#!/usr/bin/perl 
use DBI;
use Data::Dumper;
use JSON;
use feature qw/switch/;
use CGI;

my $IN = new CGI;
print $IN->header();

our $json =  JSON->new->allow_nonref;
my $sql_username = "asdfus";
my $sql_dbname = "asdfus";         
my $sql_passwd = "gTYgT&M6q";

 
sub not_specified_error{
my $param = shift;
  print $json->pretty->encode ({ ERROR => sprintf("Function parameter %s not defined", $param ) });
  exit(1);
}

our $dbh = DBI->connect("DBI:mysql:$sql_dbname", $sql_username, $sql_passwd)
  or die "Couldn't connect to database: " . DBI->errstr;
sub mysql_retrieve{
  my ($statement, @args) = @_;
  my $sth = $dbh->prepare($statement)
    or die "Couldn't prepare statement: " . $dbh->errstr;
  $sth->execute(@args) 
    or die "Couldn't execute statement: " . $sth->errstr;
  my @rows = ();
  while ($data = $sth->fetchrow_hashref()) {
    foreach (keys $data){
      $data->{$_} =~ s/NULL|null//ig;
      $data->{$_} = $data->{$_} || ""; 
    }
    push(@rows, $data);
  }
  if ($sth->rows == 0) {
    return $json->pretty->encode ({ ERROR => "No ids matched `$data_id'.\n\n" });
  }
  
  $sth->finish;
  return $json->pretty->encode({ SUCCESS => 1, data => \@rows });
}

sub main{
  my $params = {};
  my $query_string = $ENV{'QUERY_STRING'};
  my @pairs = split(/[&;]/, $query_string);
  foreach(@pairs){
   my ($key, $value) = split(/=/, $_, 2);

   $params->{$key} = $value;
  }
  my $callback = $params->{'callback'} || undef

  unless(defined $params->{f}){
    not_specified_error("f");
  }
  my $res;
  
  given($params->{f}){
    when(/info/){ 
      unless(defined $params->{id}) { not_specified_error("id"); };
      $res = mysql_retrieve('SELECT * FROM shaders WHERE id = ?', $params->{id});
    }
    when(/all/){ 
      $res =  mysql_retrieve('select * from shaders order by id'); 
    }
    when(/range/){
      unless (defined $params->{limit}){ not_specified_error("limit") };
      if (defined $params->{last}){
        $res = mysql_retrieve(sprintf(' select * from shaders order by id desc limit %s , %s', $param->{last}, $params->{limit}));
      }else{
        $res = mysql_retrieve(sprintf(' select * from shaders order by id desc limit 0 , %s', $params->{limit}));
      }
    }
    when(/history/){ 
      unless(defined $params->{id}) { not_specified_error("id"); };
      $res = mysql_retrieve('SELECT * FROM shaders WHERE shader_id = ? order by id', $params->{id});
    }
    when(/username/){
      unless(defined $params->{username}) { not_specified_error("username") };
      $res = mysql_retrieve('select * from shaders where username = ?', $params->{username}); 
    }
    when(/list_users/){
      $res = mysql_retrieve('select distinct username from shaders;');
    }
    when(/originals/){
      $res =  mysql_retrieve('select shaders.* from shader_ids cross join shaders on shader_ids.id = shaders.shader_id'); 
    }
    default { 
      if (defined $callback) {
        print $callback + "(";
        print $json->pretty->encode ({ ERROR => "Function parameter f improperly defined"}); 
        print ")";
      }
      else {
        print $json->pretty->encode ({ ERROR => "Function parameter f improperly defined"}); 
      }
      exit(1);
    }; 
  }
  if (defined $callback) {
    print $callback + "(" + $res + ")";
  }
  else {
    print $res;
  }
}
main();
exit(0);