content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 org.apache.bigtop.manager.server.mcp.converter;
  
  import org.apache.bigtop.manager.common.utils.JsonUtils;
  
  import org.jetbrains.annotations.NotNull;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.ai.tool.execution.ToolCallResultConverter;
  import org.springframework.lang.Nullable;
  
  import javax.imageio.ImageIO;
  import java.awt.image.RenderedImage;
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.lang.reflect.Type;
  import java.util.Base64;
  import java.util.Map;
  import java.util.Objects;
  
  /**
   * Custom converter only replace JsonParser to JsonUtils.
   * See original source code from {@link org.springframework.ai.tool.execution.DefaultToolCallResultConverter}
   */
  public class JsonToolCallResultConverter implements ToolCallResultConverter {
  
      private static final Logger logger = LoggerFactory.getLogger(JsonToolCallResultConverter.class);
  
      @NotNull @Override
      public String convert(@Nullable Object result, @Nullable Type returnType) {
          if (returnType == Void.TYPE) {
              logger.debug("The tool has no return type. Converting to conventional response.");
              return JsonUtils.writeAsString("Done");
          }
          if (result instanceof RenderedImage) {
              final var buf = new ByteArrayOutputStream(1024 * 4);
              try {
                  ImageIO.write((RenderedImage) result, "PNG", buf);
              } catch (IOException e) {
                  return "Failed to convert tool result to a base64 image: " + e.getMessage();
              }
              final var imgB64 = Base64.getEncoder().encodeToString(buf.toByteArray());
              return JsonUtils.writeAsString(Map.of("mimeType", "image/png", "data", imgB64));
          } else {
              logger.debug("Converting tool result to JSON.");
              return Objects.requireNonNull(JsonUtils.writeAsString(result));
          }
      }
  }
  