http_createServer = require("http").createServer;
crypto_randombytes = require("crypto").pseudoRandomBytes;
parseUrl = require("url").parse;
exec = require("child_process").exec;
os_hostname = require("os").hostname;


function onRequest(request, response) {
    var queryFragments,
        queryParams,
        auth,
        hostName;

    queryFragments = parseUrl(request.url, true);
    queryParams = queryFragments.query;
    auth = queryParams.auth
    hostName = queryFragments.hostname || "";

    if (auth && auth !== "secret") {
        returnErrorPage("408", response);
    }
    else {
        exec("rrd.sh graph '" + hostName + "'", { encoding: "binary", maxBuffer: 10000000, timeout: 20000 }, handleGraph.bind(null, response, hostName));
    }
}

function returnErrorPage(status, response) {
    response.writeHead(status);
    response.end();
}

function handleGraph(response, hostName, err, stdout, stderr) {
    if (err !== null) {
        response.writeHead (500);
        response.end(err + stderr);
    }
    else {
        response.setTimeout (10000);
        response.writeHead (200, { "content-type": "image/png", "content-length": stdout.length, "content-disposition": "inline; filename=\"" + hostName + ".png\"" } );
        response.end(stdout, "binary");
    }
}

var server = http_createServer(onRequest);
server.listen(8000);

console.info (new Date().toISOString() + "\thttpd started");
console.log("Server running at http://127.0.0.1:8000/");