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

# User Variables
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")

print("****************************************")
print(f"* Launching {PackName}")
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("launchClient.log", "a") as log:
        subprocess.run([GIT, *args], stdout=log, stderr=subprocess.STDOUT, check=True)

if Path(".git").is_dir():
    print("* Detected git repo. Updating Pack!")

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

    # ponytail: reset straight to the remote - pull-down-only means local history never matters,
    # and this can't produce a merge conflict the way fetch + merge could
    print("* * Resetting local to match upstream")
    git("reset", "--hard", f"origin/{BRANCH}")

    # ponytail: clears leftovers that would block the reset. Respects .gitignore - no -x flag,
    # so anything the game generates stays put as long as the repo ignores it
    print("* * Clearing stale untracked pack files")
    git("clean", "-fd")

    print("* Pack Update Complete!")
else:
    print("* No .git folder was found. Installing Pack!")

    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("* Pack Installation Complete!")

print("****************************************")