#!/usr/bin/perl
#
# Copy a file to stdout, with progress metering to stderr.
#	- Cameron Simpson <cs@zip.com.au> 18sep2002
#

use cs::Misc;
use cs::Upd;
use cs::Units;
use Getopt::Std;

sub copyout($;$);

$::BSize=65536;
$::Type=BINARY;
$::Units=CHAR;

$::Usage="Usage: $::cmd [-b iosize] [-BDlc] [files...]
	-b iosize	Read/write buffer size. Default: $::BSize
	-B		Use \"binary\" units (default).
	-D		Use \"decimal\" units.
	-c		Count characters (default).
	-l		Count lines.
";

$::Xit=0;

{ my $badopts=0;
  my %opt;
  getopts('b:BDcl',\%opt) || ($badopts=1);
  if (defined $opt{'b'})	{ $::BSize=$opt{'b'}+0; }
  if (defined $opt{'B'})	{ $::Type=BINARY; }
  if (defined $opt{'D'})	{ $::Type=DECIMAL; }
  if (defined $opt{'c'})	{ $::Units=CHAR; }
  if (defined $opt{'l'})	{ $::Units=LINE; }

  die $::Usage if $badopts;
}

if (! @ARGV)
{ @ARGV='-';
}

for my $f (@ARGV)
{ if ($f eq '-')
  { copyout(STDIN) || ($::Xit=1);
  }
  else
  { if (! open(COPYIN, "< $f\0"))
    { warn "$::cmd: can't read from $f: $!\n";
      $::Xit=1;
    }
    else
    { copyout(COPYIN,$f) || ($::Xit=1);
      close(COPYIN);
    }
  }
}

exit $::Xit;

sub human($;$)
{ my($n,$t)=@_;
  $t=$::Type if ! defined $t;
  return scalar( $t eq BINARY ? cs::Units::bytes2human($n,1) : cs::Units::num2human($n,1) );
}

sub copyout($;$)
{ my($FILE,$file)=@_;

  if (defined $file)
  { out("$file:");
  }

  my $size = (eval "stat($FILE)")[7];
  if (! -f _ || $size < 1)
  { undef $size;
  }

  local($_);
  my $n;
  my $off;

  my $start = time;
  my $sofar = 0;
  my $now;

  my($thruput,$pcnt,$eta);

  READ:
  while (defined($n=sysread($FILE,$_,$::BSize)) && $n > 0)
  { 
    # chuck the data out the back as early as possible
    WRITE:
    for ($off=0; $off<length; $off+=$n)
    { $n=syswrite(STDOUT,$_,length($_)-$off,$off);
      if (! defined $n)
      { warn "$::cmd: write error on stdout: $!\n";
	return 0;
      }
    }
    # and _then_ report throughput

    if ($::Units eq CHAR)
    { $sofar+=$n;
    }
    elsif ($::Units eq LINE)
    {
      my $off=0;
      LOOP:
      while (1)
      { $off=index($_,"\n",$off);
	last LOOP if $off < 0;
	$sofar++;
	$off++;
      }
    }
    else
    { die "$::cmd: unsupported units \"$::Units\"\n";
    }

    if (($now=time) > $start)
    { $elapsed=$now-$start;
      $thruput=human($sofar/$elapsed,1)."/s";
    }
    else
    { $thruput='';
    }

    if (defined $size && $size > 0)
    { $pcnt=int($sofar*100/$size)."%";
      if ($elapsed > 0)
      { $eta=sprintf("ETA: %6s",scalar(cs::Units::sec2human(int(($size-$sofar)/($sofar/$elapsed)+0.5))));
      }
      else
      { $eta='';
      }
    }
    else
    { $pcnt='';
      $eta=sprintf( ($::Units eq CHAR ? "Bytes: %4s" : "Lines: %4s"), human($sofar) );
    }
    out( (defined $file ? "$file: " : '').sprintf("%6s %4s %s",$thruput,$pcnt,$eta) );
  }

  if (($now=time) > $start)
  { $elapsed=$now-$start;
    $thruput=cs::Units::bytes2human($sofar/$elapsed,1)."/s";
  }
  else
  { $thruput='';
  }
  out('');
  nl( (defined $file ? "$file: " : '')
     .sprintf("%6s Size: %s Time: %s",
		$thruput,human($sofar),scalar(cs::Units::sec2human($elapsed))
	     )
    );

  if (! defined $n)
  { warn "$::cmd: read error: $!\n";
    return 0;
  }

  return 1;
}