[Task 3] remove data

task_3_react/package.json

@@ -30,6 +30,6 @@
     "@vitejs/plugin-react": "^4.3.2",
     "nodemon": "^3.1.7",
     "prettier": "^3.3.3",
-    "vite": "^5.4.9"
+    "vite": "^7.2.2"
   }
 }

task_3_react/src/client/App.tsx

@@ -1,83 +1,125 @@
-import "./css/App.css";
+import './css/App.css';
 import '@fortawesome/fontawesome-free/css/all.css';
-import { CSV_Data, fileInfo, responseObject } from './types';
-import { readCSV, convertCSVtoJSON } from './csv';
+import {
+    CSV_Data, fileInfo, responseObject
+} from './types';
+import React, {
+    useEffect,
+    useRef, useState
+} from 'react';
+import {
+    convertCSVtoJSON, readCSV
+} from './csv';
+import CSVCard from './components/CSVCard';
+import DataTable from './components/DataTable';
+import FileCard from './components/FileCard';
+import InfoCard from './components/InfoCard';
+import Layout from './components/Layout';
+import "./sse"
 
-import React, { useState, useRef, useEffect } from "react";
-import Layout from "./components/Layout";
-import CSVCard from "./components/CSVCard";
-import InfoCard from "./components/InfoCard";
-import DataTable from "./components/DataTable";
-import FileCard from "./components/FileCard";
+function App () {
+    const [
+        data,
+        setData
+    ] = useState( [] as CSV_Data );
+    const [
+        info,
+        setInfo
+    ] = useState( {
+        'filename': 'None',
+        'filetype': 'None',
+        'filesize': 'None',
+        'rowcount': 0
+    } );
+    const [
+        fileList,
+        setFileList
+    ] = useState( null as responseObject | null );
 
-function App() {
-  const [data, setData] = useState([] as CSV_Data);
-  const [info, setInfo] = useState({
-    filename: "None",
-    filetype: "None",
-    filesize: "None",
-    rowcount: 0
-  });
+    // Add evenbt listener for server-sent events on first render
+    const [active, setActive] = useState(false);
 
-  const [fileList, setFileList] = useState(null as responseObject | null);
-  // Effect has to be in top level of the component
-  useEffect(() => {
-    fetch("/status", { method: "GET" })
-      .then((response) => response.json())
-      .then((response) => setFileList(response))
-      .catch((error) => console.log(error));
-  });
+    useEffect( ()=> {
+        if (!active) {
+            document.addEventListener("sse:uploaded", async _ev => {
+                await fetch( '/status', {
+                    'method': 'GET'
+                } )
+                    .then( response => response.json() )
+                    .then( response => setFileList( response ) )
+                    .catch( error => console.log( error ) );
+            });
+            document.addEventListener("sse:deleted", async _ev => {
+                await fetch( '/status', {
+                    'method': 'GET'
+                } )
+                    .then( response => response.json() )
+                    .then( response => setFileList( response ) )
+                    .catch( error => console.log( error ) );
+            });
+            setActive(true);
+            // Initial fetch of file list at first component render
+            fetch( '/status', {
+                'method': 'GET'
+            } )
+                .then( response => response.json() )
+                .then( response => setFileList( response ) )
+                .catch( error => console.log( error ) );
+        }       
+    })
 
-  const formRef = useRef(null);
+    const formRef = useRef( null );
 
-  // This is triggered in CSVCard
-  const handleFileUpload = async (e: React.ChangeEvent<HTMLInputElement>): Promise<void> => {
-    const file = e.target.files?.[0];
-    if (!file) throw new Error("No file received");
+    // This is triggered in CSVCard
+    const handleFileUpload = async ( e: React.ChangeEvent<HTMLInputElement> ): Promise<void> => {
+        const file = e.target.files?.[0];
 
-    const data = await readCSV(e);
+        if ( !file ) throw new Error( 'No file received' );
 
