var activeNewsTabNumber = 0;
var activeStuffTabNumber = 0;
var activeFileTransferTabNumber = 0;

var lastNewsButtonNumber;
var lastStuffButtonNumber;
var lastFileTransferButtonNumber;

window.onload = function() {
    document.getElementById("JavaScriptWarning").style.display = "none";
    lastNewsButtonNumber = document.getElementsByClassName("newsButton").length - 1;
    lastStuffButtonNumber = document.getElementsByClassName("stuffButton").length - 1;
    lastFileTransferButtonNumber = document.getElementsByClassName("fileTransferButton").length - 1;    
}

function showNews(tabNumber) {
    hideAllNews();                
    activeNewsTabNumber = tabNumber;
    document.getElementsByClassName("newsTab")[tabNumber].style.display = "block";
    setNewsButtonState(tabNumber, 0); 
}

function showStuff(tabNumber) {
    hideAllStuff();                
    activeStuffTabNumber = tabNumber;
    document.getElementsByClassName("stuffTab")[tabNumber].style.display = "block";
    setStuffButtonState(tabNumber, 0); 
}

function showFileTransfer(tabNumber) {
    hideAllFileTransfer();                
    activeStuffTabNumber = tabNumber;
    document.getElementsByClassName("fileTransferButton")[tabNumber].style.display = "block";
    setFileTransferButtonButtonState(tabNumber, 0); 
}


function hideAllNews() {
    for (var i = 0; i < document.getElementsByClassName("newsTab").length; i++) {
        document.getElementsByClassName("newsTab")[i].style.display = "none";
    }
    for (var i = 0; i < document.getElementsByClassName("newsButton").length; i++) {
        setNewsButtonState(i, 2);
    }                
}            

function hideAllStuff() {
    for (var i = 0; i < document.getElementsByClassName("stuffTab").length; i++) {
        document.getElementsByClassName("stuffTab")[i].style.display = "none";
    }
    for (var i = 0; i < document.getElementsByClassName("stuffButton").length; i++) {
        setStuffButtonState(i, 2); 
    }                
}    

function hideAllFileTransfer() {
    for (var i = 0; i < document.getElementsByClassName("fileTransferTab").length; i++) {
        document.getElementsByClassName("fileTransferTab")[i].style.display = "none";
    }
    for (var i = 0; i < document.getElementsByClassName("fileTransferButton").length; i++) {
        setFileTransferButtonState(i, 2); 
    }                
}    

function highlightNewsButton(buttonNumber) {
    if (buttonNumber != activeNewsTabNumber) {            
        setNewsButtonState(buttonNumber, 1);
    }
}

function highlightStuffButton(buttonNumber) {
    if (buttonNumber != activeStuffTabNumber) {
        setStuffButtonState(buttonNumber, 1);
    }
}

function highlightFileTransferButton(buttonNumber) {
    if (buttonNumber != activeFileTransferTabNumber) {
        setFileTransferButtonState(buttonNumber, 1);
    }
}

function shadowNewsButton(buttonNumber) {
    if (buttonNumber != activeNewsTabNumber) {               
        setNewsButtonState(buttonNumber, 2);
    }
}

function shadowStuffButton(buttonNumber) {
    if (buttonNumber != activeStuffTabNumber) {               
        setStuffButtonState(buttonNumber, 2);
    }
}

function shadowFileTransferButton(buttonNumber) {
    if (buttonNumber != activeFileTransferTabNumber) {               
        setFileTransferButtonState(buttonNumber, 2);
    }
}

function setNewsButtonState(number, state) {
    var x;
    if (number == 0) {
        x = "left";
    } else if (number == lastNewsButtonNumber) {
        x = "right";
    } else {
        x = "center";
    } 
    var y;
    if (state == 0) {
        y = "0px";
    } else if (state == 1) {
        y = "-100px";
    } else {
        y = "-200px";
    }
    var value = "" + x + " " + y;
    document.getElementsByClassName("newsButton")[number].style.backgroundPosition = value;
}

function setStuffButtonState(number, state) {
    var x;
    if (number == 0) {
        x = "left";
    } else if (number == lastStuffButtonNumber) {
        x = "right";
    } else {
        x = "center";
    } 
    var y;
    if (state == 0) {
        y = "0px";
    } else if (state == 1) {
        y = "-100px";
    } else {
        y = "-200px";
    }
    var value = "" + x + " " + y;
    document.getElementsByClassName("stuffButton")[number].style.backgroundPosition = value;
}

function setFileTransferButtonState(number, state) {
    var x;
    if (number == 0) {
        x = "left";
    } else if (number == lastFileTransferButtonNumber) {
        x = "right";
    } else {
        x = "center";
    } 
    var y;
    if (state == 0) {
        y = "0px";
    } else if (state == 1) {
        y = "-100px";
    } else {
        y = "-200px";
    }
    var value = "" + x + " " + y;
    document.getElementsByClassName("fileTransferButton")[number].style.backgroundPosition = value;
}