import sys, json, subprocess, configparser, shutil, os, platform, urllib.request
from pathlib import Path

# User Variables
MAXRAM = "8G"
MINRAM = "4G"
JVMARGS = ""
REPO_URL = ""
BRANCH = "main"

InstanceConfig = configparser.ConfigParser()

if Path("../instance.cfg").is_file():
    # Launched by Prism/MultiMC - read the instance's own metadata
    InstanceConfig.read("../instance.cfg")
    with open("../mmc-pack.json", "r") as file:
        Components = json.load(file)["components"]
    # ponytail: match on uid, not list index - component order isn't guaranteed
    Minecraft = next(c for c in Components if c["uid"] == "net.minecraft")
    Modloader = next(c for c in Components
                     if c["uid"] != "net.minecraft" and not c.get("dependencyOnly"))
    MinecraftVersion = Minecraft["version"]
    ModloaderName = Modloader["cachedName"]
    ModloaderVersion = Modloader["version"]
elif Path("env.txt").is_file():
    # Standalone - same INI format, plus the versions mmc-pack.json would have given us
    InstanceConfig.read("env.txt")
    MinecraftVersion = InstanceConfig['General']['MinecraftVersion']
    ModloaderName = InstanceConfig['General']['ModloaderName']
    ModloaderVersion = InstanceConfig['General']['ModloaderVersion']
else:
    sys.exit("* Found neither ../instance.cfg nor env.txt - cannot identify this instance.")

PackName = InstanceConfig['General']['name']

# Program Variables DO NOT TOUCH
MINGIT_URL = "https://github.com/git-for-windows/git/releases/download/v2.45.2.windows.1/MinGit-2.45.2-64-bit.zip"
MINGIT = Path(".mingit/cmd/git.exe")

IS_NEOFORGE = ModloaderName == "NeoForge"
SERVER_JAR = Path("server-installer.jar")
# ponytail: version-stamped path - a modloader bump makes this vanish and the install re-runs for free
ARGS_FILE = Path("libraries/net/neoforged/neoforge", ModloaderVersion,
                 "win_args.txt" if os.name == "nt" else "unix_args.txt")
SERVER_JAR_URL = (
    f"https://maven.neoforged.net/releases/net/neoforged/neoforge/{ModloaderVersion}/neoforge-{ModloaderVersion}-installer.jar"
    if IS_NEOFORGE else
    f"https://meta.fabricmc.net/v2/versions/loader/{MinecraftVersion}/{ModloaderVersion}/1.0.1/server/jar"
)

JAVA_DIR = Path(".Java21")
JAVA = JAVA_DIR / "bin" / ("java.exe" if os.name == "nt" else "java")
# ponytail: Adoptium takes os/arch as path segments - build them instead of hardcoding windows/x64
JAVA_OS = {"Windows": "windows", "Linux": "linux"}[platform.system()]
JAVA_ARCH = {"AMD64": "x64", "x86_64": "x64"}[platform.machine()]
JAVA_URL = f"https://api.adoptium.net/v3/binary/latest/21/ga/{JAVA_OS}/{JAVA_ARCH}/jre/hotspot/normal/eclipse"
JAVA_ARCHIVE = "java.zip" if os.name == "nt" else "java.tar.gz"

print("****************************************")
print(f"* Launching {PackName} Server")
print(f"* {MinecraftVersion} / {ModloaderName} {ModloaderVersion}")

# ponytail: check the local MinGit before downloading - which() never sees it, it's not on PATH
GIT = shutil.which("git") or (str(MINGIT.resolve()) if MINGIT.is_file() else None)
if GIT is None:
    if os.name != "nt":
        sys.exit("* Git not found, please install Git!")
    print("* Git not found, downloading and installing Git.")
    urllib.request.urlretrieve(MINGIT_URL, "MinGit.zip")
    shutil.unpack_archive("MinGit.zip", ".mingit")
    Path("MinGit.zip").unlink()
    GIT = str(MINGIT.resolve())

def git(*args):
    with open("launchServer.log", "a") as log:
        subprocess.run([GIT, *args], stdout=log, stderr=subprocess.STDOUT, check=True)

def AcceptEula():
    eula = Path("eula.txt")
    # ponytail: substring check, not a properties parse - the file has one setting
    if eula.is_file() and "eula=true" in eula.read_text():
        return
    eula.write_text("eula=true\n")

if Path(".git").is_dir():
    print("* Updating Modpack Server from Gitlab")

    print("* * Fetching changes from upstream")
    git("fetch", "origin")

    print("* * Resetting local to match upstream")
    git("reset", "--hard", f"origin/{BRANCH}")

    print("* * Clearing stale untracked pack files")
    git("clean", "-fd")

    print("* Server Update Complete!")
else:
    print("* Installing Modpack Server from Gitlab")

    print("* * Cloning repo into temp folder")
    tmp = Path("repo.tmp")
    git("clone", "--branch", BRANCH, REPO_URL, str(tmp))

    print("* * Copying repo out of temp and into current folder")
    shutil.copytree(tmp, ".", dirs_exist_ok=True)   # ponytail: merges like robocopy /E; move refuses existing dirs
    shutil.rmtree(tmp)

    print("* Server Installation Complete!")

print("****************************************")
print("* Setting up server runtime")

if not JAVA.is_file():
    print("* * Downloading Java 21")
    urllib.request.urlretrieve(JAVA_URL, JAVA_ARCHIVE)
    print("* * Extracting Java 21")
    shutil.unpack_archive(JAVA_ARCHIVE)   # ponytail: replaces `tar -xf`, picks zip vs tar.gz by extension
    Path(JAVA_ARCHIVE).unlink()
    shutil.move(str(next(Path(".").glob("jdk-*"))), JAVA_DIR)

if IS_NEOFORGE:
    if not ARGS_FILE.is_file():
        print(f"* * Downloading {ModloaderName} installer")
        urllib.request.urlretrieve(SERVER_JAR_URL, SERVER_JAR)
        print(f"* * Installing {ModloaderName} server")
        subprocess.run([str(JAVA), "-jar", str(SERVER_JAR), "--installServer", "."], check=True)
    # NeoForge ships an @argfile instead of a runnable jar
    LoaderArgs = [f"@{ARGS_FILE}"]
else:
    if not SERVER_JAR.is_file():
        print(f"* * Downloading {ModloaderName} server jar")
        urllib.request.urlretrieve(SERVER_JAR_URL, SERVER_JAR)
    LoaderArgs = ["-jar", str(SERVER_JAR)]

print("* Server runtime ready!")

ModsList = Path("NonServerFriendlyMods.txt")
if ModsList.is_file():
    print("****************************************")
    print("* Removing mods not friendly for servers")
    for line in ModsList.read_text().splitlines():
        if line.strip():
            Path("mods", line.strip()).unlink(missing_ok=True)
    print("* Removed problematic mods")

print("****************************************")
print("* Starting Modpack Server")
AcceptEula()
subprocess.run([str(JAVA), f"-Xms{MINRAM}", f"-Xmx{MAXRAM}", *JVMARGS.split(),
                *LoaderArgs, "nogui"])
input("Press Enter to exit...")