Source code for rubato.game

"""
An abstraction surrounding the main game loop in rubato.
"""
from __future__ import annotations
from typing import TYPE_CHECKING
import sdl2, sdl2.sdlttf
import sys

from . import Time, Display, Radio, Events, Font, PrintError, IdError, Draw, InitError

if TYPE_CHECKING:
    from . import Scene


# THIS IS A STATIC CLASS
class Game:
    """
    A static class controlling rubato game flow.
    """
    RUNNING = 1
    STOPPED = 2
    PAUSED = 3

    debug: bool = False
    """Whether to use debug-mode."""
    show_fps: bool = False
    """Whether to show fps."""
    debug_font: Font
    """What font to draw debug text in."""

    state: int = STOPPED
    """
    The state of the game. The game states are::

        Game.RUNNING
        Game.STOPPED
        Game.PAUSED
    """

    _initialized = False

    _scenes: dict[str, Scene] = {}
    _scene_id: int = 0
    _current: str = ""

    def __init__(self) -> None:
        raise InitError(self)

    @classmethod
    def current(cls) -> Scene:
        """
        The current scene of the game.

        Returns:
            The current Scene.
        """
        scene = cls._scenes.get(cls._current)
        if scene:
            return scene
        raise ValueError("The current scene is invalid or not set. Make sure to create a scene or switch to it.")

    @classmethod
    def set_scene(cls, scene_id: str):
        """
        Changes the current scene. Takes effect on the next frame.

        Args:
            scene_id: The id of the new scene.
        """
        cls._current = scene_id
        cls.current().on_switch()

    @classmethod
    def _add(cls, scene: Scene, name: str | None) -> str:  # test: skip
        """
        Add a scene to the game. Also set the current scene if this is the first added scene.

        Args:
            scene: The scene to add.
            name: The name of the scene. If None, a unique name is generated.

        Raises:
            IdError: The given scene id is already used.
        """
        if name is None:
            name = "scene" + str(cls._scene_id)

        if name in cls._scenes:
            raise IdError(f"A scene with name '{name}' has already been added.")

        cls._scenes[name] = scene

        if len(cls._scenes) == 1:
            cls.set_scene(name)

        cls._scene_id += 1

        return name

    @classmethod
    def quit(cls):
        """Quit the game and close the python process."""
        Radio.broadcast(Events.EXIT)
        cls.state = cls.STOPPED
        sys.stdout.flush()
        sdl2.sdlttf.TTF_Quit()
        sdl2.SDL_Quit()
        sys.exit(0)

    @classmethod
    def _start(cls) -> None:
        """
        Starts the main game loop. Called automatically by :meth:`rubato.begin`.
        """
        cls.state = cls.RUNNING
        try:
            while True:
                cls._tick()
        except KeyboardInterrupt:
            cls.quit()
        except PrintError as e:
            sys.stdout.flush()
            raise e
        except (Exception,) as e:
            sys.stdout.flush()
            raise type(e)(
                str(e) + "\nRubato Error-ed. Was it our fault? Issue tracker: "
                "https://github.com/rubatopy/rubato/issues"
            ).with_traceback(sys.exc_info()[2])
        finally:
            sys.stdout.flush()

    @classmethod
    def _tick(cls):
        # start a new frame
        Time._start_frame()

        if cls.state == cls.STOPPED:
            sdl2.SDL_PushEvent(sdl2.SDL_Event(sdl2.SDL_QUIT))

        # Pump SDL events
        sdl2.SDL_PumpEvents()

        # Event handling
        if Radio._handle():
            cls.quit()

        # process delayed calls
        Time._process_calls()

        cls.update()

        curr = cls._scenes.get(cls._current)
        if curr:  # pylint: disable=using-constant-test
            if cls.state == Game.PAUSED:
                # process user set pause update
                curr._paused_update()
            else:
                # normal update
                curr._update()

                # fixed update
                Time._physics_counter += Time.delta_time

                while Time._physics_counter >= Time.fixed_delta:
                    curr._fixed_update()
                    Time._physics_counter -= Time.fixed_delta

            curr._draw()

            curr._dump()
        else:
            Draw.clear()

        cls.draw()

        Draw._dump()

        if cls.show_fps:
            Draw._draw_fps(cls.debug_font)

        # update renderers
        Display.renderer.present()

        # end frame
        Time._end_frame()

    @staticmethod
    def update():  # test: skip
        """An overrideable method for updating the game. Called once per frame, before the current scene updates."""
        pass

    @staticmethod
    def draw():  # test: skip
        """An overrideable method for drawing the game. Called once per frame, before the draw queue is dumped."""
        pass