// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.

use crate::io::TcpStreamResource;
use crate::resolve_addr::resolve_addr;
use crate::resolve_addr::resolve_addr_sync;
use crate::NetPermissions;
use deno_core::error::bad_resource;
use deno_core::error::custom_error;
use deno_core::error::generic_error;
use deno_core::error::type_error;
use deno_core::error::AnyError;
use deno_core::op_async;
use deno_core::op_sync;
use deno_core::AsyncRefCell;
use deno_core::ByteString;
use deno_core::CancelHandle;
use deno_core::CancelTryFuture;
use deno_core::OpPair;
use deno_core::OpState;
use deno_core::RcRef;
use deno_core::Resource;
use deno_core::ResourceId;
use deno_core::ZeroCopyBuf;
use log::debug;
use serde::Deserialize;
use serde::Serialize;
use std::borrow::Cow;
use std::cell::RefCell;
use std::net::SocketAddr;
use std::rc::Rc;
use tokio::net::TcpListener;
use tokio::net::TcpStream;
use tokio::net::UdpSocket;
use trust_dns_proto::rr::record_data::RData;
use trust_dns_proto::rr::record_type::RecordType;
use trust_dns_resolver::config::NameServerConfigGroup;
use trust_dns_resolver::config::ResolverConfig;
use trust_dns_resolver::config::ResolverOpts;
use trust_dns_resolver::error::ResolveErrorKind;
use trust_dns_resolver::system_conf;
use trust_dns_resolver::AsyncResolver;

#[cfg(unix)]
use super::ops_unix as net_unix;
#[cfg(unix)]
use crate::io::UnixStreamResource;
#[cfg(unix)]
use std::path::Path;

pub fn init<P: NetPermissions + 'static>() -> Vec<OpPair> {
  vec![
    ("op_net_accept", op_async(op_net_accept)),
    ("op_net_connect", op_async(op_net_connect::<P>)),
    ("op_net_listen", op_sync(op_net_listen::<P>)),
    ("op_dgram_recv", op_async(op_dgram_recv)),
    ("op_dgram_send", op_async(op_dgram_send::<P>)),
    ("op_dns_resolve", op_async(op_dns_resolve::<P>)),
    ("op_set_nodelay", op_sync(op_set_nodelay::<P>)),
    ("op_set_keepalive", op_sync(op_set_keepalive::<P>)),
  ]
}

#[derive(Serialize)]
#[serde(rename_all = "camelCase")]
pub struct OpConn {
  pub rid: ResourceId,
  pub remote_addr: Option<OpAddr>,
  pub local_addr: Option<OpAddr>,
}

#[derive(Serialize)]
#[serde(tag = "transport", rename_all = "lowercase")]
pub enum OpAddr {
  Tcp(IpAddr),
  Udp(IpAddr),
  #[cfg(unix)]
  Unix(net_unix::UnixAddr),
  #[cfg(unix)]
  UnixPacket(net_unix::UnixAddr),
}

#[derive(Serialize)]
#[serde(rename_all = "camelCase")]
/// A received datagram packet (from udp or unixpacket)
pub struct OpPacket {
  pub size: usize,
  pub remote_addr: OpAddr,
}

#[derive(Serialize, Clone, Debug)]
#[serde(rename_all = "camelCase")]
pub struct TlsHandshakeInfo {
  pub alpn_protocol: Option<ByteString>,
}

#[derive(Serialize)]
pub struct IpAddr {
  pub hostname: String,
  pub port: u16,
}

#[derive(Deserialize)]
pub(crate) struct AcceptArgs {
  pub rid: ResourceId,
  pub transport: String,
}

pub(crate) fn accept_err(e: std::io::Error) -> AnyError {
  // FIXME(bartlomieju): compatibility with current JS implementation
  if let std::io::ErrorKind::Interrupted = e.kind() {
    bad_resource("Listener has been closed")
  } else {
    e.into()
  }
}

async fn accept_tcp(
  state: Rc<RefCell<OpState>>,
  args: AcceptArgs,
  _: (),
) -> Result<OpConn, AnyError> {
  let rid = args.rid;

