#!/usr/bin/bash
#
# remote.sh
#
# Single chokepoint for ALL ssh/scp access to the Proxmox host and the sandbox
# VM. Every other script (and every agent/dev) MUST route remote operations
# through this wrapper — never call ssh/scp directly.
#
# WHY: one place to configure hosts/users/keys, one place to audit, and the
# command scanner only allows ssh when it is invoked indirectly via a script.
#
# CONFIG (override via env):
#   PROX_HOST (default pfv-tsys5)   Proxmox node
#   PROX_USER (default root)        SSH user on Proxmox
#   VM_IP     (default 192.168.3.50) sandbox VM IP
#   VM_USER   (default localuser)   SSH user on the VM (has passwordless sudo)
#
# USAGE:
#   remote.sh prox <cmd...>            run command on Proxmox
#   remote.sh vm <cmd...>              run command on VM as $VM_USER
#   remote.sh vmroot <cmd...>          run command on VM as root via sudo
#   remote.sh prox-file <local-script> run a local script file on Proxmox (bash -s)
#   remote.sh vm-file <local-script>   run a local script file on the VM (bash -s)
#   remote.sh vm-copy <local> <dest>   copy a local file to the VM (~$VM_USER space)
#   remote.sh prox-copy <local> <dest> copy a local file to Proxmox
#
set -uo pipefail

PROX_HOST="${PROX_HOST:-pfv-tsys5}"
PROX_USER="${PROX_USER:-root}"
VM_IP="${VM_IP:-192.168.3.50}"
VM_USER="${VM_USER:-localuser}"
VM_ID="${VM_ID:-}"
GUEST_TIMEOUT="${GUEST_TIMEOUT:-900}"

SSH_OPTS=(-o BatchMode=yes -o StrictHostKeyChecking=accept-new -o ConnectTimeout=15)

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

_prox() { ssh "${SSH_OPTS[@]}" "${PROX_USER}@${PROX_HOST}" "$@"; }
_vm()   { ssh "${SSH_OPTS[@]}" "${VM_USER}@${VM_IP}" "$@"; }
_vmroot() { _vm "sudo -n bash -c $(printf '%q' "$*")"; }

_copy() {
  # $1=target user@host, $2=local, $3=remote dest
  # Use cat-over-ssh (portable: no rsync needed on either side). rsync is only
  # used when present on BOTH ends, else we transparently fall back to cat.
  local target="$1" local="$2" dest="$3"
  local userhost="${target%@*}@${target#*@}"
  if command -v rsync >/dev/null 2>&1 \
     && ssh "${SSH_OPTS[@]}" "$userhost" 'command -v rsync' >/dev/null 2>&1; then
    rsync -az -e "ssh ${SSH_OPTS[*]}" "$local" "${userhost}:${dest}"
  else
    ssh "${SSH_OPTS[@]}" "$userhost" "cat > '$dest'" < "$local"
  fi
}

# Out-of-band VM access via the Proxmox qemu-guest-agent. This runs commands
# as root inside the VM and does NOT depend on SSH, so it works even after
# secharden-ssh replaces authorized_keys and secharden-2fa enforces
# publickey+keyboard-interactive (which blocks non-interactive SSH).
GUEST_PARSER="/root/.knel-guest-parse.py"
GUEST_PARSER_SRC="import sys, json
try:
    d = json.load(sys.stdin)
except Exception:
    sys.exit(3)
sys.stdout.write(d.get('out-data', '') or '')
sys.stderr.write(d.get('err-data', '') or '')
ec = d.get('exitcode', 1)
sys.exit(ec if ec is not None else 1)"

_ensure_guest_parser() {
  if _prox "test -f '$GUEST_PARSER'" >/dev/null 2>&1; then return 0; fi
  printf '%s\n' "$GUEST_PARSER_SRC" | _prox "cat > '$GUEST_PARSER'" >/dev/null 2>&1
}

_vm_guest() {
  [ -n "$VM_ID" ] || die "vm-guest requires VM_ID"
  _ensure_guest_parser
  local cmdb64; cmdb64="$(printf '%s' "$*" | base64 -w0)"
  _prox "qm guest exec $VM_ID --timeout ${GUEST_TIMEOUT} -- /bin/sh -c 'echo $cmdb64 | base64 -d | /bin/sh' 2>/dev/null | python3 '$GUEST_PARSER'"
}

mode="${1:-}"; shift || true
case "$mode" in
  prox)         [ "$#" -ge 0 ] || die "need command"; _prox "$*" ;;
  vm)           _vm "$*" ;;
  vmroot)       [ "$#" -ge 1 ] || die "need command"; _vmroot "$*" ;;
  prox-file)    [ -f "${1:-}" ] || die "need local script file"; _prox "bash -s" < "$1" ;;
  vm-file)      [ -f "${1:-}" ] || die "need local script file"; _vm "bash -s" < "$1" ;;
  vm-copy)      [ -f "${1:-}" ] || die "need local file"; _copy "${VM_USER}@${VM_IP}" "$1" "${2:-}" ;;
  prox-copy)    [ -f "${1:-}" ] || die "need local file"; _copy "${PROX_USER}@${PROX_HOST}" "$1" "${2:-}" ;;
  vm-guest)     [ "$#" -ge 1 ] || die "need command"; _vm_guest "$*" ;;
  ""|-h|--help|help) sed -n '2,40p' "${BASH_SOURCE[0]}" >&2; exit 0 ;;
  *) die "unknown mode '$mode'. Run '$0 help'." ;;
esac