make CLI spinner animation more robust

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "dopt-basics"
-version = "0.2.1"
+version = "0.2.2"
 description = "basic cross-project tools for Python-based d-opt projects"
 authors = [
     {name = "Florian Förster", email = "f.foerster@d-opt.com"},
@@ -69,7 +69,7 @@ directory = "reports/coverage"
 
 
 [tool.bumpversion]
-current_version = "0.2.1"
+current_version = "0.2.2"
 parse = """(?x)
     (?P<major>0|[1-9]\\d*)\\.
     (?P<minor>0|[1-9]\\d*)\\.

src/dopt_basics/cli.py

@@ -1,4 +1,5 @@
 import shutil
+import sys
 import time
 import typing as t
 from collections.abc import Callable
@@ -17,41 +18,77 @@ class LoadingAnimation:
         loading_txt: str,
         ending_text: str,
         timeout: float = 0.1,
+        force_ascii: bool = False,
     ) -> None:
         self.loading_txt = loading_txt
         self.ending_text = ending_text
         self.timeout = timeout
         self.done: bool = False
-        self.steps: list[str] = ["⢿", "⣻", "⣽", "⣾", "⣷", "⣯", "⣟", "⡿"]
 
-        self._thread: Thread = Thread(target=self._animation, daemon=True)
+        self._isatty = sys.stdout.isatty()
+        self._do_animation = bool(sys.stdout.isatty())
 
-    def __enter__(self) -> None:
+        self._animate_dots: list[str] = ["⢿", "⣻", "⣽", "⣾", "⣷", "⣯", "⣟", "⡿"]
+        self._animate_ascii: list[str] = ["|", "/", "-", "\\"]
+
+        self.frames: list[str]
+        enc = (sys.stdout.encoding or "utf-8").lower()
+        if force_ascii:
+            self.frames = self._animate_ascii
+        else:
+            try:
+                self._animate_dots[0].encode(enc)
+                self.frames = self._animate_dots
+            except Exception:
+                self.frames = self._animate_ascii
+
+        self._thread: Thread = Thread(target=self._animation)
+
+    def __enter__(self) -> t.Self:
         self.start()
+        return self
 
     def __exit__(
         self,
-        exc_type,
+        exc_type: type[Exception],
         exc_value,
         tb,
-    ) -> None:
+    ) -> bool:
+        if exc_type is not None:
+            self.stop(interrupt=True)
+            if exc_type is KeyboardInterrupt:
+                print("Operation cancelled by user. (KeyboardInterrupt)", flush=True)
+                return True
+            return False
+
         self.stop()
+        return False
 
     def _animation(self) -> None:
-        for c in cycle(self.steps):
+        for frame in cycle(self.frames):
             if self.done:
                 break
-            print(f"\r{c} {self.loading_txt}", flush=True, end="")
+            print(f"\r{frame} {self.loading_txt}", flush=True, end="")
             time.sleep(self.timeout)
 
     def start(self) -> None:
+        if self._do_animation:
             self._thread.start()
+        else:
+            print(f"\r{self.loading_txt}", end="", flush=True)
 
-    def stop(self):
+    def stop(
+        self,
+        interrupt: bool = False,
+    ) -> None:
         self.done = True
+        if self._do_animation:
+            self._thread.join()
         cols = shutil.get_terminal_size((80, 20)).columns
-        print("\r" + " " * cols, end="", flush=True)
+        print("\r" + " " * cols, end="\r", flush=True)
-        print(f"\r{self.ending_text}", flush=True)
+        if interrupt:
+            return
+        print(f"{self.ending_text}", flush=True)
 
 
 def default_loading(func: Callable[P, T]) -> Callable[P, T]:
@@ -63,6 +100,6 @@ def default_loading(func: Callable[P, T]) -> Callable[P, T]:
         with LoadingAnimation(loading_txt, ending_text):
             res = func(*args, **kwargs)
 
-        return res
+        return res  # type: ignore
 
     return wrapper