Refactor Neo API assistant message handling and function integration

- Updated streamChat method to utilize content.Type for function handling, enhancing the interaction with function calls.
- Improved the String method in Content struct to handle function arguments more robustly, including JSON unmarshalling for completed content.
- Set default message type to "text" in NewOpenAI function, ensuring consistent message processing.

These changes enhance the flexibility and maintainability of the Neo API, paving the way for improved assistant functionalities and message management.

neo/assistant/api.go

@@ -240,7 +240,7 @@ func (ast *Assistant) streamChat(
 			content.Append(value)
 			if value != "" {
 				// Handle stream
-				res, err := ast.HookStream(c, ctx, messages, content.String(), msg.Type == "tool_calls")
+				res, err := ast.HookStream(c, ctx, messages, content.String(), content.Type == "function")
 				if err == nil && res != nil {
 					if res.Output != "" {
 						value = res.Output
@@ -277,7 +277,7 @@ func (ast *Assistant) streamChat(
 
 				// Call HookDone
 				content.SetStatus(message.ContentStatusDone)
-				res, hookErr := ast.HookDone(c, ctx, messages, content.String(), msg.Type == "tool_calls")
+				res, hookErr := ast.HookDone(c, ctx, messages, content.String(), content.Type == "function")
 				if hookErr == nil && res != nil {
 					if res.Output != "" {
 						chatMessage.New().

neo/message/content.go

@@ -1,6 +1,8 @@
 package message
 
-import "fmt"
+import (
+	jsoniter "github.com/json-iterator/go"
+)
 
 const (
 	// ContentStatusPending the content status pending
@@ -36,7 +38,32 @@ func NewContent(typ string) *Content {
 // String the content string
 func (c *Content) String() string {
 	if c.Type == "function" {
-		return fmt.Sprintf(`{"id":"%s","type": "function", "function": {"name": "%s", "arguments": "%s"}}`, c.ID, c.Name, c.Bytes)
+
+		var arguments interface{} = string(c.Bytes)
+		if c.Status == ContentStatusDone {
+			var vv interface{} = nil
+			err := jsoniter.Unmarshal(c.Bytes, &vv)
+			if err != nil {
+				return ""
+			}
+			arguments = vv
+		}
+
+		data := map[string]interface{}{
+			"id":   c.ID,
+			"type": "function",
+			"function": map[string]interface{}{
+				"name":      c.Name,
+				"arguments": arguments,
+			},
+		}
+
+		raw, err := jsoniter.MarshalToString(data)
+		if err != nil {
+			return ""
+		}
+
+		return raw
 	}
 	return string(c.Bytes)
 }

neo/message/message.go

@@ -97,6 +97,7 @@ func NewOpenAI(data []byte) *Message {
 			return msg
 		}
 
+		msg.Type = "text"
 		if len(message.Choices) > 0 {
 			msg.Text = message.Choices[0].Delta.Content
 		}