package storage

import (
	"bytes"
	"crypto/sha256"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"testing"

	"github.com/docker/distribution"
	"github.com/docker/distribution/context"
	"github.com/docker/distribution/digest"
	"github.com/docker/distribution/registry/storage/cache/memory"
	"github.com/docker/distribution/registry/storage/driver/inmemory"
	"github.com/docker/distribution/testutil"
)

// TestSimpleBlobUpload covers the blob upload process, exercising common
// error paths that might be seen during an upload.
func TestSimpleBlobUpload(t *testing.T) {
	randomDataReader, tarSumStr, err := testutil.CreateRandomTarFile()

	if err != nil {
		t.Fatalf("error creating random reader: %v", err)
	}

	dgst := digest.Digest(tarSumStr)

	if err != nil {
		t.Fatalf("error allocating upload store: %v", err)
	}

	ctx := context.Background()
	imageName := "foo/bar"
	driver := inmemory.New()
	registry := NewRegistryWithDriver(ctx, driver, memory.NewInMemoryBlobDescriptorCacheProvider())
	repository, err := registry.Repository(ctx, imageName)
	if err != nil {
		t.Fatalf("unexpected error getting repo: %v", err)
	}
	bs := repository.Blobs(ctx)

	h := sha256.New()
	rd := io.TeeReader(randomDataReader, h)

	blobUpload, err := bs.Create(ctx)

	if err != nil {
		t.Fatalf("unexpected error starting layer upload: %s", err)
	}

	// Cancel the upload then restart it
	if err := blobUpload.Cancel(ctx); err != nil {
		t.Fatalf("unexpected error during upload cancellation: %v", err)
	}

	// Do a resume, get unknown upload
	blobUpload, err = bs.Resume(ctx, blobUpload.ID())
	if err != distribution.ErrBlobUploadUnknown {
		t.Fatalf("unexpected error resuming upload, should be unkown: %v", err)
	}

	// Restart!
	blobUpload, err = bs.Create(ctx)
	if err != nil {
		t.Fatalf("unexpected error starting layer upload: %s", err)
	}

	// Get the size of our random tarfile
	randomDataSize, err := seekerSize(randomDataReader)
	if err != nil {
		t.Fatalf("error getting seeker size of random data: %v", err)
	}

	nn, err := io.Copy(blobUpload, rd)
	if err != nil {
		t.Fatalf("unexpected error uploading layer data: %v", err)
	}

	if nn != randomDataSize {
		t.Fatalf("layer data write incomplete")
	}

	offset, err := blobUpload.Seek(0, os.SEEK_CUR)
	if err != nil {
		t.Fatalf("unexpected error seeking layer upload: %v", err)
	}

	if offset != nn {
		t.Fatalf("blobUpload not updated with correct offset: %v != %v", offset, nn)
	}
	blobUpload.Close()

	// Do a resume, for good fun
	blobUpload, err = bs.Resume(ctx, blobUpload.ID())
	if err != nil {
		t.Fatalf("unexpected error resuming upload: %v", err)
	}

	sha256Digest := digest.NewDigest("sha256", h)
	desc, err := blobUpload.Commit(ctx, distribution.Descriptor{Digest: dgst})
	if err != nil {
		t.Fatalf("unexpected error finishing layer upload: %v", err)
	}

	// After finishing an upload, it should no longer exist.
	if _, err := bs.Resume(ctx, blobUpload.ID()); err != distribution.ErrBlobUploadUnknown {
		t.Fatalf("expected layer upload to be unknown, got %v", err)
	}

	// Test for existence.
	statDesc, err := bs.Stat(ctx, desc.Digest)
	if err != nil {
		t.Fatalf("unexpected error checking for existence: %v, %#v", err, bs)
	}

	if statDesc != desc {
		t.Fatalf("descriptors not equal: %v != %v", statDesc, desc)
	}

	rc, err := bs.Open(ctx, desc.Digest)
	if err != nil {
		t.Fatalf("unexpected error opening blob for read: %v", err)
	}
	defer rc.Close()

	h.Reset()
	nn, err = io.Copy(h, rc)
	if err != nil {
		t.Fatalf("error reading layer: %v", err)
	}

	if nn != randomDataSize {
		t.Fatalf("incorrect read length")
	}

	if digest.NewDigest("sha256", h) != sha256Digest {
		t.Fatalf("unexpected digest from uploaded layer: %q != %q", digest.NewDigest("sha256", h), sha256Digest)
	}
}

// TestSimpleBlobRead just creates a simple blob file and ensures that basic
// open, read, seek, read works. More specific edge cases should be covered in
// other tests.
func TestSimpleBlobRead(t *testing.T) {
	ctx := context.Background()
	imageName := "foo/bar"
	driver := inmemory.New()
	registry := NewRegistryWithDriver(ctx, driver, memory.NewInMemoryBlobDescriptorCacheProvider())
	repository, err := registry.Repository(ctx, imageName)
	if err != nil {
		t.Fatalf("unexpected error getting repo: %v", err)
	}
	bs := repository.Blobs(ctx)

	randomLayerReader, tarSumStr, err := testutil.CreateRandomTarFile() // TODO(stevvooe): Consider using just a random string.
	if err != nil {
		t.Fatalf("error creating random data: %v", err)
	}

	dgst := digest.Digest(tarSumStr)

