otelzap: Implement Reflect method (#5703)

Part of
#5191

Pre-work
#5279

---------

Co-authored-by: Robert Pająk <pellared@hotmail.com>

bridges/otelzap/encoder.go

@@ -4,6 +4,8 @@
 package otelzap // import "go.opentelemetry.io/contrib/bridges/otelzap"
 
 import (
+	"fmt"
+	"reflect"
 	"time"
 
 	"go.uber.org/zap/zapcore"
@@ -93,8 +95,12 @@ func (m *objectEncoder) AddUint64(k string, v uint64) {
 		})
 }
 
-// TODO.
 func (m *objectEncoder) AddReflected(k string, v interface{}) error {
+	m.kv = append(m.kv,
+		log.KeyValue{
+			Key:   k,
+			Value: convertValue(v),
+		})
 	return nil
 }
 
@@ -177,8 +183,8 @@ func (a *arrayEncoder) AppendObject(v zapcore.ObjectMarshaler) error {
 	return err
 }
 
-// TODO.
 func (a *arrayEncoder) AppendReflected(v interface{}) error {
+	a.elems = append(a.elems, convertValue(v))
 	return nil
 }
 
@@ -231,3 +237,56 @@ func (a *arrayEncoder) AppendUint32(v uint32)          { a.AppendInt64(int64(v))
 func (a *arrayEncoder) AppendUint16(v uint16)          { a.AppendInt64(int64(v)) }
 func (a *arrayEncoder) AppendUint8(v uint8)            { a.AppendInt64(int64(v)) }
 func (a *arrayEncoder) AppendUintptr(v uintptr)        { a.AppendUint64(uint64(v)) }
+
+func convertValue(v interface{}) log.Value {
+	switch v := v.(type) {
+	case bool:
+		return log.BoolValue(v)
+	case []byte:
+		return log.BytesValue(v)
+	case float64:
+		return log.Float64Value(v)
+	case int:
+		return log.IntValue(v)
+	case int64:
+		return log.Int64Value(v)
+	case string:
+		return log.StringValue(v)
+	}
+
+	t := reflect.TypeOf(v)
+	if t == nil {
+		return log.Value{}
+	}
+	val := reflect.ValueOf(v)
+	switch t.Kind() {
+	case reflect.Struct:
+		return log.StringValue(fmt.Sprintf("%+v", v))
+	case reflect.Slice, reflect.Array:
+		items := make([]log.Value, 0, val.Len())
+		for i := 0; i < val.Len(); i++ {
+			items = append(items, convertValue(val.Index(i).Interface()))
+		}
+		return log.SliceValue(items...)
+	case reflect.Map:
+		kvs := make([]log.KeyValue, 0, val.Len())
+		for _, k := range val.MapKeys() {
+			var key string
+			// If the key is a struct, use %+v to print the struct fields.
+			if k.Kind() == reflect.Struct {
+				key = fmt.Sprintf("%+v", k.Interface())
+			} else {
+				key = fmt.Sprintf("%v", k.Interface())
+			}
+			kvs = append(kvs, log.KeyValue{
+				Key:   key,
+				Value: convertValue(val.MapIndex(k).Interface()),
+			})
+		}
+		return log.MapValue(kvs...)
+	case reflect.Ptr, reflect.Interface:
+		return convertValue(val.Elem().Interface())
+	}
+
+	return log.StringValue(fmt.Sprintf("unhandled attribute type: (%s) %+v", t, v))
+}

bridges/otelzap/encoder_test.go

@@ -65,6 +65,13 @@ func TestObjectEncoder(t *testing.T) {
 			},
 			expected: []interface{}{wantTurducken, wantTurducken},
 		},
+		{
+			desc: "AddReflected",
+			f: func(e zapcore.ObjectEncoder) {
+				assert.NoError(t, e.AddReflected("k", map[string]interface{}{"foo": 5}), "Expected AddReflected to succeed.")
+			},
+			expected: map[string]interface{}{"foo": int64(5)},
+		},
 		{
 			desc:     "AddBinary",
 			f:        func(e zapcore.ObjectEncoder) { e.AddBinary("k", []byte("foo")) },
@@ -207,6 +214,13 @@ func TestArrayEncoder(t *testing.T) {
 			},
 			expected: []interface{}{true, false},
 		},
+		{
+			desc: "AppendReflected",
+			f: func(e zapcore.ArrayEncoder) {
+				assert.NoError(t, e.AppendReflected(map[string]interface{}{"foo": 5}))
+			},
+			expected: map[string]interface{}{"foo": int64(5)},
+		},
 		{"AppendBool", func(e zapcore.ArrayEncoder) { e.AppendBool(true) }, true},
 		{"AppendByteString", func(e zapcore.ArrayEncoder) { e.AppendByteString([]byte("foo")) }, "foo"},
 		{"AppendFloat64", func(e zapcore.ArrayEncoder) { e.AppendFloat64(3.14) }, 3.14},