refactor: extract inspect rendering logic to be display handlers (#1150)

Depends on spec change: #1156 

Refactor:
- Extract output formatting logic from the inspect command layer to an
isolated display handler layer for processing rendering.
- Add `json` and `tree` inspect handlers.

Fix:
- For `tree` output, make the key names with multiple words separated by
space characters rather than capitalizing the words, which is defined in
the [inspect command
spec](https://github.com/notaryproject/notation/blob/v1.2.0/specs/commandline/inspect.md#inspect-signatures-on-the-supplied-oci-artifact-identified-by-the-digest).
- For `json` output, default to rendering time in RFC3339 with
nanoseconds (Notation expiry, signing time and certificate expiry are
accurate to 1 second. Timestamp [RFC
3161](https://www.rfc-editor.org/rfc/rfc3161#section-2.4.2) can have
fraction-of-second time value).

E2E Test:
- inspect signature with timestamp, signature expiry and user metadata
(text, json)
- inspect signatures with invalid timestamp (test, json)
- inspect with `-o` shorthand.

Resolves part of #1151

---------

Signed-off-by: Junjie Gao <junjiegao@microsoft.com>

Author: JeyJeyGao

cmd/notation/inspect.go

@@ -14,68 +14,30 @@
 package main
 
 import (
-	"crypto/sha256"
-	"crypto/x509"
-	"encoding/hex"
 	"errors"
 	"fmt"
 	"os"
-	"strconv"
-	"strings"
-	"time"
 
 	"github.com/notaryproject/notation-core-go/signature"
-	"github.com/notaryproject/notation-go/plugin/proto"
-	"github.com/notaryproject/notation-go/registry"
+	"github.com/notaryproject/notation/cmd/notation/internal/display"
 	cmderr "github.com/notaryproject/notation/cmd/notation/internal/errors"
 	"github.com/notaryproject/notation/cmd/notation/internal/experimental"
+	"github.com/notaryproject/notation/cmd/notation/internal/option"
 	"github.com/notaryproject/notation/internal/cmd"
-	"github.com/notaryproject/notation/internal/envelope"
-	"github.com/notaryproject/notation/internal/ioutil"
-	"github.com/notaryproject/notation/internal/tree"
-	"github.com/notaryproject/tspclient-go"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/spf13/cobra"
 )
 
 type inspectOpts struct {
 	cmd.LoggingFlagOpts
 	SecureFlagOpts
+	option.Common
+	option.Format
 	reference         string
-	outputFormat      string
 	allowReferrersAPI bool
 	maxSignatures     int
 }
 
-type inspectOutput struct {
-	MediaType  string `json:"mediaType"`
-	Signatures []signatureOutput
-}
-
-type signatureOutput struct {
-	MediaType             string              `json:"mediaType"`
-	Digest                string              `json:"digest"`
-	SignatureAlgorithm    string              `json:"signatureAlgorithm"`
-	SignedAttributes      map[string]string   `json:"signedAttributes"`
-	UserDefinedAttributes map[string]string   `json:"userDefinedAttributes"`
-	UnsignedAttributes    map[string]any      `json:"unsignedAttributes"`
-	Certificates          []certificateOutput `json:"certificates"`
-	SignedArtifact        ocispec.Descriptor  `json:"signedArtifact"`
-}
-
-type certificateOutput struct {
-	SHA256Fingerprint string `json:"SHA256Fingerprint"`
-	IssuedTo          string `json:"issuedTo"`
-	IssuedBy          string `json:"issuedBy"`
-	Expiry            string `json:"expiry"`
-}
-
-type timestampOutput struct {
-	Timestamp    string              `json:"timestamp,omitempty"`
-	Certificates []certificateOutput `json:"certificates,omitempty"`
-	Error        string              `json:"error,omitempty"`
-}
-
 func inspectCommand(opts *inspectOpts) *cobra.Command {
 	if opts == nil {
 		opts = &inspectOpts{}
@@ -103,6 +65,10 @@ Example - Inspect signatures on an OCI artifact identified by a digest and outpu
 			return nil
 		},
 		PreRunE: func(cmd *cobra.Command, args []string) error {
+			if err := opts.Format.Parse(cmd); err != nil {
+				return err
+			}
+			opts.Common.Parse(cmd)
 			return experimental.CheckFlagsAndWarn(cmd, "allow-referrers-api")
 		},
 		RunE: func(cmd *cobra.Command, args []string) error {
@@ -118,18 +84,21 @@ Example - Inspect signatures on an OCI artifact identified by a digest and outpu
 
