#!/usr/bin/env python3
"""Re-format YAML passed on stdin or read from any arguments."""

import yaml
import sys


# https://stackoverflow.com/a/72265455
def str_presenter(dumper, data):
    if len(data.splitlines()) > 1 or "\n" in data:
        text_list = [line.rstrip() for line in data.splitlines()]
        fixed_data = "\n".join(text_list)
        return dumper.represent_scalar("tag:yaml.org,2002:str", fixed_data, style="|")
    return dumper.represent_scalar("tag:yaml.org,2002:str", data)


yaml.add_representer(str, str_presenter)


def ymmw(files):
   if not files:
      files=[sys.stdin]

   for f in files:
     try:
        print(f)
        print(yaml.dump(yaml.load(open(f) if not f == sys.stdin else f, Loader=yaml.FullLoader)), end='')
     except OSError as ex:
        sys.exit(f"""ERROR: Couldn't read input from stdin, or couldn't write output to stdout. Exiting.

{ex}""")

if __name__ == '__main__':
   ymmw(sys.argv[1:])