#!/usr/bin/env bash
# ssh-open: open an authenticated SSH master connection per host, for later
# `ssh HOST ...`, scp, rsync and git to reuse without a new key touch.
#
# Each host needs a ControlPath in ~/.ssh/config (ControlMaster auto,
# ControlPath ~/.ssh/cm-%C); without one nothing could reuse the master, so
# the host is refused. A host's ProxyJump host is opened first, so each
# host costs one touch and the jumped host rides on the jump's master.
#
# Without a terminal (an agent, a script), the touch prompt goes to a desktop
# notification (ssh-touch-notify) unless SSH_ASKPASS is already set.
set -euo pipefail

usage() {
  cat <<'EOF'
usage: ssh-open [-t TTL] HOST...

Open a master connection to each HOST (skipping those already open), then
show their status. Touch the security key when asked.

  -t TTL   keep each master this long after its last use (ssh ControlPersist:
           10m, 1h, yes = until ssh-close); default: the host's ssh config
EOF
}

ttl=""
while getopts "t:h" opt; do
  case $opt in
    t) ttl=$OPTARG ;;
    h) usage; exit 0 ;;
    *) usage >&2; exit 2 ;;
  esac
done
shift $((OPTIND - 1))
[ $# -gt 0 ] || { usage >&2; exit 2; }

state="${XDG_RUNTIME_DIR:-$HOME/.cache}/devkit-ssh/hosts"
mkdir -p "$(dirname "$state")"
touch "$state"

# No terminal for ssh to prompt on: show the touch request on the desktop.
if [ ! -t 0 ] && [ ! -t 2 ] && [ -z "${SSH_ASKPASS:-}" ]; then
  SSH_ASKPASS="$(command -v ssh-touch-notify || true)"
  if [ -n "$SSH_ASKPASS" ]; then
    export SSH_ASKPASS SSH_ASKPASS_REQUIRE=force
  else
    unset SSH_ASKPASS
  fi
fi

ssh_opt() { ssh -G "$1" 2>/dev/null | awk -v k="$2" '$1 == k { print $2; exit }'; }

record() { grep -qxF "$1" "$state" || printf '%s\n' "$1" >>"$state"; }

declare -A seen=()
opened=()
failed=0

open_host() {
  local host=$1 jump j jumps
  [ -z "${seen[$host]:-}" ] || return 0
  seen[$host]=1

  local cpath
  cpath="$(ssh_opt "$host" controlpath)"
  if [ -z "$cpath" ] || [ "$cpath" = none ]; then
    echo "ssh-open: $host: no ControlPath in ssh config, nothing could reuse a master; add:" >&2
    echo "    ControlMaster auto" >&2
    echo "    ControlPath ~/.ssh/cm-%C" >&2
    failed=1
    return 0
  fi

  # Open bare-name jump hosts first (user@host:port forms are left to ssh).
  jump="$(ssh_opt "$host" proxyjump)"
  if [ -n "$jump" ] && [ "$jump" != none ]; then
    IFS=, read -ra jumps <<<"$jump"
    for j in "${jumps[@]}"; do
      case $j in *[@:/]*) ;; *) open_host "$j" ;; esac
    done
  fi

  if ssh -O check "$host" 2>/dev/null; then
    record "$host"
    opened+=("$host")
    return 0
  fi

  echo "ssh-open: opening $host (touch your security key when it blinks)" >&2
  local args=(-fNT -o ControlMaster=auto)
  [ -z "$ttl" ] || args+=(-o "ControlPersist=$ttl")
  # shellcheck disable=SC2029 # $host is the destination, not a remote command
  if DEVKIT_SSH_HOST=$host ssh "${args[@]}" "$host"; then
    record "$host"
    opened+=("$host")
  else
    echo "ssh-open: $host: could not connect" >&2
    failed=1
  fi
}

for host in "$@"; do open_host "$host"; done

[ ${#opened[@]} -eq 0 ] || ssh-status "${opened[@]}" || failed=1
exit "$failed"