mc_server_setup.py

import argparse
import hashlib
import json
import os
import shutil
import subprocess
import sys
import time
from urllib.request import urlopen, Request
from urllib.error import URLError, HTTPError

PISTON_META_MANIFEST = "https://piston-meta.mojang.com/mc/game/version_manifest_v2.json"


def fetch_json(url: str) -> dict:
    req = Request(url, headers={"User-Agent": "Mozilla/5.0 (MCserverPy Setup)"})
    with urlopen(req, timeout=60) as resp:
        if resp.status != 200:
            raise RuntimeError(f"HTTP {resp.status} while fetching {url}")
        data = resp.read()
        return json.loads(data.decode("utf-8"))


def get_version_info(version: str | None) -> tuple[str, dict]:
    manifest = fetch_json(PISTON_META_MANIFEST)
    if not version or version == "latest":
        version_id = manifest.get("latest", {}).get("release")
        if not version_id:
            raise RuntimeError("Could not determine latest release from manifest")
    else:
        version_id = version

    versions = manifest.get("versions", [])
    selected = next((v for v in versions if v.get("id") == version_id), None)
    if not selected:
        # Try snapshot latest if asked explicitly
        if version in ("latest-snapshot", "snapshot"):
            snap_id = manifest.get("latest", {}).get("snapshot")
            if not snap_id:
                raise RuntimeError("Could not determine latest snapshot from manifest")
            selected = next((v for v in versions if v.get("id") == snap_id), None)
            if not selected:
                raise RuntimeError(f"Snapshot {snap_id} not found in manifest")
            version_id = snap_id
        else:
            raise RuntimeError(f"Version '{version_id}' not found in manifest")

    version_meta = fetch_json(selected["url"])  # contains server download
    server_download = version_meta.get("downloads", {}).get("server")
    if not server_download:
        raise RuntimeError(f"No server download found for version {version_id}")

    return version_id, server_download


def ensure_dir(path: str):
    os.makedirs(path, exist_ok=True)


def sha1_file(path: str) -> str:
    h = hashlib.sha1()
    with open(path, "rb") as f:
        for chunk in iter(lambda: f.read(1024 * 1024), b""):
            h.update(chunk)
    return h.hexdigest()


def download_file(url: str, dest_path: str):
    tmp_path = dest_path + ".part"
    req = Request(url, headers={"User-Agent": "Mozilla/5.0 (MCserverPy Setup)"})
    with urlopen(req, timeout=300) as resp, open(tmp_path, "wb") as out:
        total = resp.length or 0
        downloaded = 0
        last_print = time.time()
        while True:
            chunk = resp.read(1024 * 64)
            if not chunk:
                break
            out.write(chunk)
            downloaded += len(chunk)
            now = time.time()
            if total and (now - last_print) > 0.5:
                pct = downloaded / total * 100
                print(f"  Downloaded {downloaded/1_000_000:.1f}MB / {total/1_000_000:.1f}MB ({pct:.1f}%)", end="\r", flush=True)
                last_print = now
    # finalize
    if os.path.exists(dest_path):
        os.remove(dest_path)
    os.replace(tmp_path, dest_path)
    print("")


def write_eula(server_dir: str, accept_eula: bool):
    eula_path = os.path.join(server_dir, "eula.txt")
    content = (
        "# By changing the setting below to TRUE you are indicating your agreement to the EULA\n"
        "# https://aka.ms/MinecraftEULA\n"
        f"eula={'true' if accept_eula else 'false'}\n"
    )
    with open(eula_path, "w", encoding="utf-8") as f:
        f.write(content)
    return eula_path


def write_start_script(server_dir: str, min_mem: str, max_mem: str, nogui: bool):
    # Windows batch helper for convenience
    cmd = f"java -Xms{min_mem} -Xmx{max_mem} -jar server.jar {'nogui' if nogui else ''}".strip()
    bat_path = os.path.join(server_dir, "start.bat")
    with open(bat_path, "w", encoding="utf-8") as f:
        f.write("@echo off\n")
        f.write("REM Generated by MCserverPy setup script\n")
        f.write(cmd + "\n")
        f.write("pause\n")
    # Cross-platform shell script as well
    sh_path = os.path.join(server_dir, "start.sh")
    with open(sh_path, "w", encoding="utf-8") as f:
        f.write("#!/usr/bin/env bash\n")
        f.write("# Generated by MCserverPy setup script\n")
        f.write(cmd + "\n")
    try:
        os.chmod(sh_path, 0o755)
    except Exception:
        pass
    return bat_path, sh_path


