feat: manually mirror opencoze's code from bytedance

Change-Id: I09a73aadda978ad9511264a756b2ce51f5761adf

backend/domain/agent/singleagent/internal/agentflow/node_prompt_variables.go

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2025 coze-dev 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
+ *
+ *     http://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 agentflow
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/cloudwego/eino/schema"
+
+	"github.com/coze-dev/coze-studio/backend/domain/agent/singleagent/entity"
+)
+
+const (
+	placeholderOfUserInput   = "_user_input"
+	placeholderOfChatHistory = "_chat_history"
+)
+
+type promptVariables struct {
+	Agent *entity.SingleAgent
+	avs   map[string]string
+}
+
+func (p *promptVariables) AssemblePromptVariables(ctx context.Context, req *AgentRequest) (variables map[string]any, err error) {
+	variables = make(map[string]any)
+
+	variables[placeholderOfTime] = time.Now().Format("Monday 2006/01/02 15:04:05 -07")
+	variables[placeholderOfAgentName] = p.Agent.Name
+
+	if req.Input != nil {
+		variables[placeholderOfUserInput] = []*schema.Message{req.Input}
+	}
+
+	// 处理对话历史
+	if len(req.History) > 0 {
+		// 将历史消息添加到变量中
+		variables[placeholderOfChatHistory] = req.History
+	}
+
+	if p.avs != nil {
+		var memoryVariablesList []string
+		for k, v := range p.avs {
+			variables[k] = v
+			memoryVariablesList = append(memoryVariablesList, fmt.Sprintf("%s: %s\n", k, v))
+		}
+		variables[placeholderOfVariables] = memoryVariablesList
+	}
+
+	return variables, nil
+}