  let resource = state
    .borrow()
    .resource_table
    .get::<TcpListenerResource>(rid)
    .map_err(|_| bad_resource("Listener has been closed"))?;
  let listener = RcRef::map(&resource, |r| &r.listener)
    .try_borrow_mut()
    .ok_or_else(|| custom_error("Busy", "Another accept task is ongoing"))?;
  let cancel = RcRef::map(resource, |r| &r.cancel);
  let (tcp_stream, _socket_addr) = listener
    .accept()
    .try_or_cancel(cancel)
    .await
    .map_err(accept_err)?;
  let local_addr = tcp_stream.local_addr()?;
  let remote_addr = tcp_stream.peer_addr()?;

  let mut state = state.borrow_mut();
  let rid = state
    .resource_table
    .add(TcpStreamResource::new(tcp_stream.into_split()));
  Ok(OpConn {
    rid,
    local_addr: Some(OpAddr::Tcp(IpAddr {
      hostname: local_addr.ip().to_string(),
      port: local_addr.port(),
    })),
    remote_addr: Some(OpAddr::Tcp(IpAddr {
      hostname: remote_addr.ip().to_string(),
      port: remote_addr.port(),
    })),
  })
}

async fn op_net_accept(
  state: Rc<RefCell<OpState>>,
  args: AcceptArgs,
  _: (),
) -> Result<OpConn, AnyError> {
  match args.transport.as_str() {
    "tcp" => accept_tcp(state, args, ()).await,
    #[cfg(unix)]
    "unix" => net_unix::accept_unix(state, args, ()).await,
    other => Err(bad_transport(other)),
  }
}

fn bad_transport(transport: &str) -> AnyError {
  generic_error(format!("Unsupported transport protocol {}", transport))
}

#[derive(Deserialize)]
pub(crate) struct ReceiveArgs {
  pub rid: ResourceId,
  pub transport: String,
}

async fn receive_udp(
  state: Rc<RefCell<OpState>>,
  args: ReceiveArgs,
  zero_copy: ZeroCopyBuf,
) -> Result<OpPacket, AnyError> {
  let mut zero_copy = zero_copy.clone();

  let rid = args.rid;

  let resource = state
    .borrow_mut()
    .resource_table
    .get::<UdpSocketResource>(rid)
    .map_err(|_| bad_resource("Socket has been closed"))?;
  let socket = RcRef::map(&resource, |r| &r.socket).borrow().await;
  let cancel_handle = RcRef::map(&resource, |r| &r.cancel);
  let (size, remote_addr) = socket
    .recv_from(&mut zero_copy)
    .try_or_cancel(cancel_handle)
    .await?;
  Ok(OpPacket {
    size,
    remote_addr: OpAddr::Udp(IpAddr {
      hostname: remote_addr.ip().to_string(),
      port: remote_addr.port(),
    }),
  })
}

async fn op_dgram_recv(
  state: Rc<RefCell<OpState>>,
  args: ReceiveArgs,
  zero_copy: ZeroCopyBuf,
) -> Result<OpPacket, AnyError> {
  match args.transport.as_str() {
    "udp" => receive_udp(state, args, zero_copy).await,
    #[cfg(unix)]
    "unixpacket" => net_unix::receive_unix_packet(state, args, zero_copy).await,
    other => Err(bad_transport(other)),
  }
}

#[derive(Deserialize)]
struct SendArgs {
  rid: ResourceId,
  transport: String,
  #[serde(flatten)]
  transport_args: ArgsEnum,
}

async fn op_dgram_send<NP>(
  state: Rc<RefCell<OpState>>,
  args: SendArgs,
  zero_copy: ZeroCopyBuf,
) -> Result<usize, AnyError>
where
  NP: NetPermissions + 'static,
{
  let zero_copy = zero_copy.clone();

  match args {
    SendArgs {
      rid,
      transport,
      transport_args: ArgsEnum::Ip(args),
    } if transport == "udp" => {
      {
        let mut s = state.borrow_mut();
        s.borrow_mut::<NP>()
          .check_net(&(&args.hostname, Some(args.port)))?;
      }
      let addr = resolve_addr(&args.hostname, args.port)
        .await?
        .next()
        .ok_or_else(|| generic_error("No resolved address found"))?;

