#!/usr/bin/env python3

import os
import sys
import subprocess
import requests
import tarfile
import shutil
import logging
import pwd
from pathlib import Path
import bcrypt

# Stałe ścieżki i konfiguracja
BIN_TARGET = '/usr/local/bin/node_exporter'
SERVICE_FILE = '/etc/systemd/system/node_exporter.service'
LOG_FILE = '/var/log/node_exporter_installer.log'
USER_NAME = 'node_exporter'
USER_HOME = '/var/lib/node_exporter'
CONFIG_DIR = '/etc/node_exporter'
CONFIG_PATH = os.path.join(CONFIG_DIR, 'config.yml')

# Konfiguracja logowania
logging.basicConfig(
    filename=LOG_FILE,
    level=logging.INFO,
    format='%(asctime)s [%(levelname)s] %(message)s'
)

# ----------------- FUNKCJE POMOCNICZE -----------------

def run_cmd(cmd, check=True):
    try:
        result = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, check=check, text=True)
        return result.stdout.strip()
    except subprocess.CalledProcessError as e:
        logging.error(f"Błąd komendy: {cmd} — {e.stderr}")
        raise

def get_latest_version():
    try:
        r = requests.get('https://api.github.com/repos/prometheus/node_exporter/releases/latest', timeout=10)
        r.raise_for_status()
        return r.json()['tag_name'].lstrip('v'), r.json()
    except requests.RequestException as e:
        logging.error(f"Błąd pobierania wersji z GitHub: {e}")
        raise

def get_local_version():
    if Path(BIN_TARGET).exists():
        try:
            output = run_cmd([BIN_TARGET, '--version'])
            for line in output.splitlines():
                if "version" in line:
                    parts = line.split()
                    if len(parts) >= 3:
                        return parts[2]
        except Exception as e:
            logging.warning(f"Nie udało się odczytać wersji lokalnej: {e}")
    return None

def download_and_extract(url, download_path='/tmp'):
    filename = os.path.join(download_path, url.split('/')[-1])
    try:
        with requests.get(url, stream=True, timeout=30) as r:
            r.raise_for_status()
            with open(filename, 'wb') as f:
                for chunk in r.iter_content(chunk_size=8192):
                    f.write(chunk)
    except requests.RequestException as e:
        logging.error(f"Błąd pobierania pliku: {e}")
        raise

    with tarfile.open(filename) as tar:
        tar.extractall(path=download_path, filter='data')
    return next(Path(download_path).glob('node_exporter-*'))

# ----------------- INSTALACJA I KONFIGURACJA -----------------

def install_binary(extracted_dir):
    src = Path(extracted_dir) / 'node_exporter'
    if Path(BIN_TARGET).exists():
        shutil.copy(BIN_TARGET, BIN_TARGET + '.bak')
        logging.info("Backup binarki zrobiony jako node_exporter.bak")
    shutil.copy(src, BIN_TARGET)
    os.chmod(BIN_TARGET, 0o755)
    logging.info("Zainstalowano binarkę do /usr/local/bin")

def create_user():
    try:
        pwd.getpwnam(USER_NAME)
        logging.info("Użytkownik node_exporter już istnieje.")
    except KeyError:
        run_cmd(['useradd', '--system', '--home', USER_HOME, '--shell', '/bin/false', USER_NAME])
        logging.info("Utworzono użytkownika node_exporter")

    home_path = Path(USER_HOME)
    home_path.mkdir(parents=True, exist_ok=True)
    shutil.chown(home_path, user=USER_NAME, group=USER_NAME)
    logging.info(f"Utworzono katalog {USER_HOME} i przypisano właściciela.")

def setup_service():
    service_content = f"""[Unit]
Description=Node Exporter
Wants=network-online.target
After=network-online.target

[Service]
User={USER_NAME}
Group={USER_NAME}
WorkingDirectory={USER_HOME}
ExecStart={BIN_TARGET}
Restart=on-failure

[Install]
WantedBy=default.target
"""
    with open(SERVICE_FILE, 'w') as f:
        f.write(service_content)
    logging.info("Zapisano konfigurację usługi systemd")

    run_cmd(['systemctl', 'daemon-reload'])
    run_cmd(['systemctl', 'enable', '--now', 'node_exporter'])
    logging.info("Włączono i uruchomiono usługę node_exporter")

def write_systemd_service(secured=False):
    exec_line = f'{BIN_TARGET} --web.config.file="{CONFIG_PATH}"' if secured else BIN_TARGET
    content = f"""[Unit]
Description=Node Exporter
Wants=network-online.target
After=network-online.target

[Service]
User={USER_NAME}
ExecStart={exec_line}

[Install]
WantedBy=default.target
"""
    with open(SERVICE_FILE, "w") as f:
        f.write(content)


def uninstall():
    if Path(SERVICE_FILE).exists():
        run_cmd(['systemctl', 'disable', '--now', 'node_exporter'])
        os.remove(SERVICE_FILE)
        logging.info("Usunięto plik usługi i zatrzymano node_exporter")
    if Path(BIN_TARGET).exists():
        os.remove(BIN_TARGET)
        logging.info("Usunięto binarkę node_exporter")
    try:
        pwd.getpwnam(USER_NAME)
        run_cmd(['userdel', USER_NAME])
        logging.info("Usunięto użytkownika node_exporter")
    except KeyError:
        logging.info("Użytkownik już nie istnieje")
    if Path(USER_HOME).exists():
        shutil.rmtree(USER_HOME)
        logging.info("Usunięto katalog /var/lib/node_exporter")

