use {
    bincode::Result,
    serde::Serialize,
    std::{
        fmt, io,
        net::{IpAddr, Ipv4Addr, SocketAddr},
    },
};

/// Maximum over-the-wire size of a Transaction
///   1280 is IPv6 minimum MTU
///   40 bytes is the size of the IPv6 header
///   8 bytes is the size of the fragment header
pub const PACKET_DATA_SIZE: usize = 1280 - 40 - 8;

#[derive(Clone, Debug, PartialEq)]
#[repr(C)]
pub struct Meta {
    pub size: usize,
    pub forwarded: bool,
    pub repair: bool,
    pub discard: bool,
    pub addr: IpAddr,
    pub port: u16,
    pub is_tracer_tx: bool,
    pub is_simple_vote_tx: bool,
}

#[derive(Clone)]
#[repr(C)]
pub struct Packet {
    pub data: [u8; PACKET_DATA_SIZE],
    pub meta: Meta,
}

impl Packet {
    pub fn new(data: [u8; PACKET_DATA_SIZE], meta: Meta) -> Self {
        Self { data, meta }
    }

    pub fn from_data<T: Serialize>(dest: Option<&SocketAddr>, data: T) -> Result<Self> {
        let mut packet = Packet::default();
        Self::populate_packet(&mut packet, dest, &data)?;
        Ok(packet)
    }

    pub fn populate_packet<T: Serialize>(
        packet: &mut Packet,
        dest: Option<&SocketAddr>,
        data: &T,
    ) -> Result<()> {
        let mut wr = io::Cursor::new(&mut packet.data[..]);
        bincode::serialize_into(&mut wr, data)?;
        let len = wr.position() as usize;
        packet.meta.size = len;
        if let Some(dest) = dest {
            packet.meta.set_addr(dest);
        }
        Ok(())
    }
}

impl fmt::Debug for Packet {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            f,
            "Packet {{ size: {:?}, addr: {:?} }}",
            self.meta.size,
            self.meta.addr()
        )
    }
}

#[allow(clippy::uninit_assumed_init)]
impl Default for Packet {
    fn default() -> Packet {
        Packet {
            data: unsafe { std::mem::MaybeUninit::uninit().assume_init() },
            meta: Meta::default(),
        }
    }
}

impl PartialEq for Packet {
    fn eq(&self, other: &Packet) -> bool {
        let self_data: &[u8] = self.data.as_ref();
        let other_data: &[u8] = other.data.as_ref();
        self.meta == other.meta && self_data[..self.meta.size] == other_data[..self.meta.size]
    }
}

impl Meta {
    pub fn addr(&self) -> SocketAddr {
        SocketAddr::new(self.addr, self.port)
    }

    pub fn set_addr(&mut self, socket_addr: &SocketAddr) {
        self.addr = socket_addr.ip();
        self.port = socket_addr.port();
    }
}

impl Default for Meta {
    fn default() -> Self {
        Self {
            size: 0,
            forwarded: false,
            repair: false,
            discard: false,
            addr: IpAddr::V4(Ipv4Addr::UNSPECIFIED),
            port: 0,
            is_tracer_tx: false,
            is_simple_vote_tx: false,
        }
    }
}