# Ultralytics YOLO 🚀, AGPL-3.0 license

import contextlib
import glob
import os
from datetime import datetime
from pathlib import Path


class WorkingDirectory(contextlib.ContextDecorator):
    # Usage: @WorkingDirectory(dir) decorator or 'with WorkingDirectory(dir):' context manager
    def __init__(self, new_dir):
        self.dir = new_dir  # new dir
        self.cwd = Path.cwd().resolve()  # current dir

    def __enter__(self):
        os.chdir(self.dir)

    def __exit__(self, exc_type, exc_val, exc_tb):
        os.chdir(self.cwd)


def increment_path(path, exist_ok=False, sep='', mkdir=False):
    """
    Increments a file or directory path, i.e. runs/exp --> runs/exp{sep}2, runs/exp{sep}3, ... etc.

    If the path exists and exist_ok is not set to True, the path will be incremented by appending a number and sep to
    the end of the path. If the path is a file, the file extension will be preserved. If the path is a directory, the
    number will be appended directly to the end of the path. If mkdir is set to True, the path will be created as a
    directory if it does not already exist.

    Args:
    path (str or pathlib.Path): Path to increment.
    exist_ok (bool, optional): If True, the path will not be incremented and will be returned as-is. Defaults to False.
    sep (str, optional): Separator to use between the path and the incrementation number. Defaults to an empty string.
    mkdir (bool, optional): If True, the path will be created as a directory if it does not exist. Defaults to False.

    Returns:
    pathlib.Path: Incremented path.
    """
    path = Path(path)  # os-agnostic
    if path.exists() and not exist_ok:
        path, suffix = (path.with_suffix(''), path.suffix) if path.is_file() else (path, '')

        # Method 1
        for n in range(2, 9999):
            p = f'{path}{sep}{n}{suffix}'  # increment path
            if not os.path.exists(p):  #
                break
        path = Path(p)

    if mkdir:
        path.mkdir(parents=True, exist_ok=True)  # make directory

    return path


def file_age(path=__file__):
    # Return days since last file update
    dt = (datetime.now() - datetime.fromtimestamp(Path(path).stat().st_mtime))  # delta
    return dt.days  # + dt.seconds / 86400  # fractional days


def file_date(path=__file__):
    # Return human-readable file modification date, i.e. '2021-3-26'
    t = datetime.fromtimestamp(Path(path).stat().st_mtime)
    return f'{t.year}-{t.month}-{t.day}'


def file_size(path):
    # Return file/dir size (MB)
    if isinstance(path, (str, Path)):
        mb = 1 << 20  # bytes to MiB (1024 ** 2)
        path = Path(path)
        if path.is_file():
            return path.stat().st_size / mb
        elif path.is_dir():
            return sum(f.stat().st_size for f in path.glob('**/*') if f.is_file()) / mb
    return 0.0


def get_latest_run(search_dir='.'):
    # Return path to most recent 'last.pt' in /runs (i.e. to --resume from)
    last_list = glob.glob(f'{search_dir}/**/last*.pt', recursive=True)
    return max(last_list, key=os.path.getctime) if last_list else ''