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162 lines (137 loc) · 3.65 KB
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export {
createEventStream,
sendOne,
RECONNECT,
CONNECT,
DISCONNECT,
defaultChannel,
};
import Emitter from "event-e3/event-e3.js";
const MIME = `text/event-stream`;
const LAST_ID = `Last-Event-ID`;
const defaultChannel = `message`;
// fields
const DATA = `data`;
const ID = `id`;
const EVENT = `event`;
const RETRY = `retry`;
const RECONNECT = Symbol();
const CONNECT = Symbol();
const DISCONNECT = Symbol();
const formatSimpleMessage = (x) => {
return `${DATA}:${x}\n\n`;
};
const formatId = (id) => {
return `${ID}:${id}\n\n`;
};
const formatEvent = (x) => {
if (typeof x === `string`) {
return formatSimpleMessage(x);
}
const { id, event, data } = x;
let message = ``;
if (id) {
message = `${ID}:${id}\n`;
}
if (event) {
message = `${message}${EVENT}:${event}\n`;
}
if (data && data !== defaultChannel) {
message = `${message}${DATA}:${data}\n`;
}
message = `${message}\n`;
return message;
};
const sendOne = (response, x) => {
const message = formatEvent(x);
response.write(message);
};
const isValidRequestForServerSentEvents = (request) => {
if (request.method !== `GET`) {
return;
}
if (request.headers.accept && !request.headers.accept.includes(MIME)) {
return;
}
return true;
};
const createEventStream = (options) => {
const { path, server, asMiddleWare } = options;
const eventStream = Emitter({ lastEventId: 0 });
let responses = [];
let onRequest;
const requestHandler = (request, response) => {
if (!isValidRequestForServerSentEvents(request)) {
return false;
}
const { socket } = request;
socket.setTimeout(0);
socket.setKeepAlive(true);
socket.setNoDelay(true);
response.writeHead(200, {
[`Content-Type`]: MIME
});
responses.push(response);
const lastId = request.headers[LAST_ID];
if (lastId) {
// opportunity to resume with sendOne
eventStream.emit(RECONNECT, {
lastId,
response
});
}
socket.once(`close`, () => {
const index = responses.indexOf(response);
if (index !== -1) {
responses.splice(index, 1);
eventStream.emit(DISCONNECT, { response });
}
});
eventStream.emit(CONNECT, { response });
return true;
};
const close = () => {
if (!asMiddleWare) {
server.off(`request`, onRequest);
}
responses.forEach(response => {
response.end();
});
responses = [];
};
const setAndSendId = (id) => {
eventStream.lastEventId = id;
const message = formatId(id);
responses.forEach(response => {
response.write(message);
});
};
const send = (x) => {
const message = formatEvent(x);
responses.forEach(response => {
response.write(message);
});
};
if (asMiddleWare) {
eventStream.middleWare = (request, response, next) => {
const handled = requestHandler(request, response);
if (!handled) {
next();
}
};
} else {
onRequest = (request, response) => {
const requestPath = request.url;
if (requestPath !== path) {
return;
}
requestHandler(request, response, responses);
};
server.on(`request`, onRequest);
}
return Object.assign(eventStream, {
send,
setAndSendId,
close,
});
};