import os
import shutil
from datetime import datetime
from typing import List
import dotenv

"""
Load config
"""
dotenv.load_dotenv()
CONFIG = {
    "source_dir": os.getenv("SOURCE_DIR"),
    "backup_dir": os.getenv("BACKUP_DIR"),
    "max_backups": int(f"{os.getenv("MAX_BACKUPS")}") 
}


def copy_to_backup() -> None:
    """
    Copies the source dir to the backup dir.
    """
    timestamp = datetime.now()

    src_dir = f"{CONFIG['source_dir']}"
    dst_dir = f"{CONFIG['backup_dir']}/{timestamp.isoformat()}"
    print(f"Copying from: {src_dir} to: {dst_dir}")
    shutil.copytree(src_dir, dst_dir)


def find_backups() -> List[str]:
    """
    List the current backups located in the backup dir.
    """
    path = f"{CONFIG["backup_dir"]}"
    return os.listdir(path)


def sort_by_oldest(path: List[str]) -> List[str]:
    """
    Sort the directories by age. from oldest to newest.
    """
    copy = path.copy()
    copy.sort()
    copy.reverse()
    return copy


def delete_backups_over_max(paths: List[str]) -> None:
    """
    Delete the oldest backups if the max backups has been reached.
    """
    max = CONFIG["max_backups"]
    paths_sorted = sort_by_oldest(paths)
    overshoot = len(paths_sorted) - max

    for i in range(0, overshoot):
        backup = paths_sorted[len(paths_sorted) - 1 - i]
        path = f"{CONFIG['backup_dir']}/{backup}"
        shutil.rmtree(path)


def main() -> None:
    copy_to_backup()
    backup_dirs = find_backups()
    if len(backup_dirs) > CONFIG["max_backups"]:
        delete_backups_over_max(backup_dirs)

    print("Done copying to destination.")


if __name__ == "__main__":
    main()