rename tokens to token

token/read.go

@@ -0,0 +1,80 @@
+package token
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/codec"
+	"github.com/ipld/go-ipld-prime/codec/dagcbor"
+	"github.com/ipld/go-ipld-prime/codec/dagjson"
+	"github.com/ipld/go-ipld-prime/datamodel"
+
+	"github.com/ucan-wg/go-ucan/token/delegation"
+	"github.com/ucan-wg/go-ucan/token/internal/envelope"
+)
+
+// Decode unmarshals the input data using the format specified by the
+// provided codec.Decoder into an arbitrary UCAN token.
+// An error is returned if the conversion fails, or if the resulting
+// Token is invalid.
+// Supported and returned types are:
+// - delegation.Token
+func Decode(b []byte, decFn codec.Decoder) (Token, error) {
+	node, err := ipld.Decode(b, decFn)
+	if err != nil {
+		return nil, err
+	}
+	return fromIPLD(node)
+}
+
+// DecodeReader is the same as Decode, but accept an io.Reader.
+func DecodeReader(r io.Reader, decFn codec.Decoder) (Token, error) {
+	node, err := ipld.DecodeStreaming(r, decFn)
+	if err != nil {
+		return nil, err
+	}
+	return fromIPLD(node)
+}
+
+// FromDagCbor unmarshals an arbitrary DagCbor encoded UCAN token.
+// An error is returned if the conversion fails, or if the resulting
+// Token is invalid.
+// Supported and returned types are:
+// - delegation.Token
+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) (Token, error) {
+	return DecodeReader(r, dagcbor.Decode)
+}
+
+// FromDagCbor unmarshals an arbitrary DagJson encoded UCAN token.
+// An error is returned if the conversion fails, or if the resulting
+// Token is invalid.
+// Supported and returned types are:
+// - delegation.Token
+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) (Token, error) {
+	return DecodeReader(r, dagjson.Decode)
+}
+
+func fromIPLD(node datamodel.Node) (Token, error) {
+	tag, err := envelope.FindTag(node)
+	if err != nil {
+		return nil, err
+	}
+
+	switch tag {
+	case delegation.Tag:
+		return delegation.FromIPLD(node)
+	default:
+		return nil, fmt.Errorf(`unknown tag "%s"`, tag)
+	}
+}