-    const newFileInfo: fileInfo = {
-      filename: file.name,
-      filetype: ".csv", // file.type delivers weird name
-      filesize: String(file.size) + "B",
-      rowcount: data.length
-    }
-    setInfo(newFileInfo);
-    setData(data);
+        const data = await readCSV( e );
+        const newFileInfo: fileInfo = {
+            'filename': file.name,
+            'filetype': '.csv', // file.type delivers weird name
+            'filesize': String( file.size ) + 'B',
+            'rowcount': data.length
+        };
 
-    if (formRef.current) {
-      // Upload to server
-      const formData = new FormData(formRef.current);
-      await fetch("/upload", {
-        method: "POST",
-        body: formData
-      });
-    }
-  }
+        setInfo( newFileInfo );
+        setData( data );
 
-  const handleFileChange = async (fileName: string) => {
-    const response = await fetch(`/download/${fileName}`);
-    const blob = await response.blob();
-    const text = await blob.text();
+        if ( formRef.current ) {
+            // Upload to server
+            const formData = new FormData( formRef.current );
 
-    if (!response) throw new Error("No file received");
+            await fetch( '/upload', {
+                'method': 'POST',
+                'body': formData
+            } );
+        }
+    };
 
-    const data = await convertCSVtoJSON(text);
+    const handleFileChange = async ( fileName: string ) => {
+        const response = await fetch( `/download/${ fileName }` );
+        const blob = await response.blob();
+        const text = await blob.text();
 
-    // Updating fileInfo requires more effort since blob doesn't have the metadata
+        if ( !response ) throw new Error( 'No file received' );
 
-    setData(data);
-  }
+        const data = await convertCSVtoJSON( text );
 
-  return (
-      <Layout>
-        <CSVCard handleChange={handleFileUpload} formRef={formRef}></CSVCard>
-        <FileCard fileList={fileList as responseObject} fileChangeHandle={handleFileChange}></FileCard>
-        <InfoCard info={info}></InfoCard>
-        <DataTable data={data}></DataTable>
-      </Layout>
-  );
+        // Updating fileInfo requires more effort since blob doesn't have the metadata
+
+        setData( data );
+    };
+
+    return (
+        <Layout>
+            <CSVCard handleChange={handleFileUpload} formRef={formRef}></CSVCard>
+            <FileCard fileList={fileList as responseObject} fileChangeHandle={handleFileChange}></FileCard>
+            <InfoCard info={info}></InfoCard>
+            <DataTable data={data}></DataTable>
+        </Layout>
+    );
 }
 
 export default App;

task_3_react/src/client/components/CSVCard.tsx

@@ -1,24 +1,29 @@
-import React from "react";
-import "../css/Layout.css";
+import '../css/Layout.css';
+import React from 'react';
 
-const CSVCard = (props: { 
-  handleChange: (e: React.ChangeEvent<HTMLInputElement>) => void,
-  formRef: React.RefObject<HTMLFormElement>
-}) => {
-  return (
-    <article>
-        <header>
-            <h2>Upload CSV data</h2>
-        </header>
-        <form ref={props.formRef} action="/upload" method="post" encType="multipart/form-data" >
-            <label htmlFor="file-input" className="custom-file-upload">
-                <i className="fa fa-file-csv"></i> Select CSV file to explore
-            </label>
-            <input id="file-input" type="file" name="dataFile" aria-describedby="fileHelp" accept="text/csv" onChange={props.handleChange}/>
-            <small>Please upload a CSV file, where the first row is the header.</small>
-        </form>
-    </article>
-  );
-}
+const CSVCard = ( props: {
+    'handleChange': ( e: React.ChangeEvent<HTMLInputElement> ) => void,
+    'formRef': React.RefObject<HTMLFormElement>
+} ) => {
+    return (
+        <article>
+            <header>
+                <h2>Upload CSV data</h2>
+            </header>
+            <form ref={props.formRef} action="/upload" method="post" encType="multipart/form-data" >
+                <label htmlFor="file-input" className="custom-file-upload">
+                    <i className="fa fa-file-csv"></i> Select CSV file to explore
+                </label>
+                <input
+                    id="file-input"
+                    type="file"
+                    name="dataFile"
+                    aria-describedby="fileHelp" accept="text/csv" onChange={props.handleChange}/>
+                <small>Please upload a CSV file, where the first row is the header.</small>
+            </form>
+        </article>
+    );
+};
 
