#!/usr/bin/env bash
# ElyFTB installer/updater. Run as your regular user, never with sudo bash.
# Downloads are pinned to one release and verified before installation.
set -euo pipefail

# Parse the whole program before executing it, including when piped into bash.
main() {
umask 022

API='https://veryultrasupereasyupdater.xxanqw.me'
method=auto
channel=''
check_only=false
for argument in "$@"; do
  case "$argument" in
    --check) check_only=true ;;
    --portable|--method=portable) method=portable ;;
    --method=arch) method=arch ;;
    --method=auto) method=auto ;;
    --channel=stable) channel=stable ;;
    --channel=prerelease) channel=prerelease ;;
    --help|-h)
      printf '%s\n' 'ElyFTB Linux installer' \
        'Usage: bash install.sh [--check] [--portable] [--channel=stable|prerelease]' \
        'Arch: pacman package. Other supported x86_64 glibc distros: per-user install.' \
        '--check never downloads a package or requests administrator privileges.'
      exit 0 ;;
    *) printf 'Unknown option: %s\n' "$argument" >&2; exit 2 ;;
  esac
done
fail() { printf 'ElyFTB: %s\n' "$*" >&2; exit 1; }
terminal_fd=''
open_terminal() {
  if [[ -n $terminal_fd ]]; then return; fi
  if ! { exec {terminal_fd}<> /dev/tty; } 2>/dev/null; then
    fail 'An interactive terminal is required for package installation. Download install.sh, then run bash install.sh from a terminal. Use --check for unattended version checks.'
  fi
}
run_privileged() {
  open_terminal
  local command_status=0
  # Never let sudo, pacman or another package manager read this script's stdin.
  sudo "$@" <&"$terminal_fd" || command_status=$?
  if (( command_status != 0 )); then
    printf 'ElyFTB: Package installation failed or was cancelled (exit %s). No successful installation was confirmed.\n' "$command_status" >&2
    exit "$command_status"
  fi
}
[[ $EUID -ne 0 ]] || fail 'Run as your regular user. Only package-manager operations use sudo.'
[[ $(uname -m) == x86_64 ]] || fail 'This Linux build currently supports x86_64 only.'
for dependency in curl sha256sum mktemp tar awk wc; do
  command -v "$dependency" >/dev/null || fail "Missing required command: $dependency"
done

if [[ $method == auto ]]; then
  distro=''
  if [[ -r /etc/os-release ]]; then
    distro="$(. /etc/os-release; printf '%s %s' "${ID:-}" "${ID_LIKE:-}")"
  fi
  if [[ " $distro " == *' arch '* ]] && command -v pacman >/dev/null && command -v vercmp >/dev/null; then
    method=arch
  else
    method=portable
  fi
fi
base="$HOME/.local/opt/elyftb"
installed=''
current=''
if [[ $method == arch ]]; then
  command -v pacman >/dev/null && command -v vercmp >/dev/null || fail 'Arch mode requires pacman and vercmp.'
  platform='arch/x86_64'
  installed="$(pacman -Q elyftb 2>/dev/null | awk '{print $2}')" || true
  if [[ -n $installed ]]; then current="${installed%-*}"; current="${current//_/-}"; fi
else
  platform='linux/x64'
  glibc="$(getconf GNU_LIBC_VERSION 2>/dev/null)" || fail 'A glibc distribution is required; Alpine/musl is not supported.'
  glibc="${glibc#glibc }"
  [[ $glibc =~ ^([0-9]+)\.([0-9]+) ]] || fail 'Cannot determine the glibc version.'
  (( BASH_REMATCH[1] > 2 || (BASH_REMATCH[1] == 2 && BASH_REMATCH[2] >= 28) )) || fail 'glibc 2.28 or newer is required.'
  if [[ -f "$base/current/version" ]]; then IFS= read -r current < "$base/current/version"; installed="$current"; fi
  [[ ! -e "$base/current" || -L "$base/current" ]] || fail "Unexpected non-symlink directory: $base/current"
fi
version_pattern='^(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)(-[0-9A-Za-z]+([.-][0-9A-Za-z]+)*)?$'
[[ -z $current || $current =~ $version_pattern ]] || fail 'Installed version is not recognized; refusing to overwrite it.'
