from __future__ import annotations

import os
import sys
from pathlib import Path
from shutil import which

from tools.console import prompt_input


def require_executable(name: str) -> str:
    executable = which(name)
    if executable:
        return executable
    fallback = _windows_default_executable(name)
    if fallback is not None:
        print(f"\n{name} was not found on PATH; using {fallback}.")
        return str(fallback)
    if not sys.stdin.isatty():
        raise RuntimeError(_missing_tool_message(name))

    print(f"\n{name} was not found on PATH.")
    while True:
        answer = prompt_input(
            f"Absolute path to {name} for this run (blank = cancel): "
        ).strip().strip('"')
        if not answer:
            raise RuntimeError(_missing_tool_message(name))
        path = Path(answer).expanduser()
        if not path.is_absolute():
            print("Please enter an absolute path.")
        elif not path.is_file():
            print(f"File not found: {path}")
        else:
            return str(path.resolve())


def _missing_tool_message(name: str) -> str:
    return (
        f"{name} was not found on PATH. Install it and make sure the "
        f"'{name}' command works before running this script."
    )


def _windows_default_executable(name: str) -> Path | None:
    if os.name != "nt" or name.casefold().removesuffix(".exe") != "mkvmerge":
        return None

    path = Path(r"C:\Program Files\MKVToolNix\mkvmerge.exe")
    return path.resolve() if path.is_file() else None