      let resource = state
        .borrow_mut()
        .resource_table
        .get::<UdpSocketResource>(rid)
        .map_err(|_| bad_resource("Socket has been closed"))?;
      let socket = RcRef::map(&resource, |r| &r.socket).borrow().await;
      let byte_length = socket.send_to(&zero_copy, &addr).await?;
      Ok(byte_length)
    }
    #[cfg(unix)]
    SendArgs {
      rid,
      transport,
      transport_args: ArgsEnum::Unix(args),
    } if transport == "unixpacket" => {
      let address_path = Path::new(&args.path);
      {
        let mut s = state.borrow_mut();
        s.borrow_mut::<NP>().check_write(address_path)?;
      }
      let resource = state
        .borrow()
        .resource_table
        .get::<net_unix::UnixDatagramResource>(rid)
        .map_err(|_| custom_error("NotConnected", "Socket has been closed"))?;
      let socket = RcRef::map(&resource, |r| &r.socket)
        .try_borrow_mut()
        .ok_or_else(|| custom_error("Busy", "Socket already in use"))?;
      let byte_length = socket.send_to(&zero_copy, address_path).await?;
      Ok(byte_length)
    }
    _ => Err(type_error("Wrong argument format!")),
  }
}

#[derive(Deserialize)]
pub struct ConnectArgs {
  transport: String,
  #[serde(flatten)]
  transport_args: ArgsEnum,
}

pub async fn op_net_connect<NP>(
  state: Rc<RefCell<OpState>>,
  args: ConnectArgs,
  _: (),
) -> Result<OpConn, AnyError>
where
  NP: NetPermissions + 'static,
{
  match args {
    ConnectArgs {
      transport,
      transport_args: ArgsEnum::Ip(args),
    } if transport == "tcp" => {
      {
        let mut state_ = state.borrow_mut();
        state_
          .borrow_mut::<NP>()
          .check_net(&(&args.hostname, Some(args.port)))?;
      }
      let addr = resolve_addr(&args.hostname, args.port)
        .await?
        .next()
        .ok_or_else(|| generic_error("No resolved address found"))?;
      let tcp_stream = TcpStream::connect(&addr).await?;
      let local_addr = tcp_stream.local_addr()?;
      let remote_addr = tcp_stream.peer_addr()?;

      let mut state_ = state.borrow_mut();
      let rid = state_
        .resource_table
        .add(TcpStreamResource::new(tcp_stream.into_split()));
      Ok(OpConn {
        rid,
        local_addr: Some(OpAddr::Tcp(IpAddr {
          hostname: local_addr.ip().to_string(),
          port: local_addr.port(),
        })),
        remote_addr: Some(OpAddr::Tcp(IpAddr {
          hostname: remote_addr.ip().to_string(),
          port: remote_addr.port(),
        })),
      })
    }
    #[cfg(unix)]
    ConnectArgs {
      transport,
      transport_args: ArgsEnum::Unix(args),
    } if transport == "unix" => {
      let address_path = Path::new(&args.path);
      super::check_unstable2(&state, "Deno.connect");
      {
        let mut state_ = state.borrow_mut();
        state_.borrow_mut::<NP>().check_read(address_path)?;
        state_.borrow_mut::<NP>().check_write(address_path)?;
      }
      let path = args.path;
      let unix_stream = net_unix::UnixStream::connect(Path::new(&path)).await?;
      let local_addr = unix_stream.local_addr()?;
      let remote_addr = unix_stream.peer_addr()?;

      let mut state_ = state.borrow_mut();
      let resource = UnixStreamResource::new(unix_stream.into_split());
      let rid = state_.resource_table.add(resource);
      Ok(OpConn {
        rid,
        local_addr: Some(OpAddr::Unix(net_unix::UnixAddr {
          path: local_addr.as_pathname().and_then(net_unix::pathstring),
        })),
        remote_addr: Some(OpAddr::Unix(net_unix::UnixAddr {
          path: remote_addr.as_pathname().and_then(net_unix::pathstring),
        })),
      })
    }
    _ => Err(type_error("Wrong argument format!")),
  }
}

