playlist.py

import os


class MapPlaylist:
    """Performs file index navigation in the directory"""

    def __init__(self, root_dir: str = "maps") -> None:
        """Initializes the class object"""
        self.root_dir: str = root_dir
        self.playlist: list[str] = []
        self.current_index: int = 0
        self._scan_directories()

    def _scan_directories(self) -> None:
        """Recursively parses valid targets into a list"""
        categories: list[str] = ["easy", "medium", "hard", "challenger"]

        for category in categories:
            cat_path: str = os.path.join(self.root_dir, category)
            if not os.path.exists(cat_path):
                continue

            files: list[str] = sorted(os.listdir(cat_path))
            for file in files:
                if file.endswith(".txt"):
                    self.playlist.append(os.path.join(cat_path, file))

    @property
    def current_map_path(self) -> str:
        """Returns filepath of the current index pointer"""

        if not self.playlist:
            raise FileNotFoundError("Directory scan yielded "
                                    "empty simulation map pool.")
        return self.playlist[self.current_index]

    def next_map(self) -> str:
        """Increments state index pointer sequentially and loops"""

        self.current_index = (self.current_index + 1) % len(self.playlist)
        return self.current_map_path

    def previous_map(self) -> str:
        """Decrements state index pointer and loops backwards"""

        self.current_index = (self.current_index - 1) % len(self.playlist)
        return self.current_map_path