#!/usr/bin/perl
# Perl V Problems V & VI
# CSHL 2013 PFB
####################
# Hashes from a file
#######################
use warnings;
use strict;

## Problem V
my $fasta = shift @ARGV;
my %sequences;   # Empty hash, will store fasta sequences from file
my $c = 0; # seq counter
my $seq = '';
my $k; 
open(FAS,'<',$fasta) or die "Can't open $fasta: $!\n";

while(my $line = <FAS>)
{
  chomp $line;
  if ($line =~ m/^>/)
  {
    $c++;
    if($c > 1)
    {
      $sequences{$k} = $seq;
      $seq = '';
    }
    $k = $line;
  }
  else
  {
    $seq .= $line;
  }
}

$sequences{$k} = $seq;

close(FAS);

## Problem VI
# Check the contents of the hash
foreach my $key (keys %sequences)
{
  print "$key:$sequences{$key}\n";
}

print "\n\n\n\n";

# Sort first
foreach my $key (sort keys %sequences)
{
  print "$key:$sequences{$key}\n";
}
print "\n\n\n\n";

# Sort numeric, small to large by value
foreach my $key (sort { length($sequences{$a}) <=> length($sequences{$b})} keys %sequences)
{
  print "$key:$sequences{$key}\t",length($sequences{$key}),"\n";
}
print "\n\n\n\n";

# Sort numeric, large to small by value
foreach my $key (sort {length($sequences{$b}) <=> length($sequences{$a}) }keys %sequences)
{
  print "$key:$sequences{$key}\t",length($sequences{$key}),"\n";
}