().StatusCode))
	}

	return d, nil
}

// blobUploadCancel stops an upload, releasing resources on the server.
func (reg *Reg) blobUploadCancel(ctx context.Context, r ref.Ref, putURL *url.URL) error {
	if putURL == nil {
		return fmt.Errorf("failed to cancel upload %s: url undefined", r.CommonName())
	}
	req := &reghttp.Req{
		MetaKind:   reqmeta.Query,
		Host:       r.Registry,
		NoMirrors:  true,
		Method:     "DELETE",
		Repository: r.Repository,
		DirectURL:  putURL,
	}
	resp, err := reg.reghttp.Do(ctx, req)
	if err != nil {
		return fmt.Errorf("failed to cancel upload %s: %w", r.CommonName(), err)
	}
	defer resp.Close()
	if resp.HTTPResponse().StatusCode != 202 {
		return fmt.Errorf("failed to cancel upload %s: %w", r.CommonName(), reghttp.HTTPError(resp.HTTPResponse().StatusCode))
	}
	return nil
}

// blobUploadStatus provides a response with headers indicating the progress of an upload
func (reg *Reg) blobUploadStatus(ctx context.Context, r ref.Ref, putURL *url.URL) (*http.Response, error) {
	req := &reghttp.Req{
		MetaKind:   reqmeta.Query,
		Host:       r.Registry,
		Method:     "GET",
		Repository: r.Repository,
		DirectURL:  putURL,
		NoMirrors:  true,
	}
	resp, err := reg.reghttp.Do(ctx, req)
	if err != nil {
		return nil, fmt.Errorf("failed to get upload status: %w", err)
	}
	defer resp.Close()
	if resp.HTTPResponse().StatusCode != 204 {
		return resp.HTTPResponse(), fmt.Errorf("failed to get upload status: %w", reghttp.HTTPError(resp.HTTPResponse().StatusCode))
	}
	return resp.HTTPResponse(), nil
}

func blobUploadCurBytes(resp *http.Response) (int64, error) {
	if resp == nil {
		return 0, fmt.Errorf("missing response")
	}
	r := resp.Header.Get("Range")
	if r == "" {
		return 0, fmt.Errorf("missing range header")
	}
	rSplit := strings.SplitN(r, "-", 2)
	if len(rSplit) < 2 {
		return 0, fmt.Errorf("missing offset in range header")
	}
	return strconv.ParseInt(rSplit[1], 10, 64)
}