add server/issuer/client examples, and lots of sanding

toolkit/issuer/http_wrapper.go

@@ -0,0 +1,83 @@
+package issuer
+
+import (
+	"fmt"
+	"io"
+	"iter"
+	"net/http"
+
+	"github.com/ucan-wg/go-ucan/did"
+	"github.com/ucan-wg/go-ucan/pkg/command"
+	"github.com/ucan-wg/go-ucan/pkg/container"
+	"github.com/ucan-wg/go-ucan/token/delegation"
+
+	"github.com/INFURA/go-ucan-toolkit/client"
+)
+
+type RequestResolver func(r *http.Request) (*ResolvedRequest, error)
+
+type ResolvedRequest struct {
+	Audience did.DID
+	Cmd      command.Command
+	Subject  did.DID
+}
+
+// HttpWrapper implements an HTTP transport for a UCAN issuer.
+// It provides a common response shape, while allowing customisation of the request.
+func HttpWrapper(requester client.DelegationRequester, resolver RequestResolver) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
+			return
+		}
+
+		resolved, err := resolver(r)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
+		}
+
+		dlgs, err := requester.RequestDelegation(r.Context(), resolved.Audience, resolved.Cmd, resolved.Subject)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+
+		cont := container.NewWriter()
+		for bundle, err := range dlgs {
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+			cont.AddSealed(bundle.Sealed)
+		}
+
+		err = cont.ToBytesGzippedWriter(w)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+	})
+}
+
+func DecodeResponse(res *http.Response) (iter.Seq2[*delegation.Bundle, error], error) {
+	defer res.Body.Close()
+	if res.StatusCode != http.StatusOK {
+		msg, err := io.ReadAll(res.Body)
+		if err != nil {
+			return nil, fmt.Errorf("request failed with status %d, then failed to read response body: %w", res.StatusCode, err)
+		}
+		return nil, fmt.Errorf("request failed with status %d: %s", res.StatusCode, msg)
+	}
+	cont, err := container.FromReader(res.Body)
+	if err != nil {
+		return nil, err
+	}
+	return func(yield func(*delegation.Bundle, error) bool) {
+		for bundle := range cont.GetAllDelegations() {
+			if !yield(&bundle, nil) {
+				return
+			}
+		}
+	}, nil
+}