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

my $IN = new CGI;
print $IN->header(-type  =>  'application/json');

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

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 { ERROR => "No ids matched `$data_id'.\n\n" };
  }
  
  $sth->finish;
  return { 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", $callback);
  }
  my $res;
  
  for($params->{f}){
    /info/ && do {
      unless(defined $params->{id}) { not_specified_error("id"); };
      $res = mysql_retrieve('SELECT * FROM shaders WHERE id = ?', $params->{id});
      last;
    };
    /all/ && do { 
      $res =  mysql_retrieve('select * from shaders order by id'); 
      last;
    };
    /range/ && do {
      unless (defined $params->{limit}){ not_specified_error("limit") };
      $res = mysql_retrieve(' select * from shaders order by id desc limit ? , ?', ($params->{last} || 0), $params->{limit});
      last;
    };
    /history/ && do{ 
      unless(defined $params->{id}) { not_specified_error("id"); };
      $res = mysql_retrieve('SELECT * FROM shaders WHERE shader_id = ? order by id', $params->{id});
      last;
    };
    /username/ && do{
      unless(defined $params->{username}) { not_specified_error("username") };
      $res = mysql_retrieve('select * from shaders where username = ?', $params->{username}); 
      last;
    };
    /list_users/ && do{
      $res = mysql_retrieve('select distinct username from shaders;');
      last;
    };
    /originals/ && do{
      $res =  mysql_retrieve('select shaders.* from shader_ids cross join shaders on shader_ids.id = shaders.shader_id'); 
      last; 
    };
    response({ ERROR => "Function parameter f improperly defined"}, $callback);
    exit(1);
  }
  response($res, $callback);
}
main();
exit(0);