use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
use tokio::net::tcp::{ReadHalf, WriteHalf};
use tokio::net::TcpStream;

use crate::prelude::*;

struct TestScope<'a> {
    reader: BufReader<ReadHalf<'a>>,
    writer: WriteHalf<'a>,
    buffer: Vec<u8>,
}
impl<'a> TestScope<'a> {
    async fn send(&mut self, str: &(impl AsRef<str> + ?Sized)) -> Result<()> {
        self.writer.write_all(str.as_ref().as_bytes()).await?;
        self.writer.flush().await?;
        Ok(())
    }

    async fn expect(&mut self, str: &(impl AsRef<str> + ?Sized)) -> Result<()> {
        let len = self.reader.read_until(b'\n', &mut self.buffer).await?;
        assert_eq!(std::str::from_utf8(&self.buffer[0..len])?, str.as_ref());
        self.buffer.clear();
        Ok(())
    }

    async fn assert(&mut self, f: impl FnOnce(&str) -> Result<()>) -> Result<()> {
        let len = self.reader.read_until(b'\n', &mut self.buffer).await?;
        let res = f(std::str::from_utf8(&self.buffer[0..len])?);
        self.buffer.clear();
        res
    }
}

async fn init_client(stream: &mut TcpStream) -> Result<TestScope> {
    let (reader, writer) = stream.split();
    let reader = BufReader::new(reader);
    let buffer = vec![];
    Ok(TestScope {
        reader,
        writer,
        buffer,
    })
}

macro_rules! send {
    ($scope: expr, $($arg:tt),*) => {{
        $scope.send(&format!($($arg,)*)).await?;
    }};
}

macro_rules! expect {
    ($scope: expr, $($arg:tt),*) => {{
        $scope.expect(&format!($($arg,)*)).await?;
    }};
}

const SERVER_HOSTNAME: &'static str = "irc.localhost";

#[rustfmt::skip]
async fn registration(scope: &mut TestScope<'_>, nickname: &str) -> Result<()> {
    expect!(scope, ":irc.localhost NOTICE * :Welcome to my server!\n");
    send!(scope, "NICK {nickname}\n");
    send!(scope, "USER UserName 0 * :Real Name\n");
    expect!(scope, ":irc.localhost 001 {nickname} :Welcome to Kek Server\n");
    expect!(scope, ":irc.localhost 002 {nickname} :Welcome to Kek Server\n");
    expect!(scope, ":irc.localhost 003 {nickname} :Welcome to Kek Server\n");
    expect!(scope, ":irc.localhost 004 {nickname} irc.localhost kek-0.1.alpha.3 r CFILPQbcefgijklmnopqrstvz\n");
    expect!(scope, ":irc.localhost 005 {nickname} CHANTYPES=# :are supported by this server\n");
    Ok(())
}

#[rustfmt::skip]
async fn join(scope: &mut TestScope<'_>, nickname: &str, chan: &str) -> Result<()> {
    send!(scope, "JOIN #{chan}\n");
    expect!(scope, ":{nickname} JOIN #{chan}\n");
    expect!(scope, ":irc.localhost 332 {nickname} #{chan} :New room\n");
    expect!(scope, ":irc.localhost 353 {nickname} = #{chan} :{nickname}\n");
    expect!(scope, ":irc.localhost 366 {nickname} #{chan} :End of /NAMES list\n");
    Ok(())
}

#[tokio::test]
async fn test_registration() -> Result<()> {
    let mut stream = TcpStream::connect("127.0.0.1:6667").await?;
    let mut scope = init_client(&mut stream).await?;

    registration(&mut scope, "NickName1").await?;
    join(&mut scope, "NickName1", "chan1").await?;
    Ok(())
}

