#!/usr/bin/env bash
set -euo pipefail

helper_dir=${SLOPTRAP_HELPER_DIR:-/run/sloptrap-helper}
queue_dir="$helper_dir/queue"
caps=${SLOPTRAP_ACTIVE_CAPABILITIES:-}
audit_log=${SLOPTRAP_AUDIT_LOG:-/codex/state/capabilities.log}
mkdir -p "$queue_dir" "$(dirname "$audit_log")"

has_capability() {
  local needle=$1
  local token
  for token in $caps; do
    if [[ $token == "$needle" ]]; then
      return 0
    fi
  done
  return 1
}

log_action() {
  local op=$1
  local details=$2
  local status=$3
  printf '%s op=%s status=%s %s\n' "$(date -u +%FT%TZ)" "$op" "$status" "$details" >>"$audit_log"
}

write_status() {
  local request_dir=$1
  local status=$2
  printf '%s\n' "$status" >"$request_dir/status"
}

run_apt_install() {
  local request_dir=$1
  has_capability "apt-install" || {
    printf 'capability apt-install is not active\n' >"$request_dir/stderr"
    write_status "$request_dir" 126
    log_action "apt-install" "packages=denied" 126
    return
  }
  local packages_file="$request_dir/packages"
  if [[ ! -f $packages_file ]]; then
    printf 'missing package list\n' >"$request_dir/stderr"
    write_status "$request_dir" 2
    log_action "apt-install" "packages=missing" 2
    return
  fi
  mapfile -t packages <"$packages_file"
  if [[ ${#packages[@]} -eq 0 ]]; then
    printf 'package list is empty\n' >"$request_dir/stderr"
    write_status "$request_dir" 2
    log_action "apt-install" "packages=empty" 2
    return
  fi
  if apt-get update >"$request_dir/stdout" 2>"$request_dir/stderr" \
    && apt-get install -y --no-install-recommends "${packages[@]}" >>"$request_dir/stdout" 2>>"$request_dir/stderr"; then
    write_status "$request_dir" 0
    log_action "apt-install" "packages=${packages[*]}" 0
    return
  fi
  write_status "$request_dir" 1
  log_action "apt-install" "packages=${packages[*]}" 1
}

run_packet_capture() {
  local request_dir=$1
  has_capability "packet-capture" || {
    printf 'capability packet-capture is not active\n' >"$request_dir/stderr"
    write_status "$request_dir" 126
    log_action "packet-capture" "interface=denied" 126
    return
  }
  local iface_file="$request_dir/interface"
  [[ -f $iface_file ]] || {
    printf 'missing interface\n' >"$request_dir/stderr"
    write_status "$request_dir" 2
    log_action "packet-capture" "interface=missing" 2
    return
  }
  local iface filter_file output_file stdout_mode
  iface=$(<"$iface_file")
  filter_file="$request_dir/filter"
  output_file="$request_dir/output"
  stdout_mode=0
  [[ -f "$request_dir/stdout_mode" ]] && stdout_mode=$(<"$request_dir/stdout_mode")
  local -a cmd=(tcpdump -i "$iface")
  if [[ -s $filter_file ]]; then
    local filter
    filter=$(<"$filter_file")
    local -a filter_tokens=()
    read -r -a filter_tokens <<< "$filter"
    cmd+=("${filter_tokens[@]}")
  fi
  if [[ -s $output_file ]]; then
    local capture_path
    capture_path=$(<"$output_file")
    mkdir -p "$(dirname "$capture_path")"
    cmd+=(-w "$capture_path")
  fi
  if [[ $stdout_mode == "1" ]]; then
    "${cmd[@]}" >"$request_dir/stdout" 2>"$request_dir/stderr" || {
      write_status "$request_dir" 1
      log_action "packet-capture" "interface=$iface stdout=1" 1
      return
    }
  else
    "${cmd[@]}" >"$request_dir/stdout" 2>"$request_dir/stderr" || {
      write_status "$request_dir" 1
      log_action "packet-capture" "interface=$iface stdout=0" 1
      return
    }
  fi
  write_status "$request_dir" 0
  log_action "packet-capture" "interface=$iface stdout=$stdout_mode" 0
}

while true; do
  shopt -s nullglob
  request_dirs=("$queue_dir"/*.req)
  shopt -u nullglob
  if [[ ${#request_dirs[@]} -eq 0 ]]; then
    sleep 1
    continue
  fi
  for request_dir in "${request_dirs[@]}"; do
    [[ -d $request_dir ]] || continue
    [[ ! -f "$request_dir/status" ]] || continue
    op=$(<"$request_dir/op")
    : >"$request_dir/stdout"
    : >"$request_dir/stderr"
    case "$op" in
      apt-install)
        run_apt_install "$request_dir"
        ;;
      packet-capture)
        run_packet_capture "$request_dir"
        ;;
      *)
        printf 'unknown operation %s\n' "$op" >"$request_dir/stderr"
        write_status "$request_dir" 2
        log_action "$op" "unknown=1" 2
        ;;
    esac
  done
done