Render native configuration differences as YAML

integrations/ckconfig/diff_report.go

@@ -1,9 +1,11 @@
 package ckconfig
 
 import (
+	"bytes"
 	"fmt"
 	"strings"
 
+	configkit "gitea.maximumdirect.net/eric/ConfigKit"
 	"go.yaml.in/yaml/v4"
 )
 
@@ -118,3 +120,55 @@ func pointerFromTokens(tokens []string) string {
 	}
 	return pointer.String()
 }
+
+func renderDiffReport(differences []configkit.Difference) ([]byte, error) {
+	additions := &yaml.Node{Kind: yaml.MappingNode, Tag: "!!map"}
+	changes := &yaml.Node{Kind: yaml.MappingNode, Tag: "!!map"}
+	deletions := &yaml.Node{Kind: yaml.SequenceNode, Tag: "!!seq"}
+
+	for _, difference := range differences {
+		path := difference.Path.String()
+		switch {
+		case !difference.Left.Present && difference.Right.Present:
+			tokens, err := decodeJSONPointer(path)
+			if err != nil {
+				return nil, fmt.Errorf("render addition at %q: %w", path, err)
+			}
+			value, err := decodeSafeSnapshot(difference.Right.YAML)
+			if err != nil {
+				return nil, fmt.Errorf("render addition at %q: %w", path, err)
+			}
+			additions, err = placeYAMLValue(additions, tokens, value)
+			if err != nil {
+				return nil, fmt.Errorf("render addition at %q: %w", path, err)
+			}
+		case difference.Left.Present && difference.Right.Present:
+			tokens, err := decodeJSONPointer(path)
+			if err != nil {
+				return nil, fmt.Errorf("render change at %q: %w", path, err)
+			}
+			value, err := decodeSafeSnapshot(difference.Right.YAML)
+			if err != nil {
+				return nil, fmt.Errorf("render change at %q: %w", path, err)
+			}
+			changes, err = placeYAMLValue(changes, tokens, value)
+			if err != nil {
+				return nil, fmt.Errorf("render change at %q: %w", path, err)
+			}
+		case difference.Left.Present && !difference.Right.Present:
+			deletions.Content = append(deletions.Content, stringKey(path))
+		}
+	}
+
+	root := &yaml.Node{Kind: yaml.MappingNode, Tag: "!!map", Content: []*yaml.Node{
+		stringKey("additions"), additions,
+		stringKey("changes"), changes,
+		stringKey("deletions"), deletions,
+	}}
+	document := &yaml.Node{Kind: yaml.DocumentNode, Content: []*yaml.Node{root}}
+	var output bytes.Buffer
+	if err := encodeYAML(&output, document); err != nil {
+		return nil, fmt.Errorf("encode configuration diff report: %w", err)
+	}
+	return output.Bytes(), nil
+}