"""Install the Vim 9 configuration on Windows."""

from pathlib import Path
from shutil import copyfile, which
import subprocess
import tempfile
import time


HOME = Path.home()
APP_PATH = Path(__file__).resolve().parent
VIM_PATH = HOME / "vimfiles"
VIMRC = HOME / "_vimrc"


def run(command, cwd=None):
    subprocess.run(command, cwd=cwd, check=True)


def require(program):
    if which(program) is None:
        raise SystemExit(f"Error: {program} must be installed.")


def check_vim_version():
    result = subprocess.run(
        ["vim", "--clean", "-Nu", "NONE", "-n", "-es", "+if v:version < 900 | cquit | endif", "+qall"]
    )
    if result.returncode:
        raise SystemExit("Error: Vim 9 or newer is required.")


def install_vim_plug():
    target = VIM_PATH / "autoload" / "plug.vim"
    target.parent.mkdir(parents=True, exist_ok=True)
    with tempfile.TemporaryDirectory() as temp:
        run(["git", "clone", "--depth", "1", "--quiet", "https://github.com/junegunn/vim-plug", temp])
        copyfile(Path(temp) / "plug.vim", target)


def install_vimrc():
    config_path = (APP_PATH / ".vimrc").as_posix().replace("'", "''")
    source_line = f"execute 'source ' . fnameescape('{config_path}')"
    if VIMRC.exists() and VIMRC.read_text(encoding="utf-8", errors="ignore").strip() != source_line:
        backup = VIMRC.with_name(f"{VIMRC.name}.{int(time.time())}.backup")
        VIMRC.replace(backup)
        print(f"Backed up existing Vim config to {backup}")
    VIMRC.write_text(source_line + "\n", encoding="utf-8")


def main():
    require("git")
    require("vim")
    check_vim_version()
    install_vim_plug()
    install_vimrc()
    run(["vim", "-Nu", str(APP_PATH / ".vimrc"), "-n", "-es", "--cmd", "set nomore", "+PlugInstall --sync", "+qall"])
    print("Vim configuration installed.")


if __name__ == "__main__":
    main()