ui/curses: add curses interface draft

pqcli/ui/curses/widgets/scrollable.py

@@ -0,0 +1,52 @@
+import curses
+import typing as T
+
+from .base import WindowWrapper
+
+
+class Scrollable(WindowWrapper):
+    def __init__(self, *args: T.Any, **kwargs: T.Any) -> None:
+        super().__init__(*args, **kwargs)
+        self._scroll_y = 0
+        self._pad: T.Optional[T.Any] = curses.newpad(1, 1)
+        self._items: T.List[T.Any] = []
+
+    def clear(self) -> None:
+        self._items = []
+        self.scroll_to_item(0)
+
+    def scroll_to_item(self, y: int) -> None:
+        if not self._items or not self._win:
+            return
+        if y < 0:
+            y %= len(self._items)
+        while not (self._scroll_y <= y < self._scroll_y + self.getmaxyx()[0]):
+            self._scroll_y += 1 if self._scroll_y < y else -1
+
+    def stop(self) -> None:
+        super().stop()
+        del self._pad
+        self._pad = None
+
+    def __len__(self) -> int:
+        return len(self._items)
+
+    def render(self) -> None:
+        if not self._pad:
+            return
+
+        if self._items:
+            self._pad.resize(
+                max(1, len(self._items)), max(1, self.getmaxyx()[1] + 1)
+            )
+        else:
+            self._pad.resize(1, 1)
+
+        self._pad.erase()
+        try:
+            self._render_impl()
+        except curses.error:
+            pass
+
+    def _render_impl(self) -> None:
+        raise NotImplementedError("not implemented")