// VpnCloud - Peer-to-Peer VPN
// Copyright (C) 2015-2021  Dennis Schwerdel
// This software is licensed under GPL-3 or newer (see LICENSE.md)

use crate::{
    error::Error,
    util::{bytes_to_hex, Encoder},
};
use byteorder::{ReadBytesExt, WriteBytesExt};
use smallvec::SmallVec;
use std::{
    fmt,
    hash::{Hash, Hasher},
    io::{Read, Write},
    net::{Ipv4Addr, Ipv6Addr},
    str::FromStr,
};

pub const NODE_ID_BYTES: usize = 16;

pub type NodeId = [u8; NODE_ID_BYTES];

#[derive(Eq, Clone, Copy)]
pub struct Address {
    pub data: [u8; 16],
    pub len: u8,
}

impl Address {
    #[inline]
    pub fn read_from<R: Read>(mut r: R) -> Result<Address, Error> {
        let len = r.read_u8().map_err(|_| Error::Parse("Address too short"))?;
        Address::read_from_fixed(r, len)
    }

    #[inline]
    pub fn read_from_fixed<R: Read>(mut r: R, len: u8) -> Result<Address, Error> {
        if len > 16 {
            return Err(Error::Parse("Invalid address, too long"));
        }
        let mut data = [0; 16];
        r.read_exact(&mut data[..len as usize]).map_err(|_| Error::Parse("Address too short"))?;
        Ok(Address { data, len })
    }

    #[inline]
    pub fn write_to<W: Write>(&self, mut w: W) {
        w.write_u8(self.len).expect("Buffer too small");
        w.write_all(&self.data[..self.len as usize]).expect("Buffer too small");
    }

    pub fn from_ipv4(ip: Ipv4Addr) -> Self {
        let mut data = [0; 16];
        data[0..4].copy_from_slice(&ip.octets());
        Self { data, len: 4 }
    }
}

impl PartialEq for Address {
    #[inline]
    fn eq(&self, rhs: &Self) -> bool {
        self.len == rhs.len && self.data[..self.len as usize] == rhs.data[..self.len as usize]
    }
}

impl Hash for Address {
    #[inline]
    fn hash<H: Hasher>(&self, hasher: &mut H) {
        hasher.write(&self.data[..self.len as usize])
    }
}

impl fmt::Display for Address {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        let d = &self.data;
        match self.len {
            4 => write!(formatter, "{}.{}.{}.{}", d[0], d[1], d[2], d[3]),
            6 => write!(formatter, "{:02x}:{:02x}:{:02x}:{:02x}:{:02x}:{:02x}",
                d[0], d[1], d[2], d[3], d[4], d[5]),
            8 => {
                let vlan = Encoder::read_u16(&d[0..2]);
                write!(formatter, "vlan{}/{:02x}:{:02x}:{:02x}:{:02x}:{:02x}:{:02x}",
                    vlan, d[2], d[3], d[4], d[5], d[6], d[7])
            },
            16 => write!(formatter, "{:02x}{:02x}:{:02x}{:02x}:{:02x}{:02x}:{:02x}{:02x}:{:02x}{:02x}:{:02x}{:02x}:{:02x}{:02x}:{:02x}{:02x}",
                d[0], d[1], d[2], d[3], d[4], d[5], d[6], d[7], d[8], d[9], d[10], d[11], d[12], d[13], d[14], d[15]),
            _ => write!(formatter, "{}", bytes_to_hex(&d[..self.len as usize]))
        }
    }
}

impl fmt::Debug for Address {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        write!(formatter, "{}", self)
    }
}

impl FromStr for Address {
    type Err = Error;

    #[allow(unknown_lints, clippy::needless_range_loop)]
    fn from_str(text: &str) -> Result<Self, Self::Err> {
        if let Ok(addr) = Ipv4Addr::from_str(text) {
            let ip = addr.octets();
            let mut res = [0; 16];
            res[0..4].copy_from_slice(&ip);
            return Ok(Address { data: res, len: 4 });
        }
        if let Ok(addr) = Ipv6Addr::from_str(text) {
            let segments = addr.segments();
            let mut res = [0; 16];
            for i in 0..8 {
                Encoder::write_u16(segments[i], &mut res[2 * i..]);
            }
            return Ok(Address { data: res, len: 16 });
        }
        let parts: SmallVec<[&str; 10]> = text.split(':').collect();
        if parts.len() == 6 {
            let mut bytes = [0; 16];
            for i in 0..6 {
                bytes[i] = u8::from_str_radix(parts[i], 16).map_err(|_| Error::Parse("Failed to parse mac"))?;
            }
            return Ok(Address { data: bytes, len: 6 });
        }
        Err(Error::Parse("Failed to parse address"))
    }
}

#[derive(PartialEq, Eq, Hash, Clone, Copy)]
pub struct Range {
    pub base: Address,
    pub prefix_len: u8,
}

pub type RangeList = SmallVec<[Range; 4]>;

impl Range {
    pub fn matches(&self, addr: Address) -> bool {
        if self.base.len != addr.len {
            return false;
        }
        let mut match_len = 0;
        for i in 0..addr.len as usize {
            let m = addr.data[i] ^ self.base.data[i];
            match_len += m.leading_zeros() as u8;
            if m != 0 {
                break;
            }
        }
        match_len >= self.prefix_len
    }

    #[inline]
    pub fn read_from<R: Read>(mut r: R) -> Result<Range, Error> {
        let base = Address::read_from(&mut r)?;
        let prefix_len = r.read_u8().map_err(|_| Error::Parse("Address too short"))?;
        Ok(Range { base, prefix_len })
    }

