Merge pull request #32 from ucan-wg/cleanups

Cleanups and Token interface

token/delegation/delegation_test.go

@@ -11,7 +11,7 @@ import (
 	"github.com/ucan-wg/go-ucan/did"
 	"github.com/ucan-wg/go-ucan/pkg/command"
 	"github.com/ucan-wg/go-ucan/pkg/policy"
-	"github.com/ucan-wg/go-ucan/tokens/delegation"
+	"github.com/ucan-wg/go-ucan/token/delegation"
 )
 
 const (

token/delegation/examples_test.go

@@ -12,11 +12,12 @@ import (
 	"github.com/ipld/go-ipld-prime/codec/dagcbor"
 	"github.com/ipld/go-ipld-prime/codec/dagjson"
 	"github.com/libp2p/go-libp2p/core/crypto"
+
 	"github.com/ucan-wg/go-ucan/did"
 	"github.com/ucan-wg/go-ucan/pkg/command"
 	"github.com/ucan-wg/go-ucan/pkg/policy"
-	"github.com/ucan-wg/go-ucan/tokens/delegation"
+	"github.com/ucan-wg/go-ucan/token/delegation"
-	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
+	"github.com/ucan-wg/go-ucan/token/internal/envelope"
 )
 
 // The following example shows how to create a delegation.Token with
@@ -50,11 +51,11 @@ func ExampleNew() {
 
 	printCIDAndSealed(id, data)
 
-	//Output:
+	// Output:
-	//CID (base58BTC): zdpuAw26pFuvZa2Z9YAtpZZnWN6VmnRFr7Z8LVY5c7RVWoxGY
+	// CID (base58BTC): zdpuAw26pFuvZa2Z9YAtpZZnWN6VmnRFr7Z8LVY5c7RVWoxGY
-	//DAG-CBOR (base64) out: 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
+	// DAG-CBOR (base64) out: glhAmnAkgfjAx4SA5pzJmtaHRJtTGNpF1y6oqb4yhGoM2H2EUGbBYT4rVDjMKBgCjhdGHjipm00L8iR5SsQh3sIEBaJhaEQ07QFxc3VjYW4vZGxnQDEuMC4wLXJjLjGoY2F1ZHg4ZGlkOmtleTp6Nk1rcTVZbWJKY1RyUEV4TkRpMjZpbXJUQ3BLaGVwakJGQlNIcXJCRE4yQXJQa3ZjY21kaC9mb28vYmFyY2V4cPZjaXNzeDhkaWQ6a2V5Ono2TWtwem4ybjNaR1QyVmFxTUdTUUMzdHptelY0VFM5UzcxaUZzRFhFMVdub05IMmNwb2yDg2I9PWcuc3RhdHVzZWRyYWZ0g2NhbGxpLnJldmlld2Vyg2RsaWtlZi5lbWFpbG0qQGV4YW1wbGUuY29tg2NhbnllLnRhZ3OCYm9ygoNiPT1hLmRuZXdzg2I9PWEuZXByZXNzY3N1Yng4ZGlkOmtleTp6Nk1rdEExdUJkQ3BxNHVKQnFFOWpqTWlMeXhaQmc5YTZ4Z1BQS0pqTXFzczZaYzJkbWV0YaBlbm9uY2VMAAECAwQFBgcICQoL
-	//Converted to DAG-JSON out:
+	// Converted to DAG-JSON out:
-	//[
+	// [
 	//	{
 	//		"/": {
 	//			"bytes": "mnAkgfjAx4SA5pzJmtaHRJtTGNpF1y6oqb4yhGoM2H2EUGbBYT4rVDjMKBgCjhdGHjipm00L8iR5SsQh3sIEBQ"
@@ -115,7 +116,7 @@ func ExampleNew() {
 	//			"sub": "did:key:z6MktA1uBdCpq4uJBqE9jjMiLyxZBg9a6xgPPKJjMqss6Zc2"
 	//		}
 	//	}
-	//]
+	// ]
 }
 
 // The following example shows how to create a UCAN root delegation.Token
@@ -148,11 +149,11 @@ func ExampleRoot() {
 
 	printCIDAndSealed(id, data)
 
