#!/usr/bin/env bash
# LAN party bootstrap: installs Fjord Launcher Unlocked (DRM-free Prism fork),
# seeds a persistent offline account, drops in the pre-built modpack instance,
# and launches straight into it on the LAN server.
#
# Host this file via: python3 -m http.server 8000
# Participants run:    curl -fsSL http://<host-ip>:8000/install.sh | bash
set -euo pipefail

# ---- EDIT ME before hosting ----
HOST_URL="http://192.168.1.50:8000"     # where THIS script + modpack.zip are served from
MODPACK_URL="$HOST_URL/modpack.zip"     # exported Prism instance folder, zipped (see HOSTING.md)
INSTANCE_NAME="LANParty"                # must match the top-level folder name inside modpack.zip
SERVER_ADDR="192.168.1.50:25565"        # your Minecraft server IP:port
GH_REPO="unmojang/FjordLauncherUnlocked" # fallback if hero-persson's fork disappears; see note below
# ---------------------------------

INSTALL_DIR="$HOME/mc-lan-party"
mkdir -p "$INSTALL_DIR"
cd "$INSTALL_DIR"

echo "==> Setting up in $INSTALL_DIR"

os="$(uname -s)"
arch="$(uname -m)"

api_url="https://api.github.com/repos/hero-persson/FjordLauncherUnlocked/releases/latest"
release_json="$(curl -fsSL "$api_url")"

pick_asset() {
  # $1 = grep pattern for the asset name
  echo "$release_json" | grep -oE '"browser_download_url": *"[^"]+"' \
    | cut -d'"' -f4 | grep -E "$1" | head -n1
}

LAUNCHER_BIN=""

if [[ "$os" == "Linux" ]]; then
  if [[ "$arch" == "aarch64" ]]; then
    url="$(pick_asset 'Linux-aarch64\.AppImage$')"
  else
    url="$(pick_asset 'Linux-x86_64\.AppImage$')"
  fi
  [[ -n "$url" ]] || { echo "Could not find a Linux AppImage in the latest release." >&2; exit 1; }
  echo "==> Downloading $url"
  curl -fsSL -o FjordLauncher.AppImage "$url"
  chmod +x FjordLauncher.AppImage
  LAUNCHER_BIN="$INSTALL_DIR/FjordLauncher.AppImage"
elif [[ "$os" == "Darwin" ]]; then
  url="$(pick_asset 'macOS-.*\.zip$')"
  [[ -n "$url" ]] || { echo "Could not find a macOS build in the latest release." >&2; exit 1; }
  echo "==> Downloading $url"
  curl -fsSL -o FjordLauncher.zip "$url"
  unzip -oq FjordLauncher.zip -d app
  app_path="$(find app -maxdepth 2 -name '*.app' | head -n1)"
  LAUNCHER_BIN="$app_path/Contents/MacOS/$(ls "$app_path/Contents/MacOS" | head -n1)"
else
  echo "Unsupported OS for install.sh: $os. Use install.ps1 on Windows." >&2
  exit 1
fi

# ---- offline account: compute Mojang-style offline UUID so playerdata persists across launches ----
read -rp "Minecraft nickname [${USER:-Player}]: " NICK
NICK="${NICK:-${USER:-Player}}"

md5hex="$(printf '%s' "OfflinePlayer:$NICK" | md5sum | cut -d' ' -f1)"
variant_nibble=$(( (16#${md5hex:16:1} & 3) | 8 ))
variant_hex="$(printf '%x' "$variant_nibble")"
patched="${md5hex:0:12}3${md5hex:13:3}${variant_hex}${md5hex:17:15}"
UUID="${patched:0:8}-${patched:8:4}-${patched:12:4}-${patched:16:4}-${patched:20:12}"
CLIENT_TOKEN="$(printf '%s' "ClientToken:$NICK" | md5sum | cut -d' ' -f1)"

cat > accounts.json <<EOF
{
  "accounts": [
    {
      "active": true,
      "type": "Offline",
      "profile": { "id": "$UUID", "name": "$NICK", "capes": [], "skin": { "id": "", "url": "", "variant": "" } },
      "entitlement": { "canPlayMinecraft": true, "ownsMinecraft": true },
      "ygg": { "token": "0", "extra": { "clientToken": "$CLIENT_TOKEN", "userName": "$NICK" }, "iat": $(date +%s) }
    }
  ],
  "formatVersion": 3
}
EOF
echo "==> Offline account '$NICK' ready (UUID $UUID)"

# ---- modpack instance ----
mkdir -p instances
if [[ ! -d "instances/$INSTANCE_NAME" ]]; then
  echo "==> Downloading modpack from $MODPACK_URL"
  curl -fsSL -o modpack.zip "$MODPACK_URL"
  unzip -oq modpack.zip -d instances
  echo "==> Modpack installed to instances/$INSTANCE_NAME"
else
  echo "==> Instance already present, skipping download"
fi

echo "==> Launching into $INSTANCE_NAME as $NICK, joining $SERVER_ADDR"
"$LAUNCHER_BIN" --dir "$INSTALL_DIR" --launch "$INSTANCE_NAME" --profile "$NICK" --server "$SERVER_ADDR"