#[rustfmt::skip]
#[tokio::test]
async fn test_two_connections_one_player() -> Result<()> {
    let mut stream1 = TcpStream::connect("127.0.0.1:6667").await?;
    let mut scope1 = init_client(&mut stream1).await?;
    let mut stream2 = TcpStream::connect("127.0.0.1:6667").await?;
    let mut scope2 = init_client(&mut stream2).await?;

    let nickname = "NickName2";
    let chan = "chan2";

    registration(&mut scope1, nickname).await?;
    registration(&mut scope2, nickname).await?;
    join(&mut scope1, nickname, chan).await?;

    // force join on second connection when the other one joins a room
    expect!(scope2, ":{nickname} JOIN #{chan}\n");
    expect!(scope2, ":{SERVER_HOSTNAME} 332 {nickname} #{chan} :New room\n");
    expect!(scope2, ":{SERVER_HOSTNAME} 353 {nickname} = #{chan} :{nickname}\n");
    expect!(scope2, ":{SERVER_HOSTNAME} 366 {nickname} #{chan} :End of /NAMES list\n");

    // force send PRIVMSG to other connections
    send!(scope1, "PRIVMSG #{chan} :Chmoki vsem v etam chati!\n");
    expect!(scope2, ":{nickname} PRIVMSG #{chan} :Chmoki vsem v etam chati!\n");
    send!(scope2, "PRIVMSG #{chan} :I tebe privetiki\n");
    expect!(scope1, ":{nickname} PRIVMSG #{chan} :I tebe privetiki\n");

    let mut stream3 = TcpStream::connect("127.0.0.1:6667").await?;
    let mut scope3 = init_client(&mut stream3).await?;
    registration(&mut scope3, nickname).await?;

    // force join on registration
    expect!(scope3, ":{nickname} JOIN #{chan}\n");
    expect!(scope3, ":{SERVER_HOSTNAME} 332 {nickname} #{chan} :New room\n");
    expect!(scope3, ":{SERVER_HOSTNAME} 353 {nickname} = #{chan} :{nickname}\n");
    expect!(scope3, ":{SERVER_HOSTNAME} 366 {nickname} #{chan} :End of /NAMES list\n");

    Ok(())
}

#[rustfmt::skip]
#[tokio::test]
async fn test_two_players() -> Result<()> {
    let mut stream1 = TcpStream::connect("127.0.0.1:6667").await?;
    let mut scope1 = init_client(&mut stream1).await?;
    let mut stream2 = TcpStream::connect("127.0.0.1:6667").await?;
    let mut scope2 = init_client(&mut stream2).await?;

    let nickname1 = "NickName3";
    let nickname2 = "NickName4";

    let chan = "chan3";

    registration(&mut scope1, "NickName3").await?;
    registration(&mut scope2, "NickName4").await?;
    join(&mut scope1, nickname1, "chan3").await?;
    send!(scope2, "JOIN #{chan}\n");
    expect!(scope2, ":{nickname2} JOIN #{chan}\n");
    expect!(scope2, ":irc.localhost 332 {nickname2} #{chan} :New room\n");
    scope2.assert(|line| {
        if line == format!(":irc.localhost 353 {nickname2} = #{chan} :{nickname1} {nickname2}\n") { return Ok(()) }
        if line == format!(":irc.localhost 353 {nickname2} = #{chan} :{nickname2} {nickname1}\n") { return Ok(()) }
        panic!("incorrect chan member list received: {line}");
    }).await?;
    expect!(scope2, ":irc.localhost 366 {nickname2} #{chan} :End of /NAMES list\n");

    expect!(scope1, ":{nickname2} JOIN #{chan}\n");

    send!(scope1, "PRIVMSG #chan3 :Chmoki vsem v etam chati!\n");
    expect!(scope2, ":{nickname1} PRIVMSG #chan3 :Chmoki vsem v etam chati!\n");
    send!(scope2, "PRIVMSG #chan3 :I tebe privetiki\n");
    expect!(scope1, ":{nickname2} PRIVMSG #chan3 :I tebe privetiki\n");

    Ok(())
}