fix(dart): Correctly encode repeated/map (#3326)

Change the previous strategy of having per-type encoders for `map` and
`repeated` fields into using list/dictionary comprehensions and then the
usual primitive encoders.

---------

Signed-off-by: Brian Quinlan <[email protected]>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: brianquinlan

internal/sidekick/dart/annotate.go

@@ -797,7 +797,7 @@ func (annotate *annotateModel) annotateField(field *api.Field) {
 		FieldBehaviorRequired: fieldRequired,
 		DefaultValue:          defaultValue,
 		FromJson:              annotate.createFromJsonLine(field, state, implicitPresence),
-		ToJson:                createToJsonLine(field, state, implicitPresence),
+		ToJson:                createToJsonLine(field, state),
 		ConstDefault:          constDefault,
 	}
 }
@@ -853,8 +853,85 @@ func (annotate *annotateModel) keyDecoder(typez api.Typez) string {
 		api.SINT64_TYPE,
 		api.SFIXED64_TYPE:
 		return "decodeIntKey"
+	case api.UINT64_TYPE,
+		api.FIXED64_TYPE:
+		return "decodeUint64Key"
+	case api.BOOL_TYPE:
+		return "decodeBoolKey"
+	default:
+		panic(fmt.Sprintf("unsupported key type: %d", typez))
+	}
+}
+
+// encoder returns a string that encodes the given field name and a bool that indicates whether the
+// field requires encoding.
+//
+// For example:
+//
+//	encoder(api.STRING_TYPE, "a_string_field") => ("a_string_field", false)
+//	encoder(api.MESSAGE_TYPE, "a_message_field") => ("a_message_field.toJson()", true)
+func encoder(typez api.Typez, name string) (string, bool) {
+	switch typez {
+	case api.INT64_TYPE,
+		api.SINT64_TYPE,
+		api.SFIXED64_TYPE,
+		api.FIXED64_TYPE,
+		api.UINT64_TYPE:
+		// All 64-bit integer types are encoded as strings. In Dart, these may be
+		// represented as `int` or `BigInt`.
+		return fmt.Sprintf("%s.toString()", name), true
+	case api.FLOAT_TYPE,
+		api.DOUBLE_TYPE:
+		// A special encoder is needed to handle NaN and Infinity.
+		return fmt.Sprintf("encodeDouble(%s)", name), true
+	case api.INT32_TYPE,
+		api.FIXED32_TYPE,
+		api.SFIXED32_TYPE,
+		api.SINT32_TYPE,
+		api.UINT32_TYPE:
+		// All 32-bit integer types are encoded as JSON numbers.
+		return name, false
+	case api.BOOL_TYPE:
+		return name, false
+	case api.STRING_TYPE:
+		return name, false
+	case api.BYTES_TYPE:
+		return fmt.Sprintf("encodeBytes(%s)", name), true
+	case api.MESSAGE_TYPE, api.ENUM_TYPE:
+		return fmt.Sprintf("%s.toJson()", name), true
+	default:
+		panic(fmt.Sprintf("unsupported type: %d", typez))
+	}
+}
+
+// keyEncoder returns a string that encodes the given field name and a bool that indicates whether the
+// field requires encoding
+//
+// For example:
+//
+//	keyEncoder(api.STRING_TYPE, "e.key") => ("e.key", false)
+//	keyEncoder(api.INT32_TYPE, "e.key") => ("e.key.toString()", true)
+func keyEncoder(typez api.Typez, name string) (string, bool) {
+	// JSON objects can only contain string keys so non-String types need to be encoded as strings.
+	// Supported key types are defined here:
+	// https://protobuf.dev/programming-guides/proto3/#maps
+	switch typez {
+	case api.STRING_TYPE:
+		return name, false
+	case api.INT32_TYPE,
+		api.FIXED32_TYPE,
+		api.SFIXED32_TYPE,
+		api.SINT32_TYPE,
+		api.UINT32_TYPE,
+		api.INT64_TYPE,
+		api.SINT64_TYPE,
+		api.SFIXED64_TYPE,
+		api.UINT64_TYPE,
+		api.FIXED64_TYPE:
+		return fmt.Sprintf("%s.toString()", name), true
+	case api.BOOL_TYPE:
+		return fmt.Sprintf("%s.toString()", name), true
 	default:
-		// TODO(https://github.com/googleapis/google-cloud-dart/issues/95): Support all key types.
 		panic(fmt.Sprintf("unsupported key type: %d", typez))
 	}
 }
@@ -904,57 +981,34 @@ func (annotate *annotateModel) createFromJsonLine(field *api.Field, state *api.A
 	return fmt.Sprintf("switch (%s) { null => %s, Object $1 => %s($1)}", data, defaultValue, decoder)
 }
 
