function submitMouseOver() {
   
   this.src = "../images/submit_btn2.png";
}

function submitMouseOut() {

   this.src = "../images/submit_btn.png";
}

function validateForm() {
   var name = document.getElementById("name").value;
   var email = document.getElementById("email").value;
   var message = document.getElementById("message").value;
   var apos = document.getElementById("email").value.indexOf("@")
   var dotpos = document.getElementById("email").value.lastIndexOf(".")
   
   if (name == "") {
      hideAllErrors();
      document.getElementById("nameError").style.display = "inline";
      document.getElementById("name").select();
      document.getElementById("name").focus();
      return false;
   } else if (email == "") {
      hideAllErrors();
      document.getElementById("emailError").style.display = "inline";
      document.getElementById("email").select();
      document.getElementById("email").focus();
      return false;
   } else if (apos < 1 || (dotpos-apos) < 2) {
      hideAllErrors();
      document.getElementById("emailError2").style.display = "inline";
      document.getElementById("email").select();
      document.getElementById("email").focus();
      return false;
   } else if (message == "") {
      hideAllErrors();
      document.getElementById("messageError").style.display = "inline";
      document.getElementById("message").select();
      document.getElementById("message").focus();
      return false;
   }
   return true;
}

function hideAllErrors() {
   document.getElementById("nameError").style.display = "none";
   document.getElementById("emailError").style.display = "none";
   document.getElementById("emailError2").style.display = "none";
   document.getElementById("messageError").style.display = "none";
}

function Tick() {
   var name = document.getElementById("name").value;
   var nameTick = document.getElementById("name_valid_entry");
   var email = document.getElementById("email").value;
   var emailTick = document.getElementById("email_valid_entry");
   var apos = document.getElementById("email").value.indexOf("@")
   var dotpos = document.getElementById("email").value.lastIndexOf(".")

   if (name != "") {
      document.getElementById("name_valid_entry").style.display = "inline";
   }
   if (email != "" && (apos > 1 && (dotpos-apos) > 2)) {
      document.getElementById("name_valid_entry").style.display = "inline";
      document.getElementById("email_valid_entry").style.display = "inline";
   }
}

function assignSubmit() {
   var submit_btn = document.getElementById("submit_btn");
   
   submit_btn.onmouseover = submitMouseOver;
   submit_btn.onmouseout = submitMouseOut;
   submit_btn.onclick = validateForm;
}

function assignTick() {
   var name = document.getElementById("name");
   var email = document.getElementById("email");
   
   name.onchange = Tick;
   email.onchange = Tick;
}

window.onload = function() {
   assignSubmit();
   assignTick();
}