 	opts.LoggingFlagOpts.ApplyFlags(command.Flags())
 	opts.SecureFlagOpts.ApplyFlags(command.Flags())
-	cmd.SetPflagOutput(command.Flags(), &opts.outputFormat, cmd.PflagOutputUsage)
 	command.Flags().IntVar(&opts.maxSignatures, "max-signatures", 100, "maximum number of signatures to evaluate or examine")
 	cmd.SetPflagReferrersAPI(command.Flags(), &opts.allowReferrersAPI, fmt.Sprintf(cmd.PflagReferrersUsageFormat, "inspect"))
+
+	// set output format
+	opts.Format.ApplyFlags(command.Flags(), option.FormatTypeText, option.FormatTypeJSON)
 	return command
 }
 
 func runInspect(command *cobra.Command, opts *inspectOpts) error {
 	// set log level
 	ctx := opts.LoggingFlagOpts.InitializeLogger(command.Context())
 
-	if opts.outputFormat != cmd.OutputJSON && opts.outputFormat != cmd.OutputPlaintext {
-		return fmt.Errorf("unrecognized output format %s", opts.outputFormat)
+	displayHandler, err := display.NewInpsectHandler(opts.Printer, opts.Format)
+	if err != nil {
+		return err
 	}
 
 	// initialize
@@ -144,7 +113,8 @@ func runInspect(command *cobra.Command, opts *inspectOpts) error {
 	if err != nil {
 		return err
 	}
-	output := inspectOutput{MediaType: manifestDesc.MediaType, Signatures: []signatureOutput{}}
+	displayHandler.OnReferenceResolved(resolvedRef, manifestDesc.MediaType)
+
 	skippedSignatures := false
 	err = listSignatures(ctx, sigRepo, manifestDesc, opts.maxSignatures, func(sigManifestDesc ocispec.Descriptor) error {
 		sigBlob, sigDesc, err := sigRepo.FetchSignatureBlob(ctx, sigManifestDesc)
@@ -161,52 +131,19 @@ func runInspect(command *cobra.Command, opts *inspectOpts) error {
 			return nil
 		}
 
-		envelopeContent, err := sigEnvelope.Content()
-		if err != nil {
-			logSkippedSignature(sigManifestDesc, err)
-			skippedSignatures = true
-			return nil
-		}
-
-		signedArtifactDesc, err := envelope.DescriptorFromSignaturePayload(&envelopeContent.Payload)
-		if err != nil {
+		if err := displayHandler.InspectSignature(sigManifestDesc, sigEnvelope); err != nil {
 			logSkippedSignature(sigManifestDesc, err)
 			skippedSignatures = true
 			return nil
 		}
-
-		signatureAlgorithm, err := proto.EncodeSigningAlgorithm(envelopeContent.SignerInfo.SignatureAlgorithm)
-		if err != nil {
-			logSkippedSignature(sigManifestDesc, err)
-			skippedSignatures = true
-			return nil
-		}
-
-		sig := signatureOutput{
-			MediaType:             sigDesc.MediaType,
-			Digest:                sigManifestDesc.Digest.String(),
-			SignatureAlgorithm:    string(signatureAlgorithm),
-			SignedAttributes:      getSignedAttributes(opts.outputFormat, envelopeContent),
-			UserDefinedAttributes: signedArtifactDesc.Annotations,
-			UnsignedAttributes:    getUnsignedAttributes(opts.outputFormat, envelopeContent),
-			Certificates:          getCertificates(opts.outputFormat, envelopeContent.SignerInfo.CertificateChain),
-			SignedArtifact:        *signedArtifactDesc,
-		}
-
-		// clearing annotations from the SignedArtifact field since they're already
-		// displayed as UserDefinedAttributes
-		sig.SignedArtifact.Annotations = nil
-
-		output.Signatures = append(output.Signatures, sig)
-
 		return nil
 	})
 	var errorExceedMaxSignatures cmderr.ErrorExceedMaxSignatures
 	if err != nil && !errors.As(err, &errorExceedMaxSignatures) {
 		return err
 	}
 
