// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.

use crate::permissions::Permissions;
use deno_core::error::bad_resource_id;
use deno_core::error::type_error;
use deno_core::error::AnyError;
use deno_core::futures::stream::SplitSink;
use deno_core::futures::stream::SplitStream;
use deno_core::futures::SinkExt;
use deno_core::futures::StreamExt;
use deno_core::serde_json::json;
use deno_core::serde_json::Value;
use deno_core::url;
use deno_core::AsyncRefCell;
use deno_core::BufVec;
use deno_core::CancelFuture;
use deno_core::CancelHandle;
use deno_core::OpState;
use deno_core::RcRef;
use deno_core::Resource;
use deno_core::{serde_json, ZeroCopyBuf};
use http::{Method, Request, Uri};
use serde::Deserialize;
use std::borrow::Cow;
use std::cell::RefCell;
use std::io::BufReader;
use std::io::Cursor;
use std::rc::Rc;
use std::sync::Arc;
use tokio::net::TcpStream;
use tokio_rustls::{rustls::ClientConfig, TlsConnector};
use tokio_tungstenite::stream::Stream as StreamSwitcher;
use tokio_tungstenite::tungstenite::Error as TungsteniteError;
use tokio_tungstenite::tungstenite::{
  handshake::client::Response, protocol::frame::coding::CloseCode,
  protocol::CloseFrame, Message,
};
use tokio_tungstenite::{client_async, WebSocketStream};
use webpki::DNSNameRef;

#[derive(Clone)]
struct WsCaData(Vec<u8>);
#[derive(Clone)]
struct WsUserAgent(String);

pub fn init(
  rt: &mut deno_core::JsRuntime,
  ca_data: Option<Vec<u8>>,
  user_agent: String,
) {
  {
    let op_state = rt.op_state();
    let mut state = op_state.borrow_mut();
    if let Some(ca_data) = ca_data {
      state.put::<WsCaData>(WsCaData(ca_data));
    }
    state.put::<WsUserAgent>(WsUserAgent(user_agent));
  }
  super::reg_json_sync(rt, "op_ws_check_permission", op_ws_check_permission);
  super::reg_json_async(rt, "op_ws_create", op_ws_create);
  super::reg_json_async(rt, "op_ws_send", op_ws_send);
  super::reg_json_async(rt, "op_ws_close", op_ws_close);
  super::reg_json_async(rt, "op_ws_next_event", op_ws_next_event);
}

type MaybeTlsStream =
  StreamSwitcher<TcpStream, tokio_rustls::client::TlsStream<TcpStream>>;

type WsStream = WebSocketStream<MaybeTlsStream>;
struct WsStreamResource {
  tx: AsyncRefCell<SplitSink<WsStream, Message>>,
  rx: AsyncRefCell<SplitStream<WsStream>>,
  // When a `WsStreamResource` resource is closed, all pending 'read' ops are
  // canceled, while 'write' ops are allowed to complete. Therefore only
  // 'read' futures are attached to this cancel handle.
  cancel: CancelHandle,
}

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

impl WsStreamResource {}

#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
struct CheckPermissionArgs {
  url: String,
}

// This op is needed because creating a WS instance in JavaScript is a sync
// operation and should throw error when permissions are not fullfiled,
// but actual op that connects WS is async.
pub fn op_ws_check_permission(
  state: &mut OpState,
  args: Value,
  _zero_copy: &mut [ZeroCopyBuf],
) -> Result<Value, AnyError> {
  let args: CheckPermissionArgs = serde_json::from_value(args)?;

  state
    .borrow::<Permissions>()
    .check_net_url(&url::Url::parse(&args.url)?)?;

  Ok(json!({}))
}

#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
struct CreateArgs {
  url: String,
  protocols: String,
}

pub async fn op_ws_create(
  state: Rc<RefCell<OpState>>,
  args: Value,
  _bufs: BufVec,
) -> Result<Value, AnyError> {
  let args: CreateArgs = serde_json::from_value(args)?;

  {
    let s = state.borrow();
    s.borrow::<Permissions>()
      .check_net_url(&url::Url::parse(&args.url)?)
      .expect(
        "Permission check should have been done in op_ws_check_permission",
      );
  }

  let ws_ca_data = state.borrow().try_borrow::<WsCaData>().cloned();
  let user_agent = state.borrow().borrow::<WsUserAgent>().0.clone();
  let uri: Uri = args.url.parse()?;
  let mut request = Request::builder().method(Method::GET).uri(&uri);

  request = request.header("User-Agent", user_agent);

  if !args.protocols.is_empty() {
    request = request.header("Sec-WebSocket-Protocol", args.protocols);
  }

  let request = request.body(())?;
  let domain = &uri.host().unwrap().to_string();
  let port = &uri.port_u16().unwrap_or(match uri.scheme_str() {
    Some("wss") => 443,
    Some("ws") => 80,
    _ => unreachable!(),
  });
  let addr = format!("{}:{}", domain, port);
  let try_socket = TcpStream::connect(addr).await;
  let tcp_socket = match try_socket.map_err(TungsteniteError::Io) {
    Ok(socket) => socket,
    Err(_) => return Ok(json!({"success": false})),
  };

