// PingV2Registry attempts to ping a v2 registry and on success return a
// challenge manager for the supported authentication types and
// whether v2 was confirmed by the response. If a response is received but
// cannot be interpreted a PingResponseError will be returned.
func PingV2Registry(endpoint APIEndpoint, transport http.RoundTripper) (auth.ChallengeManager, bool, error) {
	var (
		foundV2   = false
		v2Version = auth.APIVersion{
			Type:    "registry",
			Version: "2.0",
		}
	)

	pingClient := &http.Client{
		Transport: transport,
		Timeout:   15 * time.Second,
	}
	endpointStr := strings.TrimRight(endpoint.URL.String(), "/") + "/v2/"
	req, err := http.NewRequest("GET", endpointStr, nil)
	if err != nil {
		return nil, false, err
	}
	resp, err := pingClient.Do(req)
	if err != nil {
		return nil, false, err
	}
	defer resp.Body.Close()

	versions := auth.APIVersions(resp, DefaultRegistryVersionHeader)
	for _, pingVersion := range versions {
		if pingVersion == v2Version {
			// The version header indicates we're definitely
			// talking to a v2 registry. So don't allow future
			// fallbacks to the v1 protocol.

			foundV2 = true
			break
		}
	}

	challengeManager := auth.NewSimpleChallengeManager()
	if err := challengeManager.AddResponse(resp); err != nil {
		return nil, foundV2, PingResponseError{
			Err: err,
		}
	}

	return challengeManager, foundV2, nil
}

func (r *repositoryRetriever) ping(registry url.URL, insecure bool) (*url.URL, error) {
	pingClient := &http.Client{
		Transport: r.context.Transport,
		Timeout:   15 * time.Second,
	}
	target := registry
	target.Path = path.Join(target.Path, "v2") + "/"
	req, err := http.NewRequest("GET", target.String(), nil)
	if err != nil {
		return nil, err
	}
	resp, err := pingClient.Do(req)
	if err != nil {
		if insecure && registry.Scheme == "https" {
			glog.V(5).Infof("Falling back to an HTTP check for an insecure registry %s: %v", registry, err)
			registry.Scheme = "http"
			_, nErr := r.ping(registry, true)
			if nErr != nil {
				return nil, err
			}
			return &registry, nil
		}
		return nil, err
	}
	defer resp.Body.Close()

	versions := auth.APIVersions(resp, "Docker-Distribution-API-Version")
	if len(versions) == 0 {
		glog.V(5).Infof("Registry responded to v2 Docker endpoint, but has no header for Docker Distribution %s: %d, %#v", req.URL, resp.StatusCode, resp.Header)
		return nil, &ErrNotV2Registry{Registry: registry.String()}
	}

	r.context.Challenges.AddResponse(resp)

	return nil, nil
}

// NewV2Repository returns a repository (v2 only). It creates a HTTP transport
// providing timeout settings and authentication support, and also verifies the
// remote API version.
func NewV2Repository(repoInfo *registry.RepositoryInfo, endpoint registry.APIEndpoint, metaHeaders http.Header, authConfig *cliconfig.AuthConfig, actions ...string) (distribution.Repository, error) {
	ctx := context.Background()

	repoName := repoInfo.CanonicalName
	// If endpoint does not support CanonicalName, use the RemoteName instead
	if endpoint.TrimHostname {
		repoName = repoInfo.RemoteName
	}

	// TODO(dmcgowan): Call close idle connections when complete, use keep alive
	base := &http.Transport{
		Proxy: http.ProxyFromEnvironment,
		Dial: (&net.Dialer{
			Timeout:   30 * time.Second,
			KeepAlive: 30 * time.Second,
			DualStack: true,
		}).Dial,
		TLSHandshakeTimeout: 10 * time.Second,
		TLSClientConfig:     endpoint.TLSConfig,
		// TODO(dmcgowan): Call close idle connections when complete and use keep alive
		DisableKeepAlives: true,
	}

	modifiers := registry.DockerHeaders(metaHeaders)
	authTransport := transport.NewTransport(base, modifiers...)
	pingClient := &http.Client{
		Transport: authTransport,
		Timeout:   15 * time.Second,
	}
	endpointStr := strings.TrimRight(endpoint.URL, "/") + "/v2/"
	req, err := http.NewRequest("GET", endpointStr, nil)
	if err != nil {
		return nil, err
	}
	resp, err := pingClient.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	versions := auth.APIVersions(resp, endpoint.VersionHeader)
	if endpoint.VersionHeader != "" && len(endpoint.Versions) > 0 {
		var foundVersion bool
		for _, version := range endpoint.Versions {
			for _, pingVersion := range versions {
				if version == pingVersion {
					foundVersion = true
				}
			}
		}
		if !foundVersion {
			return nil, errors.New("endpoint does not support v2 API")
		}
	}