if [[ -z $channel ]]; then
  if [[ -n $current && $current != *-* ]]; then channel=stable; else channel=prerelease; fi
fi
printf 'ElyFTB · %s · channel: %s\n' "$platform" "$channel"
if [[ -n $installed ]]; then printf 'Installed: %s\n' "$installed"; else printf 'Not installed yet.\n'; fi
work="$(mktemp -d)"
stage=''
cleanup() {
  rm -rf -- "$work"
  if [[ -n $stage ]]; then rm -rf -- "$stage"; fi
  if [[ -n $terminal_fd ]]; then exec {terminal_fd}>&-; fi
}
trap cleanup EXIT
query="channel=$channel"
if [[ -n $current ]]; then query+="&current=$current"; fi
if ! code="$(curl --proto '=https' --proto-redir '=https' --tlsv1.2 --fail --silent --show-error --location \
  --connect-timeout 15 --max-time 40 --retry 2 --output "$work/manifest" --write-out '%{http_code}' \
  "$API/manifest/$platform?$query")"; then
  if [[ $code == 404 ]]; then printf 'No complete build is available for this channel yet. Nothing changed.\n'; exit 0; fi
  fail 'Cannot retrieve release metadata. Nothing changed.'
fi
[[ $(wc -c < "$work/manifest") -le 8192 ]] || fail 'Release manifest is too large.'
version='' package_version='' status='' url='' sha256='' size='' remote_platform=''
# Deliberately parse fields; never source or eval a remote manifest.
while IFS='=' read -r key value; do
  case "$key" in
    platform) remote_platform="$value" ;;
    version) version="$value" ;;
    package_version) package_version="$value" ;;
    status) status="$value" ;;
    url) url="$value" ;;
    sha256) sha256="$value" ;;
    size) size="$value" ;;
    *) fail 'Unknown release manifest field.' ;;
  esac
done < "$work/manifest"
[[ $remote_platform == "$platform" && $version =~ $version_pattern ]] || fail 'Invalid release identity.'
[[ $sha256 =~ ^[a-f0-9]{64}$ && $size =~ ^[1-9][0-9]{0,9}$ ]] || fail 'Invalid download checksum or size.'
(( size <= 2147483648 )) || fail 'Download exceeds the maximum expected size.'
[[ $url == "$API/download/$platform?tag=v$version" ]] || fail 'Untrusted or unpinned download URL.'
[[ $status == up-to-date || $status == update-available || $status == not-installed ]] || fail 'Invalid version-check result.'
if [[ $method == arch ]]; then
  expected_prefix="${version//-/_}-"
  [[ $package_version == "$expected_prefix"* && ${package_version#"$expected_prefix"} =~ ^[1-9][0-9]*$ ]] || fail 'Invalid pacman version.'
  if [[ -n $installed ]] && { [[ $current != "$version" && $status == up-to-date ]] || { [[ $current == "$version" ]] && [[ $(vercmp "$package_version" "$installed") -le 0 ]]; }; }; then
    printf 'ElyFTB is already up to date (%s). No package download needed.\n' "$installed"; exit 0
  fi
else
  [[ $package_version == "$version" ]] || fail 'Invalid portable version.'
  if [[ -n $installed && $status == up-to-date ]]; then
    printf 'ElyFTB is already up to date (%s). No package download needed.\n' "$installed"; exit 0
  fi
fi
printf 'Available: %s\n' "$version"
if $check_only; then printf 'An installation/update is available. Check only: nothing downloaded or installed.\n'; exit 0; fi
if [[ $method == arch ]]; then
  command -v sudo >/dev/null || fail 'sudo is required to install the pacman package.'
  open_terminal # Fail before a large download when no prompt can be answered.
fi
package="$work/elyftb-download"
printf 'Downloading the verified release…\n'
curl --proto '=https' --proto-redir '=https' --tlsv1.2 --fail --show-error --location --retry 2 \
  --connect-timeout 15 --max-time 900 --output "$package" "$url"
[[ $(wc -c < "$package") -eq $size ]] || fail 'Download size mismatch. Nothing installed.'
printf '%s  %s\n' "$sha256" "$package" | sha256sum --check --status || fail 'SHA-256 mismatch. Nothing installed.'
if [[ $method == arch ]]; then
  [[ $(pacman -Qp "$package") == "elyftb $package_version" ]] || fail 'The package name/version does not match the release.'
  run_privileged pacman -U --needed "$package"
  confirmed="$(pacman -Q elyftb 2>/dev/null | awk '{print $2}')" || true
  [[ $confirmed == "$package_version" ]] || fail "pacman did not install the expected version $package_version (installed: ${confirmed:-not installed}). Installation was not confirmed."
else
  # Reject absolute paths and traversal before extraction. Extraction is never privileged.
  tar -tzf "$package" > "$work/archive-files"
  while IFS= read -r entry; do
    [[ $entry == elyftb || $entry == elyftb/ || $entry == elyftb/* ]] || fail 'Unexpected archive layout.'
