if [ -z "${__stopwatch_sh_loaded}" ]
then
  __stopwatch_sh_loaded=yes

  __stopwatch_sh_VERSION="Stopwatch v0.1"
  __stopwatch_sh_DESCRIPTION="Stopwatch implementation supporting multiple tagged timers"
  __stopwatch_sh_COPYRIGHT=$( cat <<"END_OF_COPYRIGHT"

Copyright (c) 2000-2012, CyberLeo
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

    * Redistributions of the source code must retain the above copyright
      notice, this list of conditions, and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions, and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    * Neither the name of the organization nor the names of its contributors
      may be used to endorse or promote products derived from this software
      without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILTY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

END_OF_COPYRIGHT
)

  [ "${kvs}" ] || {
    kvs="$(mktemp -t ".stopwatch.XXXXXXXX")"
    trap "rm -f '${kvs}'" exit hup int term kill
  }
  want kvs

  stopwatch_help() {
    cat <<EOF >&2
${__stopwatch_sh_VERSION}
${__stopwatch_sh_DESCRIPTION}

${__stopwatch_sh_COPYRIGHT}

Usage: stopwatch <tag> <start|lap|stop|reset>

Simple bourne shell based stopwatch
Requires 'kvs' and the id 'stopwatch' therein
so make sure you set 'kvs' before sourcing this script if necessary.

After loading, the following commands are available:

Start a stopwatch
  stopwatch <tag> start

'Lap' a stopwatch (emit timer value without stopping)
  stopwatch <tag> lap

Stop a stopwatch; can be resumed later with 'start'
  stopwatch <tag> stop

Reset a stopwatch back to zero
  stopwatch <tag> reset

EOF
    kill -ABRT $$
  }

  # Try and format a passed integer number of seconds into something more
  # useful (like 6m10s or something)
  _stopwatch_timefmt() {
    local secs mins hurs days
    [ "${1}" -a "$(echo "${1}" | tr -Cd '0-9')" = "${1}" ] || return 255
    secs="${1}"
    mins=0
    hurs=0
    [ "${secs}" -lt 60 ] || {
      mins=$(( ${secs} / 60 ))
      secs=$(( ${secs} % 60 ))
    }
    [ "${secs}" -gt 0 ] || secs=""
    [ "${mins}" -lt 60 ] || {
      hurs=$(( ${mins} / 60 ))
      mins=$(( ${mins} % 60 ))
    }
    [ "${mins}" -gt 0 ] || mins=""
    [ "${hurs}" -lt 24 ] || {
      days=$(( ${hurs} / 24 ))
      hurs=$(( ${hurs} % 24 ))
    }
    [ "${hurs}" -gt 0 ] || hurs=""

    [ "${days}" -o "${hurs}" -o "${mins}" -o "${secs}" ] || printf "0s"
    printf "%s%s%s%s" "${days:+${days}d}" "${hurs:+${hurs}h}" "${mins:+${mins}m}" "${secs:+${secs}s}"
  }

  # Start a named stopwatch, but do nothing if the named stopwatch is already
  # running.
  stopwatch_start() {
    name="${1:-stopwatch}"
    [ "${nao}" ] || nao="$(date +%s)"
    # Is the stopwatch running?
    if kvs_has_key stopwatch "${name}"
    then
      printf "Stopwatch: %s is already running.\n" "${name}"
    else
      # start the stopwatch
      accum="$(kvs_get stopwatch "${name}_accumulator")"
      kvs_set stopwatch "${name}" "${nao}"
      [ "${accum}" ] && restart="$(printf " at %s" "$(_stopwatch_timefmt "${accum}")")"
      printf "Stopwatch: %s starts running%s.\n" "${name}" "${restart}"
    fi
  }

  # 'Lap' the named stopwatch: print out a line indicating how long the named
  # stopwatch has been running, but do not stop nor reset the stopwatch.
  stopwatch_lap() {
    name="${1:-stopwatch}"
    [ "${nao}" ] || nao="$(date +%s)"
    # Is the stopwatch running?
    if kvs_has_key stopwatch "${name}"
    then
      # emit a line indicating how long it has been running
      start="$(kvs_get stopwatch "${name}")"
      accum="$(kvs_get stopwatch "${name}_accumulator")"
      delta="$(( ${nao} - ${start} ))"
      [ "${accum}" ] && delta="$(( ${delta} + ${accum} ))"
      printf "Stopwatch: %s is running at %s.\n" "${name}" "$(_stopwatch_timefmt "${delta}")"
    else
      accum="$(kvs_get stopwatch "${name}_accumulator")"
      [ "${accum}" ] && printf "Stopwatch: %s is stopped at %s.\n" "${name}" "$(_stopwatch_timefmt "${accum}")"
    fi
  }

  # Stop the named stopwatch and print out a line indicating how long it had
  # been running up until that point; do not reset the stopwatch.
  stopwatch_stop() {
    name="${1:-stopwatch}"
    [ "${nao}" ] || nao="$(date +%s)"
    if kvs_has_key stopwatch "${name}"
    then
      start="$(kvs_get stopwatch "${name}")"
      accum="$(kvs_get stopwatch "${name}_accumulator")"
      delta="$(( ${nao} - ${start} ))"
      [ "${accum}" ] && delta="$(( ${delta} + ${accum} ))"
      kvs_set stopwatch "${name}_accumulator" "${delta}"
      kvs_unset stopwatch "${name}"
      printf "Stopwatch: %s stops running at %s.\n" "${name}" "$(_stopwatch_timefmt "${delta}")"
    else
      accum="$(kvs_get stopwatch "${name}_accumulator")"
      [ "${accum}" ] && printf "Stopwatch: %s is already stopped at %s.\n" "${name}" "$(_stopwatch_timefmt "${accum}")"
    fi
  }

  # Reset the named stopwatch back to zero.
  stopwatch_reset() {
    name="${1:-stopwatch}"
    [ "${nao}" ] || nao="$(date +%s)"
    kvs_unset stopwatch "${name}"
    kvs_unset stopwatch "${name}_accumulator"
    printf "Stopwatch: %s is reset to 0s.\n" "${name}"
  }

  stopwatch() {
    [ "${1}" -a "${2}" ] || stopwatch_help;
    nao="$(date +%s)"
    case "${2}" in
    [Ss][Tt][Aa][Rr][Tt])  stopwatch_start "${1}"  ;;
    [Ll][Aa][Pp])          stopwatch_lap "${1}"    ;;
    [Ss][Tt][Oo][Pp])      stopwatch_stop "${1}"   ;;
    [Rr][Ee][Ss][Ee][Tt])  stopwatch_reset "${1}"  ;;
    *)                     stopwatch_help          ;;
    esac
  }
fi