	challengeManager := auth.NewSimpleChallengeManager()
	if err := challengeManager.AddResponse(resp); err != nil {
		return nil, err
	}

	creds := dumbCredentialStore{auth: authConfig}
	tokenHandler := auth.NewTokenHandler(authTransport, creds, repoName, actions...)
	basicHandler := auth.NewBasicHandler(creds)
	modifiers = append(modifiers, auth.NewAuthorizer(challengeManager, tokenHandler, basicHandler))
	tr := transport.NewTransport(base, modifiers...)

	return client.NewRepository(ctx, repoName, endpoint.URL, tr)
}

// NewV2Repository returns a repository (v2 only). It creates a HTTP transport
// providing timeout settings and authentication support, and also verifies the
// remote API version.
func NewV2Repository(ctx context.Context, repoInfo *registry.RepositoryInfo, endpoint registry.APIEndpoint, metaHeaders http.Header, authConfig *types.AuthConfig, actions ...string) (repo distribution.Repository, foundVersion bool, err error) {
	repoName := repoInfo.FullName()
	// If endpoint does not support CanonicalName, use the RemoteName instead
	if endpoint.TrimHostname {
		repoName = repoInfo.RemoteName()
	}

	// TODO(dmcgowan): Call close idle connections when complete, use keep alive
	base := &http.Transport{
		Proxy: http.ProxyFromEnvironment,
		Dial: func(network, address string) (net.Conn, error) {
			dialer := &net.Dialer{
				Timeout:   30 * time.Second,
				KeepAlive: 30 * time.Second,
				DualStack: true,
			}
			netConn, err := dialer.Dial(network, address)
			if err != nil {
				return netConn, err
			}
			return &conn{
				Conn:         netConn,
				readTimeout:  time.Minute,
				writeTimeout: time.Minute,
			}, nil
		},
		TLSHandshakeTimeout: 10 * time.Second,
		TLSClientConfig:     endpoint.TLSConfig,
		// TODO(dmcgowan): Call close idle connections when complete and use keep alive
		DisableKeepAlives: true,
	}

	modifiers := registry.DockerHeaders(dockerversion.DockerUserAgent(), metaHeaders)
	authTransport := transport.NewTransport(base, modifiers...)
	pingClient := &http.Client{
		Transport: authTransport,
		Timeout:   15 * time.Second,
	}
	endpointStr := strings.TrimRight(endpoint.URL, "/") + "/v2/"
	req, err := http.NewRequest("GET", endpointStr, nil)
	if err != nil {
		return nil, false, err
	}
	resp, err := pingClient.Do(req)
	if err != nil {
		return nil, false, err
	}
	defer resp.Body.Close()

	v2Version := auth.APIVersion{
		Type:    "registry",
		Version: "2.0",
	}

	versions := auth.APIVersions(resp, registry.DefaultRegistryVersionHeader)
	for _, pingVersion := range versions {
		if pingVersion == v2Version {
			// The version header indicates we're definitely
			// talking to a v2 registry. So don't allow future
			// fallbacks to the v1 protocol.

			foundVersion = true
			break
		}
	}

	challengeManager := auth.NewSimpleChallengeManager()
	if err := challengeManager.AddResponse(resp); err != nil {
		return nil, foundVersion, err
	}

	if authConfig.RegistryToken != "" {
		passThruTokenHandler := &existingTokenHandler{token: authConfig.RegistryToken}
		modifiers = append(modifiers, auth.NewAuthorizer(challengeManager, passThruTokenHandler))
	} else {
		creds := dumbCredentialStore{auth: authConfig}
		tokenHandler := auth.NewTokenHandler(authTransport, creds, repoName, actions...)
		basicHandler := auth.NewBasicHandler(creds)
		modifiers = append(modifiers, auth.NewAuthorizer(challengeManager, tokenHandler, basicHandler))
	}
	tr := transport.NewTransport(base, modifiers...)

	repo, err = client.NewRepository(ctx, repoName, endpoint.URL, tr)
	return repo, foundVersion, err
}