rowbot/rowbot

#!/usr/bin/env bash

###
# feature switch toggling
###

shopt -s dotglob extglob lastpipe nullglob

###
# utility and helper functions
###

any_file() {
  local files=( "${1:-.}"/* ) max idx

  if (( ${#files[@]} > 1 )); then
    (( max = ${#files[@]} - 1 ))
    idx=$(random 0 "$max")
    printf %s "${files[$idx]}"
  fi
}

die() {
  local fmt=$1
  shift
  # This is a wrapper around printf so the format string isn't known ahead of
  # time.
  # shellcheck disable=SC2059
  printf "$fmt\n" "$@" >&2
  exit "${STATUS:-42}"
}

get_option() {
  if (( $# != 2 )); then
    return 1
  fi

  local var_name=${1//-/_}
  local env_var=${var_name^^}

  if [[ -v $env_var ]]; then
    config[$1]=${!env_var}
  elif [[ -v opts[$1] ]]; then
    config[$1]=${opts[$1]}
  elif [[ -v $var_name ]]; then
    config[$1]=${!var_name}
  else
    config[$1]=$2
  fi
}

has() {
  if (( $# )); then
    hash "$1" 2>/dev/null
  else
    return 1
  fi
}

is_parent() {
  (( BASHPID == $$ ))
}

is_reloaded() {
  [[ $RELOADED = yes ]] || (( LORE_LIVES > 1 ))
}

random() {
  local min=$1 max=$2
  (( (RANDOM % max) + min ))
}

run_callbacks() {
  if (( ! $# )); then
    return 1
  fi

  local filter=$1
  shift

  while IFS= read -r; do
    "$REPLY" "$@"
  done < <(compgen -A function "$filter")

  return 0
}

###
# configure rowbot's environment
###

# parse command line arguments

declare -A opts
cmd_line=( "${@:0}" )

while (( $# )); do
  case $1 in
  --*=*)
    key=${1#--} key=${key%%=*}
    opts[$key]=${1#--*=}
    ;;
  --no-*)
    key=${1#--no-}
    opts[$key]=no
    ;;
  --)
    shift
    break
    ;;
  --*)
    key=${1#--}
    opts[$key]=yes
    ;;
  *)
    break
  esac

  shift
done

# load custom configuration files

for file do
  if [[ -f $file ]]; then
    # These files (if any) are provided dynamically at run-time.
    # shellcheck disable=SC1090
    . "$file" # ha, dot file
  else
    die "could not locate config file %s" "$file"
  fi
done

# cleanup

unset key file

###
# load default config
###

declare -A config

# irc registration settings

get_option nick rowbot-dev
get_option ident rowbot
get_option realname rowbot
get_option chan ""

# bot control settings

get_option owner "${USER:-uplime}"
get_option trigger \`
get_option dev yes

###
# bootup sequence
###

on_first_001_bootup() {
  log_info "rowbot's pid is %d" "$$"
}

###
# logger
###

log() {
  if [[ -v LOG_LEVEL ]] && (( log_levels[$log_level] <= log_levels[$LOG_LEVEL] )); then
    printf "%s: $1\n" "${LOG_LEVEL^^}" "${@:2}" >&"$log_fd"
  fi
}

log_debug() {
  LOG_LEVEL=debug log "$@"
}

log_info() {
  LOG_LEVEL=info log "$@"
}

log_warn() {
  LOG_LEVEL=warn log "$@"
}

log_error() {
  LOG_LEVEL=error log "$@"
}

log_has_level() {
  local level

  for level in "${!log_levels[@]}"; do
    if [[ ${1,,} = "$level" ]]; then
      return 0
    fi
  done

  return 1
}

on_init_001_log() {
  declare -gA log_levels=( [debug]=1 [info]=2 [warn]=3 [error]=4 )
  get_option log-level info

  if ! log_has_level "${config[log-level]}"; then
    die "%s is not a valid logging level" "${config[log-level]}"
  fi

  get_option log ""
  get_option overwrite no
  log_level=${config[log-level]}

  if [[ ${config[log]} ]]; then
    if [[ ${config[overwrite]} = yes ]]; then
      exec {log_fd}>"${config[log]}"
    else
      exec {log_fd}>>"${config[log]}"
    fi
  else
    log_fd=1
  fi
}

on_exit_001_log() {
  if [[ -v log_fd ]] && (( log_fd != 1 )); then
    exec {log_fd}>&-
  fi
}

###
# net code
###

net_recv() {
  declare -n sock_line=$1
  IFS= read -r "$1" <&"$in_sock"
  sock_line=${sock_line%$'\r'}
  log_debug "received line: %s" "$sock_line"
}

net_send() {
  local fmt
  # As this is a printf wrapper, the format string is provided as an argument.
  # shellcheck disable=SC2059
  printf -v fmt "$1" "${@:2}"
  printf '%s\r\n' "$fmt" >&"$out_sock"
  log_debug "sending line: %s" "$fmt"
}

on_init_002_net() {
  get_option server irc.libera.chat
  get_option tls no

  if [[ ${config[tls]} = no ]]; then
    get_option port 6667
  else
    get_option client-cert ""
    get_option port 6697
  fi
}

on_first_002_net() {
  local irc_sock conn_args

  if [[ ${config[tls]} = no ]]; then
    log_info "rowbot is connecting to irc://%s:%s" "${config[server]}" "${config[port]}"
    exec {irc_sock}<>/dev/tcp/"${config[server]}"/"${config[port]}"
    in_sock=$irc_sock out_sock=$irc_sock
  else
    if ! has socat; then
      die "please install socat to use tls with rowbot."
    fi

    log_info "rowbot is connecting to ircs://%s:%s" "${config[server]}" "${config[port]}"
    sock_dir=$(mktemp -d)
    log_debug "socket directory is %s" "$sock_dir"
    mkfifo "$sock_dir"/rowbot-{in,out}.sock

    # This is a false positive
    # shellcheck disable=SC2102
    if [[ -v config[client-cert] ]]; then
      if [[ ! -f ${config[client-cert]} ]]; then
        die "client certificate not found: %s" "${config[client-cert]}"
      fi

      conn_args=OPENSSL:${config[server]}:${config[port]},cert=${config[client-cert]}
    else
      conn_args=OPENSSL:${config[server]}:${config[port]}
    fi

    socat "$conn_args" - <"$sock_dir"/rowbot-in.sock >"$sock_dir"/rowbot-out.sock &
    tls_pid=$!
    exec {out_sock}>"$sock_dir"/rowbot-out.sock {in_sock}<"$sock_dir"/rowbot-in.sock
    log_debug "process %d is handling tls" "$tls_pid"
  fi
}

###
# cleanup
###

cleanup() {
  log_info "There’s a lot of beauty in ordinary things. Isn’t that kind of the point?"
  run_callbacks on_exit_
}

trap cleanup EXIT

###
# live code reloader
###

reload_config() {
  local setting setting_name
  run_callbacks on_before_

  for setting in "${!config[@]}"; do
    setting_name=${setting//-/_}
    export "${setting_name^^}"="${config[$setting]}"
  done

  exec "${cmd_line[@]}"
}

reload_hup() {
  log_info "received reload signal (HUP)"
  reload_config
}

trap reload_hup HUP

###
# initialization sequence
###

run_callbacks on_init_

if is_reloaded; then
  run_callbacks on_after_
else
  run_callbacks on_first_
fi