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/* socket.js, a simple wrapper for a YWOT websocket connection */
const ws = require('ws')
const EventEmitter = require('events');
let mod = (div, end) => ( ( (div % end) + end ) % end ) // Makes it such that (-2) % 3 = 1 instead of -2.
class retryws extends EventEmitter{ // a wrapper on ws that retries on failure
constructor(addr) {
super();
this._sock;
this._sockdown = true;
this._addr = addr;
this.sockinit();
}
send(message){
if (this._sockdown){
throw "Socket is down!";
}
this._sock.send(message);
}
sockinit(){ // addr is not expected to change, so not handed as input; similarly, sock is not passed in a chain because behavior is expected to be serial (either initializing or retrying)
let self = this;
this._sock = new ws(this._addr);
this._sock.on('open', () => { self._sockdown = false; self.emit('open'); });
this._sock.on('close', (err) => { console.log('close', err);
setTimeout(self.sockinit,1000); self._sockdown = true; self.emit('close'); });
this._sock.on('error', (err) => { console.log('error', err); self._sock.close(); });
this._sock.on('message', (message) => { self.emit('message',message);});
}
}
class Socket extends retryws {
constructor(world=''){ // Takes the name of the world, which can be an empty string.
let loc = (world == '') ? '' : `${world}/`;
let addr = `wss://www.yourworldoftext.com/${loc}ws/`;
super(addr);
this._writect = 0; // A running counter to make the server write confirmations meaningful
this.on('message', this._msgparse);
}
_msgparse(msg){
msg = JSON.parse(msg);
switch (msg.kind){
case 'write':
this.emit('write', msg.accepted, msg.rejected); break; // A confirmation message for writes (accepted/rejected updates)
case 'cursor':
this.emit('cursor', msg.positions.map(pos => [pos.tileY*8+pos.charY,pos.tileX*16+pos.charX]), msg.sender); break; // Must be used for self-identification
case 'tileUpdate':
this.emit('tileUpdate', msg.sender, msg.source, msg.tiles); break; // Any change by another user or possibly oneself
case 'fetch':
this.emit('fetch', msg.tiles); break; // The response to a fetch request
}
}
fetch(coords){ //coords is a list of min/max pairs of y/x coordinate pairs which each describe at most 1000 tiles
for (let i=0; i<coords.length; i++){
let c = coords[i];
if ( (c[1][0]-c[0][0]+1) * (c[1][1]-c[0][1]+1) > 1000) throw "Fetch has overlarge rectangular request";
coords[i] = {"minY":c[0][0], "minX":c[0][1], "maxY":c[1][0], "maxX":c[1][1]};
}
this.send( JSON.stringify({
"fetchRectangles": coords,
"kind": "fetch",
"v": "3"
}));
}
write(chars){ //chars is an list of pairs [ pixel coordinate (y/x < 16), char ]
if (chars.length > 200) throw "Too many characters to write by server decree";
if (chars.length == 0) throw "Send at least a character.";
let write = [];
for (let cha of chars){
let coord = cha[0];
write.push([
Math.floor(coord[0]/8),
Math.floor(coord[1]/16),
mod(coord[0], 8),
mod(coord[1], 16),
0,
cha[1],
this._writect
]);
this._writect++;
}
this.send( JSON.stringify({
"edits": write,
"kind": "write"
}));
return this._writect-1; // Last label within write for cross-referencing with confirmation
}
cursor(coords){ //coords is just one pair of char coords; I think the api could handle more, but it's unnecessary for now.
this.send( JSON.stringify({
"kind": "cursor",
"positions":
[
{
"tileY": Math.floor(coords[0]/8),
"tileX": Math.floor(coords[1]/16),
"charY": coords[0] % 8,
"charX": coords[1] % 16
}
]
}));
}
}
module.exports = Socket;
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