#!/usr/bin/env sh
# docker/install.sh — install full (rootful) Docker Engine and let the
# invoking user talk to it without sudo.
#
# What it does:
#   1. Installs Docker Engine via Docker's official convenience script
#      (get.docker.com — supports both RHEL- and Debian-family distros and
#      sets up the upstream package repo). Skipped when `docker` is already
#      installed.
#   2. Enables and starts the service (systemd hosts only).
#   3. Adds the invoking user to the `docker` group so the daemon socket is
#      usable without sudo. Takes effect at next login.
#
# Deliberately no-ops when a rootless Docker daemon is detected (e.g. Kasm
# ships its own rootless setup) — installing rootful Docker there would fight
# the existing runtime. See docker-rootless-cgroup/ for the Kasm-side config.
#
# Idempotent and safe to re-run. Uses sudo.
set -eu

say() { printf '%s\n' "$*" >&2; }

# --- skip on rootless-Docker hosts -------------------------------------------
if command -v docker >/dev/null 2>&1 &&
   docker info -f '{{println .SecurityOptions}}' 2>/dev/null | grep -q 'name=rootless'; then
  say "docker: rootless Docker daemon detected; leaving it alone."
  exit 0
fi

# --- 1. install engine -------------------------------------------------------
if command -v docker >/dev/null 2>&1; then
  say "docker: engine already installed ($(docker --version 2>/dev/null || echo 'version unknown'))."
else
  say "docker: installing Docker Engine via get.docker.com..."
  tmp="$(mktemp)"
  if command -v curl >/dev/null 2>&1; then
    curl -fsSL https://get.docker.com -o "$tmp"
  elif command -v wget >/dev/null 2>&1; then
    wget -qO "$tmp" https://get.docker.com
  else
    say "docker: need curl or wget"; exit 1
  fi
  sudo sh "$tmp"
  rm -f "$tmp"
fi

# --- 2. enable + start the service (systemd only) ----------------------------
if [ -d /run/systemd/system ] && command -v systemctl >/dev/null 2>&1; then
  sudo systemctl enable --now docker
else
  say "docker: no systemd; not managing the service (start dockerd yourself)."
fi

# --- 3. group membership for the invoking user -------------------------------
user="$(id -un)"
if id -nG "$user" | tr ' ' '\n' | grep -qx docker; then
  say "docker: $user already in the docker group."
else
  sudo usermod -aG docker "$user"
  say "docker: added $user to the docker group."
  say "  Log out and back in (or run 'newgrp docker') for it to take effect."
fi