	// Test for existence.
	desc, err := bs.Stat(ctx, dgst)
	if err != distribution.ErrBlobUnknown {
		t.Fatalf("expected not found error when testing for existence: %v", err)
	}

	rc, err := bs.Open(ctx, dgst)
	if err != distribution.ErrBlobUnknown {
		t.Fatalf("expected not found error when opening non-existent blob: %v", err)
	}

	randomLayerSize, err := seekerSize(randomLayerReader)
	if err != nil {
		t.Fatalf("error getting seeker size for random layer: %v", err)
	}

	descBefore := distribution.Descriptor{Digest: dgst, MediaType: "application/octet-stream", Length: randomLayerSize}
	t.Logf("desc: %v", descBefore)

	desc, err = addBlob(ctx, bs, descBefore, randomLayerReader)
	if err != nil {
		t.Fatalf("error adding blob to blobservice: %v", err)
	}

	if desc.Length != randomLayerSize {
		t.Fatalf("committed blob has incorrect length: %v != %v", desc.Length, randomLayerSize)
	}

	rc, err = bs.Open(ctx, desc.Digest) // note that we are opening with original digest.
	if err != nil {
		t.Fatalf("error opening blob with %v: %v", dgst, err)
	}
	defer rc.Close()

	// Now check the sha digest and ensure its the same
	h := sha256.New()
	nn, err := io.Copy(h, rc)
	if err != nil {
		t.Fatalf("unexpected error copying to hash: %v", err)
	}

	if nn != randomLayerSize {
		t.Fatalf("stored incorrect number of bytes in blob: %d != %d", nn, randomLayerSize)
	}

	sha256Digest := digest.NewDigest("sha256", h)
	if sha256Digest != desc.Digest {
		t.Fatalf("fetched digest does not match: %q != %q", sha256Digest, desc.Digest)
	}

	// Now seek back the blob, read the whole thing and check against randomLayerData
	offset, err := rc.Seek(0, os.SEEK_SET)
	if err != nil {
		t.Fatalf("error seeking blob: %v", err)
	}

	if offset != 0 {
		t.Fatalf("seek failed: expected 0 offset, got %d", offset)
	}

	p, err := ioutil.ReadAll(rc)
	if err != nil {
		t.Fatalf("error reading all of blob: %v", err)
	}

	if len(p) != int(randomLayerSize) {
		t.Fatalf("blob data read has different length: %v != %v", len(p), randomLayerSize)
	}

	// Reset the randomLayerReader and read back the buffer
	_, err = randomLayerReader.Seek(0, os.SEEK_SET)
	if err != nil {
		t.Fatalf("error resetting layer reader: %v", err)
	}

	randomLayerData, err := ioutil.ReadAll(randomLayerReader)
	if err != nil {
		t.Fatalf("random layer read failed: %v", err)
	}

	if !bytes.Equal(p, randomLayerData) {
		t.Fatalf("layer data not equal")
	}
}

// TestLayerUploadZeroLength uploads zero-length
func TestLayerUploadZeroLength(t *testing.T) {
	ctx := context.Background()
	imageName := "foo/bar"
	driver := inmemory.New()
	registry := NewRegistryWithDriver(ctx, driver, memory.NewInMemoryBlobDescriptorCacheProvider())
	repository, err := registry.Repository(ctx, imageName)
	if err != nil {
		t.Fatalf("unexpected error getting repo: %v", err)
	}
	bs := repository.Blobs(ctx)

	wr, err := bs.Create(ctx)
	if err != nil {
		t.Fatalf("unexpected error starting upload: %v", err)
	}

	nn, err := io.Copy(wr, bytes.NewReader([]byte{}))
	if err != nil {
		t.Fatalf("error copying into blob writer: %v", err)
	}

	if nn != 0 {
		t.Fatalf("unexpected number of bytes copied: %v > 0", nn)
	}

	dgst, err := digest.FromReader(bytes.NewReader([]byte{}))
	if err != nil {
		t.Fatalf("error getting zero digest: %v", err)
	}

	if dgst != digest.DigestSha256EmptyTar {
		// sanity check on zero digest
		t.Fatalf("digest not as expected: %v != %v", dgst, digest.DigestTarSumV1EmptyTar)
	}

	desc, err := wr.Commit(ctx, distribution.Descriptor{Digest: dgst})
	if err != nil {
		t.Fatalf("unexpected error committing write: %v", err)
	}

	if desc.Digest != dgst {
		t.Fatalf("unexpected digest: %v != %v", desc.Digest, dgst)
	}
}

// seekerSize seeks to the end of seeker, checks the size and returns it to
// the original state, returning the size. The state of the seeker should be
// treated as unknown if an error is returned.
func seekerSize(seeker io.ReadSeeker) (int64, error) {
	current, err := seeker.Seek(0, os.SEEK_CUR)
	if err != nil {
		return 0, err
	}

	end, err := seeker.Seek(0, os.SEEK_END)
	if err != nil {
		return 0, err
	}

	resumed, err := seeker.Seek(current, os.SEEK_SET)
	if err != nil {
		return 0, err
	}

	if resumed != current {
		return 0, fmt.Errorf("error returning seeker to original state, could not seek back to original location")
	}

	return end, nil
}

// addBlob simply consumes the reader and inserts into the blob service,
// returning a descriptor on success.
func addBlob(ctx context.Context, bs distribution.BlobIngester, desc distribution.Descriptor, rd io.Reader) (distribution.Descriptor, error) {
	wr, err := bs.Create(ctx)
	if err != nil {
		return distribution.Descriptor{}, err
	}
	defer wr.Cancel(ctx)

	if nn, err := io.Copy(wr, rd); err != nil {
		return distribution.Descriptor{}, err
	} else if nn != desc.Length {
		return distribution.Descriptor{}, fmt.Errorf("incorrect number of bytes copied: %v != %v", nn, desc.Length)
	}

	return wr.Commit(ctx, desc)
}