audiowaveform-server.js

const http = require('http');
const { exec } = require("child_process");
const MultipartDownload = require("multipart-download");
const os = require("os");
const fs = require("fs");

const hostname = '0.0.0.0';
const port = process.env.PORT || 4000;

let tempDir = os.homedir() + "\\audiowaveform-server";
if(os.platform() != "win32") {
    tempDir = os.homedir() + "/audiowaveform-server";
}

const server = http.createServer((req, res) => {
    const params = req.url.substr(req.url.indexOf("?")+1).split("&");
    const urlParam = params.find(p => p.split("=")[0] === "url");

    if(urlParam) {
        const url = decodeURIComponent(urlParam.split("=")[1]);

        const operation = new MultipartDownload().start(url, {
            numOfConnections: 3,
            saveDirectory: tempDir,
            headers: {"accept": "audio/*"}
        }).on("error", error => {
            error && handleError(res, error);
        }).on("end", (filePath) => {
            console.log("Downloaded file: " + filePath);
            runAudiowaveform(res, filePath, tempDir);
        });
    }
    else {
        handleError(res, {error: "\"url\" parameter not found"});
    }
});

server.listen(port, hostname, () => {
    console.log(`Starting server at http://${hostname}:${port}/`);
    exec("audiowaveform -v", (error) => {
        error ?
            server.close(() => {
                console.log("Audiowaveform not on path. Closing server.");
            }) :
            console.log("Found Audiowaveform on path");
    });

    exec("python -V", (error) => {
        error ?
            server.close(() => {
                console.log("Python not on path. Closing server.");
            }) :
            console.log("Found Python on path")
    });

    !fs.existsSync(tempDir) && fs.mkdir(tempDir, (error) => {
        error ?
            server.close(() => {
                console.log("Error creating temp folder: " + JSON.stringify(error));
            }) :
            console.log("Created temp folder: " + tempDir);
    });

    setTimeout(() => {
        server.listening ?
            console.log("Server is up and running") :
            console.log("Server is stopped");
    }, 2000)
});

function runAudiowaveform(response, filePath, tempDir) {
    let filename = filePath.split("\\")[filePath.split("\\").length-1].split(".")[0];
    let outFile = tempDir + "\\" + filename + ".json";

    if(os.platform() != "win32") {
        filename = filePath.split("/")[filePath.split("/").length-1].split(".")[0];
        outFile = tempDir + "/" + filename + ".json";
    }

    const cmd = "audiowaveform -i " + filePath + " -o " + outFile + " --pixels-per-second 20 --bits 8";
        execCmd(response, cmd, () => {
            console.log(response);
            runScaleFile(response, outFile, () => {
                cleanup(filePath);
                cleanup(outFile);
            });
        });
}

function runScaleFile(response, audiowaveformJsonFile, callback) {
    const cmd = "python ./scale-json.py " + audiowaveformJsonFile;

    execCmd(response, cmd, () => {
        fs.readFile(audiowaveformJsonFile, (error, data) => {
            if(error) {
                handleError(response, error);
            }
            else {
                console.log("Done generating waveform file: " + audiowaveformJsonFile)
                response.statusCode = 200;
                response.setHeader("Content-Type", "application/json");
                response.setHeader("Access-Control-Allow-Origin", "*");
                response.end(data);
            }

            callback();
        });
    });
}

function cleanup(filePath) {
    fs.unlink(filePath, (error) => {
        error ?
            console.log("Error deleting file: " + filePath + " " + error) :
            console.log("Deleted file: " + filePath);
    });
}

function execCmd(res, cmd, callback) {
    console.log("Exec: " + cmd);

    exec(cmd, (error, stdout, stderror) => {
        console.log(stdout);
        if(error) {
            handleError(res, error);
            return;
        }
        stderror && console.log(stderror);

        callback(stdout);
    });
}

function handleError(res, message) {
    res.statusCode = 500;
    res.setHeader('Content-Type', 'application/json');
    res.end(JSON.stringify(message));
}