Integrate history prefixes into load handoffs

internal/engine/override_context.go

@@ -10,6 +10,7 @@ type postDecodeOverrideContext struct {
 	preCLIOrigins   map[string]Origin
 	decoded         decodedConfiguration
 	metadata        Metadata
+	historyBuilder  *historyBuilder
 	resolution      resolutionInput
 	applications    []historyApplication
 	postDecodeApps  []historyApplication
@@ -60,6 +61,7 @@ func preparePostDecodeOverrideContext(input assembledInput, before decodedConfig
 		appendPostDecodeCLIHistory(&metadata, cliRecords, postDecodeApps, before.final)
 	}
 	metadata.historyBuilder.observePostCLICheckpoint(after.final, after.origins)
+	metadata.historyBuilder.prefixReady = true
 
 	sources := cloneSourceInfos(input.sources)
 	knownSources := make(map[string]bool, len(sources)+len(assigned.overrides))
@@ -85,6 +87,7 @@ func preparePostDecodeOverrideContext(input assembledInput, before decodedConfig
 		preCLIOrigins:   cloneOrigins(before.origins),
 		decoded:         after,
 		metadata:        metadata,
+		historyBuilder:  metadata.historyBuilder,
 		resolution:      resolution,
 		applications:    applications,
 		postDecodeApps:  postDecodeApps,
@@ -197,13 +200,12 @@ func documentWithMetadataLocations(root *document.Node, metadata Metadata, fallb
 		if lookup == nil {
 			lookup = buildDocumentLookup(fallbackRoot)
 		}
-		return nearestDocumentLocationWithLookup(fallbackRoot, path, lookup)
+		return nearestConcreteDocumentLocationWithLookup(fallbackRoot, path, lookup)
 	}
 	var visit func(*document.Node, Path)
 	visit = func(node *document.Node, path Path) {
-		pointer := path.String()
-		if info, exists := metadata.fields[pointer]; exists {
-			if location, ok := metadataFieldLocation(metadata, pointer, info.Origin); ok {
+		if info, exists := metadata.effectiveField(path); exists {
+			if location, ok := metadataFieldLocation(metadata, path, info.Origin); ok {
 				node.Location = location
 			} else if location, ok := fallbackLocation(path); ok {
 				node.Location = location
@@ -216,8 +218,8 @@ func documentWithMetadataLocations(root *document.Node, metadata Metadata, fallb
 			for index := range node.Mapping {
 				entry := &node.Mapping[index]
 				childPath := path.Key(entry.Key)
-				if info, exists := metadata.fields[childPath.String()]; exists {
-					if location, ok := metadataFieldLocation(metadata, childPath.String(), info.Origin); ok {
+				if info, exists := metadata.effectiveField(childPath); exists {
+					if location, ok := metadataFieldLocation(metadata, childPath, info.Origin); ok {
 						entry.KeyLocation = location
 						entry.ValueLocation = location
 					} else if location, ok := fallbackLocation(childPath); ok {
@@ -240,19 +242,57 @@ func documentWithMetadataLocations(root *document.Node, metadata Metadata, fallb
 	return located
 }
 
-func metadataFieldLocation(metadata Metadata, pointer string, origin Origin) (document.Location, bool) {
+func nearestConcreteDocumentLocationWithLookup(root *document.Node, path Path, lookup *documentLookup) (document.Location, bool) {
+	if root == nil || !path.valid() {
+		return document.Location{}, false
+	}
+	current := root
+	nearest := current.Location
+	for _, segment := range path.segments {
+		switch current.Kind {
+		case document.Mapping:
+			if segment.kind != pathSegmentKey {
+				return nearest, locationKnown(nearest)
+			}
+			position := -1
+			if lookup != nil {
+				position = lookup.find(current, segment.key)
+			} else {
+				for index, entry := range current.Mapping {
+					if entry.Key == segment.key {
+						position = index
+						break
+					}
+				}
+			}
+			if position < 0 || position >= len(current.Mapping) {
+				return nearest, locationKnown(nearest)
+			}
+			current = current.Mapping[position].Value
+		case document.Sequence:
+			if segment.kind != pathSegmentIndex || segment.index < 0 || segment.index >= len(current.Sequence) {
+				return nearest, locationKnown(nearest)
+			}
+			current = current.Sequence[segment.index]
+		default:
+			return nearest, locationKnown(nearest)
+		}
+		if current == nil {
+			return nearest, locationKnown(nearest)
+		}
+		nearest = current.Location
+	}
+	return nearest, locationKnown(nearest)
+}
+
+func metadataFieldLocation(metadata Metadata, path Path, origin Origin) (document.Location, bool) {
 	if location, ok := latestOriginDocumentLocation(origin); ok {
 		return location, true
 	}
-	for index := len(metadata.history[pointer]) - 1; index >= 0; index-- {
-		change := metadata.history[pointer][index]
-		if location, ok := latestOriginDocumentLocation(change.Origin); ok {
-			return location, true
-		}
-		for prior := len(change.Previous) - 1; prior >= 0; prior-- {
-			if location, ok := latestOriginDocumentLocation(change.Previous[prior]); ok {
-				return location, true
-			}
+	if model := metadata.currentHistoryModel(); model != nil {
+		location, ok := model.latestHistoricalLocation(path)
+		if ok {
+			return document.Location{SourceID: location.SourceID, Line: location.Line, Column: location.Column}, true
 		}
 	}
 	return document.Location{}, false