use jppe::{BorrowByteDecode, BorrowByteEncode};
use jppe_derive::{BorrowByteEncode, BorrowByteDecode};


#[derive(Debug, Default, PartialEq, Eq, BorrowByteEncode, BorrowByteDecode)]
pub struct Tcp<'a> {
    pub sport: u16,
    pub dport: u16,
    pub seq: u32,
    pub ack: u32,
    #[jppe(bits_start=0xf000, value_decode="header_length * 4", value_encode="header_length / 4", untake)]
    pub header_length: u16,
    #[jppe(bits=0x0fff)]
    pub flags: u16,
    pub window: u16,
    pub checksum: u16,
    pub urgent_pointer: u16,
    #[jppe(length="header_length - 20")]
    pub options: &'a [u8],
}


fn main() {
    let input = b"\xc8\xd3\x01\xf6\xe0\x76\x90\x16\xc4\x44\x9b\x5a\x80\x18\xff\xff\
    \x6c\x1c\x00\x00\x01\x01\x08\x0a\x37\xc4\x50\xe2\x00\xba\x7c\x1c";    

    // decode
    let (input_remain, value) = Tcp::decode(input, None, None).unwrap();
    println!("{value:?} {input_remain:?}");
    assert_eq!(value, Tcp {
        sport: 51411,
        dport: 502,
        seq: 3765866518,
        ack: 3292830554,
        header_length: 32,
        flags: 24,
        window: 65535,
        checksum: 27676,
        urgent_pointer: 0,
        options: b"\x01\x01\x08\x0a\x37\xc4\x50\xe2\x00\xba\x7c\x1c",
    } );

    // encode
    let mut buf = vec![];
    value.encode(&mut buf, None, None);
    assert_eq!(buf, input);
    assert_eq!(input_remain.is_empty(), true);
}