use Data::Dumper;

my $foo = "one,123,a s d f,a,b,c,d,e,f,g,h";
my @bar = $foo =~ /^([a-z]{3}),([0-9]{3}),([a-z\s]{1,7}),(?:([a-z]),|([a-z]$)){1,}/;

print Dumper(\@bar);