Centralize Scriptorium input source policy across config, analyze, and previous-cache

internal/artifactpolicy/policy.go

@@ -1,6 +1,7 @@
 package artifactpolicy
 
 import (
+	"errors"
 	"fmt"
 	"regexp"
 	"strings"
@@ -19,6 +20,11 @@ const (
 var configuredSourceRE = regexp.MustCompile(`^narratio\.artifact\.([a-z][a-z0-9_]*)$`)
 var previousSourceRE = regexp.MustCompile(`^narratio\.previous_session\.artifact\.([a-z][a-z0-9_]*)$`)
 
+var (
+	ErrUnsupportedScriptoriumInputSource = errors.New("unsupported scriptorium input source")
+	ErrInvalidPreviousSessionSource      = errors.New("invalid previous-session source format")
+)
+
 type SourceKind string
 
 const (
@@ -34,6 +40,28 @@ type Source struct {
 	ConfiguredKey string
 }
 
+// ScriptoriumInputSourceDescriptor describes one validated Scriptorium input source.
+type ScriptoriumInputSourceDescriptor struct {
+	Source          Source
+	PreviousSession *PreviousSessionSourceDescriptor
+}
+
+// PreviousSessionSourceDescriptor describes one canonical previous-session input source.
+type PreviousSessionSourceDescriptor struct {
+	SourceID           string
+	ConfiguredKey      string
+	ConfiguredSourceID string
+}
+
+// UnknownConfiguredArtifactError reports a source that references an undefined configured artifact key.
+type UnknownConfiguredArtifactError struct {
+	ConfiguredKey string
+}
+
+func (e *UnknownConfiguredArtifactError) Error() string {
+	return fmt.Sprintf("references unknown artifact %q", e.ConfiguredKey)
+}
+
 // ConfiguredSourceID converts a configured artifact key into source id form.
 func ConfiguredSourceID(key string) string {
 	return configuredSourcePrefix + strings.TrimSpace(key)
@@ -83,6 +111,70 @@ func ClassifySource(source string) (Source, error) {
 	return Source{}, fmt.Errorf("unsupported artifact source %q", source)
 }
 
+// DescribeScriptoriumInputSource classifies one input source and returns descriptor
+// metadata used by config validation, analyze input resolution, and previous-cache planning.
+func DescribeScriptoriumInputSource(source string) (ScriptoriumInputSourceDescriptor, error) {
+	trimmed := strings.TrimSpace(source)
+	if trimmed == "" {
+		return ScriptoriumInputSourceDescriptor{}, ErrUnsupportedScriptoriumInputSource
+	}
+	if strings.HasPrefix(trimmed, "narratio.previous_session.artifact") {
+		descriptor, err := DescribePreviousSessionSource(trimmed)
+		if err != nil {
+			return ScriptoriumInputSourceDescriptor{}, err
+		}
+		return ScriptoriumInputSourceDescriptor{
+			Source: Source{
+				ID:            descriptor.SourceID,
+				Kind:          SourceKindPreviousArtifact,
+				ConfiguredKey: descriptor.ConfiguredKey,
+			},
+			PreviousSession: &descriptor,
+		}, nil
+	}
+
+	classified, err := ClassifySource(trimmed)
+	if err != nil {
+		return ScriptoriumInputSourceDescriptor{}, ErrUnsupportedScriptoriumInputSource
+	}
+	return ScriptoriumInputSourceDescriptor{Source: classified}, nil
+}
+
+// DescribePreviousSessionSource validates a canonical previous-session source id
+// and returns both previous and configured-source vocabulary descriptors.
+func DescribePreviousSessionSource(source string) (PreviousSessionSourceDescriptor, error) {
+	configuredKey, ok := ParsePreviousSessionSource(source)
+	if !ok {
+		return PreviousSessionSourceDescriptor{}, ErrInvalidPreviousSessionSource
+	}
+	return PreviousSessionSourceDescriptor{
+		SourceID:           PreviousSessionSourceID(configuredKey),
+		ConfiguredKey:      configuredKey,
+		ConfiguredSourceID: ConfiguredSourceID(configuredKey),
+	}, nil
+}
+
+// PreviousSessionSourceDescriptorForConfiguredKey derives a previous-session source descriptor
+// from a configured artifact key.
+func PreviousSessionSourceDescriptorForConfiguredKey(configuredKey string) (PreviousSessionSourceDescriptor, error) {
+	return DescribePreviousSessionSource(PreviousSessionSourceID(configuredKey))
+}
+
+// ValidateInputConfiguredReference checks that configured/previous-session sources
+// reference configured artifacts known to the current Scriptorium config.
+func ValidateInputConfiguredReference(
+	descriptor ScriptoriumInputSourceDescriptor,
+	configured map[string]struct{},
+) error {
+	switch descriptor.Source.Kind {
+	case SourceKindConfiguredArtifact, SourceKindPreviousArtifact:
+		if _, ok := configured[descriptor.Source.ConfiguredKey]; !ok {
+			return &UnknownConfiguredArtifactError{ConfiguredKey: descriptor.Source.ConfiguredKey}
+		}
+	}
+	return nil
+}
+
 // ValidatePublishSource validates that a source is publish-compatible and references a known configured artifact.
 func ValidatePublishSource(source string, configured map[string]string) (Source, error) {
 	classified, err := ClassifySource(source)