content: /*
   * Copyright 2024-2025 the original author or authors.
   *
   * 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 com.alibaba.cloud.ai.graph.node;
  
  import com.alibaba.cloud.ai.graph.OverAllState;
  import com.alibaba.cloud.ai.graph.action.NodeAction;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * Render the template in AnswerNodeData into the final answer string.
   */
  public class AnswerNode implements NodeAction {
  
  	private static final Pattern PLACEHOLDER_PATTERN = Pattern.compile("\\{\\s*(.+?)\\s*\\}");
  
  	private final String answerTemplate;
  
  	private final String outputKey;
  
  	private AnswerNode(String answerTemplate, String outputKey) {
  		this.answerTemplate = answerTemplate;
  		this.outputKey = outputKey;
  	}
  
  	@Override
  	public Map<String, Object> apply(OverAllState state) {
  		// Replace {{key}} in the answerTemplate with the value of state.get(key).
  		StringBuffer sb = new StringBuffer();
  		Matcher matcher = PLACEHOLDER_PATTERN.matcher(answerTemplate);
  		while (matcher.find()) {
  			String key = matcher.group(1);
  			Object val = state.value(key).orElse("");
  			String replacement = val != null ? val.toString() : "";
  			replacement = replacement.replace("\\", "\\\\").replace("$", "\\$");
  			matcher.appendReplacement(sb, replacement);
  		}
  		matcher.appendTail(sb);
  		String resolved = sb.toString();
  
  		// Write the final result back to the state with the key name fixed to "answer"
  		Map<String, Object> result = new HashMap<>();
  		result.put(this.outputKey, resolved);
  		return result;
  	}
  
  	public static Builder builder() {
  		return new Builder();
  	}
  
  	public static class Builder {
  
  		private String answerTemplate;
  
  		private String outputKey = "answer";
  
  		public Builder answer(String answerTemplate) {
  			this.answerTemplate = answerTemplate;
  			return this;
  		}
  
  		public Builder outputKey(String outputKey) {
  			this.outputKey = outputKey;
  			return this;
  		}
  
  		public AnswerNode build() {
  			return new AnswerNode(answerTemplate, outputKey);
  		}
  
  	}
  
  }
  