 export default CSVCard;
+

task_3_react/src/client/components/DataTable.tsx

@@ -1,37 +1,53 @@
-import { Key, SetStateAction, useState } from "react";
-import { CSV_Data } from "../types";
+import {
+    Key, SetStateAction, useState
+} from 'react';
+import {
+    CSV_Data
+} from '../types';
 
-const DataTable = (props: {data: CSV_Data}) => {
-    if (props.data.length == 0) return <></>;
+const DataTable = ( props: {
+    'data': CSV_Data
+} ) => {
+    if ( props.data.length == 0 ) return <></>;
 
-    const header = Object.keys(props.data[0]!);
-    const [sortCol, setSortCol] = useState("None");
-    const [sortType, setSortType] = useState("asc");
+    const header = Object.keys( props.data[0]! );
+    const [
+        sortCol,
+        setSortCol
+    ] = useState( 'None' );
+    const [
+        sortType,
+        setSortType
+    ] = useState( 'asc' );
 
-    const sortingHandler = (col: String) => { 
-        if (sortCol !== col) {
-            setSortCol(col as SetStateAction<string>); 
-            setSortType("asc");
-        } else if (sortType === "asc") {
-            setSortType("desc");
+    const sortingHandler = ( col: string ) => {
+        if ( sortCol !== col ) {
+            setSortCol( col as SetStateAction<string> );
+            setSortType( 'asc' );
+        } else if ( sortType === 'asc' ) {
+            setSortType( 'desc' );
         } else {
-            setSortCol("None");
-            setSortType("None");
+            setSortCol( 'None' );
+            setSortType( 'None' );
         }
-    }
+    };
+
+    if ( sortCol !== 'None' && sortType === 'asc' ) {
+        props.data.sort( ( a, b ) => {
+            if ( a[sortCol]! < b[sortCol]! ) return -1;
+
+            if ( a[sortCol]! > b[sortCol]! ) return 1;
 
-    if (sortCol !== "None" && sortType === "asc") {
-        props.data.sort( (a, b) => {
-            if (a[sortCol]! < b[sortCol]!) return -1;
-            if (a[sortCol]! > b[sortCol]!) return 1;
             return 0;
-        }); 
-    } else if (sortCol !== "None" && sortType === "desc") {
-        props.data.sort( (a, b) => {
-            if (a[sortCol]! > b[sortCol]!) return -1;
-            if (a[sortCol]! < b[sortCol]!) return 1;
+        } );
+    } else if ( sortCol !== 'None' && sortType === 'desc' ) {
+        props.data.sort( ( a, b ) => {
+            if ( a[sortCol]! > b[sortCol]! ) return -1;
+
+            if ( a[sortCol]! < b[sortCol]! ) return 1;
+
             return 0;
-        });
+        } );
     }
 
     return (
@@ -43,49 +59,61 @@ const DataTable = (props: {data: CSV_Data}) => {
                 <table id="table-content">
                     <thead>
                         <tr>
-                        {
-                            header.map( (col) => (
-                                <ColHeader col={col} sortingHandle={sortingHandler} isSelected={col == sortCol} sortType={sortType}></ColHeader>
-                            ))
-                        }
+                            {
+                                header.map( col => <ColHeader
+                                    col={col}
+                                    sortingHandle={sortingHandler}
+                                    isSelected={col == sortCol}
+                                    sortType={sortType}></ColHeader> )
+                            }
                         </tr>
                     </thead>
                     <tbody>
                         {
-                            props.data.map( (row, i) => (
+                            props.data.map( ( row, i ) => (
                                 <tr key={i}>
                                     {
-                                        header.map( (col) => (
-                                            <Row key={i} col={col} content={row[col] as String}></Row>
-                                        ))
+                                        header.map( col => <Row key={i} col={col} content={row[col] as string}></Row> )
                                     }
                                 </tr>
-                            ))
+                            ) )
                         }
                     </tbody>
                 </table>
             </div>
         </article>
-    )
-}
+    );
+};
 
