import random
import time
from collections.abc import Callable
from threading import Lock, Thread

import matplotlib
import matplotlib.artist
import matplotlib.axes
import matplotlib.figure
import matplotlib.pyplot as plt

matplotlib.use("QtAgg")


class LivePlotter:
    """Show a live plot and expose the ability to add points on demand."""

    fig: matplotlib.figure.Figure
    ax: matplotlib.axes.Axes

    def __init__(self):
        # NOTE: matplotlib is not thread safe, SEE:
        # https://matplotlib.org/stable/users/faq/howto_faq.html#work-with-threads
        self._plot_lock = Lock()
        self.fig, self.ax = plt.subplots()
        self.ax.set_xlim(0, 1)
        self.ax.set_ylim(0, 1)
        self.ax.grid()
        self.fig.tight_layout()
        plt.show(block=False)
        plt.pause(0.1)
        self.bg = self.fig.canvas.copy_from_bbox(self.fig.bbox)
        self._artists: list[matplotlib.artist.Artist] = []

    def _draw_animated(self) -> None:
        """Restore the bg, draw all artists, and blit."""
        self.fig.canvas.restore_region(self.bg)
        for a in self._artists:
            self.fig.draw_artist(a)
        self.fig.canvas.blit(self.fig.bbox)

    def add_line(self) -> Callable[[], None]:
        x_data, y_data = [], []
        with self._plot_lock:
            (line,) = self.ax.plot(x_data, y_data, animated=True, marker=".", lw=2.0)
            self._artists.append(line)
            plt.pause(0.1)
            self._draw_animated()

        def append_point() -> None:
            with self._plot_lock:
                x_data.append(random.random())
                y_data.append(random.random())
                line.set_data(x_data, y_data)
                self._draw_animated()
                self.fig.canvas.flush_events()

        return append_point


def make_points(
    updater: Callable[[], None], num_points: int = 5000, sleep_duration: float = 0.001
) -> None:
    for _ in range(num_points):
        updater()
        time.sleep(sleep_duration)


def main() -> None:
    plotter = LivePlotter()
    updater_1 = plotter.add_line()
    updater_2 = plotter.add_line()

    threads = [
        Thread(target=make_points, args=(updater_1,), daemon=False),
        Thread(target=make_points, args=(updater_2,), daemon=False),
    ]
    for thread in threads:
        thread.start()

    plt.show()

    for thread in threads:
        thread.join()


if __name__ == "__main__":
    main()