# ws

ws module is made to provide helpers to create WebSocket client/server.

## Usage

### Server

```ts
import { serve } from "https://deno.land/std/http/server.ts";
import {
  acceptWebSocket,
  isWebSocketCloseEvent,
  isWebSocketPingEvent,
  WebSocket,
} from "https://deno.land/std/ws/mod.ts";

/** websocket echo server */
const port = Deno.args[0] || "8080";
console.log(`websocket server is running on :${port}`);
for await (const req of serve(`:${port}`)) {
  const { headers, conn } = req;
  acceptWebSocket({
    conn,
    headers,
    bufReader: req.r,
    bufWriter: req.w,
  })
    .then(
      async (sock: WebSocket): Promise<void> => {
        console.log("socket connected!");
        const it = sock.receive();
        while (true) {
          try {
            const { done, value } = await it.next();
            if (done) {
              break;
            }
            const ev = value;
            if (typeof ev === "string") {
              // text message
              console.log("ws:Text", ev);
              await sock.send(ev);
            } else if (ev instanceof Uint8Array) {
              // binary message
              console.log("ws:Binary", ev);
            } else if (isWebSocketPingEvent(ev)) {
              const [, body] = ev;
              // ping
              console.log("ws:Ping", body);
            } else if (isWebSocketCloseEvent(ev)) {
              // close
              const { code, reason } = ev;
              console.log("ws:Close", code, reason);
            }
          } catch (e) {
            console.error(`failed to receive frame: ${e}`);
            await sock.close(1000).catch(console.error);
          }
        }
      }
    )
    .catch((err: Error): void => {
      console.error(`failed to accept websocket: ${err}`);
    });
}
```

### Client

```ts
import {
  connectWebSocket,
  isWebSocketCloseEvent,
  isWebSocketPingEvent,
  isWebSocketPongEvent,
} from "https://deno.land/std/ws/mod.ts";
import { encode } from "https://deno.land/std/strings/mod.ts";
import { BufReader } from "https://deno.land/std/io/bufio.ts";
import { TextProtoReader } from "https://deno.land/std/textproto/mod.ts";
import { blue, green, red, yellow } from "https://deno.land/std/fmt/colors.ts";

const endpoint = Deno.args[0] || "ws://127.0.0.1:8080";
/** simple websocket cli */
const sock = await connectWebSocket(endpoint);
console.log(green("ws connected! (type 'close' to quit)"));
(async function (): Promise<void> {
  for await (const msg of sock.receive()) {
    if (typeof msg === "string") {
      console.log(yellow("< " + msg));
    } else if (isWebSocketPingEvent(msg)) {
      console.log(blue("< ping"));
    } else if (isWebSocketPongEvent(msg)) {
      console.log(blue("< pong"));
    } else if (isWebSocketCloseEvent(msg)) {
      console.log(red(`closed: code=${msg.code}, reason=${msg.reason}`));
    }
  }
})();

const tpr = new TextProtoReader(new BufReader(Deno.stdin));
while (true) {
  await Deno.stdout.write(encode("> "));
  const line = await tpr.readLine();
  if (line === null) {
    break;
  }
  if (line === "close") {
    break;
  } else if (line === "ping") {
    await sock.ping();
  } else {
    await sock.send(line);
  }
  // FIXME: Without this,
  // sock.receive() won't resolved though it is readable...
  await new Promise((resolve): void => {
    setTimeout(resolve, 0);
  });
}
await sock.close(1000);
// FIXME: conn.close() won't shutdown process...
Deno.exit(0);
```

## API

### isWebSocketCloseEvent

Returns true if input value is a WebSocketCloseEvent, false otherwise.

### isWebSocketPingEvent

Returns true if input value is a WebSocketPingEvent, false otherwise.

### isWebSocketPongEvent

Returns true if input value is a WebSocketPongEvent, false otherwise.

### append

This module is used to merge two Uint8Arrays.

- note: This module might move to common/util.

```ts
import { append } from "https://deno.land/std/ws/mod.ts";

// a = [1], b = [2]
append(a, b); // output: [1, 2]

// a = [1], b = null
append(a, b); // output: [1]

// a = [], b = [2]
append(a, b); // output: [2]
```

### unmask

Unmask masked WebSocket payload.

### writeFrame

Write WebSocket frame to inputted writer.

### readFrame

Read WebSocket frame from inputted BufReader.

### createMask

Create mask from the client to the server with random 32bit number.

### acceptable

Returns true if input headers are usable for WebSocket, otherwise false

### createSecAccept

Create value of Sec-WebSocket-Accept header from inputted nonce.

### acceptWebSocket

Upgrade inputted TCP connection into WebSocket connection.

### createSecKey

Returns base64 encoded 16 bytes string for Sec-WebSocket-Key header.

### connectWebSocket

Connect to WebSocket endpoint url with inputted endpoint string and headers.

- note: Endpoint must be acceptable for URL.