-const ColHeader = (props: {col: String, sortingHandle: (s: String) => void, isSelected: boolean, sortType: String}) => {
+const ColHeader = ( props: {
+    'col': string,
+    'sortingHandle': ( s: string ) => void,
+    'isSelected': boolean,
+    'sortType': string
+} ) => {
     return (
         <th
             className={
                 props.isSelected
-                ? (props.sortType === "asc" ? "active sorting asc" : "active sorting desc")
-                : "sortable"
+                    ? ( props.sortType === 'asc' ? 'active sorting asc' : 'active sorting desc' )
+                    : 'sortable'
             }
-            onClick={() => {props.sortingHandle!(props.col)}} 
+            onClick={() => {
+                props.sortingHandle!( props.col );
+            }}
             key={props.col as Key}>
             {props.col}
         </th>
     );
-}
+};
 
-const Row = (props: {col: String, content: String, key: Key}) => {
+const Row = ( props: {
+    'col': string,
+    'content': string,
+    'key': Key
+} ) => {
     return <td key={props.col as Key}>{props.content}</td>;
-}
+};
 
 export default DataTable;
+

task_3_react/src/client/components/FileCard.tsx

@@ -1,58 +1,65 @@
-import { responseObject } from "../types";
+import {
+    responseObject
+} from '../types';
 
-const FileCard = (props: {
-    fileList: responseObject,
-    fileChangeHandle: (fileName: string) => Promise<void>
-}) => {
+const FileCard = ( props: {
+    'fileList': responseObject,
+    'fileChangeHandle': ( fileName: string ) => Promise<void>
+} ) => {
+    const convert = ( res: responseObject ) => {
+        const list = [];
 
-    const convert = (res: responseObject) => {
-        let list = [];
-        for (let i = 0; i < res.names.length; i++) {
+        for ( let i = 0; i < res.names.length; i++ ) {
             const elem = {
-                filename: res.names[i],
-                uploadTime: res.uploadTimes[i]
-            }
-            list.push(elem);
-        }
-        return list;
-    }
+                'filename': res.names[i],
+                'uploadTime': res.uploadTimes[i]
+            };
 
-    const list = props.fileList != null ? convert(props.fileList) : null;
+            list.push( elem );
+        }
+
+        return list;
+    };
+
+    const list = props.fileList != null ? convert( props.fileList ) : null;
 
     return (
         <article className="wide">
             <header>
                 <h2>Select a File</h2>
             </header>
-                <table id="table-content">
-                    <thead>
-                        <tr>
-                            <th>Filename</th>
-                            <th>Upload Time</th>
-                            <th>Action</th>
-                        </tr>
-                    </thead>
-                    <tbody>
-                        {
-                            list ? list.map( (file, i) => (
-                                <FileRow key={i} filename={file.filename!} uploadTime={file.uploadTime!} fileChangeHandle={props.fileChangeHandle}></FileRow>
-                            )) : <tr></tr>
-                        }
-                    </tbody>
-                </table>
+            <table id="table-content">
+                <thead>
+                    <tr>
+                        <th>Filename</th>
+                        <th>Upload Time</th>
+                        <th>Action</th>
+                    </tr>
+                </thead>
+                <tbody>
+                    {
+                        list ? list.map( ( file, i ) => <FileRow
+                            key={i}
+                            filename={file.filename!}
+                            uploadTime={file.uploadTime!}
+                            fileChangeHandle={props.fileChangeHandle}/> ) : <tr></tr>
+                    }
+                </tbody>
+            </table>
         </article>
     );
-}
+};
 
