#include <ros/common.h>
#include <assert.h>
#include <socket.h>
#include <bits/netinet.h>
#include <net.h>
#include <net/ip.h>
#include <net/udp.h>
#include <net/tcp_impl.h>
#include <ros/errno.h>
#include <net/nic_common.h>

/* statically configured next gateway */
const uint8_t GTWAY[6] = {0xda, 0x76, 0xe7, 0x4c, 0xca, 0x7e};

/* TODO: ip id unique for all ip packets? or is it unique for a flow? */
// can do atomic increment at a minimum
static uint16_t ip_id = 0;

/* TODO: build arp table, and look up */
int eth_send(struct pbuf *p, struct in_addr *dest) {
	uint32_t bytes_sent; 
	printk("size of pbuf_header movement %d\n", sizeof(struct ethernet_hdr));
	if (pbuf_header(p, sizeof(struct ethernet_hdr)) != 0){
		warn("eth_send buffer ran out");
		/* unsuccessful, needs to allocate */	
		return -ENOBUFS;
	}

	struct ethernet_hdr *ethhdr = (struct ethernet_hdr *)p->payload; 
	// TODO: for now just forward to gateway
	memcpy(ethhdr->dst_mac, GTWAY, 6);
	memcpy(ethhdr->src_mac, device_mac, 6);
	ethhdr->eth_type = htons(IP_ETH_TYPE);
	/* The reason for not sending to send_nic for each pbuf in the chain
	 * is so that we can send from multi-buffer later.
	 */
	if (send_pbuf){
		bytes_sent = send_pbuf(p);
		return bytes_sent;
	}
	else {
		warn("no pbuf send function \n");
		return -1;
	}
	/* is the address local , if no, search for MAC of the gateway and dest to gateway */
	/* if address is local, use arp etc */

}

/* while it would be nice to write a generic send_pbuf it is impossible to do so in
 * efficiently.
 */
/* Assume no ip options */
int ip_output(struct pbuf *p, struct in_addr *src, struct in_addr *dest, 
							uint8_t ttl, uint8_t tos, uint8_t proto) {
	struct pbuf *q;
	struct ip_hdr *iphdr;
	printk ("ip output reached\n");
	/* TODO: Check for IP_HDRINCL */
	if (dest->s_addr == IP_HDRINCL) {
		/*send right away since */
		warn("header included in the ip packets");
		return -1;
	}
	if (pbuf_header(p, IP_HDR_SZ)) {
		warn("buffer ran out");
		/* unsuccessful, needs to allocate */	
		return -ENOBUFS;
	}
	iphdr = (struct ip_hdr *) p->payload;

	/* successful */
	iphdr->version = IPPROTO_IPV4;
	/* assume no IP options */
	iphdr->hdr_len = IP_HDR_SZ >> 2;
	if (tos != 0) {
		iphdr->tos = htons(tos);
	}
	else {
		iphdr->tos = 0;
	}
	iphdr->packet_len = htons(p->tot_len);
	// TODO: NET_LOCK
	iphdr->id = htons (ip_id); // 1
	ip_id++;
	iphdr->flags_frags = htons(0); // 4000  may fragment
	iphdr->protocol = proto;
	iphdr->ttl = ttl; //DEFAULT_TTL;
	/* Eventually if we support more than one device this may change */
	printk("src ip %x, dest ip %x \n", src->s_addr, dest->s_addr);
	iphdr->src_addr = htonl(src->s_addr);
	iphdr->dst_addr = (dest->s_addr);
	/* force hardware checksum
	 * TODO: provide option to do both hardware/software checksum
	 */
	/* Since the IP header is set already, we can compute the checksum. */
	/* TODO: Use the card to calculate the checksum */
	iphdr->checksum = 0;
	iphdr->checksum = ip_checksum(iphdr); //7ab6
	if (p->tot_len > DEFAULT_MTU) /*MAX MTU? header included */
		return -1;//ip_frag(p, dest);
	else
		return eth_send(p, dest);
}

int ip_input(struct pbuf *p) {
	uint32_t iphdr_hlen, iphdr_len;
	struct ip_hdr *iphdr = (struct ip_hdr *)p->payload;
	//printk("start of ip %p \n", p->payload);
	//print_pbuf(p);
	/* use that info to build arp table */
  if (iphdr->version != 4) {
		warn("ip version not 4!\n");
    pbuf_free(p);
		return -1;
	}
	iphdr_hlen = iphdr->hdr_len * 4;
	iphdr_len = ntohs(iphdr->packet_len);
	// printk("ip input coming from %x of size %d", ntohs(iphdr->dst_addr), iphdr_len);
  /* header length exceeds first pbuf length, or ip length exceeds total pbuf length? */
  if ((iphdr_hlen > p->len) || (iphdr_len > p->tot_len)) {
    if (iphdr_hlen > p->len) {
        warn("IP header (len 0x%X) does not fit in first pbuf (len %X), IP packet dropped.\n",
        iphdr_hlen, p->len);
    }
    if (iphdr_len > p->tot_len) {
        warn("IP (len %X) is longer than pbuf (len %X), IP packet dropped.\n",
        iphdr_len, p->tot_len);
    }
    /* free (drop) packet pbufs */
    pbuf_free(p);
    return -1;
  }
	if (ip_checksum(iphdr) != 0) {
		warn("checksum failed \n");
		pbuf_free(p);
		return -1;
	}

	/* check if it is destined for me? */
	/* XXX: IP address for the interface is IP_ANY */
	if (ntohl(iphdr->dst_addr) != LOCAL_IP_ADDR.s_addr){
		printk("dest ip in network order%x\n", ntohl(iphdr->dst_addr));
		printk("dest ip in network order%x\n", LOCAL_IP_ADDR.s_addr);
		warn("ip mismatch \n");
		pbuf_free(p);
		/* TODO:forward packets */
		// ip_forward(p, iphdr, inp);
	}

	if ((ntohs(iphdr->flags_frags) & (IP_OFFMASK | IP_MF)) != 0){
		panic ("ip fragment detected\n");
		pbuf_free(p);
	}

	//printk ("loc head %p, loc protocol %p\n", iphdr, &iphdr->protocol);
	/* currently a noop, compared to the memory wasted, cutting out ipheader is not really saving much */
	// pbuf_realloc(p, iphdr_len);
	switch (iphdr->protocol) {
		case IPPROTO_UDP:
			return udp_input(p);
		case IPPROTO_TCP:
			tcp_input(p);
			// XXX: error handling for tcp
			return 0;
		default:
			printk("IP protocol type %02x\n", iphdr->protocol);
			warn("protocol not supported! \n");
	}
	return -1;
}

void print_ipheader(struct ip_hdr* iph){

	
}