#!/usr/bin/env python3
"""Install per-user launchers without sudo or changing shell configuration."""
import argparse
from datetime import datetime, timezone
import os
from pathlib import Path
import subprocess
import sys
import uuid


def install(bin_dir: Path) -> None:
    root = Path(__file__).resolve().parent.parent
    bin_dir = bin_dir.expanduser().absolute()
    bin_dir.mkdir(parents=True, exist_ok=True)
    changed = []
    try:
        for name in ('einvoice', 'jr-einvoice'):
            source = root / 'bin' / name
            target = bin_dir / name
            if target.is_symlink() and target.resolve() == source:
                print(f'Bereits eingerichtet: {target}', flush=True)
                continue
            backup = None
            if target.exists() or target.is_symlink():
                if target.is_dir():
                    raise RuntimeError(f'Ziel ist ein Verzeichnis: {target}')
                stamp = datetime.now(timezone.utc).strftime('%Y%m%dT%H%M%SZ')
                backup = target.with_name(f'{name}.before-einvoice-{stamp}-{uuid.uuid4().hex[:8]}')
                if target.is_symlink():
                    backup.symlink_to(os.readlink(target))
                else:
                    import shutil
                    shutil.copy2(target, backup)
                print(f'Bisheriger Befehl gesichert: {backup}', flush=True)
            temporary = target.with_name(f'.{name}-{uuid.uuid4().hex}.next')
            try:
                temporary.symlink_to(source)
                os.replace(temporary, target)
            finally:
                temporary.unlink(missing_ok=True)
            changed.append((target, backup))
            print(f'Eingerichtet: {target} -> {source}', flush=True)
        # A different cwd verifies that symlinks resolve to the checkout correctly.
        for name in ('einvoice', 'jr-einvoice'):
            subprocess.run([str(bin_dir / name), '--help'], cwd=bin_dir,
                           stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True, check=True)
        print('OK: Beide Konsolenbefehle geprüft.', flush=True)
    except BaseException:
        for target, backup in reversed(changed):
            if backup is None:
                target.unlink(missing_ok=True)
            else:
                os.replace(backup, target)
        raise
    if str(bin_dir) not in os.environ.get('PATH', '').split(os.pathsep):
        import shlex
        print(f'Für diese Shell ausführen: export PATH={shlex.quote(str(bin_dir))}:"$PATH"')
    print('Ab jetzt: einvoice --help | einvoice --update --status | jr-einvoice --help')
    print('Falls die Shell noch den alten Pfad merkt: rehash (zsh) bzw. hash -r (bash).')


def main():
    parser = argparse.ArgumentParser(description='einvoice und jr-einvoice im Benutzer-Suchpfad einrichten.')
    parser.add_argument('--bin-dir', type=Path, default=Path.home() / '.local/bin')
    args = parser.parse_args()
    try:
        install(args.bin_dir)
    except (Exception, KeyboardInterrupt) as exc:
        print(f'FEHLER: {exc}; geänderte Befehle wurden zurückgesetzt.', file=sys.stderr)
        if isinstance(exc, subprocess.CalledProcessError) and exc.stderr:
            print(exc.stderr.strip(), file=sys.stderr)
        return 1
    return 0


if __name__ == '__main__':
    raise SystemExit(main())