#!/usr/bin/perl -s

BEGIN
{

  $usage = <<"  DONE"
  Usage:
  $0 [-h] [-ms] [-ts=FRACTION] INTEGER [INTEGER ...]
    -h
        Display this help message.
    -ms
        Display timings in milliseconds.
        Default is to use seconds instead.
    -ts=FRACTION
        Specify a time signature with FRACTION, i.e. 6/8, 4/2.
        Default is 4/4.
    INTEGER
        Number of beats per minute.
  Example: $0 -ts=3/4 96
  DONE
  ;

  if($h) #user wants help
  {
      print($usage);
      exit(0);
  } #end if

  if(!@ARGV)
  {
      warn("!No arguments given.\n${usage}");
      exit(1);
  } #end

  sub positive_integer($)
  {
      $_[0] > 0 and $_[0] eq int $_[0];
  } #end sub

  if($ms) #milliseconds switch
  {
      $main::time_factor = 60_000; #milliseconds per minute
      $main::time_unit = 'ms';
  } #end if
  else
  {
      $main::time_factor = 60; #seconds per minute
      $main::time_unit = 's';
  } #end else

  if($ts) #time signature switch
  {
      my($numerator, $denominator) = split('/', $ts);
      if(positive_integer($numerator) && positive_integer($denominator))
      {
          $main::beats_per_bar = $numerator;
          $main::note_value = $denominator;
      } #end if:if
      else
      {
          warn(qq/!:Invalid time signature: ${ts}\n${usage}"/);
          exit(2);
      } # end if:else
  } #end if
  else
  {
      $main::beats_per_bar = 4;
      $main::note_value = 4;
  } #end else

  sub beat_length($)
  {
      $time_factor * 4/$note_value / $_[0];
  } #end sub
  sub bar_length($)
  {
      $beats_per_bar * beat_length($_[0]);
  } #end sub

} #end BEGIN


### Main program ###

foreach $beats_per_minute(@ARGV)
{
    if(positive_integer($beats_per_minute))
    {
        printf
        (
            "%sBPM: beat = %g %s, bar = %g %s\n",
            $beats_per_minute,
            beat_length($beats_per_minute), $time_unit,
            bar_length($beats_per_minute), $time_unit
        );
    } #end foreach:if
    else
    {
        warn("!Not a positive integer: ${beats_per_minute}\n${usage}");
    } #end foreach:else
} #end foreach

### End of main program ###