#!/usr/bin/perl -w -s


use Data::Dumper;
use LWP::Simple;
use IO::Socket qw(:DEFAULT :crlf);
use Net::hostent; # for OO version of gethostbyaddr
use POSIX 'WNOHANG';

use constant PORT => 2007;

our $CACHE_DIR = "cache";
mkdir($CACHE_DIR) unless(-d $CACHE_DIR);
system("touch $CACHE_DIR/cache.info") unless(-f "$CACHE_DIR/cache.info");


our $ERROR_PAGE = "$CACHE_DIR/error.html";

# Configuraçao do socket e mensagens de diagnostico
$listen_socket = IO::Socket::INET->new( Proto     => 'tcp',
                                 LocalPort => PORT,
                                 Listen    => SOMAXCONN,
                                 Reuse     => 1);
die "can't setup server" unless $listen_socket;
warn "[SProxy running and waiting for connections ...]\n";
warn "[SProxy $0 accepting clients at ".PORT."]\n";

# Night of the Living Dead :-)
$SIG{CHLD} = sub {while(waitpid(-1, WNOHANG)>0){}};

# quit handler (Ctrl+C (SIGINT) )
my $quit = 0;
$SIG{INT} = sub { 
		$quit++ 
	};

while(!$quit) {
	next unless my $connection = $listen_socket->accept; # Chegou cliente!
	my $peer = gethostbyaddr($connection->peeraddr,AF_INET) || $connection->peerhost; #TODO
	my $port = $connection->peerport;
	warn "Accepted connection from $peer:$port\n";
	
	#my $ip = $connection->peeraddr;
	#my $host = gethostbyaddr($ip,AF_INET);
	#my $port = $connection->peerport;
	#warn "Accepted connection for client at IP: $peer, ADDRESS: $peer, PORT: $port\n";
	
	defined(my $child = fork()) or die "Can't fork: $!\n";
	if($child == 0) {
		$listen_socket->close;
		conn_handler($connection);
		exit 0;
	}
	$connection->close;
}

sub conn_handler {
	my $sock = shift;
	my $answer;
	while(<$sock>) { #TODO mais tarde sera: $/=\n\n e analisar pedido `a lupa.
		chomp;
		my $req = $_;
		$answer = req_handler($req);
		print $sock $answer."\n";
	}
}

sub req_handler {
	use Digest::MD5;
	my $req = shift;
	my $content;
	my ($type,$url);
	if($req=~/^(\w+)\s+(.*)/g) { ($type,$url) = ($1,$2); } #Verifica request na forma: GET url (por exemplo)

	stats_handler($url);
	
	my $head = head($url);
	if(!$head) { $content = `cat $ERROR_PAGE`; }
	elsif($type eq "GET") {
		if(in_cache($url)) {
			my $head = head($url);
			warn "$url: temos sim senhor!\n";
			my $path = url2path($url);
			$content = `cat $path`;
		} else {
			warn "$url: essa eh nova!\n";
			$content = new_page($url);
		}
	}
	$content;
}

sub new_page {
	my $url = shift;
	use URI;
	use Digest::MD5;
	my $uri = URI->new($url);
    my ($host,$path,$query) = ($uri->host,$uri->path,$uri->query);
    my @path_segments = array_rem_empty($uri->path_segments);
	my $tail = pop(@path_segments);
    my $path2 = "$CACHE_DIR/$host/"; mkdir($path2);
    map { $path2.="$_/"; mkdir($path2); } @path_segments;
    $content = get($url);
	my ($content_type, $document_length, $modified_time, $expires, $server) = head($url);
	my $md5 =  Digest::MD5::md5_hex($content);
    $content = transf($content);
    open(F,">$path2$tail"); print F $content; close F;
    open(F,">>$CACHE_DIR/cache.info"); print F "$url§$modified_time§$expires§$md5\n"; close F;
	$content;
}

sub array_rem_empty {
	my @foo = ();
	map { push(@foo,$_) if($_=~m/./g) } @_;
	@foo;
}

sub url2path {
	my $url = shift;
	use URI;
	my $uri = URI->new($url);
	my ($host,$path,$query) = ($uri->host,$uri->path,$uri->query);
	my @path_segments = array_rem_empty($uri->path_segments);
	my $tail = pop(@path_segments);
	my $path2 = "$CACHE_DIR/$host/".join("/",@path_segments)."/$tail";
	$path2;
}

sub path2url {
}

sub in_cache {
	my $url = shift;
	return (grep {/$url§/} split(/\n/,`cat $CACHE_DIR/cache.info`));
}

sub stats_handler {
	my ($url,$content) = @_;
}

sub transf {
	my $content = shift;
	$content=~s/\n//g;
	$content;
}