refactor: Enhance form and button label flexibility

- Make submit and cancel button labels optional in form and widgets
- Refactor chatmark header construction for conditional button labels
- Implement assertion for Radio widget's default_selected option

libs/chatmark/form.py

@@ -14,8 +14,8 @@ class Form:
         self,
         components: List[Union[Widget, str]],
         title: Optional[str] = None,
-        submit_button_name="Submit",
+        submit_button_name: Optional[str] = None,
-        cancel_button_name="Cancel",
+        cancel_button_name: Optional[str] = None
     ):
         """
         components: components in the form, can be widgets (except Button) or strings
@@ -78,8 +78,12 @@ class Form:
 
         self._rendered = True
 
+        chatmark_header = "```chatmark"
+        chatmark_header += f" submit={self._submit}" if self._submit else ""
+        chatmark_header += f" cancel={self._cancel}" if self._cancel else ""
+
         lines = [
-            f"```chatmark submit={self._submit} cancel={self._cancel}",
+            chatmark_header,
             self._in_chatmark(),
             "```",
         ]

libs/chatmark/widgets.py

@@ -9,7 +9,7 @@ class Widget(ABC):
     Abstract base class for widgets
     """
 
-    def __init__(self, submit: Optional[str] = None, cancel: str = "Cancel"):
+    def __init__(self, submit: Optional[str] = None, cancel: Optional[str] = None):
         self._rendered = False
         # Prefix for IDs/keys in the widget
         self._id_prefix = self.gen_id_prefix()
@@ -42,10 +42,9 @@ class Widget(ABC):
 
         self._rendered = True
 
-        if self._submit is None:
+        chatmark_header = "```chatmark"
-            chatmark_header = "```chatmark"
+        chatmark_header += f" submit={self._submit}" if self._submit else ""
-        else:
+        chatmark_header += f" cancel={self._cancel}" if self._cancel else ""
-            chatmark_header = f"```chatmark submit={self._submit} cancel={self._cancel}"
 
         lines = [
             chatmark_header,
@@ -261,9 +260,8 @@ class Radio(Widget):
         default_selected: index of the option to be selected by default, default to None
         title: title of the widget
         """
-        # TODO: implement default_selected after the design is ready
+        if default_selected is not None:
-        # if default_selected is not None:
+            assert 0 <= default_selected < len(options)
-        #     assert 0 <= default_selected < len(options)
 
         super().__init__(submit_button_name, cancel_button_name)
 
@@ -299,7 +297,7 @@ class Radio(Widget):
         for idx, option in enumerate(self._options):
             key = self.gen_id(self._id_prefix, idx)
             if self._selection is not None and self._selection == idx:
-                lines.append(f"> X ({key}) {option}")
+                lines.append(f"> x ({key}) {option}")
             else:
                 lines.append(f"> - ({key}) {option}")