#!/usr/bin/env python3

import shutil
import contextlib
import typing as t
from pathlib import Path

import click


shebangs = {
    "bash": None,
    "python3": None,
    "perl": None,
    "zsh": None,
    "elixir": None,
    "node": None,
    "php": None,
    "sh": "#!/bin/sh",  # use absolute path for compatibility
}

body = {
    "python3": """
def main() -> None:
    print("hello world")

if __name__ == "__main__":
    main()""",
    "bash": """
set -o pipefail

main() {
    echo hello world
}

main || exit $?""",
    "php": r"""<?php
echo "hello world\n";""",
    "node": 'console.log("hello world")',
    "perl": r'print "hello world\n"',
}

names = list(shebangs.keys())


def _autocomplete(
    ctx: click.Context, args: t.Sequence[str], incomplete: str
) -> t.List[str]:
    return [n for n in names if n.startswith(incomplete)]


@click.command()
@click.option(
    "-o",
    "--output",
    type=click.Path(exists=False, dir_okay=False, path_type=Path),
    default=None,
    help="Write to output file, instead of STDOUT",
)
@click.argument("SHEBANG", shell_complete=_autocomplete, required=True)
def main(shebang: str, output: t.Optional[Path]) -> None:
    """
    Create a SCRIPT with a SHEBANG

    If the shebang is known, adds a basic body as well
    """
    computed_shebang: str
    if shebang in shebangs:
        if shebangs[shebang] is None:
            computed_shebang = f"#!/usr/bin/env {shebang}"
        else:
            shebang_value = shebangs[shebang]
            assert shebang_value is not None
            # use string
            computed_shebang = shebang_value
    else:
        path = shutil.which(shebang)
        if path is None:
            click.echo(f"Warning: Could not find {shebang} on your $PATH", err=True)
        computed_shebang = f"#!/usr/bin/env {shebang}"
    buf = str(computed_shebang)
    if shebang in body:
        buf += "\n"
        buf += body[shebang]
    if output is None:
        click.echo(buf)
    else:
        output.write_text(buf + "\n")
        output.chmod(0o700)
        click.secho(f"Created '{output}' with contents:", fg="green", err=True)
        click.echo(buf, err=True)


if __name__ == "__main__":
    with contextlib.suppress(KeyboardInterrupt):
        main()