Add D&D scene description validation

internal/modules/dnd/validate/scenedescriptions/invariants/validator.go

@@ -0,0 +1,119 @@
+// Package invariants validates normalized D&D scene description artifacts.
+package invariants
+
+import (
+	"context"
+	"fmt"
+	"sort"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
+	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
+	"gitea.maximumdirect.net/eric/notarius/internal/framework/pipeline"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/shared/diagnostics"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/validate/scenedescriptions/shape"
+)
+
+const (
+	Key        = "normalize/dnd/scene-descriptions/invariants"
+	ReasonCode = "invalid_scene_description_normalization"
+	policy     = "dnd.scene_descriptions.validator.invariants.v1"
+)
+
+type Options struct{}
+type Validator struct{}
+
+var _ contracts.TypedValidator[dnd.SceneDescriptionList] = (*Validator)(nil)
+var _ pipeline.CheckpointFingerprintProvider = (*Validator)(nil)
+
+func New(Options) *Validator      { return &Validator{} }
+func (v *Validator) Name() string { return Key }
+func (v *Validator) ExecutionClass() contracts.ExecutionClass {
+	return contracts.ExecutionClassDeterministic
+}
+func (v *Validator) CheckpointFingerprints() []pipeline.CheckpointFingerprint {
+	return []pipeline.CheckpointFingerprint{{Name: "policy", Value: policy}}
+}
+
+func (v *Validator) Validate(_ context.Context, req contracts.TypedValidationRequest[dnd.SceneDescriptionList]) (contracts.ValidationResult, error) {
+	if shape.Validate(req.Value) != nil || !sourceRefsValid(req.Source, req.Value) {
+		return contracts.ValidationResult{Approved: true}, nil
+	}
+	issues := issuesFor(req.Source, req.Value)
+	if len(issues) == 0 {
+		return contracts.ValidationResult{Approved: true}, nil
+	}
+	return contracts.ValidationResult{
+		Approved: false, ReasonCode: ReasonCode,
+		Message: diagnostics.Aggregate("invalid scene description normalization", issues),
+	}, nil
+}
+
+func sourceRefsValid(doc *source.SourceDocument, value dnd.SceneDescriptionList) bool {
+	for _, scene := range value.Scenes {
+		if source.ValidateRef(doc, scene.SourceRef) != nil {
+			return false
+		}
+	}
+	return true
+}
+
+func issuesFor(doc *source.SourceDocument, value dnd.SceneDescriptionList) []string {
+	issues := make([]string, 0)
+	if !sort.SliceIsSorted(value.Scenes, func(left, right int) bool {
+		leftStart, _ := source.UnitIndex(doc, value.Scenes[left].SourceRef.StartUnitID)
+		rightStart, _ := source.UnitIndex(doc, value.Scenes[right].SourceRef.StartUnitID)
+		if leftStart != rightStart {
+			return leftStart < rightStart
+		}
+		return value.Scenes[left].ID < value.Scenes[right].ID
+	}) {
+		issues = append(issues, "scenes are not in canonical source order")
+	}
+
+	byID := make(map[string]int, len(value.Scenes))
+	byRange := make(map[source.SourceRef]int, len(value.Scenes))
+	for index, scene := range value.Scenes {
+		if index > 0 && value.Scenes[index-1] == scene {
+			issues = append(issues, fmt.Sprintf("scenes[%d] duplicates scenes[%d]", index, index-1))
+		}
+		if previous, ok := byID[scene.ID]; ok && value.Scenes[previous] != scene {
+			issues = append(issues, fmt.Sprintf("scenes[%d] conflicts with scenes[%d] for scene ID", index, previous))
+		} else if !ok {
+			byID[scene.ID] = index
+		}
+		if previous, ok := byRange[scene.SourceRef]; ok && !sameModelContent(value.Scenes[previous], scene) {
+			issues = append(issues, fmt.Sprintf("scenes[%d] conflicts with scenes[%d] for source range", index, previous))
+		} else if !ok {
+			byRange[scene.SourceRef] = index
+		}
+	}
+	return issues
+}
+
+func sameModelContent(left, right dnd.SceneDescription) bool {
+	return left.Kind == right.Kind && left.Title == right.Title && left.Summary == right.Summary
+}
+
+func Spec() pipeline.ValidatorSpec {
+	return pipeline.ValidatorSpec{Key: Key, ExecutionClass: contracts.ExecutionClassDeterministic}
+}
+
+func Register(registry *pipeline.ValidatorRegistry) error {
+	return pipeline.RegisterTypedValidatorBuilder(registry, dnd.SceneDescriptionListKind, Spec(), validateOptions, func(request pipeline.BuildRequest) (contracts.TypedValidator[dnd.SceneDescriptionList], error) {
+		options, err := DecodeOptions(request.Options)
+		if err != nil {
+			return nil, err
+		}
+		return New(options), nil
+	})
+}
+
+func DecodeOptions(options map[string]any) (Options, error) {
+	if err := pipeline.RejectUnknownOptions(options); err != nil {
+		return Options{}, err
+	}
+	return Options{}, nil
+}
+
+func validateOptions(options map[string]any) error { _, err := DecodeOptions(options); return err }