Return write evidence from Gitea operations

internal/gitea/backend.go

@@ -2,6 +2,7 @@ package gitea
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"io"
 	"net/http"
@@ -75,6 +76,92 @@ func (b *Backend) Preflight(ctx context.Context) error {
 	return nil
 }
 
+func (b *Backend) CreateRelease(ctx context.Context, request forge.CreateReleaseRequest) (forge.Release, forge.WriteEvidence, error) {
+	if strings.TrimSpace(request.Tag) == "" || !validObjectID(request.Commit) {
+		return forge.Release{}, forge.WriteEvidence{Disposition: forge.WriteNotAttempted}, &forge.Failure{
+			Kind: forge.FailureInvalid, Err: errors.New("a full tag and lowercase Git commit ID are required"),
+		}
+	}
+	_, apiRoot, err := b.destinationAPI("create release")
+	if err != nil {
+		return forge.Release{}, forge.WriteEvidence{Disposition: forge.WriteNotAttempted}, err
+	}
+	body, err := json.Marshal(createReleaseRequest{
+		TagName: request.Tag, TargetCommitish: request.Commit,
+		Name: request.Title, Body: request.Body,
+		Draft: request.Draft, Prerelease: request.Prerelease,
+	})
+	if err != nil {
+		return forge.Release{}, forge.WriteEvidence{Disposition: forge.WriteNotAttempted}, &forge.Failure{Kind: forge.FailureInvalid, Err: err}
+	}
+	created, status, err := b.client.postRelease(ctx, b.client.httpClient(), b.destination.Token, apiRoot+"/releases", body)
+	if err == nil && created.ID <= 0 {
+		err = failure(FailureMalformed, "verify created release", status, errors.New("release response does not contain a positive ID"))
+	}
+	evidence := writeEvidence(status, err)
+	if err != nil {
+		return forge.Release{}, evidence, neutralFailure(err)
+	}
+	return forge.Release{
+		URL:        created.URL,
+		Tag:        created.TagName,
+		Title:      created.Title,
+		Body:       created.Body,
+		Draft:      created.Draft,
+		Prerelease: created.Prerelease,
+		Handle:     releaseHandle{id: created.ID},
+	}, evidence, nil
+}
+
+func (b *Backend) UploadAsset(ctx context.Context, handle any, filename string, content io.Reader) (forge.WriteEvidence, error) {
+	release, ok := handle.(releaseHandle)
+	if !ok || release.id <= 0 {
+		return forge.WriteEvidence{Disposition: forge.WriteNotAttempted}, &forge.Failure{Kind: forge.FailureInvalid, Err: errors.New("release handle was not created by the Gitea backend")}
+	}
+	if strings.TrimSpace(filename) == "" || content == nil {
+		return forge.WriteEvidence{Disposition: forge.WriteNotAttempted}, &forge.Failure{Kind: forge.FailureInvalid, Err: errors.New("asset filename and content reader are required")}
+	}
+	_, apiRoot, err := b.destinationAPI("upload release asset")
+	if err != nil {
+		return forge.WriteEvidence{Disposition: forge.WriteNotAttempted}, err
+	}
+	status, err := b.client.uploadAsset(ctx, b.client.httpClient(), b.destination.Token, apiRoot, release.id, filename, content)
+	evidence := writeEvidence(status, err)
+	if err != nil {
+		return evidence, neutralFailure(err)
+	}
+	return evidence, nil
+}
+
+func writeEvidence(status int, err error) forge.WriteEvidence {
+	evidence := forge.WriteEvidence{Attempted: status != 0, Disposition: forge.WriteNotAttempted}
+	var backendFailure *Failure
+	if err != nil && errors.As(err, &backendFailure) && backendFailure.Kind == FailureTransport {
+		evidence.Attempted = true
+	}
+	if !evidence.Attempted {
+		return evidence
+	}
+	if err == nil {
+		evidence.Disposition = forge.WriteAccepted
+		return evidence
+	}
+	if status == http.StatusConflict {
+		evidence.Disposition = forge.WriteConflict
+		return evidence
+	}
+	if status >= http.StatusInternalServerError || errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
+		evidence.Disposition = forge.WriteUncertain
+		return evidence
+	}
+	if errors.As(err, &backendFailure) && (backendFailure.Kind == FailureTransport || backendFailure.Kind == FailureMalformed) {
+		evidence.Disposition = forge.WriteUncertain
+		return evidence
+	}
+	evidence.Disposition = forge.WriteRejected
+	return evidence
+}
+
 func (repository repositoryResponse) matches(destination Destination) bool {
 	if repository.ID <= 0 || !strings.EqualFold(repository.Name, destination.Repository) {
 		return false
@@ -237,3 +324,5 @@ func neutralFailure(err error) error {
 	}
 	return &forge.Failure{Kind: kind, Err: err}
 }
+
+var _ forge.Backend = (*Backend)(nil)