use HTTP::Proxy;
use HTTP::Proxy::HeaderFilter::simple;
use HTTP::Proxy::Engine::NoFork;
use Config::IniFiles;

#initialize ini file loading
my $ini = 'SM_Proxy.ini';
my $cfg = new Config::IniFiles(-file => $ini);
die "invalid ini file $ini" unless defined($cfg);

#reads specified config file entry
sub read_cfg {
  my ($section, $key) = @_;
  my $val = $cfg->val($section, $key);
  die "undefined key $key in section $section" unless defined($val);
  $val;
}

#read values from ini file
my $port = read_cfg('proxy_setup', 'port');
my $header_key = read_cfg('proxy_setup', 'header_key');
my $header_value = read_cfg('proxy_setup', 'header_value');

#define proxy and header filter(adding entry read from ini file to each request header)
my $proxy = HTTP::Proxy->new( host => "127.0.0.1", port => $port );
my $filter = HTTP::Proxy::HeaderFilter::simple->new(
  sub { $_[1]->header( $header_key => $header_value); }
);
$proxy->push_filter( request => $filter );
$proxy->start;