use std::net::{IpAddr, Ipv4Addr, SocketAddr};
use std::env;

use cross_socket::datalink::interface::Interface;
use cross_socket::packet::ethernet::EtherType;
use cross_socket::packet::ip::IpNextLevelProtocol;
use cross_socket::packet::tcp::{TcpFlag, TcpOption, TcpPacketBuilder};
use cross_socket::socket::{DataLinkSocket, IpVersion, Socket, SocketOption, SocketType};

// Send TCP SYN packets to 1.1.1.1:80 and check reply
// This example is for Unix(Linux, macOS ...) only.
// For Windows, use examples/datalink_socket/tcp_ping.rs instead.
// (Due to Winsock2 limitation.)
fn main() {
    let interface: Interface = match env::args().nth(1) {
        Some(n) => {
            // Use interface specified by user
            let interfaces: Vec<Interface> = default_net::get_interfaces();
            let interface: Interface = interfaces
                .into_iter()
                .find(|interface| interface.name == n)
                .expect("Failed to get interface information");
            interface
        },
        None => {
            // Use default interface
            default_net::get_default_interface().expect("Failed to get default interface information")
        }
    };
    let use_tun: bool = interface.is_tun();
    let src_ip: IpAddr = IpAddr::V4(interface.ipv4[0].addr);
    let dst_ipv4: Ipv4Addr = Ipv4Addr::new(1, 1, 1, 1);
    let dst_ip: IpAddr = IpAddr::V4(dst_ipv4);
    let dst_socket_addr: SocketAddr = SocketAddr::new(dst_ip, 80);
    let socket_option = SocketOption {
        ip_version: IpVersion::V4,
        socket_type: SocketType::Raw,
        protocol: Some(IpNextLevelProtocol::Tcp),
        timeout: None,
        ttl: None,
        non_blocking: false,
    };
    // Sender socket
    let socket: Socket = Socket::new(socket_option).unwrap();

    // Receiver socket
    // RAW SOCKET recvfrom not working for TCP. So we use DataLinkSocket instead.
    let mut listener_socket: DataLinkSocket = DataLinkSocket::new(interface, false).unwrap();

    // Packet builder for TCP SYN
    let mut tcp_packet_builder = TcpPacketBuilder::new(
        SocketAddr::new(src_ip, 53443),
        SocketAddr::new(dst_ip, 80),
    );
    tcp_packet_builder.flags = vec![TcpFlag::Syn];
    tcp_packet_builder.options = vec![
        TcpOption::mss(1460),
        TcpOption::sack_perm(),
        TcpOption::nop(),
        TcpOption::nop(),
        TcpOption::wscale(7),
    ];

    // Send TCP SYN packet to 1.1.1.1
    match socket.send_to(&tcp_packet_builder.build(), dst_socket_addr) {
        Ok(packet_len) => {
            println!("Sent {} bytes", packet_len);
        }
        Err(e) => {
            println!("Error: {}", e);
        }
    }

    // Receive packets
    println!("Waiting for TCP SYN+ACK... ");
    loop {
        match listener_socket.receive() {
            Ok(packet) => {
                if use_tun {
                    // Logic for TUN interface
                    let ip_packet =
                        cross_socket::packet::ipv4::Ipv4Packet::from_bytes(&packet);
                    if ip_packet.next_protocol != IpNextLevelProtocol::Tcp
                        || ip_packet.source != dst_ipv4
                    {
                        continue;
                    }
                    println!("Received {} bytes from {}", packet.len(), ip_packet.source);
                    let tcp_packet =
                        cross_socket::packet::tcp::TcpPacket::from_bytes(&ip_packet.payload);
                    println!("Packet: {:?}", tcp_packet);
                    break;
                }else {
                    let ethernet_packet =
                        cross_socket::packet::ethernet::EthernetPacket::from_bytes(&packet);
                    if ethernet_packet.ethertype != EtherType::Ipv4 {
                        continue;
                    }
                    let ip_packet =
                        cross_socket::packet::ipv4::Ipv4Packet::from_bytes(&ethernet_packet.payload);
                    if ip_packet.next_protocol != IpNextLevelProtocol::Tcp
                        || ip_packet.source != dst_ipv4
                    {
                        continue;
                    }
                    println!("Received {} bytes from {}", packet.len(), ip_packet.source);
                    let tcp_packet =
                        cross_socket::packet::tcp::TcpPacket::from_bytes(&ip_packet.payload);
                    println!("Packet: {:?}", tcp_packet);
                    break;
                }
            }
            Err(e) => {
                println!("Error: {}", e);
            }
        }
    }
}