#!/usr/bin/env bash

# exit if required variables are not set
set -o nounset

# interpret all arguments as the command to be run
command_to_run="$*"

# set timezone for error time stamps
timezone="America/Chicago"

# set log file path
log_directory="${HOME}/logs/errwrapper/$(TZ="${timezone}" date +%Y-%m-%d)"
log_name="$(TZ="${timezone}" date +%H%M%S.%N)_$(basename "${1}" ".sh").log"
log_file="${log_directory}/${log_name}"

# configure mailer
mail_from=""
mail_auth=""
mail_to=""
mail_server=""
mail_port=""
mail_password="$(cat "${HOME}/.mailauth")"

# configure pid file location
pid_directory="${HOME}/pids"
pid_file="${pid_directory}/$(basename "${1}" ".sh").pid"

# commands required for script execution
required_commands="swaks twilio.sh"

# configure sms
sms_to=""

function check_dependencies() {
  local missing_counter
  missing_counter=0
  for command in ${required_commands}; do
    if ! hash "${command}" >/dev/null 2>&1; then
      printf "Command not found in PATH: %s\n" "${command}" >&2
      ((missing_counter++))
    fi
  done
  if ((missing_counter > 0)); then
    printf "%d or more commands are missing from PATH. Exiting.\n" "${missing_counter}" >&2
    exit 1
  fi
}

function check_pid() {
  if [ ! -d "${pid_directory}" ]; then
    mkdir -p "${pid_directory}"
  fi
  if [ -f "${pid_file}" ]; then
    echo "Another instance seems to already be running. Please kill it before running again."
    exit 1
  else
    if ! { echo $$ > "${pid_file}"; } 2>/dev/null; then
      echo "Specified pid file location ${pid_file} is not writable. Exiting."
      exit 1
    fi
  fi
}

function cleanup() {
  if ! rm "${pid_file}"; then
    echo "Cleanup failed. You may need to manually remove ${pid_file}."
  fi
}

function log_command() {
  if [ ! -d "${log_directory}" ]; then
    if ! mkdir -p "${log_directory}"; then
      echo "Failed to create logging directory ${log_directory}. Exiting."
      exit 1
    fi
  fi

  {
    # log the command invocation
    echo -e "### Command: ${command_to_run} ###\n"

    # log the start time
    echo -e "### Started at $(TZ="${timezone}" date +%r) on $(TZ="${timezone}" date +%F) ###\n"

    # log the command output
    ( ${command_to_run} )

    # store the exit code
    return_code="$?"

    # log the stop time
    echo "### Stopped at $(TZ="${timezone}" date +%r) on $(TZ="${timezone}" date +%F) ###"
  } >> "${log_file}"

  # return the exit code of the subcommand
  return "${return_code}"
}

function send_mail() {
  swaks \
    --body - \
    --to "${mail_to}" \
    --header "Subject: ${subject}" \
    --from "${mail_from}" \
    --server "${mail_server}:${mail_port}" \
    --auth LOGIN \
    --auth-user "${mail_auth}" \
    --auth-password "${mail_password}" \
    -tlsc \
    >/dev/null 2>&1 \
    < "${log_file}"
}

function send_sms() {
  echo "${subject}" | twilio.sh "${sms_to}" >/dev/null 2>&1
}

function set_path() {
  if [ -d "${HOME}/bin" ] ; then
    PATH="$HOME/bin:$PATH"
  else
    echo "Private bin directory not found."
    exit 1
  fi
}

function main() {
  # set path for running in cron
  set_path

  # check for required script dependencies
  check_dependencies

  # check if another instance of the script is running, or didn't exit cleanly
  check_pid

  # clean up pid file on exit
  trap cleanup EXIT

  # run the command passed as an argument, logging output
  log_command

  # store the exit code
  return_code="$?"

  # do nothing if the previous command succeeded
  if [ "${return_code}" -eq 0 ]; then
    exit 0
  fi

  # set the subject for the email and the contents of the sms
  subject="\`${command_to_run}\` failed on $(hostname) at $(TZ="${timezone}" date +%Y/%m/%d-%H:%M:%S)"

  # send an email containing the command name, time, and output
  send_mail

  # send an sms containing the command name and time
  send_sms

  # exit with the return code of the above command
  exit "${return_code}"
}

# run the script
main