-	//Output:
+	// Output:
-	//CID (base58BTC): zdpuAnbsR3e6DK8hBk5WA7KwbHYN6CKY4a3Bv1GNehvFYShQ8
+	// CID (base58BTC): zdpuAnbsR3e6DK8hBk5WA7KwbHYN6CKY4a3Bv1GNehvFYShQ8
-	//DAG-CBOR (base64) out: 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
+	// DAG-CBOR (base64) out: 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
-	//Converted to DAG-JSON out:
+	// Converted to DAG-JSON out:
-	//[
+	// [
 	//	{
 	//		"/": {
 	//			"bytes": "67ASBczF/wlIP0ESENn+4ZNQKukjcTNz+fo7K2tYa6OUm0rWICDJJkDWm7lJeQt+KvSA+Y4ctHTQbAr3Lr7mDg"
@@ -213,7 +214,7 @@ func ExampleRoot() {
 	//			"sub": "did:key:z6Mkpzn2n3ZGT2VaqMGSQC3tzmzV4TS9S71iFsDXE1WnoNH2"
 	//		}
 	//	}
-	//]
+	// ]
 }
 
 // The following example demonstrates how to get a delegation.Token from
@@ -236,18 +237,18 @@ func ExampleToken_FromSealed() {
 	fmt.Println("NotBefore (nbf):", tkn.NotBefore())
 	fmt.Println("Expiration (exp):", tkn.Expiration())
 
-	//Output:
+	// Output:
-	//DAG-CBOR (base64) in: 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
+	// DAG-CBOR (base64) in: 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
-	//CID (base58BTC): zdpuAw26pFuvZa2Z9YAtpZZnWN6VmnRFr7Z8LVY5c7RVWoxGY
+	// CID (base58BTC): zdpuAw26pFuvZa2Z9YAtpZZnWN6VmnRFr7Z8LVY5c7RVWoxGY
-	//Issuer (iss): did:key:z6Mkpzn2n3ZGT2VaqMGSQC3tzmzV4TS9S71iFsDXE1WnoNH2
+	// Issuer (iss): did:key:z6Mkpzn2n3ZGT2VaqMGSQC3tzmzV4TS9S71iFsDXE1WnoNH2
-	//Audience (aud): did:key:z6Mkq5YmbJcTrPExNDi26imrTCpKhepjBFBSHqrBDN2ArPkv
+	// Audience (aud): did:key:z6Mkq5YmbJcTrPExNDi26imrTCpKhepjBFBSHqrBDN2ArPkv
-	//Subject (sub): did:key:z6MktA1uBdCpq4uJBqE9jjMiLyxZBg9a6xgPPKJjMqss6Zc2
+	// Subject (sub): did:key:z6MktA1uBdCpq4uJBqE9jjMiLyxZBg9a6xgPPKJjMqss6Zc2
-	//Command (cmd): /foo/bar
+	// Command (cmd): /foo/bar
-	//Policy (pol): TODO
+	// Policy (pol): TODO
-	//Nonce (nonce): 000102030405060708090a0b
+	// Nonce (nonce): 000102030405060708090a0b
-	//Meta (meta): TODO
+	// Meta (meta): TODO
-	//NotBefore (nbf): <nil>
+	// NotBefore (nbf): <nil>
-	//Expiration (exp): <nil>
+	// Expiration (exp): <nil>
 }
 
 func exampleCBORData() []byte {

token/delegation/ipld.go

@@ -12,7 +12,7 @@ import (
 	"github.com/libp2p/go-libp2p/core/crypto"
 
 	"github.com/ucan-wg/go-ucan/did"
-	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
+	"github.com/ucan-wg/go-ucan/token/internal/envelope"
 )
 
 // ToSealed wraps the delegation token in an envelope, generates the
@@ -32,7 +32,7 @@ func (t *Token) ToSealed(privKey crypto.PrivKey) ([]byte, cid.Cid, error) {
 	return data, id, nil
 }
 
-// ToSealedWriter is the same as Seal but accepts an io.Writer.
+// ToSealedWriter is the same as ToSealed but accepts an io.Writer.
 func (t *Token) ToSealedWriter(w io.Writer, privKey crypto.PrivKey) (cid.Cid, error) {
 	cidWriter := envelope.NewCIDWriter(w)
 
@@ -93,7 +93,7 @@ func (t *Token) Encode(privKey crypto.PrivKey, encFn codec.Encoder) ([]byte, err
 	return ipld.Encode(node, encFn)
 }
 
-// EncodeWriter is the same as Encode but accepts an io.Writer.
+// EncodeWriter is the same as Encode, but accepts an io.Writer.
 func (t *Token) EncodeWriter(w io.Writer, privKey crypto.PrivKey, encFn codec.Encoder) error {
 	node, err := t.toIPLD(privKey)
 	if err != nil {
@@ -108,7 +108,7 @@ func (t *Token) ToDagCbor(privKey crypto.PrivKey) ([]byte, error) {
 	return t.Encode(privKey, dagcbor.Encode)
 }
 
