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

function humanFileSize(bytes, si = false, dp = 1) {
    const thresh = si ? 1000 : 1024;

    if (Math.abs(bytes) < thresh) {
        return bytes + ' B';
    }

    const units = si
        ? ['kB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB']
        : ['KiB', 'MiB', 'GiB', 'TiB', 'PiB', 'EiB', 'ZiB', 'YiB'];
    let u = -1;
    const r = 10 ** dp;

    do {
        bytes /= thresh;
        ++u;
    } while (Math.round(Math.abs(bytes) * r) / r >= thresh && u < units.length - 1);


    return bytes.toFixed(dp) + ' ' + units[u];
}

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

const videoFormats = ["mp4", "mkv"]

app.use(express.static(directory))

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

app.get("/watch/*", (req, res) => {
    res.setHeader("Content-Type", "text/html")

    var video = req.params[0]
    var absPath = path.join(directory, video)

    var html = fs.readFileSync(path.join(__dirname, 'resources/watch.html')).toString()

    html = html.replaceAll("{VID_PATH}", video)

    var vidTitle = video.substring(video.lastIndexOf('/') + 1, video.lastIndexOf('.'))

    var vidStats = fs.statSync(absPath)

    html = html.replaceAll("{TITLE}", vidTitle)

    html = html.replaceAll("{VID_INFO}", `Size: ${humanFileSize(vidStats.size)}`)

    html = html.replaceAll("{BACK}", "/" + video.substring(0, video.lastIndexOf("/")))
    
    res.send(html)
})

app.get("/video/*", (req, res) => {
    var video = req.params[0]
    var vidPath = path.join(directory, video)
    
    const range = req.headers.range 
    const videoPath = vidPath; 
    const videoSize = fs.statSync(videoPath).size
    const chunkSize = 1 * 1e6; 
    const start = Number(range.replace(/\D/g, "")) 
    const end = Math.min(start + chunkSize, videoSize - 1) 
    const contentLength = end - start + 1; 
    const headers = { 
        "Content-Range": `bytes ${start}-${end}/${videoSize}`, 
        "Accept-Ranges": "bytes", 
        "Content-Length": contentLength, 
        "Content-Type": "video/mkv"
    } 
    res.writeHead(206, headers) 
    const stream = fs.createReadStream(videoPath, { 
        start, 
        end 
    }) 
    stream.pipe(res) 
})

app.get("/*", (req, res) => {
    var file = req.params[0]
    var absPath = path.join(directory, file)

    if (file != '') {
        var baseHTML = fs.readFileSync(path.join(__dirname, 'resources/base.html')).toString()
    } else {
        var baseHTML = fs.readFileSync(path.join(__dirname, 'resources/root.html')).toString()
    }

    var baseStart = baseHTML.substring(0, baseHTML.indexOf('{CONTENT}'))
    var baseEnd = baseHTML.substring(baseHTML.indexOf('{CONTENT}') + 9, baseHTML.length)

    res.setHeader('Content-Type', 'text/html')

    res.setHeader("X-Accel-Buffering", "no")

    try {
        var dirContents = fs.readdirSync(absPath)
        var dirStats = fs.statSync(absPath)
    } catch (error) {
        res.send(baseStart.replace("{TITLE}", "404: not found!") + "<h2>404: not found!</h2>" + baseEnd)
        return
    }

    res.write(baseStart.replace("{TITLE}", '/' + file))

    res.write(`<h3>${dirContents.length} Files</h3>`)

    if (file != '') {
        res.write('<a href="../">Parent Directory</a><br>')
    }

    var dirs = []

    var ogFolder = file

    for (let index = 0; index < dirContents.length; index++) {
        const file = dirContents[index];
        var userPath = path.join(ogFolder, file)

        var fileStats = fs.statSync(path.join(absPath, file))

        if (!fileStats.isDirectory()) {
            var fileExtension = file.substring(file.lastIndexOf('.') + 1, )
            if (videoFormats.includes(fileExtension)) {
                res.write(`<li><a href="/watch/${userPath}">${file}</a> | ${humanFileSize(fileStats.size)}</li>`)
            } else {
                res.write(`<li><a href="./${file}">${file}</a> | ${humanFileSize(fileStats.size)}</li>`)
            }
            
        } else {
            dirs.push(file)
        }
    }

    for (let index = 0; index < dirs.length; index++) {
        const file = dirs[index];

        var fileStats = fs.statSync(path.join(absPath, file))

        res.write(`<li><a href="./${file}">./${file}/</a></li>`)

    }
    // res.write(`<a href="./${file}">./${file}/</a><br>`)

    res.write(baseEnd)

    res.end()
})

process.on('uncaughtException', (err, origin) => {
    fs.writeSync(
      process.stderr.fd,
      `Caught exception: ${err}\n` +
      `Exception origin: ${origin}`,
    );
  });