    #[inline]
    pub fn write_to<W: Write>(&self, mut w: W) {
        self.base.write_to(&mut w);
        w.write_u8(self.prefix_len).expect("Buffer too small")
    }
}

impl FromStr for Range {
    type Err = Error;

    fn from_str(text: &str) -> Result<Self, Self::Err> {
        let pos = match text.find('/') {
            Some(pos) => pos,
            None => return Err(Error::Parse("Invalid range format")),
        };
        let prefix_len = u8::from_str(&text[pos + 1..]).map_err(|_| Error::Parse("Failed to parse prefix length"))?;
        let base = Address::from_str(&text[..pos])?;
        Ok(Range { base, prefix_len })
    }
}

impl fmt::Display for Range {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        write!(formatter, "{}/{}", self.base, self.prefix_len)
    }
}

impl fmt::Debug for Range {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        write!(formatter, "{}", self)
    }
}

#[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq)]
pub enum Mode {
    #[serde(rename = "normal")]
    Normal,
    #[serde(rename = "hub")]
    Hub,
    #[serde(rename = "switch")]
    Switch,
    #[serde(rename = "router")]
    Router,
}
impl fmt::Display for Mode {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        match *self {
            Mode::Normal => write!(formatter, "normal"),
            Mode::Hub => write!(formatter, "hub"),
            Mode::Switch => write!(formatter, "switch"),
            Mode::Router => write!(formatter, "router"),
        }
    }
}
impl FromStr for Mode {
    type Err = &'static str;

    fn from_str(text: &str) -> Result<Self, Self::Err> {
        Ok(match &text.to_lowercase() as &str {
            "normal" => Self::Normal,
            "hub" => Self::Hub,
            "switch" => Self::Switch,
            "router" => Self::Router,
            _ => return Err("Unknown mode"),
        })
    }
}

#[cfg(test)]
mod tests {

    use super::*;

    use std::io::Cursor;

    #[test]
    fn address_parse_fmt() {
        assert_eq!(format!("{}", Address::from_str("120.45.22.5").unwrap()), "120.45.22.5");
        assert_eq!(format!("{}", Address::from_str("78:2d:16:05:01:02").unwrap()), "78:2d:16:05:01:02");
        assert_eq!(
            format!("{}", Address { data: [3, 56, 120, 45, 22, 5, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0], len: 8 }),
            "vlan824/78:2d:16:05:01:02"
        );
        assert_eq!(
            format!("{}", Address::from_str("0001:0203:0405:0607:0809:0a0b:0c0d:0e0f").unwrap()),
            "0001:0203:0405:0607:0809:0a0b:0c0d:0e0f"
        );
        assert_eq!(format!("{:?}", Address { data: [1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], len: 2 }), "0102");
        assert!(Address::from_str("").is_err()); // Failed to parse address
    }

    #[test]
    fn address_decode_encode() {
        let mut buf = vec![];
        let addr = Address::from_str("120.45.22.5").unwrap();
        addr.write_to(Cursor::new(&mut buf));
        assert_eq!(&buf[0..5], &[4, 120, 45, 22, 5]);
        assert_eq!(addr, Address::read_from(Cursor::new(&buf)).unwrap());
        assert_eq!(addr, Address::read_from_fixed(Cursor::new(&buf[1..]), 4).unwrap());
        buf.clear();
        let addr = Address::from_str("78:2d:16:05:01:02").unwrap();
        addr.write_to(Cursor::new(&mut buf));
        assert_eq!(&buf[0..7], &[6, 0x78, 0x2d, 0x16, 0x05, 0x01, 0x02]);
        assert_eq!(addr, Address::read_from(Cursor::new(&buf)).unwrap());
        assert_eq!(addr, Address::read_from_fixed(Cursor::new(&buf[1..]), 6).unwrap());
        assert!(Address::read_from(Cursor::new(&buf[0..1])).is_err()); // Address too short
        buf[0] = 100;
        assert!(Address::read_from(Cursor::new(&buf)).is_err()); // Invalid address, too long
        buf[0] = 5;
        assert!(Address::read_from(Cursor::new(&buf[0..4])).is_err()); // Address too short
    }

    #[test]
    fn address_eq() {
        assert_eq!(
            Address::read_from_fixed(Cursor::new(&[1, 2, 3, 4]), 4).unwrap(),
            Address::read_from_fixed(Cursor::new(&[1, 2, 3, 4]), 4).unwrap()
        );
        assert_ne!(
            Address::read_from_fixed(Cursor::new(&[1, 2, 3, 4]), 4).unwrap(),
            Address::read_from_fixed(Cursor::new(&[1, 2, 3, 5]), 4).unwrap()
        );
        assert_eq!(
            Address::read_from_fixed(Cursor::new(&[1, 2, 3, 4]), 3).unwrap(),
            Address::read_from_fixed(Cursor::new(&[1, 2, 3, 5]), 3).unwrap()
        );
        assert_ne!(
            Address::read_from_fixed(Cursor::new(&[1, 2, 3, 4]), 3).unwrap(),
            Address::read_from_fixed(Cursor::new(&[1, 2, 3, 4]), 4).unwrap()
        );
    }

    #[test]
    fn address_range_decode_encode() {
        let mut buf = vec![];
        let range =
            Range { base: Address { data: [0, 1, 2, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], len: 4 }, prefix_len: 24 };
        range.write_to(Cursor::new(&mut buf));
        assert_eq!(&buf[0..6], &[4, 0, 1, 2, 3, 24]);
        assert_eq!(range, Range::read_from(Cursor::new(&buf)).unwrap());
        assert!(Range::read_from(Cursor::new(&buf[..5])).is_err()); // Missing prefix length
        buf[0] = 17;
        assert!(Range::read_from(Cursor::new(&buf)).is_err());
    }
}