Moved broadly useful helper functions upstream into feedkit

processors/normalize/helpers.go

@@ -0,0 +1,84 @@
+package normalize
+
+import (
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+// PayloadJSONBytes extracts a JSON payload into bytes suitable for json.Unmarshal.
+//
+// Supported payload shapes:
+//   - json.RawMessage
+//   - []byte
+//   - string
+//   - map[string]any
+func PayloadJSONBytes(e event.Event) ([]byte, error) {
+	if e.Payload == nil {
+		return nil, fmt.Errorf("payload is nil")
+	}
+
+	switch v := e.Payload.(type) {
+	case json.RawMessage:
+		if len(v) == 0 {
+			return nil, fmt.Errorf("payload is empty json.RawMessage")
+		}
+		return []byte(v), nil
+	case []byte:
+		if len(v) == 0 {
+			return nil, fmt.Errorf("payload is empty []byte")
+		}
+		return v, nil
+	case string:
+		if v == "" {
+			return nil, fmt.Errorf("payload is empty string")
+		}
+		return []byte(v), nil
+	case map[string]any:
+		b, err := json.Marshal(v)
+		if err != nil {
+			return nil, fmt.Errorf("marshal map payload: %w", err)
+		}
+		return b, nil
+	default:
+		return nil, fmt.Errorf("unsupported payload type %T", e.Payload)
+	}
+}
+
+// DecodeJSONPayload extracts the event payload as bytes and unmarshals it into T.
+func DecodeJSONPayload[T any](in event.Event) (T, error) {
+	var zero T
+
+	b, err := PayloadJSONBytes(in)
+	if err != nil {
+		return zero, fmt.Errorf("extract payload: %w", err)
+	}
+
+	var parsed T
+	if err := json.Unmarshal(b, &parsed); err != nil {
+		return zero, fmt.Errorf("decode raw payload: %w", err)
+	}
+
+	return parsed, nil
+}
+
+// FinalizeEvent builds the output event envelope by copying the input and applying
+// the new schema/payload, plus optional EffectiveAt.
+func FinalizeEvent(in event.Event, outSchema string, outPayload any, effectiveAt time.Time) (*event.Event, error) {
+	out := in
+	out.Schema = outSchema
+	out.Payload = outPayload
+
+	if !effectiveAt.IsZero() {
+		t := effectiveAt.UTC()
+		out.EffectiveAt = &t
+	}
+
+	if err := out.Validate(); err != nil {
+		return nil, err
+	}
+
+	return &out, nil
+}

processors/normalize/helpers_test.go

@@ -0,0 +1,118 @@
+package normalize
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+func TestPayloadJSONBytesSupportedShapes(t *testing.T) {
+	cases := []struct {
+		name    string
+		payload any
+		want    string
+	}{
+		{name: "rawmessage", payload: json.RawMessage(`{"a":1}`), want: `{"a":1}`},
+		{name: "bytes", payload: []byte(`{"a":2}`), want: `{"a":2}`},
+		{name: "string", payload: `{"a":3}`, want: `{"a":3}`},
+		{name: "map", payload: map[string]any{"a": 4}, want: `{"a":4}`},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			got, err := PayloadJSONBytes(event.Event{Payload: tc.payload})
+			if err != nil {
+				t.Fatalf("PayloadJSONBytes() unexpected error: %v", err)
+			}
+			if string(got) != tc.want {
+				t.Fatalf("PayloadJSONBytes() = %s, want %s", string(got), tc.want)
+			}
+		})
+	}
+}
+
+func TestPayloadJSONBytesRejectsInvalidPayloads(t *testing.T) {
+	cases := []struct {
+		name    string
+		payload any
+		want    string
+	}{
+		{name: "nil", payload: nil, want: "payload is nil"},
+		{name: "empty rawmessage", payload: json.RawMessage{}, want: "payload is empty json.RawMessage"},
+		{name: "empty bytes", payload: []byte{}, want: "payload is empty []byte"},
+		{name: "empty string", payload: "", want: "payload is empty string"},
+		{name: "unsupported", payload: 123, want: "unsupported payload type"},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			_, err := PayloadJSONBytes(event.Event{Payload: tc.payload})
+			if err == nil {
+				t.Fatalf("PayloadJSONBytes() expected error")
+			}
+			if !strings.Contains(err.Error(), tc.want) {
+				t.Fatalf("PayloadJSONBytes() error = %q, want substring %q", err, tc.want)
+			}
+		})
+	}
+}
+
+func TestDecodeJSONPayload(t *testing.T) {
+	type payload struct {
+		Name string `json:"name"`
+	}
+
+	got, err := DecodeJSONPayload[payload](event.Event{
+		Payload: json.RawMessage(`{"name":"alice"}`),
+	})
+	if err != nil {
+		t.Fatalf("DecodeJSONPayload() unexpected error: %v", err)
+	}
+	if got.Name != "alice" {
+		t.Fatalf("DecodeJSONPayload() = %#v, want name alice", got)
+	}
+}
+
+func TestFinalizeEventPreservesEnvelopeAndEffectiveAtBehavior(t *testing.T) {
+	existingEffectiveAt := time.Date(2026, 3, 28, 11, 0, 0, 0, time.UTC)
+	in := event.Event{
+		ID:          "evt-1",
+		Kind:        event.Kind("observation"),
+		Source:      "source-a",
+		EmittedAt:   time.Date(2026, 3, 28, 12, 0, 0, 0, time.UTC),
+		EffectiveAt: &existingEffectiveAt,
+		Schema:      "raw.example.v1",
+		Payload:     map[string]any{"old": true},
+	}
+
+	out, err := FinalizeEvent(in, "example.v1", map[string]any{"value": 1.234567}, time.Time{})
+	if err != nil {
+		t.Fatalf("FinalizeEvent() unexpected error: %v", err)
+	}
+	if out.ID != in.ID || out.Kind != in.Kind || out.Source != in.Source || out.EmittedAt != in.EmittedAt {
+		t.Fatalf("FinalizeEvent() changed preserved envelope fields: %#v", out)
+	}
+	if out.EffectiveAt == nil || !out.EffectiveAt.Equal(existingEffectiveAt) {
+		t.Fatalf("FinalizeEvent() effectiveAt = %#v, want preserved existing value", out.EffectiveAt)
+	}
+
+	nextEffectiveAt := time.Date(2026, 3, 28, 13, 0, 0, 0, time.FixedZone("x", -4*3600))
+	out, err = FinalizeEvent(in, "example.v1", map[string]any{"value": 1.234567}, nextEffectiveAt)
+	if err != nil {
+		t.Fatalf("FinalizeEvent() unexpected overwrite error: %v", err)
+	}
+	if out.EffectiveAt == nil || !out.EffectiveAt.Equal(nextEffectiveAt.UTC()) {
+		t.Fatalf("FinalizeEvent() effectiveAt = %#v, want %s", out.EffectiveAt, nextEffectiveAt.UTC())
+	}
+
+	payloadMap, ok := out.Payload.(map[string]any)
+	if !ok {
+		t.Fatalf("FinalizeEvent() payload type = %T, want map[string]any", out.Payload)
+	}
+	if payloadMap["value"] != 1.234567 {
+		t.Fatalf("FinalizeEvent() payload value = %#v, want unrounded 1.234567", payloadMap["value"])
+	}
+}