-// ToDagCborWriter is the same as ToDagCbor but it accepts an io.Writer.
+// ToDagCborWriter is the same as ToDagCbor, but it accepts an io.Writer.
 func (t *Token) ToDagCborWriter(w io.Writer, privKey crypto.PrivKey) error {
 	return t.EncodeWriter(w, privKey, dagcbor.Encode)
 }
@@ -118,7 +118,7 @@ func (t *Token) ToDagJson(privKey crypto.PrivKey) ([]byte, error) {
 	return t.Encode(privKey, dagjson.Encode)
 }
 
-// ToDagJsonWriter is the same as ToDagJson but it accepts an io.Writer.
+// ToDagJsonWriter is the same as ToDagJson, but it accepts an io.Writer.
 func (t *Token) ToDagJsonWriter(w io.Writer, privKey crypto.PrivKey) error {
 	return t.EncodeWriter(w, privKey, dagjson.Encode)
 }

token/delegation/schema.go

@@ -11,7 +11,7 @@ import (
 	"github.com/ipld/go-ipld-prime/schema"
 
 	"github.com/ucan-wg/go-ucan/pkg/meta"
-	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
+	"github.com/ucan-wg/go-ucan/token/internal/envelope"
 )
 
 // [Tag] is the string used as a key within the SigPayload that identifies

token/delegation/schema_test.go

@@ -11,8 +11,8 @@ import (
 	"github.com/stretchr/testify/require"
 	"gotest.tools/v3/golden"
 
-	"github.com/ucan-wg/go-ucan/tokens/delegation"
+	"github.com/ucan-wg/go-ucan/token/delegation"
-	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
+	"github.com/ucan-wg/go-ucan/token/internal/envelope"
 )
 
 //go:embed delegation.ipldsch

token/inspect.go

@@ -1,9 +1,9 @@
-package tokens
+package token
 
 import (
 	"github.com/ipld/go-ipld-prime/datamodel"
 
-	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
+	"github.com/ucan-wg/go-ucan/token/internal/envelope"
 )
 
 type Info = envelope.Info

token/interface.go

@@ -0,0 +1,41 @@
+package token
+
+import (
+	"io"
+
+	"github.com/ipfs/go-cid"
+	"github.com/ipld/go-ipld-prime/codec"
+	"github.com/libp2p/go-libp2p/core/crypto"
+
+	"github.com/ucan-wg/go-ucan/did"
+	"github.com/ucan-wg/go-ucan/pkg/meta"
+)
+
+type Token interface {
+	Marshaller
+
+	// Issuer returns the did.DID representing the Token's issuer.
+	Issuer() did.DID
+	// Meta returns the Token's metadata.
+	Meta() *meta.Meta
+}
+
+type Marshaller interface {
+	// ToSealed wraps the token in an envelope, generates the signature, encodes
+	// the result to DAG-CBOR and calculates the CID of the resulting binary data.
+	ToSealed(privKey crypto.PrivKey) ([]byte, cid.Cid, error)
+	// ToSealedWriter is the same as ToSealed but accepts an io.Writer.
+	ToSealedWriter(w io.Writer, privKey crypto.PrivKey) (cid.Cid, error)
+	// Encode marshals a Token to the format specified by the provided codec.Encoder.
+	Encode(privKey crypto.PrivKey, encFn codec.Encoder) ([]byte, error)
+	// EncodeWriter is the same as Encode, but accepts an io.Writer.
+	EncodeWriter(w io.Writer, privKey crypto.PrivKey, encFn codec.Encoder) error
+	// ToDagCbor marshals the Token to the DAG-CBOR format.
+	ToDagCbor(privKey crypto.PrivKey) ([]byte, error)
+	// ToDagCborWriter is the same as ToDagCbor, but it accepts an io.Writer.
+	ToDagCborWriter(w io.Writer, privKey crypto.PrivKey) error
+	// ToDagJson marshals the Token to the DAG-JSON format.
+	ToDagJson(privKey crypto.PrivKey) ([]byte, error)
+	// ToDagJsonWriter is the same as ToDagJson, but it accepts an io.Writer.
+	ToDagJsonWriter(w io.Writer, privKey crypto.PrivKey) error
+}

token/internal/envelope/cid_test.go

@@ -11,7 +11,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"gotest.tools/v3/golden"
 
