FORM VALIDATION

<?php
session_start();
$_SESSION['POST'] = $_POST;
include('dbh.php');

if(isset($_POST['submit'])){
if(isset($_FILES) & $_FILES['photo']['name']!=''){

$mem_id = $_POST['member_id'];
$mem_name = $_POST['member_name'];
$fa_name  = $_POST['fa_name'];
$mo_name = $_POST['mo_name'];
$address = $_POST['address'];
$email = $_POST['email'];
$mobile = $_POST['phone_num'];
$da_birth = $_POST['da_birth'];
$nid = $_POST['n_id'];
$gender = $_POST['sex'];
$area = $_POST['area'];
$digit = substr($mobile,0,3);
$number_code= ['015', '016', '017', '018', '019'];
$gender_array=["male","female"];

$file_name = $_FILES['photo']['name'];

$file_size = $_FILES['photo']['size'];

$file_ext = explode('.',$file_name);

$file_axu_ext = array_pop($file_ext );

$file_allowed = ['jpg','png','jpeg','gif'];

$new_file_name = time().'_'.rand(10000,100000).'_'.$file_name;

if($file_size > 500000 ){
$_SESSION['err_msg'] = "Invalide file size(ex :450 kb)";
header ("Location: user_reg.php");
exit();
}

if(!in_array($file_axu_ext,$file_allowed)){
$_SESSION['err_msg'] = "Invalide file size(ex :450 kb)";
header ("Location : user_reg.php");
exit();
}
#member id cannot null.
if($mem_id ===''){
$_SESSION['err_msg'] = 'Member ID is required.';

header("Location: user_reg.php");

exit();
}
#If member id cannot duble;
$sql_mem_id = "SELECT * FROM user_reg WHERE member_id = '$mem_id' LIMIT 1";

$query_mem_id = mysqli_query($conn,$sql_mem_id);

$query_mem_id_check = mysqli_num_rows($query_mem_id);

if($query_mem_id_check > 0){
$_SESSION['err_msg'] = "Member ID already exist.";

header("Location: user_reg.php");

exit();  #-------mem id.
}
#If member name cannot duble or empty.;
if($mem_name===''){
$_SESSION['err_msg'] = 'Member name is required.';

header("Location: user_reg.php");

exit();
}

$sql_mem_name = "SELECT * FROM user_reg WHERE member_name = '$mem_name' LIMIT 1";

$query_mem_name = mysqli_query($conn,$sql_mem_name);

$query_mem_name_check = mysqli_num_rows($query_mem_name);

if($query_mem_name_check > 0){
$_SESSION['err_msg'] = "Member name already exist.";

header("Location: user_reg.php");

exit();  #-----end--mem name.
}

#for email validation and checked Limit 1 .
if(!filter_var($email,FILTER_VALIDATE_EMAIL)){
$_SESSION['err_msg'] = 'Please Enter a valide email';

header("Location: user_reg.php");
exit();
}

$sql_email = "SELECT * FROM user_reg WHERE email = '$email' LIMIT 1";
$query_email = mysqli_query($conn,$sql_email);
$query_email_result = mysqli_num_rows($query_email);

if($query_email_result > 0){
$_SESSION['err_msg'] = "This email is already taken";
header("Location: user_reg.php");

exit();
}# ---END Of EMAIL validation -----

#mobile validation---
if((strlen($mobile)!=11) || (!in_array($digit,$number_code))){
$_SESSION['err_msg'] = "Invalide Mobile(Ex.017XXXXXXXX)";
header("Location: user_reg.php");
exit();
}
$sql_mobile = "SELECT * FROM user_reg WHERE phone_num = '$mobile' LIMIT 1";
$query_mobile = mysqli_query($conn,$sql_mobile);
$queryResult = mysqli_num_rows($query_mobile);
if($queryResult > 0 ){
$_SESSION ['err_msg'] = "You already use This phone number.";
header("Location: user_reg.php");
exit();
}
# end ----Mobile validation---

if((strlen($nid) != 13) && strlen($nid) !=17){
$_SESSION['err_msg'] = "Invalide Nid ,Please Enter 13 or 17 digit.";
header("Location: user_reg.php");
exit();
}

if(!(in_array($gender,$gender_array))){
$_SESSION['err_msg'] = "Invalide gender value.";
header("Location: user_reg.php");
exit();
}
#---End of gender validaiton.

$sql = "INSERT INTO user_reg (photo,member_id,member_name,fa_name,mo_name,address,email,phone_num,da_birth,n_id,sex,area)
VALUES('$new_file_name','$mem_id ', '$mem_name','$fa_name', '$mo_name', '$address', '$email', '$mobile', '$da_birth', '$nid', '$gender','$area')";
$query = mysqli_query($conn,$sql);

move_uploaded_file($_FILES['photo']['tmp_name'],"images/profile_pic/".$new_file_name);

$_SESSION['err_msg'] = "Successfully save data";

header("Location: user_reg.php");

}else
{
$_SESSION['err_msg'] = 'Profile photo is required.';
header("Location:user_reg.php");
}


 }
?>