-const FileRow = (props: {
-    filename: string,
-    uploadTime: string,
-    fileChangeHandle: (fileName: string) => Promise<void>
-}) => {
-
-    const remFile = async () => {
-        await fetch(`/delete/${props.filename}`, { method: "DELETE" });
-    }
+const FileRow = ( props: {
+    'filename': string,
+    'uploadTime': string,
+    'fileChangeHandle': ( fileName: string ) => Promise<void>
+} ) => {
+    const rmFile = async () => {
+        await fetch( `/delete/${ props.filename }`, {
+            'method': 'DELETE'
+        } );
+    };
 
     return (
         <tr>
@@ -60,12 +67,17 @@ const FileRow = (props: {
             <td>{props.uploadTime}</td>
             <td>
                 <div className="action-icons">
-                    <i onClick={() => { remFile()} }  className="fa-solid fa-trash-can"></i>
-                    <i onClick={() => {props.fileChangeHandle(props.filename)}} className="fa-solid fa-file-arrow-down"></i>
+                    <i onClick={() => {
+                        rmFile();
+                    } } className="fa-solid fa-trash-can"></i>
+                    <i onClick={() => {
+                        props.fileChangeHandle( props.filename );
+                    }} className="fa-solid fa-file-arrow-down"></i>
                 </div>
             </td>
         </tr>
-    )
-}
+    );
+};
 
 export default FileCard;
+

task_3_react/src/client/components/InfoCard.tsx

@@ -1,34 +1,37 @@
-import { fileInfo } from "../types";
+import {
+    fileInfo
+} from '../types';
 
-const InfoCard = (props: { 
-    info: fileInfo
-}) => {
+const InfoCard = ( props: {
+    'info': fileInfo
+} ) => {
+    let noFileMessage = <div></div>;
 
-  let noFileMessage = <div></div> 
-  if (props.info.filename === "None") 
-    noFileMessage = <div id="data-info-placeholder">No file selected</div>;
+    if ( props.info.filename === 'None' )
+        noFileMessage = <div id="data-info-placeholder">No file selected</div>;
 
-  return (
-    <article>
-         <header>
-            <h2>Data infos</h2>
-        </header>
-         <div className="info">
-            {noFileMessage}
-            <h4>Filename</h4>
-            <p>{props.info.filename}</p>
+    return (
+        <article>
+            <header>
+                <h2>Data infos</h2>
+            </header>
+            <div className="info">
+                {noFileMessage}
+                <h4>Filename</h4>
+                <p>{props.info.filename}</p>
 
-            <h4>File type</h4>
-            <p>{props.info.filetype}</p>
+                <h4>File type</h4>
+                <p>{props.info.filetype}</p>
 
-            <h4>File size</h4>
-            <p>{props.info.filesize}</p>
+                <h4>File size</h4>
+                <p>{props.info.filesize}</p>
 
-            <h4>Number of rows</h4>
-            <p>{props.info.rowcount}</p>
-        </div>
-    </article>
-  );
-}
+                <h4>Number of rows</h4>
+                <p>{props.info.rowcount}</p>
+            </div>
+        </article>
+    );
+};
 
 export default InfoCard;
+

task_3_react/src/client/components/Layout.tsx

@@ -1,21 +1,23 @@
-import React from "react";
-import "../css/Layout.css";
+import '../css/Layout.css';
+import React from 'react';
 
-const Layout = (props: { children: React.ReactNode }) => {
-  return (
-    <>
-      <nav className="container-fluid">
-        <ul>
-          <li>
-            <h1>Open data explorer</h1>
-          </li>
-        </ul>
-      </nav>
-      <main className="container-fluid">
-        {props.children}
-      </main>
-    </>
-  );
+const Layout = ( props: {
+    'children': React.ReactNode
+} ) => {
+    return (
+        <>
+            <nav className="container-fluid">
+                <ul>
+                    <li>
+                        <h1>Open data explorer</h1>
+                    </li>
+                </ul>
+            </nav>
+            <main className="container-fluid">
+                {props.children}
+            </main>
+        </>
+    );
 };
 
 export default Layout;

task_3_react/src/client/csv.ts

@@ -1,5 +1,9 @@
-import { CSV_Data } from './types';
-import { csv2json } from 'json-2-csv';
+import {
+    CSV_Data
+} from './types';
+import {
+    csv2json
+} from 'json-2-csv';
 
 export const convertCSVtoJSON = async ( csvText: string ) => {
     // Type cast OK, as the typing of the external library is not perfect -> Actually it is.

