1 files changed, 86 insertions, 0 deletions
diff --git a/internal/flamegraph/nativejson.go b/internal/flamegraph/nativejson.go
new file mode 100644
index 0000000..088bcfc
--- /dev/null
+++ b/internal/flamegraph/nativejson.go
@@ -0,0 +1,86 @@
+package flamegraph
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"iter"
+	"os"
+	"strings"
+)
+
+type jsonNode struct {
+	Name     string     `json:"name"`
+	Value    uint64     `json:"value"`
+	Total    uint64     `json:"total"`
+	Children []jsonNode `json:"children,omitempty"`
+}
+
+type jsonFlamegraph struct {
+	Fields     []string `json:"fields"`
+	CountField string   `json:"countField"`
+	Root       jsonNode `json:"root"`
+}
+
+func (n NativeSVG) WriteJSONFromFile(iorDataFile string) (outFile string, err error) {
+	outFile = fmt.Sprintf("%s.%s-by-%s.json",
+		strings.TrimSuffix(iorDataFile, ".ior.zst"),
+		strings.Join(n.fields, ":"),
+		n.countField,
+	)
+	defer func() {
+		if err != nil {
+			_ = os.Remove(outFile)
+		}
+	}()
+
+	iod, err := newIorDataFromFile(iorDataFile)
+	if err != nil {
+		return outFile, fmt.Errorf("read ior data: %w", err)
+	}
+
+	fd, err := os.Create(outFile)
+	if err != nil {
+		return outFile, fmt.Errorf("create output %s: %w", outFile, err)
+	}
+	defer fd.Close()
+
+	if err := n.WriteJSONFromIter(iod.iter(), fd); err != nil {
+		return outFile, err
+	}
+	return outFile, nil
+}
+
+func (n NativeSVG) WriteJSONFromIter(records iter.Seq[IterRecord], w io.Writer) error {
+	tr, err := n.buildTrieFromIter(records)
+	if err != nil {
+		return err
+	}
+
+	payload := jsonFlamegraph{
+		Fields:     append([]string(nil), n.fields...),
+		CountField: n.countField,
+		Root:       jsonNodeFromTrieNode(tr.root, "root"),
+	}
+
+	enc := json.NewEncoder(w)
+	enc.SetIndent("", "  ")
+	return enc.Encode(payload)
+}
+
+func jsonNodeFromTrieNode(node *trieNode, name string) jsonNode {
+	out := jsonNode{
+		Name:  name,
+		Value: node.value,
+		Total: node.total,
+	}
+	if len(node.children) == 0 {
+		return out
+	}
+
+	out.Children = make([]jsonNode, 0, len(node.children))
+	for _, child := range node.children {
+		out.Children = append(out.Children, jsonNodeFromTrieNode(child, child.name))
+	}
+	return out
+}