#!/usr/bin/env bash
# install-discord.sh — Install Discord from the latest official Linux .deb.
# Hardened: official latest endpoint, idempotent, --dry-run.

set -euo pipefail
IFS=$'\n\t'

readonly SCRIPT_NAME="${0##*/}"
DRY_RUN=0
DOWNLOAD_URL="https://discord.com/api/download?platform=linux&format=deb"

usage() {
  cat <<EOF
Usage: sudo $SCRIPT_NAME [--dry-run] [--help]

Downloads Discord from Discord's official latest Linux .deb endpoint and
installs it with apt-get.

Options:
  --dry-run    Print actions without executing.
  --help, -h   Show this help.
EOF
}

log()  { printf '\033[1;34m[%s]\033[0m %s\n' "${SCRIPT_NAME%.sh}" "$*"; }
die()  { printf '\033[1;31m[%s] ERROR:\033[0m %s\n' "${SCRIPT_NAME%.sh}" "$*" >&2; exit 1; }
run()  { if (( DRY_RUN )); then printf '  DRY-RUN: %s\n' "$*"; else eval "$@"; fi; }
trap 'rc=$?; (( rc )) && printf "\033[1;31m[%s] failed at line %s (exit %d)\033[0m\n" "${SCRIPT_NAME%.sh}" "$LINENO" "$rc" >&2' ERR

while (( $# )); do
  case "$1" in
    --dry-run) DRY_RUN=1 ;;
    -h|--help) usage; exit 0 ;;
    *) die "Unknown argument: $1 (try --help)" ;;
  esac
  shift
done

(( EUID == 0 )) || die "Must run as root. Try: sudo $SCRIPT_NAME"

[[ -r /etc/os-release ]] || die "/etc/os-release not found."
# shellcheck disable=SC1091
. /etc/os-release
case "${ID:-}:${ID_LIKE:-}" in
  *ubuntu*|*debian*) : ;;
  *) die "Unsupported distro: ${PRETTY_NAME:-unknown}." ;;
esac

ARCH="$(dpkg --print-architecture)"
[[ "$ARCH" == "amd64" ]] || die "Discord's official Linux .deb targets amd64 only (detected: $ARCH)."
log "Detected: ${PRETTY_NAME:-unknown}, arch: $ARCH"

export DEBIAN_FRONTEND=noninteractive
log "Installing prerequisites..."
run "apt-get update -qq"
run "apt-get install -y curl ca-certificates"

STAGE="$(mktemp -d -t discord.XXXXXX)"
trap 'rm -rf "$STAGE"' EXIT
DEB="$STAGE/discord.deb"

log "Downloading latest Discord .deb..."
run "curl -fL -o '$DEB' '$DOWNLOAD_URL'"

if (( DRY_RUN )); then
  printf '  DRY-RUN: apt-get install -y %s\n' "$DEB"
  log "Done."
  exit 0
fi

log "Installing Discord..."
run "apt-get install -y '$DEB'"

if command -v discord >/dev/null 2>&1; then
  log "Installed: $(discord --version 2>/dev/null || dpkg-query -W -f='${Version}' discord 2>/dev/null || echo Discord)"
else
  log "Installed: $(dpkg-query -W -f='${Version}' discord 2>/dev/null || echo Discord)"
fi
log "Done."