//
//  Beacon.m
//
//  This class implements a simple UDP broadcast facilty for discovery of
//  devices on the same subnet.
//
//  Created by Simon Urbanek on 2/6/12.
//  Copyright 2012 Simon Urbanek. All rights reserved.
//

#import "Beacon.h"

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <ifaddrs.h>

// for now it uses static payload
static const char beacon_pkt[] = "BEACON1!";

@implementation Beacon

- (id) initWithPort: (int) beaconPort
{
	self = [super init];
	if (self != nil) {
		int broadcast = 1;
		send_sock = -1;
		active = 1;
		port = beaconPort;
		recv_sock = socket(AF_INET, SOCK_DGRAM, 0);
		if (recv_sock != -1) {
			setsockopt(recv_sock, SOL_SOCKET, SO_BROADCAST, &broadcast, sizeof (broadcast));
		
			struct sockaddr_in saSocket;
			memset(&saSocket, 0, sizeof(saSocket));
			saSocket.sin_family      = AF_INET;
			saSocket.sin_addr.s_addr = htonl(INADDR_ANY);
			saSocket.sin_port        = htons(port);
			
			bind(recv_sock, (struct sockaddr *) &saSocket, sizeof(saSocket));
			
			[NSThread detachNewThreadSelector:@selector(receivingThread:) toTarget:self withObject:nil];
			[NSThread detachNewThreadSelector:@selector(broadcastThread:) toTarget:self withObject:nil];
		}
	}
	return self;
}

+ (Beacon*) beaconWithPort: (int) port
{
	Beacon *beacon = [[Beacon alloc] initWithPort:port];
	if (beacon) [beacon autorelease];
	return beacon;
}

- (void) sendBeaconTo: (struct in_addr) dstAddr
{
	if (send_sock == -1) {
		int broadcast = 1;
		send_sock = socket(AF_INET, SOCK_DGRAM, 0);
		if (send_sock != -1)
			setsockopt(send_sock, SOL_SOCKET, SO_BROADCAST, &broadcast, sizeof (broadcast));
	}
	if (send_sock != -1) {
		struct sockaddr_in addr;
		memset(&addr, 0, sizeof(addr));
		addr.sin_family = AF_INET;
		addr.sin_port = htons(port);
		addr.sin_addr = dstAddr;
		char dbuf[64];
		NSLog(@" - sending beacon to %s",
		      inet_ntop(addr.sin_family, &addr.sin_addr, dbuf, sizeof(dbuf)));
		sendto(send_sock, beacon_pkt, 8, 0, (struct sockaddr*) &addr, sizeof(addr));
	}
}

- (void) broadcast
{
	struct ifaddrs *ia, *root;
	if (!getifaddrs(&root)) {
		ia = root;
		while (ia) {
			NSLog(@"interface '%s', family: %d (expecting %d)", ia->ifa_name, ia->ifa_dstaddr ? ia->ifa_dstaddr->sa_family : -1, AF_INET);
			if (ia->ifa_dstaddr && ia->ifa_dstaddr->sa_family == AF_INET)
				[self sendBeaconTo:((struct sockaddr_in*)ia->ifa_dstaddr)->sin_addr];
			ia = ia->ifa_next;
		}
		freeifaddrs(ia);
	}
}

- (void) receivingThread: (id) dummy
{
	NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
	while (active) {
		char buf[64], dbuf[64];
		struct sockaddr_in addr;
		socklen_t al = sizeof(addr);
		int n = recvfrom(recv_sock, buf, sizeof(buf), 0, (struct sockaddr*) &addr, &al);
		inet_ntop(addr.sin_family, &addr.sin_addr, dbuf, sizeof(dbuf));
		NSLog(@" - received %d bytes from %s", n, dbuf);
		if (n == 8 && !memcmp(buf, beacon_pkt, 8) && delegate && [delegate respondsToSelector:@selector(didReceiveBeaconFrom:)])
			[delegate performSelectorOnMainThread:@selector(didReceiveBeaconFrom:) withObject:[NSString stringWithUTF8String:dbuf] waitUntilDone:NO];
			
	}
	[pool release];
}

- (void) broadcastThread: (id) dummy
{
	NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
	while (active) {
		[self broadcast];
		[NSThread sleepForTimeInterval:10.0];
	}
	[pool release];
}

- (id) delegate
{
	return delegate;
}

- (void) setDelegate: (id) newDelegate
{
	if (delegate == newDelegate) return;
	if (delegate)
		[delegate release];
	[delegate = newDelegate retain];
}

#ifdef TEST_ME
- (void) didReceiveBeaconFrom: (NSString*) src
{
	NSLog(@"didReceiveBeaconFrom: %@", src);
}
#endif

@end

#ifdef TEST_ME
int main(int ac, char**av) {
	NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
	Beacon *beacon = [[Beacon alloc] initWithPort:12345];
	[beacon setDelegate:beacon];
	[[NSRunLoop currentRunLoop] run];
	[pool release];
	return 0;
}
#endif