feat: function call support

src/chatgpt-api.ts

@@ -140,7 +140,9 @@ export class ChatGPTAPI {
       onProgress,
       stream = onProgress ? true : false,
       completionParams,
-      isFineTune
+      isFineTune,
+      functions,
+      function_call
     } = opts
 
     let { abortSignal } = opts
@@ -173,7 +175,8 @@ export class ChatGPTAPI {
       role: 'assistant',
       id: uuidv4(),
       parentMessageId: messageId,
-      text: ''
+      text: '',
+      finish_reason: ''
     }
 
     const responseP = new Promise<types.ChatMessage>(
@@ -190,6 +193,8 @@ export class ChatGPTAPI {
           max_tokens: maxTokens,
           ...this._completionParams,
           ...completionParams,
+          functions,
+          function_call,
           stream
         } as any
 
@@ -228,12 +233,14 @@ export class ChatGPTAPI {
                   }
 
                   if (response?.choices?.length) {
+                    const choice = response?.choices[0]
                     const delta = isFineTune
                       ? {
                           content: (response.choices[0] as any).text,
                           role: 'assistant' as any
                         }
                       : response.choices[0].delta
+
                     result.delta = delta.content
                     if (delta?.content) result.text += delta.content
                     result.detail = response
@@ -242,6 +249,26 @@ export class ChatGPTAPI {
                       result.role = delta.role
                     }
 
+                    const functionCall = (delta as any)
+                      ?.function_call as types.FunctionCall
+                    if (functionCall) {
+                      if (!result.functionCall) {
+                        result.functionCall = {
+                          arguments: '',
+                          name: ''
+                        }
+                      }
+
+                      if (functionCall.arguments) {
+                        result.functionCall.arguments += functionCall.arguments
+                      }
+
+                      if (functionCall.name) {
+                        result.functionCall.name = functionCall.name
+                      }
+                    }
+                    result.finish_reason = choice?.finish_reason
+
                     onProgress?.(result)
                   }
                 } catch (err) {

src/types.ts

@@ -32,6 +32,50 @@ export type ChatGPTAPIOptions = {
   fetch?: FetchFn
 }
 
+export interface ChatCompletionRequestMessageFunctionCall {
+  /**
+   * The name of the function to call.
+   * @type {string}
+   */
+  name?: string
+  /**
+   * The arguments to call the function with, as generated by the model in JSON format. Note that the model does not always generate valid JSON, and may hallucinate parameters not defined by your function schema. Validate the arguments in your code before calling your function.
+   * @type {string}
+   */
+  arguments?: string
+}
+
+export interface ChatCompletionFunctions {
+  /**
+   * The name of the function to be called. Must be a-z, A-Z, 0-9, or contain underscores and dashes, with a maximum length of 64.
+   * @type {string}
+   */
+  name: string
+  /**
+   * The description of what the function does.
+   * @type {string}
+   */
+  description?: string
+  /**
+   * The parameters the functions accepts, described as a JSON Schema object. See the [guide](/docs/guides/gpt/function-calling) for examples, and the [JSON Schema reference](https://json-schema.org/understanding-json-schema/) for documentation about the format.
+   * @type {{ [key: string]: any; }}
+   */
+  parameters?: { [key: string]: any }
+}
+
+export interface CreateChatCompletionRequestFunctionCallOneOf {
+  /**
+   * The name of the function to call.
+   * @type {string}
+   * @memberof CreateChatCompletionRequestFunctionCallOneOf
+   */
+  name: string
+}
+
+export type CreateChatCompletionRequestFunctionCall =
+  | CreateChatCompletionRequestFunctionCallOneOf
+  | string
+
 export type SendMessageOptions = {
   /** The name of a user in a multi-user chat. */
   name?: string
@@ -47,6 +91,18 @@ export type SendMessageOptions = {
     Omit<openai.CreateChatCompletionRequest, 'messages' | 'n' | 'stream'>
   >
   isFineTune?: boolean
+  /**
+   * A list of functions the model may generate JSON inputs for.
+   * @type {Array<ChatCompletionFunctions>}
+   * @memberof CreateChatCompletionRequest
+   */
+  functions?: Array<ChatCompletionFunctions>
+  /**
+   *
+   * @type {CreateChatCompletionRequestFunctionCall}
+   * @memberof CreateChatCompletionRequest
+   */
+  function_call?: CreateChatCompletionRequestFunctionCall
 }
 
 export type MessageActionType = 'next' | 'variant'
@@ -68,11 +124,17 @@ export interface ChatMessage {
   name?: string
   delta?: string
   detail?: any
+  finish_reason?: string
 
   // relevant for both ChatGPTAPI and ChatGPTUnofficialProxyAPI
   parentMessageId?: string
   // only relevant for ChatGPTUnofficialProxyAPI
   conversationId?: string
+
+  functionCall?: {
+    arguments?: string
+    name?: string
+  }
 }
 
 export class ChatGPTError extends Error {
@@ -175,6 +237,8 @@ export type MessageContent = {
 
 export type MessageMetadata = any
 
+export type FunctionCall = { arguments: string; name: string }
+
 export namespace openai {
   export interface CreateChatCompletionDeltaResponse {
     id: string
@@ -186,6 +250,7 @@ export namespace openai {
         delta: {
           role: Role
           content?: string
+          function_call?: FunctionCall
         }
         index: number
         finish_reason: string | null