autoreload.py

"""This module contains functionality to run a command with autoreload.

The command will autoreload everytime a file in the folder or it's subfolders are updated

Use this as for example

```bash
python autoreload panel serve *.py
```

To run [panel](https://panel.pyviz.org/) with autoreload.
"""
import os
import sys
import subprocess
import time
from typing import Generator


def watch_file(name: str) -> bool:
    """Whether or not to watch the file

    Arguments:
        name {str} -- The name of the file. For example 'main.py'

    Returns:
        bool -- True if the file should be watched. Otherwise Falses
    """
    return not name.startswith(".")


def modified_times_of_files_to_watch(path: str = ".") -> Generator[float, None, None]:
    """The modified times of the files to Watch

    Keyword Arguments:
        path {str} -- The path (default: {"."})

    Yields:
        Generator[float, None, None] -- [description]
    """
    for root, _, files in os.walk(path):
        for file in filter(watch_file, files):
            yield os.path.getmtime(os.path.join(root, file))


def print_stdout(process: subprocess.Popen):
    """Prints to standard out

    Arguments:
        process_ {subprocess.Popen} -- The process
    """
    stdout = process.stdout
    if stdout is not None:
        print(stdout)


def main(command: str):
    """The command will autoreload everytime a file in the folder or it's subfolders are updated

    Use this as for example

    ```bash
    python autoreload panel serve *.py
    ```

    To run [panel](https://panel.pyviz.org/) with autoreload.

    Arguments:
        command {str} -- [description]
    """
    # The path to watch
    path = "."

    # How often we check the filesystem for changes (in seconds)
    wait = 1

    # The process to autoreload
    process = subprocess.Popen(command, shell=False)

    # The current maximum file modified time under the watched directory
    last_mtime = max(modified_times_of_files_to_watch(path))

    while True:
        max_mtime = max(modified_times_of_files_to_watch(path))
        print_stdout(process)
        if max_mtime > last_mtime:
            last_mtime = max_mtime
            print("Killing Proces.")
            process.kill()
            process.wait()
            print("Retarting Process.")
            process = subprocess.Popen(command, shell=False)
        time.sleep(wait)


if __name__ == "__main__":
    # We concatenate all of the arguments together, and treat that as the command to run
    COMMAND = " ".join(sys.argv[1:])
    main(COMMAND)