task_3_react/src/client/sse.ts

@@ -0,0 +1,21 @@
+interface SSEMessage {
+    'event': string,
+    'data': string
+}
+const eventSource: EventSource = new EventSource( '/sse' );
+
+eventSource.onopen = () => {
+    document.dispatchEvent( new CustomEvent( 'sse:connect', {
+        'detail': 'success',
+        'cancelable': false
+    } ) );
+};
+
+eventSource.onmessage = event => {
+    const data: SSEMessage = JSON.parse( event.data );
+
+    document.dispatchEvent( new CustomEvent( 'sse:' + data.event, {
+        'cancelable': false,
+        'detail': data.data
+    } ) );
+};

task_3_react/src/server/main.ts

@@ -1,81 +1,160 @@
-import express from "express";
-import ViteExpress from "vite-express";
-import multer from "multer";
-import * as fs from "node:fs/promises";
-import { responseObject } from "./types";
-import path from "path";
+import * as fs from 'node:fs/promises';
+import {
+    EventEmitter
+} from 'node:stream';
+import ViteExpress from 'vite-express';
+import express from 'express';
+import multer from 'multer';
+import path from 'path';
+import {
+    responseObject
+} from './types';
 
 const app = express();
-
 // Set up file storage
-const storage = multer.diskStorage({
-  destination: "./src/server/uploads",
-  filename: (_req, file, cb) => {
+const storage = multer.diskStorage( {
+    'destination': './src/server/uploads',
+    'filename': (
+        _req, file, cb
+    ) => {
     // Suggested in Multer's readme
-    const uniqueSuffix = Date.now() + "-" + Math.round(Math.random() * 1E3);
-    cb(null, file.fieldname + "-" + uniqueSuffix);
-  }
-});
+        const uniqueSuffix = Date.now() + '-' + Math.round( Math.random() * 1E3 );
 
+        fileEvent.emit( 'uploaded', file.fieldname + '-' + uniqueSuffix );
+
+        cb( null, file.fieldname + '-' + uniqueSuffix );
+    }
+} );
 // CSV file upload endpoint
-const upload = multer({ storage: storage });
+const upload = multer( {
+    'storage': storage
+} );
+
+class FileEvent extends EventEmitter {}
+
+const fileEvent = new FileEvent();
+
 app.post(
-  "/upload", 
-  upload.single("dataFile"), 
-  (req, res, next) => {
-    console.log(req, res, next)
-  }
+    '/upload',
+    upload.single( 'dataFile' ),
+    (
+        req, res, next
+    ) => {
+        console.log(
+            req, res, next
+        );
+    }
 );
 
 // Endpoint to send back file names/upload times
-app.get("/status", async (_req, res) => {
-  const resObject: responseObject = {
-    names: [],
-    uploadTimes: []
-  };
+app.get( '/status', async ( _req, res ) => {
+    const resObject: responseObject = {
+        'names': [],
+        'uploadTimes': []
+    };
+    const dir = await fs.opendir( './src/server/uploads/' );
 
-  const dir = await fs.opendir("./src/server/uploads/");
-  for await (const file of dir) {
-    resObject.names.push(file.name);
-    const stats = await fs.stat(`./src/server/uploads/${file.name}`);
-    resObject.uploadTimes.push(stats.birthtime.toString());
-  }
+    for await ( const file of dir ) {
+        resObject.names.push( file.name );
+        const stats = await fs.stat( `./src/server/uploads/${ file.name }` );
 
