#!/bin/sh
#
# kopia-server - start/stop the Kopia web UI server for the current user.
#
# No root, no /etc/rc.d. The server runs as whoever invokes this script,
# with its password kept in a 0600 env file rather than on the command
# line (where "ps" would show it to every user on the box).
#
# Usage:
#   kopia-server setup     create the env file with a random password
#   kopia-server start
#   kopia-server stop
#   kopia-server restart
#   kopia-server status
#   kopia-server log       tail the server log
#
# Environment overrides:
#   KOPIA_ADDRESS   listen address (default 127.0.0.1:51515)
#   KOPIA_BIN       path to the kopia binary (default: from PATH)

set -e

PRGNAM=kopia-server
KOPIA_BIN="${KOPIA_BIN:-kopia}"
ADDRESS="${KOPIA_ADDRESS:-127.0.0.1:51515}"

CONFDIR="${XDG_CONFIG_HOME:-$HOME/.config}/kopia"
ENVFILE="$CONFDIR/server.env"

RUNDIR="${XDG_RUNTIME_DIR:-$HOME/.cache}/kopia"
PIDFILE="$RUNDIR/server.pid"
LOGFILE="$RUNDIR/server.log"

die() { echo "$PRGNAM: $*" 1>&2; exit 1; }

ensure_dirs() {
  mkdir -p "$CONFDIR" "$RUNDIR"
  chmod 700 "$CONFDIR" "$RUNDIR"
}

# True only if the pidfile points at a live process that is actually kopia.
# The comm check matters: PIDs get reused, and killing a stranger's process
# because a stale pidfile happened to match would be a bad day.
running() {
  [ -s "$PIDFILE" ] || return 1
  pid=$(cat "$PIDFILE" 2>/dev/null) || return 1
  case "$pid" in
    ''|*[!0-9]*) return 1 ;;
  esac
  [ -d "/proc/$pid" ] || return 1
  read -r comm < "/proc/$pid/comm" 2>/dev/null || return 1
  [ "$comm" = "kopia" ]
}

check_envfile() {
  [ -f "$ENVFILE" ] || die "no $ENVFILE - run '$PRGNAM setup' first"
  perms=$(stat -c %a "$ENVFILE")
  case "$perms" in
    600|400) ;;
    *) die "$ENVFILE is mode $perms - must be 600 (chmod 600 '$ENVFILE')" ;;
  esac
}

cmd_setup() {
  ensure_dirs
  if [ -e "$ENVFILE" ]; then
    echo "$PRGNAM: $ENVFILE already exists, leaving it alone"
    return 0
  fi
  pw=$(od -An -tx1 -N32 /dev/urandom | tr -d ' \n')
  ( umask 077
    cat > "$ENVFILE" <<EOF
# Kopia server credentials. Keep this file at mode 0600.
KOPIA_SERVER_USERNAME=kopia
KOPIA_SERVER_PASSWORD=$pw
EOF
  )
  chmod 600 "$ENVFILE"
  echo "$PRGNAM: wrote $ENVFILE"
  echo "  username: kopia"
  echo "  password: $pw"
}

cmd_start() {
  ensure_dirs
  check_envfile
  command -v "$KOPIA_BIN" >/dev/null 2>&1 || die "kopia binary not found"

  if running; then
    echo "$PRGNAM: already running (pid $(cat "$PIDFILE")) on http://$ADDRESS"
    return 0
  fi

  # shellcheck disable=SC1090
  . "$ENVFILE"
  export KOPIA_SERVER_USERNAME KOPIA_SERVER_PASSWORD

  # --insecure is fine only because we bind to loopback. If you ever change
  # ADDRESS to a routable interface, drop --insecure and add TLS instead:
  #   --tls-generate-cert --tls-cert-file ... --tls-key-file ...
  case "$ADDRESS" in
    127.*|localhost:*|\[::1\]:*) insecure="--insecure" ;;
    *) die "refusing --insecure on non-loopback address $ADDRESS; add TLS flags and edit this script" ;;
  esac

  nohup "$KOPIA_BIN" server start \
    $insecure \
    --address "$ADDRESS" \
    --server-username "$KOPIA_SERVER_USERNAME" \
    >> "$LOGFILE" 2>&1 &

  echo $! > "$PIDFILE"
  chmod 600 "$PIDFILE" "$LOGFILE"

  # Give it a moment to either bind or die, so the exit status means something.
  sleep 1
  if running; then
    echo "$PRGNAM: started (pid $(cat "$PIDFILE")) on http://$ADDRESS"
    echo "  username: $KOPIA_SERVER_USERNAME"
    echo "  log:      $LOGFILE"
  else
    : > "$PIDFILE"
    echo "$PRGNAM: failed to start - last lines of $LOGFILE:" 1>&2
    tail -n 20 "$LOGFILE" 1>&2
    exit 1
  fi
}

cmd_stop() {
  if ! running; then
    echo "$PRGNAM: not running"
    [ -f "$PIDFILE" ] && : > "$PIDFILE"
    return 0
  fi
  pid=$(cat "$PIDFILE")
  kill "$pid" 2>/dev/null || true

  n=0
  while [ $n -lt 20 ]; do
    running || break
    sleep 0.5
    n=$((n + 1))
  done

  if running; then
    echo "$PRGNAM: pid $pid ignored SIGTERM, sending SIGKILL" 1>&2
    kill -9 "$pid" 2>/dev/null || true
    sleep 1
  fi

  : > "$PIDFILE"
  echo "$PRGNAM: stopped"
}

cmd_status() {
  if running; then
    pid=$(cat "$PIDFILE")
    echo "$PRGNAM: running (pid $pid) on http://$ADDRESS"
    echo "  started: $(ps -o lstart= -p "$pid" 2>/dev/null)"
    echo "  log:     $LOGFILE"
  else
    echo "$PRGNAM: not running"
    return 3
  fi
}

case "${1:-}" in
  setup)   cmd_setup ;;
  start)   cmd_start ;;
  stop)    cmd_stop ;;
  restart) cmd_stop; cmd_start ;;
  status)  cmd_status ;;
  log)     exec tail -n 50 -f "$LOGFILE" ;;
  *) echo "usage: $PRGNAM {setup|start|stop|restart|status|log}" 1>&2; exit 1 ;;
esac