#!/usr/bin/perl
# ##D:/Perl/bin/perl.exe
#
# atomrest.pl - a Perl implementation of the AtomAPI
# draft 6: http://bitworking.org/rfc/draft-gregorio-06.html
#
# future names: dormant.pl or inert.pl (What else do you call an atom at rest?)
#
# by Isofarro
#

# Configuration
# Configuration
#my $fileRoot = "D:/www/default/rest";	# The filesystem root directory
#my $urlRoot = "http://localhost/rest";	# The root URL of the REST folder
#my $scriptRoot = "http://localhost/cgi-bin/atomrest.pl"; # self reference to the REST root
my $fileRoot = "/home/isofarro/public_html/rest";	# The filesystem root directory
my $urlRoot = "http://www.isolani.co.uk/rest";	# The root URL of the REST folder
my $scriptRoot = "http://www.isolani.co.uk/cgi-bin/atomrest.pl"; # self reference to the REST root

# ------------------------------------------------------------------------- #
# Request-Method
my $requestMethod;

# Content-Length of the response body
my $contentLength;  

# The XML string
my $xmlString;

# Path Information
my $pathInfo;

init();

if ($requestMethod =~ /^GET$|^POST$|^PUT$|^DELETE$/) {
	&doGet		if ($requestMethod eq "GET");
	&doPost		if ($requestMethod eq "POST");
	&doPut		if ($requestMethod eq "PUT");
	&doDelete	if ($requestMethod eq "DELETE");
} else {
	returnStatusError("400 Bad Request");
}

#debugInfo();	
#&debugInfo();
	
#print end_html;

# ------------------------------------------------------------------------- #
#    Atom Functions
# ------------------------------------------------------------------------- #

sub listBlogEntries() {
	if (-d "$fileRoot$pathInfo") {
		opendir(DIR, "$fileRoot$pathInfo") ||
			die "Couldn't open directory $fileRoot$pathInfo: $!\n";
		print "Content-Type: text/xml\n\n";
		print "<?xml version=\"1.0\" encoding=\"iso-8859-1\"?>\n";
		print "<feed version=\"0.1\" xmlns=\"http://example.com/newformat#\">\n";

		while (defined($file = readdir(DIR))) {
			if (-f "$fileRoot$pathInfo$file") {
				print "\t<entry>\n";
				print "\t\t<link>$scriptRoot$pathInfo$file</link>\n";
				print "\t\t<id>$scriptRoot$pathInfo$file</id>\n";
				print "\t</entry>\n\n";
			}
		}
		print "</feed>\n";
		closedir(DIR);
	} else {
		returnStatusMessage("404 Not Found");
	}
}


# ------------------------------------------------------------------------- #
#    HTTP request handers
# ------------------------------------------------------------------------- #
sub doGet() {
	if ($pathInfo) {
		if (-f "$fileRoot$pathInfo") {
			open (ENTRY, "<$fileRoot$pathInfo") ||
				die "Couldn't open $fileRoot$pathInfo for writing: $!\n";
			print "Content-Type: text/xml\n\n";
			while (<ENTRY>) {
				print $_;
			}
			close(ENTRY);
		} elsif (-d "$fileRoot$pathInfo") {
			# It may be a root request
			&listBlogEntries();
		} else {
			# TODO redirect back to the blog index via a get
			#returnRedirect("");
			returnStatusMessage("404 Not Found");
		}
	} else {
		&debugInfo();
		#returnStatusMessage("404 Not Found");
	}
}

sub doPost() {
	if ($pathInfo) {
		if (-d "$fileRoot$pathInfo") {
			$fileName = &getNewFileName();
			open(ENTRY, ">$fileRoot$pathInfo$fileName") ||
				die "Couldn't open $fileRoot$pathInfo$fileName for writing: $!\n";
			print ENTRY $xmlString;
			close(ENTRY);
			returnStatusMessage("201 Created");
		} else {
			returnStatusMessage("520 Bogus Resource");			
		}
	} else {
		# No PathInfo, so no REST resource found
		returnStatusMessage("404 Not Found");
	}
}

sub doPut() {
	if ($pathInfo) {
		if (-f "$fileRoot$pathInfo") {
			open (ENTRY, ">$fileRoot$pathInfo") ||
				die "Couldn't open $fileRoot$pathInfo for updating: $!\n";
			print ENTRY $xmlString;
			close(ENTRY);
			returnStatusMessage("201 Created");
		} else {
			# The actual resource to be updated doesn't exist
			returnStatusMessage("404 Not Found");
		}
	} else {
		# No PathInfo so no REST resources found
		returnStatusMessage("404 Not Found");
	}
}

sub doDelete() {
	if ($pathInfo) {
		if (-f "$fileRoot$pathInfo") {
			unlink("$fileRoot$pathInfo") ||
				die "Can't delete $fileRoot$pathInfo: $!\n";
		} else {
			returnStatusMessage("403 Forbidden");
		}
	} else {
		returnStatusMessage("404 Not Found");
	}
}

sub init() {
	$requestMethod = $ENV{'REQUEST_METHOD'};
	$pathInfo = $ENV{'PATH_INFO'};
	
	# Populate the xmlString on a POST or PUT
	if ($requestMethod eq "POST" || $requestMethod eq "PUT") {
		$xmlString = getRequestBody();
	} else {
		$xmlString="";
	}
}

sub getRequestBody() {
	my ($in);
	binmode STDIN;
	read(STDIN,$in,$ENV{'CONTENT_LENGTH'}) ||
		die "Can't read from STDIN: $!\n";
	
	return $in;
}

sub getNewFileName() {
	# Just loop around looking for the next available timestamp
	# I probably should do some file locking beforehand incase of simultaneous access
	$fileName = time() . ".xml";
	while (-e "$fileRoot$pathInfo$fileName") {
		sleep(1);
		$fileName = time() . ".xml";
	}
	return $fileName;
}

sub returnStatusMessage() {
	my ($msg) = @_;
	print "Status: $msg\n\n";
	exit();
}

sub debugInfo() {
	print "Status: 201 Created\n";
	print "Content-type: text/plain\n\n";

	print $xmlString;
	print "\n\n";
	print "PathInfo:      $pathInfo\n";
	print "RequestMethod: $requestMethod\n";
	print "\n";
}