-  res.status(200).json(resObject);
-})
+        resObject.uploadTimes.push( stats.birthtime.toString() );
+    }
+
+    res.status( 200 ).json( resObject );
+} );
 
 // Endpoint to send back whole files
-app.get("/download/:fileName", (req, res) => {
-  const fileName = req.params.fileName;
-  const filePath = path.join(__dirname, "uploads", fileName); // Filepaths must be absolute
-  res.sendFile(filePath, err => {
-    if (err) {
-      console.error("Error sending file:", err);
-      res.status(500).send("Error downloading file");
-    }
-  });
-}) 
+app.get( '/download/:fileName', ( req, res ) => {
+    const fileName = req.params.fileName;
+    const filePath = path.join(
+        __dirname, 'uploads', fileName
+    ); // Filepaths must be absolute
+
+    res.sendFile( filePath, err => {
+        if ( err ) {
+            console.error( 'Error sending file:', err );
+            res.status( 500 ).send( 'Error downloading file' );
+        }
+    } );
+} );
 
 // Endpoint to remove files from server
-app.delete("/delete/:fileName", async (req, res) => {
-  const fileName = req.params.fileName;
-  const filePath = path.join(__dirname, "uploads", fileName);
-  try {
-    await fs.unlink(filePath);    // deletes the file
-    res.status(200).send("File deleted successfully");
-  } catch (error) {
-    console.error("Error deleting file:", error);
-    res.status(500).send("Error deleting file");
-  }
-});
+app.delete( '/delete/:fileName', async ( req, res ) => {
+    const fileName = req.params.fileName;
+    const filePath = path.join(
+        __dirname, 'uploads', fileName
+    );
 
+    try {
+        await fs.rm( filePath ); // deletes the file
+        res.status( 200 ).send( 'File deleted successfully' );
+        fileEvent.emit( 'deleted', filePath );
+    } catch ( error ) {
+        console.error( 'Error deleting file:', error );
+        res.status( 500 ).send( 'Error deleting file' );
+    }
+} );
 
 // example route which returns a message
-app.get("/hello", async function (_req, res) {
-  res.status(200).json({ message: "Hello World!" });
-});
+app.get( '/hello', async function ( _req, res ) {
+    res.status( 200 ).json( {
+        'message': 'Hello World!'
+    } );
+} );
+
+
+interface SSESubscriber {
+    'uuid': string;
+    'response': express.Response;
+}
+
+interface SSESubscribers {
+    [id: string]: SSESubscriber | undefined;
+}
+const subscribers: SSESubscribers = {};
+
+app.get( '/sse', async ( request: express.Request, response: express.Response ) => {
+    response.writeHead( 200, {
+        'Content-Type': 'text/event-stream',
+        'Cache-Control': 'no-cache',
+        'Connection': 'keep-alive',
+    } );
+    response.status( 200 );
+    response.flushHeaders();
+    response.write( `data: ${ JSON.stringify( [] ) }\n\n` );
+
+    const uuid = crypto.randomUUID();
+
+    subscribers[uuid] = {
+        'uuid': uuid,
+        'response': response
+    };
+
+    request.on( 'close', () => {
+        subscribers[ uuid ] = undefined;
+    } );
+} );
+
+const sendSSEData = ( event: string, data: string ) => {
+    const subs = Object.values( subscribers );
+
+    for ( let i = 0; i < subs.length; i++ ) {
+        subs[i]!.response.write( `data: ${ JSON.stringify( {
+            'event': event,
+            'data': data
+        } ) }\n\n` );
+    }
+};
+
+fileEvent.on( 'uploaded', file => {
+    sendSSEData( 'uploaded', file );
+} );
+fileEvent.on( 'deleted', file => {
+    sendSSEData( 'deleted', file );
+} );
 
 // Do not change below this line
-ViteExpress.listen(app, 5173, () =>
-    console.log("Server is listening on http://localhost:5173"),
+ViteExpress.listen(
+    app, 5173, () => console.log( 'Server is listening on http://localhost:5173' ),
 );