-func createToJsonLine(field *api.Field, state *api.APIState, required bool) string {
+func createToJsonLine(field *api.Field, state *api.APIState) string {
 	name := fieldName(field)
-	message := state.MessageByID[field.TypezID]
-
-	isList := field.Repeated
-	isMap := message != nil && message.IsMap
-
-	bang := "!"
-	if required {
-		bang = ""
-	}
 
 	switch {
-	case isList:
-		switch field.Typez {
-		case api.BYTES_TYPE:
-			return fmt.Sprintf("encodeListBytes(%s)", name)
-		case api.MESSAGE_TYPE, api.ENUM_TYPE:
-			return fmt.Sprintf("encodeList(%s)", name)
-		default:
-			// identity
-			return name
+	case field.Repeated:
+		if encoder, encodingRequired := encoder(field.Typez, "i"); encodingRequired {
+			return fmt.Sprintf(
+				"[for (final i in %s) %s]",
+				name, encoder)
 		}
-	case isMap:
-		valueField := message.Fields[1]
+		return name
+	case field.Map:
+		message := state.MessageByID[field.TypezID]
+		keyType := message.Fields[0].Typez
+		keyEncoder, keyEncodingRequired := keyEncoder(keyType, "e.key")
+		valueType := message.Fields[1].Typez
+		valueEncoder, valueEncodingRequired := encoder(valueType, "e.value")
 
-		switch valueField.Typez {
-		case api.BYTES_TYPE:
-			return fmt.Sprintf("encodeMapBytes(%s)", name)
-		case api.MESSAGE_TYPE, api.ENUM_TYPE:
-			return fmt.Sprintf("encodeMap(%s)", name)
-		default:
-			// identity
-			return name
+		if keyEncodingRequired || valueEncodingRequired {
+			return fmt.Sprintf(
+				"{for (final e in %s.entries) %s: %s}",
+				name, keyEncoder, valueEncoder)
 		}
-	case field.Typez == api.MESSAGE_TYPE || field.Typez == api.ENUM_TYPE:
-		return fmt.Sprintf("%s%s.toJson()", name, bang)
-	case field.Typez == api.BYTES_TYPE:
-		return fmt.Sprintf("encodeBytes(%s)", name)
-	case field.Typez == api.INT64_TYPE || field.Typez == api.SINT64_TYPE ||
-		field.Typez == api.SFIXED64_TYPE:
-		return fmt.Sprintf("encodeInt64(%s)", name)
-	case field.Typez == api.FIXED64_TYPE || field.Typez == api.UINT64_TYPE:
-		return fmt.Sprintf("encodeUint64(%s)", name)
-	case field.Typez == api.FLOAT_TYPE || field.Typez == api.DOUBLE_TYPE:
-		return fmt.Sprintf("encodeDouble(%s)", name)
-	default:
+		return name
 	}
 
-	// No encoding necessary.
-	return name
+	enc, _ := encoder(field.Typez, name)
+	return enc
 }
 
 // buildQueryLines builds a string or strings representing query parameters for the given field.