<?php
// Please specify your Mail Server - Example: mail.example.com.
//ini_set("SMTP","localhost");
// Please specify an SMTP Number 25 and 8889 are valid SMTP Ports.
//ini_set("smtp_port","25");
// Please specify the return address to use
//ini_set('sendmail_from', 'example@localhost');

// define variables and set to empty values
$sendernameErr = $emailErr = $websiteErr = $commentErr = "";
$sendername = $email = $comment = $website = "";
$sendernameErrFlag = $emailErrFlag = $websiteErrFlag = $commentErrFlag = 2;
//Set variable inputs from form.
  function test_input($data) {
  $data = trim($data);
  $data = stripslashes($data);
  $data = htmlspecialchars($data);
  return $data;
}
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    if ($referrer == "") {
        $referrer = "This page was accessed directly";
    }
  if (empty($_POST["sendername"])) {
    $sendernameErr = "Name is required";
    $sendernameErrFlag = 1;
  } else {
    $sendername = test_input($_POST["sendername"]);
    // check if sendername only contains letters and whitespace
    if (!preg_match("/^[a-zA-Z ]*$/",$sendername)) {
      $sendernameErr = "Only letters and white space allowed";
      $sendernameErrFlag = 1;
    } else {
      $sendernameErrFlag = 0;
  }
  }

  if (empty($_POST["email"])) {
    $emailErr = "Email is required";
    $emailErrFlag = 1;
  } else {
    $email = test_input($_POST["email"]);
    // check if e-mail address is well-formed
    if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
      $emailErr = "Invalid email format";
      $emailErrFlag = 1;
    } else {
      $emailErrFlag = 0;
  }
  }

  if (empty($_POST["website"])) {
    $website = "";
  } else {
    $website = test_input($_POST["website"]);
    // check if URL address syntax is valid (this regular expression also allows dashes in the URL)
    if (!preg_match("/b(?:(?:https?|ftp)://|www.)[-a-z0-9+&@#/%?=~_|!:,.;]*[-a-z0-9+&@#/%=~_|]/i",$website)) {
      $websiteErr = "Invalid URL";
      $websiteErrFlag = 1;
    } else {
      $websiteErrFlag = 0;
  }
  }
  if (empty($_POST["comment"])) {
    $commentErr = "Comment is required";
    $commentErrFlag = 1;
  } else {
    $comment = test_input($_POST["comment"]);
    $commentErrFlag = 0;
  }
}
?>
<p><span class="error">* required field.</span></p>
<form method="post" action="<?php echo the_permalink();//htmlspecialchars($_SERVER["REQUEST_URI"], ENT_QUOTES, "utf-8");?>">
    Name: <input type="text" name="sendername" value="<?php echo $sendername;?>">
  <span class="error">* <?php echo $sendernameErr;?></span>
  <br><br>
  E-mail: <input type="text" name="email" value="<?php echo $email;?>">
  <span class="error">* <?php echo $emailErr;?></span>
  <br><br>
  Website: <input type="text" name="website" value="<?php echo $website;?>">
  <span class="error"><?php echo $websiteErr;?></span>
  <br><br>
  Comment: <textarea name="comment" rows="5" cols="40"><?php echo $comment;?></textarea>
  <span class="error">* <?php echo $commentErr;?></span>
  <br><br>
  <input type="submit" name="submit" value="Submit">
</form>
<?php
/*
echo "<h2>Your Input:</h2>";
echo $sendername;
echo "<br>";
echo $email;
echo "<br>";
echo $website;
echo "<br>";
echo $comment;
echo "<br>";
echo $headers;
*/
//print_r($_POST);
//echo $sendernameErrFlag . "<br/>" . $emailErrFlag . "<br/>" . $websiteErrFlag . "<br/>" . $commentErrFlag;
if($sendernameErrFlag == 0 && $emailErrFlag == 0 && $websiteErrFlag == 0 && $commentErrFlag == 0) {
    $headers = "From: <".$_POST["sendername"].">".$_POST["email"];
    mail("test@gmail.com","My subject",$comment,$headers);
    echo '<script>alert("Message sent successfully!!!");</script>';
} else {
    $sendernameErrFlag = $emailErrFlag = $websiteErrFlag = $commentErrFlag = 2;
}
?>

/* Email SMTP */
add_action( 'phpmailer_init', 'my_phpmailer_init' );
function my_phpmailer_init( PHPMailer $phpmailer ) {
    $phpmailer->IsSMTP();
    $phpmailer->Host = 'localhost';
    $phpmailer->Port = 25; // could be different
    //$phpmailer->Username = 'test@example.com'; // if required
    //$phpmailer->Password = 'password'; // if required
    $phpmailer->SMTPAuth = false; // if required
    //$phpmailer->SMTPSecure = 'tls'; // enable if required, 'tls' is another possible value
}