#!/usr/bin/env bash

if [[ -v IS_SOURCED_UTIL ]]; then return 0; fi
IS_SOURCED_UTIL=1

# Show the usage if requested and exit
maybe_show_usage_and_exit() {
  local -r arg="${1}"
  if [[ "${arg}" =~ ^(-h|-(-)?help)$ ]]; then
    printf %s "${USAGE:-No help}" 1>&2
    exit 0
  fi
}

# Get the ms since the epoch until now
tick_now() {
  local -r out_name="${1}"
  printf -v "${out_name}" %.0f "$(date +%s.%N)"e3
}

# Get the ms since the epoch until the given at spec
tick_at() {
  local -r out_name="${1}" at_spec="${2}"
  local -i now_ms now_s h m s s_to_d
  tick_now now_ms
  if [[ "${at_spec}" =~ ^[0-9]+$ ]]; then
    printf -v "${out_name}" %d $((now_ms + at_spec))
  else
    now_s=$((now_ms / 1000))
    case "${at_spec}" in
      m)
        printf -v "${out_name}" %d $(((now_s + 60 - now_s % 60) * 1000))
        ;;
      h)
        printf -v "${out_name}" %d $(((now_s + 3600 - now_s % 3600) * 1000))
        ;;
      d)
        # Work off the local time to account for the timezone since the
        # epoch is aligned to a UTC day boundary
        read -r h m s < <(date +'%H %M %S')
        s_to_d=$(((24 - h) * 3600 - m * 60 - s))
        printf -v "${out_name}" %d $(((now_s + s_to_d) * 1000))
        ;;
      *)
        return 1
        ;;
    esac
  fi
}

# Get the ms from now until the given ms since the epoch
ms_until() {
  local -r out_name="${1}" until_ms="${2}"
  local -i now_ms
  tick_now now_ms
  printf -v "${out_name}" %d $((until_ms - now_ms))
}

# Convert integer milliseconds to floating point seconds
ms_to_s() {
  local -r out_name="${1}"
  local -ri ms="${2}"
  printf -v "${out_name}" %.3f "${ms}e-3"
}

# Map the module file name to the module function
mod_to_fn() {
  local -r out_name="${1}" file_name="${2}"
  printf mod_%s "${file_name//-/_}"
}

# Get the pid of the ancestor process with the given name
root_pid() {
  local -r out_name="${1}"
  local -ri pid="${2:-$$}"
  local -r root_name="${3:-login}"
  local -i current_pid="${pid}"
  local name
  while [[ "${current_pid}" -ne 1 ]]; do
    if [[ ! -r "/proc/${current_pid}/status" ]]; then return 1; fi
    mapfile info < \
      <('grep' --null -E -m 2 '^(Name|PPid):' "/proc/${current_pid}/status" \
        | 'sort' | 'cut' -f 2)
    name="${info[0]##[[:space:]]}"
    name="${name%%[[:space:]]}"
    if [[ "${name}" = "${root_name}" ]]; then
      printf -v "${out_name}" %s "${current_pid}"
      return 0
    fi
    current_pid="${info[1]##[[:space:]]}"
    current_pid="${current_pid%%[[:space:]]}"
  done
  return 1
}