FileSharer/index.js

const express = require("express"),
fs = require("fs"),
path = require("path")

var app = express()

var PORT = process.env.PORT || 8080

var directory = process.env.FILES_DIR

var baseHTML = fs.readFileSync(path.join(__dirname, 'resources/base.html')).toString()
var baseStart = baseHTML.substring(0, baseHTML.indexOf('{CONTENT}'))
var baseEnd = baseHTML.substring(baseHTML.indexOf('{CONTENT}') + 9, baseHTML.length)

app.use(express.static(directory))

if (!directory) {
    console.error("No directory specified! Please specify one using the environment variable FILES_DIR.")
    return
}

app.listen(PORT, () => {
    console.log("Now listening on PORT: " + PORT)
})

app.get("/*", (req, res) => {
    var file = req.params[0]
    var absPath = path.join(directory, file)
    try {
        var dirContents = fs.readdirSync(absPath)
    } catch (error) {
        res.send("<p>404: not found!</p>")
    }

    res.write(baseStart)

    res.write('<a href="../">Parent Directory</a><br>')

    for (let index = 0; index < dirContents.length; index++) {
        const file = dirContents[index];
        res.write(`<a href="./${file}">${file}</a><br>`)
    }

    res.write(baseEnd)

    res.end()
})