  let socket: MaybeTlsStream = match uri.scheme_str() {
    Some("ws") => StreamSwitcher::Plain(tcp_socket),
    Some("wss") => {
      let mut config = ClientConfig::new();
      config
        .root_store
        .add_server_trust_anchors(&webpki_roots::TLS_SERVER_ROOTS);

      if let Some(ws_ca_data) = ws_ca_data {
        let reader = &mut BufReader::new(Cursor::new(ws_ca_data.0));
        config.root_store.add_pem_file(reader).unwrap();
      }

      let tls_connector = TlsConnector::from(Arc::new(config));
      let dnsname =
        DNSNameRef::try_from_ascii_str(&domain).expect("Invalid DNS lookup");
      let tls_socket = tls_connector.connect(dnsname, tcp_socket).await?;
      StreamSwitcher::Tls(tls_socket)
    }
    _ => unreachable!(),
  };

  let (stream, response): (WsStream, Response) =
    client_async(request, socket).await.map_err(|err| {
      type_error(format!(
        "failed to connect to WebSocket: {}",
        err.to_string()
      ))
    })?;

  let (ws_tx, ws_rx) = stream.split();
  let resource = WsStreamResource {
    rx: AsyncRefCell::new(ws_rx),
    tx: AsyncRefCell::new(ws_tx),
    cancel: Default::default(),
  };
  let mut state = state.borrow_mut();
  let rid = state.resource_table.add(resource);

  let protocol = match response.headers().get("Sec-WebSocket-Protocol") {
    Some(header) => header.to_str().unwrap(),
    None => "",
  };
  let extensions = response
    .headers()
    .get_all("Sec-WebSocket-Extensions")
    .iter()
    .map(|header| header.to_str().unwrap())
    .collect::<String>();
  Ok(json!({
    "success": true,
    "rid": rid,
    "protocol": protocol,
    "extensions": extensions
  }))
}

#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
struct SendArgs {
  rid: u32,
  text: Option<String>,
}

pub async fn op_ws_send(
  state: Rc<RefCell<OpState>>,
  args: Value,
  bufs: BufVec,
) -> Result<Value, AnyError> {
  let args: SendArgs = serde_json::from_value(args)?;

  let msg = match args.text {
    Some(text) => Message::Text(text),
    None => Message::Binary(bufs[0].to_vec()),
  };
  let rid = args.rid;

  let resource = state
    .borrow_mut()
    .resource_table
    .get::<WsStreamResource>(rid)
    .ok_or_else(bad_resource_id)?;
  let mut tx = RcRef::map(&resource, |r| &r.tx).borrow_mut().await;
  tx.send(msg).await?;
  Ok(json!({}))
}

#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
struct CloseArgs {
  rid: u32,
  code: Option<u16>,
  reason: Option<String>,
}

pub async fn op_ws_close(
  state: Rc<RefCell<OpState>>,
  args: Value,
  _bufs: BufVec,
) -> Result<Value, AnyError> {
  let args: CloseArgs = serde_json::from_value(args)?;
  let rid = args.rid;
  let msg = Message::Close(args.code.map(|c| CloseFrame {
    code: CloseCode::from(c),
    reason: match args.reason {
      Some(reason) => Cow::from(reason),
      None => Default::default(),
    },
  }));

  let resource = state
    .borrow_mut()
    .resource_table
    .get::<WsStreamResource>(rid)
    .ok_or_else(bad_resource_id)?;
  let mut tx = RcRef::map(&resource, |r| &r.tx).borrow_mut().await;
  tx.send(msg).await?;
  Ok(json!({}))
}

#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
struct NextEventArgs {
  rid: u32,
}

pub async fn op_ws_next_event(
  state: Rc<RefCell<OpState>>,
  args: Value,
  _bufs: BufVec,
) -> Result<Value, AnyError> {
  let args: NextEventArgs = serde_json::from_value(args)?;

  let resource = state
    .borrow_mut()
    .resource_table
    .get::<WsStreamResource>(args.rid)
    .ok_or_else(bad_resource_id)?;

  let mut rx = RcRef::map(&resource, |r| &r.rx).borrow_mut().await;
  let cancel = RcRef::map(resource, |r| &r.cancel);
  let val = rx.next().or_cancel(cancel).await?;
  let res = match val {
    Some(Ok(Message::Text(text))) => json!({
      "type": "string",
      "data": text
    }),
    Some(Ok(Message::Binary(data))) => {
      // TODO(ry): don't use json to send binary data.
      json!({
        "type": "binary",
        "data": data
      })
    }
    Some(Ok(Message::Close(Some(frame)))) => json!({
      "type": "close",
      "code": u16::from(frame.code),
      "reason": frame.reason.as_ref()
    }),
    Some(Ok(Message::Close(None))) => json!({ "type": "close" }),
    Some(Ok(Message::Ping(_))) => json!({"type": "ping"}),
    Some(Ok(Message::Pong(_))) => json!({"type": "pong"}),
    Some(Err(_)) => json!({"type": "error"}),
    None => {
      state.borrow_mut().resource_table.close(args.rid).unwrap();
      json!({"type": "closed"})
    }
  };
  Ok(res)
}