-	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
+	"github.com/ucan-wg/go-ucan/token/internal/envelope"
 )
 
 func TestCidFromBytes(t *testing.T) {

token/internal/envelope/example_test.go

@@ -18,7 +18,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"gotest.tools/v3/golden"
 
-	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
+	"github.com/ucan-wg/go-ucan/token/internal/envelope"
 )
 
 const (

token/internal/envelope/ipld.go

@@ -43,7 +43,7 @@ import (
 	"github.com/libp2p/go-libp2p/core/crypto"
 
 	"github.com/ucan-wg/go-ucan/did"
-	"github.com/ucan-wg/go-ucan/tokens/internal/varsig"
+	"github.com/ucan-wg/go-ucan/token/internal/varsig"
 )
 
 const (

token/internal/envelope/ipld_test.go

@@ -13,7 +13,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"gotest.tools/v3/golden"
 
-	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
+	"github.com/ucan-wg/go-ucan/token/internal/envelope"
 )
 
 func TestDecode(t *testing.T) {

token/internal/varsig/varsig_test.go

@@ -8,7 +8,7 @@ import (
 	"github.com/libp2p/go-libp2p/core/crypto/pb"
 	"github.com/stretchr/testify/assert"
 
-	"github.com/ucan-wg/go-ucan/tokens/internal/varsig"
+	"github.com/ucan-wg/go-ucan/token/internal/varsig"
 )
 
 func TestDecode(t *testing.T) {

token/read.go

@@ -1,4 +1,4 @@
-package tokens
+package token
 
 import (
 	"fmt"
@@ -10,8 +10,8 @@ import (
 	"github.com/ipld/go-ipld-prime/codec/dagjson"
 	"github.com/ipld/go-ipld-prime/datamodel"
 
-	"github.com/ucan-wg/go-ucan/tokens/delegation"
+	"github.com/ucan-wg/go-ucan/token/delegation"
-	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
+	"github.com/ucan-wg/go-ucan/token/internal/envelope"
 )
 
 // Decode unmarshals the input data using the format specified by the
@@ -20,7 +20,7 @@ import (
 // Token is invalid.
 // Supported and returned types are:
 // - delegation.Token
-func Decode(b []byte, decFn codec.Decoder) (any, error) {
+func Decode(b []byte, decFn codec.Decoder) (Token, error) {
 	node, err := ipld.Decode(b, decFn)
 	if err != nil {
 		return nil, err
@@ -29,7 +29,7 @@ func Decode(b []byte, decFn codec.Decoder) (any, error) {
 }
 
 // DecodeReader is the same as Decode, but accept an io.Reader.
-func DecodeReader(r io.Reader, decFn codec.Decoder) (any, error) {
+func DecodeReader(r io.Reader, decFn codec.Decoder) (Token, error) {
 	node, err := ipld.DecodeStreaming(r, decFn)
 	if err != nil {
 		return nil, err
@@ -42,12 +42,12 @@ func DecodeReader(r io.Reader, decFn codec.Decoder) (any, error) {
 // Token is invalid.
 // Supported and returned types are:
 // - delegation.Token
-func FromDagCbor(b []byte) (any, error) {
+func FromDagCbor(b []byte) (Token, error) {
 	return Decode(b, dagcbor.Decode)
 }
 
 // FromDagCborReader is the same as FromDagCbor, but accept an io.Reader.
-func FromDagCborReader(r io.Reader) (any, error) {
+func FromDagCborReader(r io.Reader) (Token, error) {
 	return DecodeReader(r, dagcbor.Decode)
 }
 
@@ -56,16 +56,16 @@ func FromDagCborReader(r io.Reader) (any, error) {
 // Token is invalid.
 // Supported and returned types are:
 // - delegation.Token
-func FromDagJson(b []byte) (any, error) {
+func FromDagJson(b []byte) (Token, error) {
 	return Decode(b, dagjson.Decode)
 }
 
 // FromDagJsonReader is the same as FromDagJson, but accept an io.Reader.
-func FromDagJsonReader(r io.Reader) (any, error) {
+func FromDagJsonReader(r io.Reader) (Token, error) {
 	return DecodeReader(r, dagjson.Decode)
 }
 
-func fromIPLD(node datamodel.Node) (any, error) {
+func fromIPLD(node datamodel.Node) (Token, error) {
 	tag, err := envelope.FindTag(node)
 	if err != nil {
 		return nil, err