time_funcs

#!/bin/bash

shopt -s extglob

# usage: hr_to_s TIME
# Converts TIME of the format [HH:]MM:SS to seconds, printing the result to the
# standand output. Returns 0 if successful, 1 if not (usually due to an invalid
# TIME). Requires extended globs to be enabled prior to the function definition
# (shopt -s extglob)
hr_to_s() {
  local tm len t mult secs=0

  # validate TIME
  if [[ $1 != ?(+([0-9]):)?([0-9])[0-9]:?([0-9])[0-9] ]]; then
    return 1
  fi

  # split TIME into an array
  IFS=: read -ra tm <<<"$1"
  len=${#tm[@]}

  # loop backwards over each element, adding the value and the appropriate
  # multiplier to the final value
  for ((t=len-1, mult=1; t>=0; t--, mult*=60)); do
    ((secs += tm[t] * mult))
  done

  printf '%d\n' "$secs"
}

# usage: s_to_hr SECS
# Converts SECS seconds to the human readable format HH:MM:SS, printing the new
# timestamp to the standard output. Returns 0 if successful, 1 if not (because
# SECS is not a valid integer).
s_to_hr() {
  local hrs=$1 mins secs

  # validate SECS
  if [[ $hrs = *[!0-9]* ]]; then
    return 1
  fi

  # get the hours, minutes, and seconds using basic math
  ((secs = hrs % 60,
    hrs = hrs / 60,
    mins = hrs % 60,
    hrs = hrs / 60))

  # print the converted timestamp
  printf '%02d:%02d:%02d\n' "$hrs" "$mins" "$secs"
}


# usage: s_to_shr SECS
# Converts SECS seconds to the human readable format [HH:[MM:]]SS, where HH
# and MM are only added as needed (if it's only 5 minutes, the result will be
# 05:00, whereas for 3 hours it would be 03:00:00). Prints the result to the
# standard output. Returns 0 if successful, 1 if not (because SECS is not a
# valid integer).
s_to_shr() {
  local hrs=$1 mins secs

  # validate SECS
  if [[ $hrs = *[!0-9]* ]]; then
    return 1
  fi

  # get the hours, minutes, and seconds using basic math
  ((secs = hrs % 60,
    hrs = hrs / 60,
    mins = hrs % 60,
    hrs = hrs / 60))

  # print the converted timestamp
  if ((hrs)); then
    printf '%02d:%02d:%02d\n' "$hrs" "$mins" "$secs"
  elif ((mins)); then
    printf '%02d:%02d\n' "$mins" "$secs"
  else
    printf '%02d\n' "$secs"
  fi
}

# usage: s_to_wdhr SECS
# Converts SECS seconds to the human readable format W weeks, D days, HH:MM:SS,
# printing the result to the standard output. Returns 0 if successful, 1 if not
# (because SECS is not a valid integer).
s_to_wdhr() {
  local wks=$1 days hrs mins secs

  # validate SECS
  if [[ $wks = *[!0-9]* ]]; then
    return 1
  fi

  # get the weeks, days, hours, minutes and seconds using basic math
  ((secs = wks % 60,
    wks = wks / 60,
    mins = wks % 60,
    wks = wks / 60,
    hrs = wks % 24,
    wks = wks / 24,
    days = wks % 7,
    wks = wks / 7))

  # print the converted timestamp
  printf '%d weeks, %d days, %02d:%02d:%02d\n' \
         "$wks" "$days" "$hrs" "$mins" "$secs"
}

# usage: s_to_swdhr SECS
# Converts SECS seconds to the human readable format
# [W weeks, [D days, [HH:[MM:]]]]SS, where "W weeks", "D days", HH and MM are
# only added as needed (if it's only 5 minutes, the result will be 05:00,
# whereas for 3 hours it would be 03:00:00, and 10 weeks and 3 days would be
# "10 weeks, 3 days, 00:00:00"). Prints the result to the standard output.
# Returns 0 if successful, 1 if not (because SECS is not a valid integer).
s_to_swdhr() {
  local wks=$1 days hrs mins secs

  # validate SECS
  if [[ $wks = *[!0-9]* ]]; then
    return 1
  fi

  # get the weeks, days, hours, minutes and seconds using basic math
  ((secs = wks % 60,
    wks = wks / 60,
    mins = wks % 60,
    wks = wks / 60,
    hrs = wks % 24,
    wks = wks / 24,
    days = wks % 7,
    wks = wks / 7))

  # print the converted timestamp
  if ((wks)); then
    printf '%d weeks, %d days, %02d:%02d:%02d\n' \
           "$wks" "$days" "$hrs" "$mins" "$secs"
  elif ((days)); then
    printf '%d days, %02d:%02d:%02d\n' "$days" "$hrs" "$mins" "$secs"
  elif ((hrs)); then
    printf '%02d:%02d:%02d\n' "$hrs" "$mins" "$secs"
  elif ((mins)); then
    printf '%02d:%02d\n' "$mins" "$secs"
  else
    printf '%02d\n' "$secs"
  fi
}