Add function calling fallback when the bot is calling a function not exists

Author: intitni

Tool/Sources/OpenAIService/ChatGPTService.swift

@@ -182,7 +182,7 @@ extension ChatGPTService {
     func sendMemory() async throws -> AsyncThrowingStream<StreamContent, Error> {
         guard let url = URL(string: configuration.endpoint)
         else { throw ChatGPTServiceError.endpointIncorrect }
-        
+
         await memory.refresh()
 
         let messages = await memory.messages.map {
@@ -282,7 +282,7 @@ extension ChatGPTService {
     func sendMemoryAndWait() async throws -> ChatMessage? {
         guard let url = URL(string: configuration.endpoint)
         else { throw ChatGPTServiceError.endpointIncorrect }
-        
+
         await memory.refresh()
 
         let messages = await memory.messages.map {
@@ -368,16 +368,7 @@ extension ChatGPTService {
         let messageId = messageId ?? uuidGenerator()
 
         guard var function = functionProvider.function(named: call.name) else {
-            let content = "Error: function not found"
-            let responseMessage = ChatMessage(
-                id: messageId,
-                role: .function,
-                content: content,
-                name: call.name,
-                summary: "Function `\(call.name)` not found."
-            )
-            await memory.appendMessage(responseMessage)
-            return content
+            return await fallbackFunctionCall(call, messageId: messageId)
         }
 
         // Insert the chat message into memory to indicate the start of the function.
@@ -414,6 +405,56 @@ extension ChatGPTService {
             return content
         }
     }
+
+    /// Mock a function call result when the bot is calling a function that is not implemented.
+    func fallbackFunctionCall(
+        _ call: ChatMessage.FunctionCall,
+        messageId: String
+    ) async -> String {
+        let memory = ConversationChatGPTMemory(systemPrompt: {
+            if call.name == "python" {
+                return """
+                Act like a Python interpreter.
+                I will give you Python code and you will execute it.
+                Reply with output of the code and tell me it's an answer generated by LLM.
+                """
+            } else {
+                return """
+                You are a function simulator. Your name is \(call.name).
+                Act like a function.
+                I will send you the arguments.
+                Reply with output of the function and tell me it's an answer generated by LLM.
+                """
+            }
+        }())
+
+        let service = ChatGPTService(
+            memory: memory,
+            configuration: OverridingChatGPTConfiguration(overriding: configuration, with: .init(
+                temperature: 0
+            )),
+            functionProvider: NoChatGPTFunctionProvider()
+        )
+
+        let content: String = await {
+            do {
+                return try await service.sendAndWait(content: """
+                \(call.arguments)
+                """) ?? "No result."
+            } catch {
+                return "No result."
+            }
+        }()
+        let responseMessage = ChatMessage(
+            id: messageId,
+            role: .function,
+            content: content,
+            name: call.name,
+            summary: "Finished running function."
+        )
+        await memory.appendMessage(responseMessage)
+        return content
+    }
 }
 
 extension ChatGPTService {
@@ -430,5 +471,5 @@ func maxTokenForReply(model: String, remainingTokens: Int?) -> Int? {
     guard let remainingTokens else { return nil }
     guard let model = ChatGPTModel(rawValue: model) else { return remainingTokens }
     return min(model.maxToken / 2, remainingTokens)
-}      
+}