pub struct TcpListenerResource {
  pub listener: AsyncRefCell<TcpListener>,
  pub cancel: CancelHandle,
}

impl Resource for TcpListenerResource {
  fn name(&self) -> Cow<str> {
    "tcpListener".into()
  }

  fn close(self: Rc<Self>) {
    self.cancel.cancel();
  }
}

struct UdpSocketResource {
  socket: AsyncRefCell<UdpSocket>,
  cancel: CancelHandle,
}

impl Resource for UdpSocketResource {
  fn name(&self) -> Cow<str> {
    "udpSocket".into()
  }

  fn close(self: Rc<Self>) {
    self.cancel.cancel()
  }
}

#[derive(Deserialize)]
struct IpListenArgs {
  hostname: String,
  port: u16,
}

#[derive(Deserialize)]
#[serde(untagged)]
enum ArgsEnum {
  Ip(IpListenArgs),
  #[cfg(unix)]
  Unix(net_unix::UnixListenArgs),
}

#[derive(Deserialize)]
struct ListenArgs {
  transport: String,
  #[serde(flatten)]
  transport_args: ArgsEnum,
}

fn listen_tcp(
  state: &mut OpState,
  addr: SocketAddr,
) -> Result<(u32, SocketAddr), AnyError> {
  let std_listener = std::net::TcpListener::bind(&addr)?;
  std_listener.set_nonblocking(true)?;
  let listener = TcpListener::from_std(std_listener)?;
  let local_addr = listener.local_addr()?;
  let listener_resource = TcpListenerResource {
    listener: AsyncRefCell::new(listener),
    cancel: Default::default(),
  };
  let rid = state.resource_table.add(listener_resource);

  Ok((rid, local_addr))
}

fn listen_udp(
  state: &mut OpState,
  addr: SocketAddr,
) -> Result<(u32, SocketAddr), AnyError> {
  let std_socket = std::net::UdpSocket::bind(&addr)?;
  std_socket.set_nonblocking(true)?;
  // Enable messages to be sent to the broadcast address (255.255.255.255) by default
  std_socket.set_broadcast(true)?;
  let socket = UdpSocket::from_std(std_socket)?;
  let local_addr = socket.local_addr()?;
  let socket_resource = UdpSocketResource {
    socket: AsyncRefCell::new(socket),
    cancel: Default::default(),
  };
  let rid = state.resource_table.add(socket_resource);

  Ok((rid, local_addr))
}

fn op_net_listen<NP>(
  state: &mut OpState,
  args: ListenArgs,
  _: (),
) -> Result<OpConn, AnyError>
where
  NP: NetPermissions + 'static,
{
  match args {
    ListenArgs {
      transport,
      transport_args: ArgsEnum::Ip(args),
    } => {
      {
        if transport == "udp" {
          super::check_unstable(state, "Deno.listenDatagram");
        }
        state
          .borrow_mut::<NP>()
          .check_net(&(&args.hostname, Some(args.port)))?;
      }
      let addr = resolve_addr_sync(&args.hostname, args.port)?
        .next()
        .ok_or_else(|| generic_error("No resolved address found"))?;
      let (rid, local_addr) = if transport == "tcp" {
        listen_tcp(state, addr)?
      } else {
        listen_udp(state, addr)?
      };
      debug!(
        "New listener {} {}:{}",
        rid,
        local_addr.ip().to_string(),
        local_addr.port()
      );
      let ip_addr = IpAddr {
        hostname: local_addr.ip().to_string(),
        port: local_addr.port(),
      };
      Ok(OpConn {
        rid,
        local_addr: Some(match transport.as_str() {
          "udp" => OpAddr::Udp(ip_addr),
          "tcp" => OpAddr::Tcp(ip_addr),
          // NOTE: This could be unreachable!()
          other => return Err(bad_transport(other)),
        }),
        remote_addr: None,
      })
    }
    #[cfg(unix)]
    ListenArgs {
      transport,
      transport_args: ArgsEnum::Unix(args),
    } if transport == "unix" || transport == "unixpacket" => {
      let address_path = Path::new(&args.path);
      {
        if transport == "unix" {
          super::check_unstable(state, "Deno.listen");
        }
        if transport == "unixpacket" {
          super::check_unstable(state, "Deno.listenDatagram");
        }
        let permissions = state.borrow_mut::<NP>();
        permissions.check_read(address_path)?;
        permissions.check_write(address_path)?;
      }
      let (rid, local_addr) = if transport == "unix" {
        net_unix::listen_unix(state, address_path)?
      } else {
        net_unix::listen_unix_packet(state, address_path)?
      };
      debug!("New listener {} {:?}", rid, local_addr);
      let unix_addr = net_unix::UnixAddr {
        path: local_addr.as_pathname().and_then(net_unix::pathstring),
      };

