background.js

function checkForInternet() {
	console.log("checking for internet connection...");

    pingMCL(function() {
        console.log("we are online");
        chrome.browserAction.setIcon({path: "icon.png"});
    }, function(respText) {
        console.log("no internet!");
        chrome.browserAction.setIcon({path: "icon-offline.png"});

        // Try find a token in the NU-NET auth page
        var token = grabTokenNuNet(respText);

        // If found then lets attempt an auth
        if (token) {
            console.log("NU-NET detected: " + token);
            connectNuNet(token);
        }
    });
}

function pingMCL(success, fail) {
    var xhrCheck = new XMLHttpRequest();
    var url = "http://mobcomlab.s3.amazonaws.com/pingtest.json?_=" + new Date().getTime();
    console.log(url);
    xhrCheck.open("GET", "http://mobcomlab.s3.amazonaws.com/pingtest.json?_=" + new Date().getTime(), true);
    xhrCheck.onreadystatechange = function() {
        if (xhrCheck.readyState == 4 && xhrCheck.status === 200) {
            try {
                if (JSON.parse(xhrCheck.responseText).success) {
                    success();
                }
            } catch (e) {
                fail(xhrCheck.responseText);
            }
        }
        else {
            fail("");
        }
    };
    xhrCheck.send();
}


function grabTokenNuNet(respText) {
    console.log("Getting token from NU-NET");
    var pattern = new RegExp('magic" value="[a-z0-9]+');
    var token = pattern.exec(respText);
    if (token === null) {
        console.log("Token from NU-NET: null");
        return null;
    }

    token = token[0].substr(14);
    return token;
}

function connectNuNet(token) {
    console.log("connecting to NU-NET");

    var username = localStorage["username"];
    var password = localStorage["password"];

    var xhr = new XMLHttpRequest();
    xhr.open("POST", "https://login3.nu.ac.th:1000/", true);
    xhr.setRequestHeader("Content-type","application/x-www-form-urlencoded");
    xhr.onreadystatechange = function() {
        if (xhr.readyState == 4) {
            pingMCL(function() {
                console.log("connect success");
                chrome.browserAction.setIcon({path: "icon.png"});
            }, function(respText) {
                console.log("connect unsuccessful, maybe not NU");
            });
        }
    };
    xhr.send("magic="+token+"&username="+username+"&password="+password);
}

function connectNuWireless() {

}

// Default icon is offline
chrome.browserAction.setIcon({path: "icon-offline.png"});

// Open options on button click
chrome.browserAction.onClicked.addListener(function() {
	chrome.tabs.create({url: "options.html"});
});

// Check for internet when the first tab is loaded
chrome.tabs.onCreated.addListener(function() {
    checkForInternet();
});
chrome.windows.onCreated.addListener(function() {
    checkForInternet();
});

// Set up alarm to check internet every 3 minutes
chrome.alarms.onAlarm.addListener(function() {
  checkForInternet();
});
chrome.alarms.create({when: 0, periodInMinutes: 3});