hide kill button when the process is done (aiidalab#648)

* add process status information along with the kill button
* hide kill button when the process is done, and replace it with "Workflow completed successfully!"

src/aiidalab_qe/app/result/__init__.py

@@ -13,6 +13,10 @@
 # trigger registration of the viewer widget:
 from .workchain_viewer import WorkChainViewer  # noqa: F401
 
+PROCESS_COMPLETED = "<h4>Workflow completed successfully!</h4>"
+PROCESS_EXCEPTED = "<h4>Workflow is excepted!</h4>"
+PROCESS_RUNNING = "<h4>Workflow is running!</h4>"
+
 
 class ViewQeAppWorkChainStatusAndResultsStep(ipw.VBox, WizardAppWidgetStep):
     process = tl.Unicode(allow_none=True)
@@ -50,8 +54,15 @@ def __init__(self, **kwargs):
             layout=ipw.Layout(width="120px", height="40px"),
         )
         self.kill_button.on_click(self._on_click_kill_button)
+        self.process_info = ipw.HTML()
 
-        super().__init__([self.kill_button, self.process_status], **kwargs)
+        super().__init__(
+            [
+                ipw.HBox(children=[self.kill_button, self.process_info]),
+                self.process_status,
+            ],
+            **kwargs,
+        )
 
         self._update_kill_button_layout()
 
@@ -75,21 +86,31 @@ def _update_state(self):
                 ProcessState.WAITING,
             ):
                 self.state = self.State.ACTIVE
+                self.process_info.value = PROCESS_RUNNING
             elif (
                 process_state in (ProcessState.EXCEPTED, ProcessState.KILLED)
                 or process.is_failed
             ):
                 self.state = self.State.FAIL
+                self.kill_button.layout.display = "none"
+                self.process_info.value = PROCESS_EXCEPTED
             elif process.is_finished_ok:
                 self.state = self.State.SUCCESS
+                self.kill_button.layout.display = "none"
+                self.process_info.value = PROCESS_COMPLETED
 
     def _update_kill_button_layout(self):
         """Update the layout of the kill button."""
         # If no process is selected, hide the button.
-        if self.process is None:
+        if self.process is None or self.process == "":
             self.kill_button.layout.display = "none"
         else:
-            self.kill_button.layout.display = "block"
+            process = orm.load_node(self.process)
+            # If the process is finished or excepted, hide the button.
+            if process.is_finished or process.is_excepted:
+                self.kill_button.layout.display = "none"
+            else:
+                self.kill_button.layout.display = "block"
 
         # If the step is not activated, no point to click the button, so disable it.
         # Only enable it if the process is on (RUNNING, CREATED, WAITING).