      Ok(OpConn {
        rid,
        local_addr: Some(match transport.as_str() {
          "unix" => OpAddr::Unix(unix_addr),
          "unixpacket" => OpAddr::UnixPacket(unix_addr),
          other => return Err(bad_transport(other)),
        }),
        remote_addr: None,
      })
    }
    #[cfg(unix)]
    _ => Err(type_error("Wrong argument format!")),
  }
}

#[derive(Serialize, PartialEq, Debug)]
#[serde(untagged)]
pub enum DnsReturnRecord {
  A(String),
  Aaaa(String),
  Aname(String),
  Cname(String),
  Mx {
    preference: u16,
    exchange: String,
  },
  Ptr(String),
  Srv {
    priority: u16,
    weight: u16,
    port: u16,
    target: String,
  },
  Txt(Vec<String>),
}

#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ResolveAddrArgs {
  query: String,
  record_type: RecordType,
  options: Option<ResolveDnsOption>,
}

#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ResolveDnsOption {
  name_server: Option<NameServer>,
}

fn default_port() -> u16 {
  53
}

#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct NameServer {
  ip_addr: String,
  #[serde(default = "default_port")]
  port: u16,
}

pub async fn op_dns_resolve<NP>(
  state: Rc<RefCell<OpState>>,
  args: ResolveAddrArgs,
  _: (),
) -> Result<Vec<DnsReturnRecord>, AnyError>
where
  NP: NetPermissions + 'static,
{
  let ResolveAddrArgs {
    query,
    record_type,
    options,
  } = args;

  let (config, opts) = if let Some(name_server) =
    options.as_ref().and_then(|o| o.name_server.as_ref())
  {
    let group = NameServerConfigGroup::from_ips_clear(
      &[name_server.ip_addr.parse()?],
      name_server.port,
      true,
    );
    (
      ResolverConfig::from_parts(None, vec![], group),
      ResolverOpts::default(),
    )
  } else {
    system_conf::read_system_conf()?
  };

  {
    let mut s = state.borrow_mut();
    let perm = s.borrow_mut::<NP>();

    // Checks permission against the name servers which will be actually queried.
    for ns in config.name_servers() {
      let socker_addr = &ns.socket_addr;
      let ip = socker_addr.ip().to_string();
      let port = socker_addr.port();
      perm.check_net(&(ip, Some(port)))?;
    }
  }

  let resolver = AsyncResolver::tokio(config, opts)?;

  let results = resolver
    .lookup(query, record_type, Default::default())
    .await
    .map_err(|e| {
      let message = format!("{}", e);
      match e.kind() {
        ResolveErrorKind::NoRecordsFound { .. } => {
          custom_error("NotFound", message)
        }
        ResolveErrorKind::Message("No connections available") => {
          custom_error("NotConnected", message)
        }
        ResolveErrorKind::Timeout => custom_error("TimedOut", message),
        _ => generic_error(message),
      }
    })?
    .iter()
    .filter_map(rdata_to_return_record(record_type))
    .collect();

