feat(sidekick): maps for discovery docs (#2379)

Author: coryan

internal/sidekick/internal/parser/discovery/map_field.go

@@ -0,0 +1,121 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package discovery
+
+import (
+	"fmt"
+
+	"github.com/googleapis/librarian/internal/sidekick/internal/api"
+)
+
+func maybeMapField(model *api.API, message *api.Message, input *property) (*api.Field, error) {
+	if input.Schema.Type != "object" || input.Schema.Format != "" {
+		return nil, nil
+	}
+	if input.Schema.AdditionalProperties == nil {
+		return nil, nil
+	}
+
+	if field := maybeMapOfObjectField(model, message, input); field != nil {
+		return field, nil
+	}
+	if field, err := maybeMapOfEnumField(model, message, input); err != nil || field != nil {
+		return field, err
+	}
+	return maybeMapOfPrimitiveField(model, message, input)
+}
+
+func maybeMapOfObjectField(model *api.API, message *api.Message, input *property) *api.Field {
+	if input.Schema.AdditionalProperties.Ref == "" {
+		return nil
+	}
+	valueTypezID := fmt.Sprintf(".%s.%s", model.PackageName, input.Schema.AdditionalProperties.Ref)
+	typezID := insertMapType(model, api.MESSAGE_TYPE, valueTypezID)
+	field := &api.Field{
+		Name:          input.Name,
+		JSONName:      input.Name,
+		ID:            fmt.Sprintf("%s.%s", message.ID, input.Name),
+		Documentation: input.Schema.Description,
+		Typez:         api.MESSAGE_TYPE,
+		TypezID:       typezID,
+	}
+	return field
+}
+
+func maybeMapOfEnumField(model *api.API, message *api.Message, input *property) (*api.Field, error) {
+	if input.Schema.AdditionalProperties.Enums == nil {
+		return nil, nil
+	}
+	if err := makeMessageEnum(model, message, input.Name, input.Schema.AdditionalProperties); err != nil {
+		return nil, err
+	}
+	valueTypezID := fmt.Sprintf("%s.%s", message.ID, input.Name)
+	typezID := insertMapType(model, api.ENUM_TYPE, valueTypezID)
+	field := &api.Field{
+		Name:          input.Name,
+		JSONName:      input.Name,
+		ID:            fmt.Sprintf("%s.%s", message.ID, input.Name),
+		Documentation: input.Schema.Description,
+		Typez:         api.MESSAGE_TYPE,
+		TypezID:       typezID,
+	}
+	return field, nil
+}
+
+func maybeMapOfPrimitiveField(model *api.API, message *api.Message, input *property) (*api.Field, error) {
+	valueTypez, valueTypezID, err := scalarType(model, message.ID, input.Name, input.Schema.AdditionalProperties)
+	if err != nil {
+		return nil, err
+	}
+	typezID := insertMapType(model, valueTypez, valueTypezID)
+	field := &api.Field{
+		Name:          input.Name,
+		JSONName:      input.Name,
+		ID:            fmt.Sprintf("%s.%s", message.ID, input.Name),
+		Documentation: input.Schema.Description,
+		Typez:         api.MESSAGE_TYPE,
+		TypezID:       typezID,
+	}
+	return field, nil
+}
+
+func insertMapType(model *api.API, valueTypez api.Typez, valueTypezId string) string {
+	id := fmt.Sprintf("$map<string, %s>", valueTypezId)
+	if _, ok := model.State.MessageByID[id]; ok {
+		return id
+	}
+	key := &api.Field{
+		Name:    "key",
+		ID:      fmt.Sprintf("%s.key", id),
+		Typez:   api.STRING_TYPE,
+		TypezID: "string",
+	}
+	value := &api.Field{
+		Name:    "value",
+		ID:      fmt.Sprintf("%s.value", id),
+		Typez:   valueTypez,
+		TypezID: valueTypezId,
+	}
+	message := &api.Message{
+		Name:          id,
+		ID:            id,
+		Documentation: id,
+		Package:       "$",
+		IsMap:         true,
+		Fields:        []*api.Field{key, value},
+	}
+	model.State.MessageByID[message.ID] = message
+	return id
+}