"""Streaming text buffer — smooth reveal of bursty network chunks.

Accumulates text from the provider and reveals it at ~60fps with a
~200ms target reveal pace, so the UI sees a smooth stream regardless
of network burst patterns.

All methods must be called from the GTK main thread.
"""

from typing import Callable

from gi.repository import GLib


class StreamingTextBuffer:
    TICK_MS = 16          # ~60fps
    REVEAL_TARGET_MS = 200

    def __init__(self, on_reveal: Callable[[str], None]):
        self._pending = ""
        self._on_reveal = on_reveal
        self._timer_id: int | None = None

    def push(self, text: str):
        self._pending += text
        if self._timer_id is None:
            self._timer_id = GLib.timeout_add(self.TICK_MS, self._tick)

    def _tick(self) -> bool:
        if not self._pending:
            self._timer_id = None
            return False
        n = max(1, len(self._pending) * self.TICK_MS // self.REVEAL_TARGET_MS)
        reveal, self._pending = self._pending[:n], self._pending[n:]
        self._on_reveal(reveal)
        return True

    def flush(self):
        if self._pending:
            self._on_reveal(self._pending)
            self._pending = ""
        if self._timer_id is not None:
            GLib.source_remove(self._timer_id)
            self._timer_id = None

    def cancel(self):
        self._pending = ""
        if self._timer_id is not None:
            GLib.source_remove(self._timer_id)
            self._timer_id = None