  Ok(results)
}

pub fn op_set_nodelay<NP>(
  state: &mut OpState,
  rid: ResourceId,
  nodelay: bool,
) -> Result<(), AnyError> {
  let resource: Rc<TcpStreamResource> =
    state.resource_table.get::<TcpStreamResource>(rid)?;
  resource.set_nodelay(nodelay)
}

pub fn op_set_keepalive<NP>(
  state: &mut OpState,
  rid: ResourceId,
  keepalive: bool,
) -> Result<(), AnyError> {
  let resource: Rc<TcpStreamResource> =
    state.resource_table.get::<TcpStreamResource>(rid)?;
  resource.set_keepalive(keepalive)
}

fn rdata_to_return_record(
  ty: RecordType,
) -> impl Fn(&RData) -> Option<DnsReturnRecord> {
  use RecordType::*;
  move |r: &RData| -> Option<DnsReturnRecord> {
    match ty {
      A => r.as_a().map(ToString::to_string).map(DnsReturnRecord::A),
      AAAA => r
        .as_aaaa()
        .map(ToString::to_string)
        .map(DnsReturnRecord::Aaaa),
      ANAME => r
        .as_aname()
        .map(ToString::to_string)
        .map(DnsReturnRecord::Aname),
      CNAME => r
        .as_cname()
        .map(ToString::to_string)
        .map(DnsReturnRecord::Cname),
      MX => r.as_mx().map(|mx| DnsReturnRecord::Mx {
        preference: mx.preference(),
        exchange: mx.exchange().to_string(),
      }),
      PTR => r
        .as_ptr()
        .map(ToString::to_string)
        .map(DnsReturnRecord::Ptr),
      SRV => r.as_srv().map(|srv| DnsReturnRecord::Srv {
        priority: srv.priority(),
        weight: srv.weight(),
        port: srv.port(),
        target: srv.target().to_string(),
      }),
      TXT => r.as_txt().map(|txt| {
        let texts: Vec<String> = txt
          .iter()
          .map(|bytes| {
            // Tries to parse these bytes as Latin-1
            bytes.iter().map(|&b| b as char).collect::<String>()
          })
          .collect();
        DnsReturnRecord::Txt(texts)
      }),
      // TODO(magurotuna): Other record types are not supported
      _ => todo!(),
    }
  }
}

#[cfg(test)]
mod tests {
  use super::*;
  use deno_core::Extension;
  use deno_core::JsRuntime;
  use deno_core::RuntimeOptions;
  use socket2::SockRef;
  use std::net::Ipv4Addr;
  use std::net::Ipv6Addr;
  use std::path::Path;
  use trust_dns_proto::rr::rdata::mx::MX;
  use trust_dns_proto::rr::rdata::srv::SRV;
  use trust_dns_proto::rr::rdata::txt::TXT;
  use trust_dns_proto::rr::record_data::RData;
  use trust_dns_proto::rr::Name;

  #[test]
  fn rdata_to_return_record_a() {
    let func = rdata_to_return_record(RecordType::A);
    let rdata = RData::A(Ipv4Addr::new(127, 0, 0, 1));
    assert_eq!(
      func(&rdata),
      Some(DnsReturnRecord::A("127.0.0.1".to_string()))
    );
  }

  #[test]
  fn rdata_to_return_record_aaaa() {
    let func = rdata_to_return_record(RecordType::AAAA);
    let rdata = RData::AAAA(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1));
    assert_eq!(func(&rdata), Some(DnsReturnRecord::Aaaa("::1".to_string())));
  }

  #[test]
  fn rdata_to_return_record_aname() {
    let func = rdata_to_return_record(RecordType::ANAME);
    let rdata = RData::ANAME(Name::new());
    assert_eq!(func(&rdata), Some(DnsReturnRecord::Aname("".to_string())));
  }

  #[test]
  fn rdata_to_return_record_cname() {
    let func = rdata_to_return_record(RecordType::CNAME);
    let rdata = RData::CNAME(Name::new());
    assert_eq!(func(&rdata), Some(DnsReturnRecord::Cname("".to_string())));
  }

  #[test]
  fn rdata_to_return_record_mx() {
    let func = rdata_to_return_record(RecordType::MX);
    let rdata = RData::MX(MX::new(10, Name::new()));
    assert_eq!(
      func(&rdata),
      Some(DnsReturnRecord::Mx {
        preference: 10,
        exchange: "".to_string()
      })
    );
  }

  #[test]
  fn rdata_to_return_record_ptr() {
    let func = rdata_to_return_record(RecordType::PTR);
    let rdata = RData::PTR(Name::new());
    assert_eq!(func(&rdata), Some(DnsReturnRecord::Ptr("".to_string())));
  }

