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use pnet::packet::util::checksum as generic_checksum;
use pnet::packet::Packet;
use std::net::Ipv4Addr;
use L4Checksum;

macro_rules! icmp_pkt_macro_generator {
  ($($name:ident => $icmp_type:ty), *) => {
    $(
      #[macro_export]
      macro_rules! $name {
        ($args:tt, $payload_pkt:expr, $proto:expr, $buf:expr) => {{
          icmp!($args, $payload_pkt, $icmp_type, $buf) 
        }};
        ($args:tt, $buf:expr) => {{
          icmp!($args, $icmp_type, $buf) 
        }}; 
      }
    )*
  };
}

macro_rules! icmp_checksum_func_gen {
  ($($icmp_type:ty),*) => {
    $(
      impl <'p>L4Checksum for $icmp_type {
        fn checksum_ipv4(&mut self, _source: &Ipv4Addr, _destination: &Ipv4Addr) {
          // ICMP checksum is the same as IP
          self.set_checksum(generic_checksum(&self.packet(), 1)); 
        }
      }
    )*
  };
}

icmp_checksum_func_gen!(pnet::packet::icmp::echo_reply::MutableEchoReplyPacket<'p>, 
                        pnet::packet::icmp::echo_request::MutableEchoRequestPacket<'p>, 
                        pnet::packet::icmp::destination_unreachable::MutableDestinationUnreachablePacket<'p>, 
                        pnet::packet::icmp::time_exceeded::MutableTimeExceededPacket<'p>); 

icmp_pkt_macro_generator!(icmp_echo_req => pnet::packet::icmp::echo_request::MutableEchoRequestPacket,
                          icmp_echo_reply => pnet::packet::icmp::echo_reply::MutableEchoReplyPacket,
                          icmp_dest_unreach => pnet::packet::icmp::destination_unreachable::MutableDestinationUnreachablePacket,
                          icmp_time_exceed => pnet::packet::icmp::time_exceeded::MutableTimeExceededPacket);

#[macro_export]
macro_rules! icmp {
   ({$($func:ident => $value:expr), *}, $icmp_type:ty, $buf:expr) => {{
      let total_len = <$icmp_type>::minimum_packet_size();
      let buf_len = $buf.len();
      let mut pkt = <$icmp_type>::new(&mut $buf[buf_len - total_len..]).unwrap();
      pkt.set_icmp_type(IcmpTypes::EchoRequest);
      $(
        pkt.$func($value);
      )*
      (pkt, pnet::packet::ip::IpNextHeaderProtocols::Icmp)
   }};
   ({$($func:ident => $value:expr), *}, $payload_pkt:expr, $icmp_type:ty, $buf:expr) => {{
      let total_len = <$icmp_type>::minimum_packet_size() + $payload_pkt.packet().len();
      let buf_len = $buf.len();
      let mut pkt = <$icmp_type>::new(&mut $buf[buf_len - total_len..]).unwrap();
      pkt.set_icmp_type(IcmpTypes::EchoRequest);
      $(
        pkt.$func($value);
      )*
      (pkt, pnet::packet::ip::IpNextHeaderProtocols::Icmp)
   }};
}


#[cfg(test)]
mod tests {
   use pnet::packet::Packet;
   use ::payload;
   use payload::PayloadData;
   use pnet::packet::icmp::{IcmpTypes};
   use icmp;

   #[test]
   fn macro_icmp_basic() {
      let mut buf = [0; 13];
      let (pkt, proto) = icmp_dest_unreach!({set_icmp_type => IcmpTypes::DestinationUnreachable},
        payload!({"hello".to_string().into_bytes()}, buf).0, None, buf);
      assert_eq!(proto, pnet::packet::ip::IpNextHeaderProtocols::Icmp);

      let buf_expected = vec![0; 13];
      let mut pkt_expected = pnet::packet::icmp::destination_unreachable::MutableDestinationUnreachablePacket::owned(buf_expected).unwrap();
      pkt_expected.set_icmp_type(IcmpTypes::DestinationUnreachable);
      pkt_expected.set_payload(&"hello".to_string().into_bytes()); 
      assert_eq!(pkt_expected.packet(), pkt.packet());
   }
}