def install():
    if Path(BIN_TARGET).exists():
        print("Node Exporter jest już zainstalowany.")
        response = input("Czy chcesz przeinstalować z konfiguracją secured (TLS + Basic Auth)? [t/N]: ")
        if response.lower() == 't':
            uninstall()
            install()
            setup_secured_config()
            write_systemd_service(secured=True)
            run_cmd(['systemctl', 'daemon-reexec'])
            run_cmd(['systemctl', 'restart', 'node_exporter'])
            print("✅ Node Exporter przeinstalowany z konfiguracją secured.")
        else:
            print("ℹ️ Instalacja przerwana - bez zmian.")
        return

    version, release = get_latest_version()
    url = next(asset['browser_download_url'] for asset in release['assets'] if 'linux-amd64.tar.gz' in asset['browser_download_url'])
    extracted = download_and_extract(url)
    install_binary(extracted)
    create_user()
    write_systemd_service(secured=False)
    run_cmd(['systemctl', 'daemon-reload'])
    run_cmd(['systemctl', 'enable', '--now', 'node_exporter'])
    logging.info("Instalacja zakończona")

def update():
    local_version = get_local_version()
    latest_version, release = get_latest_version()
    if local_version == latest_version:
        print(f"Node Exporter już aktualny ({local_version})")
        return
    print(f"Aktualizacja z {local_version} do {latest_version}...")

    run_cmd(['systemctl', 'stop', 'node_exporter'])
    url = next(asset['browser_download_url'] for asset in release['assets'] if 'linux-amd64.tar.gz' in asset['browser_download_url'])
    extracted = download_and_extract(url)
    install_binary(extracted)
    run_cmd(['systemctl', 'start', 'node_exporter'])
    logging.info(f"Zaktualizowano Node Exporter do wersji {latest_version}")

def setup_secured_config():
    os.makedirs(CONFIG_DIR, exist_ok=True)
    subprocess.run([
        "openssl", "req", "-new", "-newkey", "rsa:4096", "-days", "3650", "-nodes", "-x509",
        "-subj", "/C=PL/ST=X/L=X/O=secure/CN=localhost",
        "-keyout", f"{CONFIG_DIR}/node_exporter.key",
        "-out", f"{CONFIG_DIR}/node_exporter.crt"
    ], check=True)

    config = """basic_auth_users:
  root: $2y$10$SNr5iyJMvqiecOx6tXgDTuBpxyd40Byp2j.iBM5lR/oQnlpi8nAje

tls_server_config:
  cert_file: node_exporter.crt
  key_file: node_exporter.key
"""
    with open(CONFIG_PATH, "w") as f:
        f.write(config)

    shutil.chown(CONFIG_DIR, user=USER_NAME, group=USER_NAME)
    for f_name in os.listdir(CONFIG_DIR):
        shutil.chown(os.path.join(CONFIG_DIR, f_name), user=USER_NAME, group=USER_NAME)

def change_password(user, password):
    if not os.path.exists(CONFIG_PATH):
        print("Brak pliku config.yml – najpierw użyj --install-secured")
        return
    hashed = bcrypt.hashpw(password.encode(), bcrypt.gensalt()).decode()

    with open(CONFIG_PATH, 'r') as f:
        lines = f.readlines()

    new_lines = []
    in_auth = False
    user_updated = False

    for line in lines:
        if line.strip().startswith("basic_auth_users:"):
            in_auth = True
            new_lines.append(line)
            continue
        if in_auth and line.startswith("  ") and ":" in line:
            existing_user = line.split(":")[0].strip()
            if existing_user == user:
                new_lines.append(f"  {user}: {hashed}\n")
                user_updated = True
            else:
                new_lines.append(line)
        elif in_auth and not line.startswith("  "):
            if not user_updated:
                new_lines.append(f"  {user}: {hashed}\n")
                user_updated = True
            in_auth = False
            new_lines.append(line)
        else:
            new_lines.append(line)

    if in_auth and not user_updated:
        new_lines.append(f"  {user}: {hashed}\n")

    with open(CONFIG_PATH, "w") as f:
        f.writelines(new_lines)

    print(f"Zmieniono hasło dla użytkownika '{user}'")

def print_help():
    print("""
Użycie:
    node_exporter_manager.py --install                  # Instaluje node_exporter i uruchamia usługę
    node_exporter_manager.py --update                   # Aktualizuje node_exporter do najnowszej wersji (jeśli potrzeba)
    node_exporter_manager.py --uninstall                # Usuwa node_exporter, usługę, użytkownika
    node_exporter_manager.py --setup                    # Instaluje ten skrypt do /usr/local/bin, dodaje CRON i logrotate
    node_exporter_manager.py --install-secured          # Instalacja z TLS + basic auth (certyfikat + config.yml)
    node_exporter_manager.py --set-password=user:haslo  # Zmiana hasła w config.yml
""")

# ----------------- GŁÓWNY BLOK -----------------

if __name__ == '__main__':
    if os.geteuid() != 0:
        print("Ten skrypt musi być uruchomiony jako root.")
        sys.exit(1)

    if len(sys.argv) != 2:
        print_help()
        sys.exit(1)

    arg = sys.argv[1]

    try:
        if arg == '--install':
            install()
        elif arg == '--update':
            update()
        elif arg == '--uninstall':
            uninstall()
        elif arg == '--setup':
            setup()
        elif arg == '--install-secured':
            install()
            setup_secured_config()
        elif arg.startswith('--set-password='):
            user_pass = arg.split('=')[1]
            if ':' not in user_pass:
                print("Użyj formatu --set-password=user:haslo")
                sys.exit(1)
            user, passwd = user_pass.split(':', 1)
            change_password(user, passwd)
        else:
            print_help()
            sys.exit(1)
    except Exception as e:
        logging.error(f"Błąd krytyczny: {e}")
        print(f"Wystąpił błąd: {e}")
        sys.exit(1)