-	if err := printOutput(opts.outputFormat, resolvedRef, output); err != nil {
+	if err := displayHandler.Render(); err != nil {
 		return err
 	}
 
@@ -224,169 +161,3 @@ func runInspect(command *cobra.Command, opts *inspectOpts) error {
 func logSkippedSignature(sigDesc ocispec.Descriptor, err error) {
 	fmt.Fprintf(os.Stderr, "Warning: Skipping signature %s because of error: %v\n", sigDesc.Digest.String(), err)
 }
-
-func getSignedAttributes(outputFormat string, envContent *signature.EnvelopeContent) map[string]string {
-	signedAttributes := map[string]string{
-		"signingScheme": string(envContent.SignerInfo.SignedAttributes.SigningScheme),
-		"signingTime":   formatTimestamp(outputFormat, envContent.SignerInfo.SignedAttributes.SigningTime),
-	}
-	expiry := envContent.SignerInfo.SignedAttributes.Expiry
-	if !expiry.IsZero() {
-		signedAttributes["expiry"] = formatTimestamp(outputFormat, expiry)
-	}
-
-	for _, attribute := range envContent.SignerInfo.SignedAttributes.ExtendedAttributes {
-		signedAttributes[fmt.Sprint(attribute.Key)] = fmt.Sprint(attribute.Value)
-	}
-
-	return signedAttributes
-}
-
-func getUnsignedAttributes(outputFormat string, envContent *signature.EnvelopeContent) map[string]any {
-	unsignedAttributes := make(map[string]any)
-
-	if envContent.SignerInfo.UnsignedAttributes.TimestampSignature != nil {
-		unsignedAttributes["timestampSignature"] = parseTimestamp(outputFormat, envContent.SignerInfo)
-	}
-
-	if envContent.SignerInfo.UnsignedAttributes.SigningAgent != "" {
-		unsignedAttributes["signingAgent"] = envContent.SignerInfo.UnsignedAttributes.SigningAgent
-	}
-
-	return unsignedAttributes
-}
-
-func formatTimestamp(outputFormat string, t time.Time) string {
-	switch outputFormat {
-	case cmd.OutputJSON:
-		return t.Format(time.RFC3339)
-	default:
-		return t.Format(time.ANSIC)
-	}
-}
-
-func getCertificates(outputFormat string, certChain []*x509.Certificate) []certificateOutput {
-	certificates := []certificateOutput{}
-
-	for _, cert := range certChain {
-		h := sha256.Sum256(cert.Raw)
-		fingerprint := strings.ToLower(hex.EncodeToString(h[:]))
-
-		certificate := certificateOutput{
-			SHA256Fingerprint: fingerprint,
-			IssuedTo:          cert.Subject.String(),
-			IssuedBy:          cert.Issuer.String(),
-			Expiry:            formatTimestamp(outputFormat, cert.NotAfter),
-		}
-
-		certificates = append(certificates, certificate)
-	}
-
-	return certificates
-}
-
-func printOutput(outputFormat string, ref string, output inspectOutput) error {
-	if outputFormat == cmd.OutputJSON {
-		return ioutil.PrintObjectAsJSON(output)
-	}
-
-	if len(output.Signatures) == 0 {
-		fmt.Printf("%s has no associated signature\n", ref)
-		return nil
-	}
-
-	fmt.Println("Inspecting all signatures for signed artifact")
-	root := tree.New(ref)
-	cncfSigNode := root.Add(registry.ArtifactTypeNotation)
-
-	for _, signature := range output.Signatures {
-		sigNode := cncfSigNode.Add(signature.Digest)
