undo3d/support/development-server.js

Undo3D helps you build free-roaming 3D web apps where thousands of users can collaborate creatively in real time. Expect the first public beta mid-2019, and the first production release mid-2020.

//// Mainly needed to serve new extensions like .mjs and .wasm with the proper
//// MIME types. Later on we might add some handy developer helpers...




//// INIT

//// Ensure we’re running in Node, and that this script is in ‘undo3d/support/’.
if ('object' !== typeof process || 'function' !== typeof require)
    throw Error('Run in Node.js')
const containerDirs = __dirname.split('/').slice(-2).join('/')
if ('undo3d/support' !== containerDirs )
    throw Error(`In ‘${containerDirs}/’ not ‘undo3d/support/’`)

//// Load Node’s 'http' and 'exec' modules, and set some constants.
const
    app = require('http').createServer(server)
  , { exec } = require('child_process')
  , { readFileSync, existsSync } = require('fs')
  , { join } = require('path')
  , port = process.env.PORT || 3000 // Heroku sets the environment $PORT value
  , dir = join(__dirname, '..')

//// Shut down if the server hits an error. This wouldn’t be good in production!
app.on('error', e => {
    console.error('Server error: ' + e.message)
    app.close()
})

//// Start the server and open a browser window.
app.listen( port, () => {
    console.log(`Server is listening on port ${port}`)
    exec(`open http://localhost:${port}/`) //@TODO test in Windows and Linux
})




//// SERVE

//// Serve the proper response.
function server (req, res) {

    //// Any GET request is a static file.
    if ('GET' === req.method)
        return serveFile(req, res)

    //// Anything else is an error.
    return error(res, 9300, 405, 'Use GET')
}


//// Serve a file.
function serveFile (req, res) {

    //// Serve a request for the homepage.
    if ('/' === req.url || '/test' === req.url || '/test/' === req.url) {
        res.writeHead(200, { 'Content-Type':'text/html' })
        res.end( readFileSync( join(dir, req.url, 'index.html') ) )
        return
    }

    //// Get the extension, MIME type and absolute path.
    const
        ext = (req.url.match(/\.([a-z]{2,4}2?)$/) || [])[1]
      , mime = extToMimeType(ext)
      , path = join(dir, req.url)
    if (! ext)  return error(res, 9101, 404, 'Invalid extension')
    if (! mime) return error(res, 9102, 404, `Extension .${ext} not recognised`)

    //// Check that the resource exists.
    if (! existsSync(path) )
        return error(res, 9100, 404, 'No such resource, ' + req.url)

    //// Serve the request.
    res.writeHead(200, { 'Content-Type':mime })
    res.end( readFileSync(path) )
}




//// UTILITY

//// Sends a response after a request which failed.
function error (res, code, status, remarks, contentType='text/plain') {
    const headers = { 'Content-Type': contentType }
    remarks = remarks.replace(/\\/g, '\\\\')
                     .replace(/"/g, '\\"')
                     .replace(/\n/g, '\\n')
    res.writeHead(status, headers)
    res.end(`{ "code":${code}, "error":"${remarks}", "status":${status} }\n`)
    return false
}

//// Returns a given extension’s MIME type, or undefined if not recognised.
function extToMimeType (ext) {
    return ({
        js:   'application/javascript' // a standard JavaScript script
      , mjs:  'application/javascript' // the new JavaScript module extension
      , json: 'application/json'       // JSON data, eg package.json
      , mem:  'application/wasm'       // asm.js memory, used by threecap.js.mem @TODO proper MIME type?
      , wasm: 'application/wasm'       // WebAssembly memory
      , mp3:  'audio/mpeg'             // MP3 audio
      , ttf:  'font/ttf'               // TrueType Font
      , otf:  'font/otf'               // OpenType Font
      , woff: 'font/woff'              // Web Open Font Format
      , woff2:'font/woff2'             // Web Open Font Format 2.0
      , gif:  'image/gif'              // GIF image
      , jpg:  'image/jpeg'             // JPEG image
      , jpeg: 'image/jpeg'             // JPEG image
      , png:  'image/png'              // PNG image
      , svg:  'image/svg+xml'          // SVG image
      , ico:  'image/x-icon'           // usually favicon.ico
      , css:  'text/css'               // CSS stylesheet
      , htm:  'text/html'              // HTML page
      , html: 'text/html'              // HTML page
      , txt:  'text/plain'             // plain text document
      , mp4:  'video/mp4'              // MP4 video
      , webm: 'video/webm'             // WEBM video
    })[ext]
}