use tokio::{
    io::{AsyncReadExt, BufReader},
    net::tcp::OwnedReadHalf,
};

use num_enum::TryFromPrimitive;
use tracing::debug;

#[derive(Debug)]
pub struct SdlanTcp {
    pub _packet_id: u32,
    pub packet_type: PacketType,
    pub current_packet: Vec<u8>,
}

#[derive(Debug, Copy, Clone, TryFromPrimitive)]
#[repr(u8)]
pub enum EventType {
    KnownIP = 0x01,

    DropIP = 0x02,

    NatChanged = 0x03,

    SendRegister = 0x04,

    NetworkShutdown = 0xFF,
}

#[derive(Debug, Copy, Clone, TryFromPrimitive)]
#[repr(u8)]
pub enum StunProbeAttr {
    None = 0,
    Port = 1,
    Peer = 2,
}

#[derive(Debug, Copy, Clone, TryFromPrimitive)]
#[repr(u8)]
pub enum NatType {
    Blocked = 0,
    NoNat = 1,
    FullCone = 2,
    PortRestricted = 3,
    ConeRestricted = 4,
    Symmetric = 5,
    Invalid = 0xff,
}

#[derive(Debug, Copy, Clone, TryFromPrimitive)]
#[repr(u8)]
pub enum NakMsgCode {
    InvalidToken = 1,
    NodeDisabled = 2,
    NoIpAddress = 3,
    NetworkFault = 4,
    InternalFault = 5,
}

#[derive(Debug, Copy, Clone, TryFromPrimitive)]
#[repr(u8)]
pub enum PacketType {
    Empty = 0x00,
    RegisterSuper = 0x01,
    RegisterSuperACK = 0x02,
    RegisterSuperNAK = 0x04,

    UnRegisterSuper = 0x05,

    QueryInfo = 0x06,
    PeerInfo = 0x07,

    Ping = 0x08,
    Pong = 0x09,

    Event = 0x10,

    Command = 0x11,
    CommandACK = 0x12,

    FlowTracer = 0x15,

    Register = 0x20,
    RegisterACK = 0x21,

    StunRequest = 0x30,
    StunReply = 0x31,

    StunProbe = 0x32,
    StunProbeReply = 0x33,

    Data = 0xff,
}

pub async fn read_a_packet(
    reader: &mut BufReader<OwnedReadHalf>,
) -> Result<SdlanTcp, std::io::Error> {
    debug!("read a packet");
    let size = reader.read_u16().await?;
    debug!("1");
    let packet_id = reader.read_u32().await?;
    debug!("2");
    let packet_type = reader.read_u8().await?;
    debug!("3");

    if size < 5 {
        return Err(std::io::Error::new(
            std::io::ErrorKind::Other,
            "size less than five",
        ));
    }

    let bufsize = (size - 5) as usize;
    let mut binary = vec![0; bufsize];

    let mut to_read = bufsize;
    loop {
        if to_read == 0 {
            break;
        }
        let size_got = reader.read(&mut binary[(bufsize - to_read)..]).await?;

        if size_got == 0 {
            return Err(std::io::Error::new(
                std::io::ErrorKind::Other,
                "read got zero bytes",
            ));
        }
        to_read -= size_got;
    }
    let Ok(packet_type) = packet_type.try_into() else {
        return Err(std::io::Error::new(
            std::io::ErrorKind::Other,
            "packet type error",
        ));
    };
    let result = SdlanTcp {
        _packet_id: packet_id,
        packet_type,
        current_packet: binary,
    };
    Ok(result)
}

/*
pub async fn read_a_packet2(reader: &mut OwnedReadHalf) -> Result<SdlanTcp, std::io::Error> {
    debug!("read a packet");
    let size = reader.read_u16().await?;
    debug!("1");
    let packet_id = reader.read_u32().await?;
    debug!("2");
    let packet_type = reader.read_u8().await?;
    debug!("3");

    if size < 5 {
        return Err(std::io::Error::new(
            std::io::ErrorKind::Other,
            "size less than five",
        ));
    }

    let mut binary = vec![0; (size - 5) as usize];

    let mut bytes_read = 0;
    loop {
        let size_got = reader.read(&mut binary[bytes_read..]).await?;
        if size_got == 0 {
            return Err(std::io::Error::new(
                std::io::ErrorKind::Other,
                "read got zero bytes",
            ));
        }
        bytes_read += size_got;
        if bytes_read == (size - 5) as usize {
            break;
        }
    }
    let Ok(packet_type) = packet_type.try_into() else {
        return Err(std::io::Error::new(
            std::io::ErrorKind::Other,
            "packet type error",
        ));
    };
    let result = SdlanTcp {
        _packet_id: packet_id,
        packet_type,
        current_packet: binary,
    };
    Ok(result)
}

impl SdlanTcpCodec {
    pub fn new() -> Self {
        Self
    }
}

#[derive(Debug)]
pub enum Item {
    Data(Vec<u8>),
}

impl Decoder for SdlanTcpCodec {
    type Item = SdlanTcp;
    type Error = std::io::Error;

    fn decode(
        &mut self,
        src: &mut tokio_util::bytes::BytesMut,
    ) -> Result<Option<Self::Item>, Self::Error> {
        if src.is_empty() {
            return Ok(None);
        }
        let size = src.get_u16();
        let packet_id = src.get_u32();
        let packet_type = src.get_u8();
        let mut binary = Vec::with_capacity((size - 5).into());
        for i in 0..(size - 5) {
            let data = src.get_u8();
            binary.push(data);
        }
        let Ok(packet_type) = packet_type.try_into() else {
            return Ok(None);
        };
        let result = SdlanTcp {
            _packet_id: packet_id,
            packet_type,
            current_packet: binary,
        };
        Ok(Some(result))
    }
}
*/