def check_java_version() -> tuple[bool, str]:
    try:
        proc = subprocess.run(["java", "-version"], stdout=subprocess.PIPE, stderr=subprocess.STDOUT, text=True)
        out = proc.stdout.strip()
        # Example: 'java version "17.0.12" 2024-07-16 LTS'
        version_str = ""
        for line in out.splitlines():
            if "version" in line and '"' in line:
                version_str = line.split('"')[1]
                break
        is_ok = False
        try:
            major = int(version_str.split(".")[0])
            is_ok = major >= 17
        except Exception:
            # fallback: allow if we can find 17 in string
            is_ok = "17" in version_str or "18" in version_str or "19" in version_str or "20" in version_str or "21" in version_str
        return is_ok, out
    except FileNotFoundError:
        return False, "java not found in PATH"


def start_server(server_dir: str, min_mem: str, max_mem: str, nogui: bool):
    jar_path = os.path.join(server_dir, "server.jar")
    if not os.path.isfile(jar_path):
        raise RuntimeError("server.jar not found. Run setup first.")
    cmd = [
        "java",
        f"-Xms{min_mem}",
        f"-Xmx{max_mem}",
        "-jar",
        jar_path,
    ]
    if nogui:
        cmd.append("nogui")
    print("Launching server... Press Ctrl+C to stop.")
    subprocess.call(cmd, cwd=server_dir)


def main():
    parser = argparse.ArgumentParser(description="Minecraft Java Edition server setup helper (vanilla)")
    parser.add_argument("--version", default="latest", help="Server version to install (e.g., 1.20.4), or 'latest' (default) or 'snapshot'")
    parser.add_argument("--dir", default=os.path.join(os.getcwd(), "mc_server"), help="Directory to install/setup the server")
    parser.add_argument("--min-memory", default="1G", help="Initial heap size for JVM (e.g., 1G)")
    parser.add_argument("--max-memory", default="2G", help="Maximum heap size for JVM (e.g., 2G)")
    parser.add_argument("--nogui", action="store_true", help="Run server without GUI (recommended)")
    parser.add_argument("--accept-eula", action="store_true", help="Automatically accept the Minecraft EULA (https://aka.ms/MinecraftEULA)")
    parser.add_argument("--start", action="store_true", help="Start the server after setup completes")
    parser.add_argument("--force", action="store_true", help="Re-download server.jar even if it exists")

    args = parser.parse_args()

    server_dir = os.path.abspath(args.dir)
    ensure_dir(server_dir)

    print(f"Target directory: {server_dir}")

    ok_java, java_out = check_java_version()
    if not ok_java:
        print("WARNING: Java 17+ not detected. Minecraft 1.18+ requires Java 17 or newer.")
        print("java -version output:")
        print(java_out)
        print("You can continue setup, but starting the server will likely fail until Java is installed.")

    try:
        print(f"Resolving Minecraft version '{args.version}'...")
        version_id, server_download = get_version_info(args.version)
        url = server_download.get("url")
        expected_sha1 = server_download.get("sha1")
        if not url:
            raise RuntimeError("Server download URL missing in metadata")
        print(f"Resolved version: {version_id}")

        jar_path = os.path.join(server_dir, "server.jar")
        if os.path.exists(jar_path) and not args.force:
            print("server.jar already exists. Skipping download (use --force to re-download).")
        else:
            print("Downloading server.jar ...")
            download_file(url, jar_path)
            print("Download complete.")

        if expected_sha1 and os.path.exists(jar_path):
            print("Verifying SHA1...")
            actual_sha1 = sha1_file(jar_path)
            if actual_sha1.lower() != expected_sha1.lower():
                raise RuntimeError(f"SHA1 mismatch for server.jar (got {actual_sha1}, expected {expected_sha1})")
            print("SHA1 verified.")

        eula_path = write_eula(server_dir, args.accept_eula)
        if args.accept_eula:
            print(f"EULA accepted and written to {eula_path}")
        else:
            print(f"EULA not accepted yet. Update {eula_path} to 'eula=true' before starting the server.")

        bat_path, sh_path = write_start_script(server_dir, args.min_memory, args.max_memory, args.nogui)
        print(f"Created helper scripts: {os.path.basename(bat_path)}, {os.path.basename(sh_path)}")

        if args.start:
            if not args.accept_eula:
                print("Refusing to auto-start because EULA not accepted. Re-run with --accept-eula to start automatically.")
            else:
                start_server(server_dir, args.min_memory, args.max_memory, args.nogui)

        print("Setup complete.")
        print("Next steps:")
        print(f"  - Review {os.path.join(server_dir, 'eula.txt')} and ensure eula=true.")
        print(f"  - Start the server using start.bat (Windows) or start.sh (macOS/Linux), or run:\n        java -Xms{args.min_memory} -Xmx{args.max_memory} -jar server.jar {'nogui' if args.nogui else ''}")

    except (HTTPError, URLError) as e:
        print(f"Network error: {e}")
        sys.exit(1)
    except Exception as e:
        print(f"Error: {e}")
        sys.exit(1)


if __name__ == "__main__":
    main()