    [[ /$entry/ != *'/../'* ]] || fail 'Unsafe path in archive.'
  done < "$work/archive-files"
  mkdir -p "$base/releases"
  stage="$(mktemp -d "$base/releases/.staging.XXXXXXXX")"
  tar --extract --gzip --file "$package" --directory "$stage" --strip-components=1 --no-same-owner --no-same-permissions
  [[ -x "$stage/elyftb" && -f "$stage/resources/app.asar" && -f "$stage/version" && -f "$stage/elyftb.png" ]] || fail 'Incomplete Linux payload.'
  IFS= read -r payload_version < "$stage/version"
  [[ $payload_version == "$version" ]] || fail 'Archive version does not match the release.'
  command -v ldd >/dev/null || fail 'ldd is required to check runtime libraries.'
  ldd "$stage/elyftb" > "$work/libraries" 2>&1 || true
  if grep -q 'not found' "$work/libraries"; then
    printf 'Some desktop runtime libraries are missing. Your package manager will ask for approval.\n'
    command -v sudo >/dev/null || fail 'Install the missing runtime libraries and retry (sudo is unavailable).'
    if command -v apt-get >/dev/null; then
      apt_library() { if apt-cache show "${1}t64" >/dev/null 2>&1; then printf '%s' "${1}t64"; else printf '%s' "$1"; fi; }
      run_privileged apt-get update
      run_privileged apt-get install "$(apt_library libgtk-3-0)" libnss3 "$(apt_library libasound2)" libgbm1 libxss1 libxkbcommon0 "$(apt_library libcups2)"
    elif command -v dnf >/dev/null; then
      run_privileged dnf install gtk3 nss alsa-lib libXScrnSaver mesa-libgbm libxkbcommon cups-libs
    elif command -v zypper >/dev/null; then
      run_privileged zypper install libgtk-3-0 mozilla-nss libasound2 libgbm1 libXss1 libxkbcommon0 libcups2
    elif command -v pacman >/dev/null; then
      run_privileged pacman -S --needed gtk3 nss alsa-lib libxss mesa libxkbcommon libcups
    else
      fail 'Unsupported package manager. Install the runtime libraries shown by ldd and retry.'
    fi
    ldd "$stage/elyftb" > "$work/libraries" 2>&1 || true
    if grep -q 'not found' "$work/libraries"; then fail 'Runtime libraries are still missing. The existing app has not been replaced.'; fi
  fi
  release_dir="$base/releases/$version-$$"
  mv -- "$stage" "$release_dir"
  stage=''
  bin="$HOME/.local/bin"
  data="${XDG_DATA_HOME:-$HOME/.local/share}"
  mkdir -p "$bin" "$data/applications" "$data/icons/hicolor/512x512/apps"
  install -m644 "$release_dir/elyftb.png" "$data/icons/hicolor/512x512/apps/elyftb.png"
  launcher="$bin/elyftb"
  quoted_launcher="${launcher//\\/\\\\}"
  quoted_launcher="${quoted_launcher//\"/\\\"}"
  quoted_launcher="${quoted_launcher//\$/\\\$}"
  quoted_launcher="${quoted_launcher//\`/\\\`}"
  printf '[Desktop Entry]\nType=Application\nName=ElyFTB\nComment=Ely.by-enabled modpack launcher\nExec="%s" %%u\nIcon=elyftb\nTerminal=false\nCategories=Game;\nMimeType=x-scheme-handler/ftb;\nStartupWMClass=elyftb\n' \
    "$quoted_launcher" > "$data/applications/elyftb.desktop"
  ln -sfn "$base/current/elyftb" "$launcher"
  ln -s "releases/$(basename "$release_dir")" "$base/.current-$$"
  mv -Tf "$base/.current-$$" "$base/current"
  if command -v update-desktop-database >/dev/null; then update-desktop-database "$data/applications" >/dev/null 2>&1 || true; fi
  printf 'Per-user installation: %s\n' "$base/current"
  printf 'Start from your application menu, or run: %s\n' "$launcher"
  printf 'Previous release directories are retained so a running launcher is not disrupted.\n'
fi
printf 'ElyFTB %s installed. Restart the launcher if it is already open. Your modpacks and worlds are unchanged.\n' "$version"
}

main "$@"