ui/curses: estimate time in progress bars

pqcli/ui/curses/widgets/progress_bar.py

@@ -1,17 +1,51 @@
 import curses
+import datetime
+import typing as T
 
-from .base import WindowWrapper
+from pqcli.lingo import format_timespan
+from pqcli.ui.curses.widgets.base import WindowWrapper
 
 
 class ProgressBar(WindowWrapper):
-    def set_position(self, position: float, max_: float) -> None:
+    def __init__(
+        self, parent: T.Any, h: int, w: int, y: int, x: int, show_time: bool
+    ) -> None:
+        super().__init__(parent, h, w, y, x)
+
+        self._cur_pos = 0.0
+        self._max_pos = 1.0
+
+        self._show_time = show_time
+        self._last_tick: T.Optional[T.Tuple[datetime.datetime, float]] = None
+
+    @property
+    def time_left(self) -> T.Optional[datetime.timedelta]:
+        if self._last_tick is None:
+            return None
+        time_then, pos_then = self._last_tick
+        time_now, pos_now = datetime.datetime.now(), self._cur_pos
+        speed = (pos_now - pos_then) / (time_now - time_then).total_seconds()
+        if not speed:
+            return None
+        return datetime.timedelta(seconds=(self._max_pos - pos_now) / speed)
+
+    def set_position(self, cur_pos: float, max_pos: float) -> None:
         if not self._win:
             return
         self._win.erase()
-        text = f"{position / max_:.02%}"
+
+        if self._last_tick is None or cur_pos == 0 or max_pos != self._max_pos:
+            self._last_tick = (datetime.datetime.now(), cur_pos)
+        self._cur_pos = cur_pos
+        self._max_pos = max_pos
+
+        text = f"{cur_pos / max_pos:.02%}"
+        if self.time_left and self._show_time:
+            text += f" ({format_timespan(self.time_left)})"
+
         x = max(0, (self.getmaxyx()[1] - len(text)) // 2)
         self._win.addnstr(0, x, text, min(len(text), self.getmaxyx()[1] - 1))
-        x = int(position * self.getmaxyx()[1] // max_)
+        x = int(cur_pos * self.getmaxyx()[1] // max_pos)
         if x > 0:
             self._win.chgat(0, 0, curses.A_REVERSE)
             if x < self.getmaxyx()[1]: