var tellafriendURL = "tellafriend/tellafriend.php";
var emailAdd ="";

function tellafriend() {
    emailAdd = $('Text4').value;
    if(checkEmail(emailAdd)) { 
        httpRequestFriend = createHttpObject();
        httpRequestFriend.onreadystatechange=sendMail;
        httpRequestFriend.open("GET",tellafriendURL+"?email="+emailAdd,true);
        httpRequestFriend.send(null);
    }
}

function sendMail() {
    if (httpRequestFriend.readyState == 4){
        var res = httpRequestFriend.responseText;
        if(res == 1) {
            alert("تم الإرسال بنجاح إلى "+emailAdd); 
        }
        else {
            alert("Failure\nServer said: "+res);
        }
    }
}

function checkEmail(str) {
    var at="@"
    var dot="."
    var lat= str.indexOf(at)
    var lstr=str.length
    var ldot=str.indexOf(dot)
    if (str.indexOf(at)==-1){
        alert("Invalid E-mail ID")
        return false
    }

    if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr){
        alert("Invalid E-mail ID")
        return false
    }

    if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr){
        alert("Invalid E-mail ID") 
        return false
    }

    if (str.indexOf(at,(lat+1))!=-1){
        alert("Invalid E-mail ID")
        return false
    }

    if (str.substring(lat-1,lat)==dot || str.substring (lat+1,lat+2)==dot){
        alert("Invalid E-mail ID")
        return false
    }

    if (str.indexOf(dot,(lat+2))==-1){
        alert("Invalid E-mail ID")
        return false
    }

    if (str.indexOf(" ")!=-1){
        alert("Invalid E-mail ID")
        return false
    }
    return true
}