  #[test]
  fn rdata_to_return_record_srv() {
    let func = rdata_to_return_record(RecordType::SRV);
    let rdata = RData::SRV(SRV::new(1, 2, 3, Name::new()));
    assert_eq!(
      func(&rdata),
      Some(DnsReturnRecord::Srv {
        priority: 1,
        weight: 2,
        port: 3,
        target: "".to_string()
      })
    );
  }

  #[test]
  fn rdata_to_return_record_txt() {
    let func = rdata_to_return_record(RecordType::TXT);
    let rdata = RData::TXT(TXT::from_bytes(vec![
      "foo".as_bytes(),
      "bar".as_bytes(),
      &[0xa3],             // "£" in Latin-1
      &[0xe3, 0x81, 0x82], // "あ" in UTF-8
    ]));
    assert_eq!(
      func(&rdata),
      Some(DnsReturnRecord::Txt(vec![
        "foo".to_string(),
        "bar".to_string(),
        "£".to_string(),
        "ã\u{81}\u{82}".to_string(),
      ]))
    );
  }

  struct TestPermission {}

  impl NetPermissions for TestPermission {
    fn check_net<T: AsRef<str>>(
      &mut self,
      _host: &(T, Option<u16>),
    ) -> Result<(), AnyError> {
      Ok(())
    }

    fn check_read(&mut self, _p: &Path) -> Result<(), AnyError> {
      Ok(())
    }

    fn check_write(&mut self, _p: &Path) -> Result<(), AnyError> {
      Ok(())
    }
  }

  #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
  async fn tcp_set_no_delay() {
    let set_nodelay = Box::new(|state: &mut OpState, rid| {
      op_set_nodelay::<TestPermission>(state, rid, true).unwrap();
    });
    let test_fn = Box::new(|socket: SockRef| {
      assert!(socket.nodelay().unwrap());
      assert!(!socket.keepalive().unwrap());
    });
    check_sockopt(String::from("127.0.0.1:4245"), set_nodelay, test_fn).await;
  }

  #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
  async fn tcp_set_keepalive() {
    let set_keepalive = Box::new(|state: &mut OpState, rid| {
      op_set_keepalive::<TestPermission>(state, rid, true).unwrap();
    });
    let test_fn = Box::new(|socket: SockRef| {
      assert!(!socket.nodelay().unwrap());
      assert!(socket.keepalive().unwrap());
    });
    check_sockopt(String::from("127.0.0.1:4246"), set_keepalive, test_fn).await;
  }

  async fn check_sockopt(
    addr: String,
    set_sockopt_fn: Box<dyn Fn(&mut OpState, u32)>,
    test_fn: Box<dyn FnOnce(SockRef)>,
  ) {
    let clone_addr = addr.clone();
    tokio::spawn(async move {
      let listener = TcpListener::bind(addr).await.unwrap();
      let _ = listener.accept().await;
    });
    let my_ext = Extension::builder()
      .state(move |state| {
        state.put(TestPermission {});
        Ok(())
      })
      .build();

    let mut runtime = JsRuntime::new(RuntimeOptions {
      extensions: vec![my_ext],
      ..Default::default()
    });

    let conn_state = runtime.op_state();

    let server_addr: Vec<&str> = clone_addr.split(':').collect();
    let ip_args = IpListenArgs {
      hostname: String::from(server_addr[0]),
      port: server_addr[1].parse().unwrap(),
    };
    let connect_args = ConnectArgs {
      transport: String::from("tcp"),
      transport_args: ArgsEnum::Ip(ip_args),
    };

    let connect_fut =
      op_net_connect::<TestPermission>(conn_state, connect_args, ());
    let conn = connect_fut.await.unwrap();

    let rid = conn.rid;
    let state = runtime.op_state();
    set_sockopt_fn(&mut state.borrow_mut(), rid);

    let resource = state
      .borrow_mut()
      .resource_table
      .get::<TcpStreamResource>(rid)
      .unwrap();

    let wr = resource.wr_borrow_mut().await;
    let stream = wr.as_ref().as_ref();
    let socket = socket2::SockRef::from(stream);
    test_fn(socket);
  }
}