use hashbrown::HashSet;
use integer_encoding::{FixedInt, VarInt};
use secretbox::CipherType::Salsa20;
use secretbox::SecretBox;
use serde::Serialize;
use std::io::{Error, Read, Write};
use std::net::{Shutdown, TcpStream};

/// Connections provides an interface for manage sets of connections on top of a particular
/// ACN.
pub mod service;

#[derive(Debug)]
pub enum ServiceError {
    ClosedNormally,
    ConnectionFailed(String),
    ListenFailed(String),
}

#[derive(Clone)]
pub struct InboundConnection(());
#[derive(Clone)]
pub struct OutboundConnection(());

#[derive(Clone, Eq, PartialEq, Hash)]
pub struct Capability(pub &'static str);

pub struct Connection<Direction> {
    conn: TcpStream,
    direction: Direction,
    key: Vec<u8>,
    hostname: String,
    capabilities: HashSet<Capability>,
}

pub trait ConnectionInterface {
    fn set_hostname(&mut self, hostname: &String);
    fn hostname(&self) -> String;
    fn enable_encryption(&mut self, key: Vec<u8>);
    fn send(&mut self, amsg: &String) -> Result<(), Error>;
    fn send_encrypted(&mut self, msg: Vec<u8>) -> Result<(), Error>;
    fn expect_encrypted(&mut self) -> Vec<u8>;
    fn expect(&mut self) -> Result<Vec<u8>, Error>;
    fn shutdown(&mut self);

    fn set_capability(&mut self, capability: &Capability);
    fn has_capability(&self, capability: &Capability) -> bool;
}

impl<Direction> ConnectionInterface for Connection<Direction> {
    fn set_hostname(&mut self, hostname: &String) {
        self.hostname = hostname.clone()
    }

    fn hostname(&self) -> String {
        self.hostname.clone()
    }

    fn enable_encryption(&mut self, key: Vec<u8>) {
        self.key = key
    }

    fn send(&mut self, amsg: &String) -> Result<(), Error> {
        let mut len = [0u8; 2];
        (amsg.len() as u16).encode_var(&mut len);
        let mut msg = vec![];
        msg.extend_from_slice(len.as_slice());
        msg.extend_from_slice(amsg.as_bytes());
        let mut msg = msg;
        while msg.len() < 8192 {
            msg.push(0);
        }
        self.conn.write_all(msg.as_slice())
    }

    fn send_encrypted(&mut self, msg: Vec<u8>) -> Result<(), Error> {
        let mut msg = msg;
        while msg.len() < 8192 - 40 {
            msg.push(0);
        }
        let secret_box = SecretBox::new(&self.key, Salsa20).unwrap();
        let msg = secret_box.easy_seal(msg.as_slice());
        self.conn.write_all(msg.as_slice())
    }

    fn expect_encrypted(&mut self) -> Vec<u8> {
        let secret_box = SecretBox::new(&self.key, Salsa20).unwrap();
        let mut result = [0u8; 8192];
        match self.conn.read_exact(&mut result) {
            Err(_e) => {
                return vec![];
            }
            _ => {}
        }

        let msg = match secret_box.easy_unseal(&result) {
            Some(msg) => msg,
            _ => {
                return vec![];
            }
        };

        let msg = msg.as_slice();
        let _len_bytes = [0u8; 2];
        let len = u16::decode_fixed(&msg[0..2]) as usize;
        if len > 8192 {
            return vec![]; // lol no.
        }
        msg[2..len + 2].to_vec()
    }

    fn expect(&mut self) -> Result<Vec<u8>, Error> {
        let mut msg = [0; 8192];
        let result = self.conn.read_exact(&mut msg);
        match result {
            Err(e) => Err(e),
            Ok(()) => {
                // TODO why did I decide to use varints here?!?!
                let len = u16::decode_var(&msg[0..2]).unwrap().0 as usize;
                // println!("{} [{}]", len, String::from_utf8(msg[2..len + 2].to_vec()).unwrap());
                return Ok(msg[2..len + 2].to_vec());
            }
        }
    }

    fn shutdown(&mut self) {
        match self.conn.shutdown(Shutdown::Both) {
            _ => {} // If anything bad happens we will know soon enough...
        }
    }

    fn set_capability(&mut self, capability: &Capability) {
        self.capabilities.insert(capability.clone());
    }

    fn has_capability(&self, capability: &Capability) -> bool {
        self.capabilities.contains(capability)
    }
}

impl<Direction> Connection<Direction>
where
    Direction: Clone,
{
    pub fn new_inbound(conn: TcpStream) -> Connection<InboundConnection> {
        Connection {
            conn,
            direction: InboundConnection(()),
            key: vec![],
            hostname: String::new(),
            capabilities: HashSet::new(),
        }
    }

    pub fn new_outbound(conn: TcpStream) -> Connection<OutboundConnection> {
        Connection {
            conn,
            direction: OutboundConnection(()),
            key: vec![],
            hostname: String::new(),
            capabilities: HashSet::new(),
        }
    }

    /// Send anything implemented Serialize as JSON
    pub fn send_json_encrypted<T>(&mut self, data: T) -> Result<(), Error>
    where
        T: Serialize,
    {
        let mut msg = vec![];
        let mut len = [0u8; 2];
        let json = serde_json::to_string(&data).unwrap();
        (json.len() as u16).encode_fixed(&mut len);
        msg.extend_from_slice(len.as_slice());
        msg.extend_from_slice(json.as_bytes());
        self.send_encrypted(msg)
    }

    pub fn try_clone(&self) -> Connection<Direction> {
        Connection {
            conn: self.conn.try_clone().unwrap(),
            direction: self.direction.clone(),
            key: self.key.clone(),
            hostname: self.hostname.clone(),
            capabilities: self.capabilities.clone(),
        }
    }
}

pub struct Hostname {}