Add cast prototype

cast.js

@@ -0,0 +1,92 @@
+import dgram from 'dgram'
+import { getPrinters } from './print.js'
+
+export function discover() {
+    const socket = dgram.createSocket({ type: 'udp4', reuseAddr: true })
+    const origin = Math.random().toString(36).substring(2, 15) + Math.random().toString(36).substring(2, 15)
+    const discoveredPrinters = []
+    const discoverInterval = 10000
+    const timeoutInterval = 30000
+
+    const broadcast = (event, payload) => {
+        socket.send(Buffer.from(JSON.stringify({
+            event,
+            origin,
+            ...payload,
+        })), 4446, '230.0.0.0', function (err) {
+            if (err) console.error(err)
+        })
+    }
+
+    socket.bind(4446, function () {
+        socket.addMembership('230.0.0.0')
+    })
+
+    socket.on('listening', function () {
+        console.log('UDP Socket listening on ' + JSON.stringify(socket.address()))
+    })
+
+    socket.on('message', async function (message, rinfo) {
+        console.log(`Received message: ${message} from ${rinfo.address}:${rinfo.port}`)
+        try {
+            const payload = JSON.parse(message.toString())
+            if (payload.event === 'printer-list') {
+                const printers = await getPrinters()
+
+                printers.map(printer => {
+                    broadcast('printer', {
+                        printer: {
+                            default: false,
+                            format: 'PDF',
+                            id: printer.printer || printer.deviceId,
+                            name: printer.printer || printer.name,
+                        },
+                    })
+                })
+            } else if (payload.event === 'printer') {
+                console.log('Printer list received')
+                const { printer } = payload
+                const existingPrinter = discoveredPrinters.find(p => p.id === printer.id)
+                const last_seen = new Date().getTime()
+
+                if (existingPrinter) {
+                    existingPrinter.last_seen = last_seen
+                } else {
+                    discoveredPrinters.push({
+                        ...printer,
+                        uri: `http://${rinfo.address}/printers/${encodeURIComponent(printer.id)}/print`,
+                        last_seen,
+                    })
+                }
+            }
+        } catch (e) {
+            console.log('Error parsing message', e)
+        }
+    })
+
+    // Your list
+    let list = [{ origin, port: 1903 }]
+
+    // Serialize the list to JSON
+    let jsonList = JSON.stringify(list)
+
+    setInterval(() => broadcast('printer-list'), discoverInterval)
+    broadcast('printer-list')
+
+    setInterval(() => {
+        const now = new Date().getTime()
+        discoveredPrinters.forEach(printer => {
+            if (now - printer.last_seen > timeoutInterval) {
+                const index = discoveredPrinters.indexOf(printer)
+                discoveredPrinters.splice(index, 1)
+            }
+        })
+        console.log('Discovered printers', discoveredPrinters)
+    }, 5000)
+
+    return {
+        printers: list,
+    }
+}
+
+discover()

index.js

@@ -10,6 +10,8 @@ const port = 1903
 
 const upload = multer({ dest: 'uploads/' })
 
+const discovery = discover()
+
 app.use(cors())
 app.use(bodyParser.json())
 app.use(bodyParser.urlencoded({ extended: true }))
@@ -19,7 +21,9 @@ app.get('/', (req, res) => {
 })
 
 app.get('/printers', async (req, res) => {
+    try {
         const printers = await getPrinters()
+
         return res.json(printers.map(printer => {
             return {
                 default: false,
@@ -28,6 +32,10 @@ app.get('/printers', async (req, res) => {
                 name: printer.printer || printer.name,
             }
         }))
+    } catch (e) {
+        console.log('Error getting printers', e)
+        return res.json([])
+    }
 })
 
 app.post('/printers/:printer/print', upload.single('file'), async (req, res) => {