"""Drives the marching-dash flow animation on edge items via a timer."""
from __future__ import annotations

from PyQt6.QtCore import QObject, QTimer


class FlowAnimator(QObject):
    """Advances an animation phase and pushes it to every edge item."""

    def __init__(self, scene, config, parent=None):
        super().__init__(parent)
        self._scene = scene
        self._config = config
        self._phase = 0.0
        self._timer = QTimer(self)
        self._timer.setInterval(40)  # ~25 fps
        self._timer.timeout.connect(self._tick)
        self.running = False

    def start(self) -> None:
        if not self.running:
            self.running = True
            self._timer.start()

    def stop(self) -> None:
        self.running = False
        self._timer.stop()

    def toggle(self) -> None:
        self.stop() if self.running else self.start()

    def reset(self) -> None:
        self._phase = 0.0
        self._push()

    def step(self) -> None:
        """Advance one frame (used for tests without a running event loop)."""
        self._tick()

    def _tick(self) -> None:
        self._phase += max(0.1, self._config.animation_speed)
        self._push()

    def _push(self) -> None:
        for item in self._scene.edge_items.values():
            item.set_phase(self._phase)