-		sigNode.AddPair("media type", signature.MediaType)
-		sigNode.AddPair("signature algorithm", signature.SignatureAlgorithm)
-
-		signedAttributesNode := sigNode.Add("signed attributes")
-		addMapToTree(signedAttributesNode, signature.SignedAttributes)
-
-		userDefinedAttributesNode := sigNode.Add("user defined attributes")
-		addMapToTree(userDefinedAttributesNode, signature.UserDefinedAttributes)
-
-		unsignedAttributesNode := sigNode.Add("unsigned attributes")
-		for k, v := range signature.UnsignedAttributes {
-			switch value := v.(type) {
-			case string:
-				unsignedAttributesNode.AddPair(k, value)
-			case timestampOutput:
-				timestampNode := unsignedAttributesNode.Add("timestamp signature")
-				if value.Error != "" {
-					timestampNode.AddPair("error", value.Error)
-					break
-				}
-				timestampNode.AddPair("timestamp", value.Timestamp)
-				addCertificatesToTree(timestampNode, "certificates", value.Certificates)
-			}
-		}
-
-		addCertificatesToTree(sigNode, "certificates", signature.Certificates)
-
-		artifactNode := sigNode.Add("signed artifact")
-		artifactNode.AddPair("media type", signature.SignedArtifact.MediaType)
-		artifactNode.AddPair("digest", signature.SignedArtifact.Digest.String())
-		artifactNode.AddPair("size", strconv.FormatInt(signature.SignedArtifact.Size, 10))
-	}
-
-	root.Print()
-	return nil
-}
-
-func addMapToTree(node *tree.Node, m map[string]string) {
-	if len(m) > 0 {
-		for k, v := range m {
-			node.AddPair(k, v)
-		}
-	} else {
-		node.Add("(empty)")
-	}
-}
-
-func addCertificatesToTree(node *tree.Node, name string, certs []certificateOutput) {
-	certListNode := node.Add(name)
-	for _, cert := range certs {
-		certNode := certListNode.AddPair("SHA256 fingerprint", cert.SHA256Fingerprint)
-		certNode.AddPair("issued to", cert.IssuedTo)
-		certNode.AddPair("issued by", cert.IssuedBy)
-		certNode.AddPair("expiry", cert.Expiry)
-	}
-}
-
-func parseTimestamp(outputFormat string, signerInfo signature.SignerInfo) timestampOutput {
-	signedToken, err := tspclient.ParseSignedToken(signerInfo.UnsignedAttributes.TimestampSignature)
-	if err != nil {
-		return timestampOutput{
-			Error: fmt.Sprintf("failed to parse timestamp countersignature: %s", err.Error()),
-		}
-	}
-	info, err := signedToken.Info()
-	if err != nil {
-		return timestampOutput{
-			Error: fmt.Sprintf("failed to parse timestamp countersignature: %s", err.Error()),
-		}
-	}
-	timestamp, err := info.Validate(signerInfo.Signature)
-	if err != nil {
-		return timestampOutput{
-			Error: fmt.Sprintf("failed to parse timestamp countersignature: %s", err.Error()),
-		}
-	}
-	certificates := getCertificates(outputFormat, signedToken.Certificates)
-	var formatTimestamp string
-	switch outputFormat {
-	case cmd.OutputJSON:
-		formatTimestamp = timestamp.Format(time.RFC3339)
-	default:
-		formatTimestamp = timestamp.Format(time.ANSIC)
-	}
-	return timestampOutput{
-		Timestamp:    formatTimestamp,
-		Certificates: certificates,
-	}
-}