<?php
class Newsletter {
  // (A) PROPERTIES & SETTINGS
  private $pdo = null; // pdo object
  private $stmt = null; // sql statement
  private $from = "promo@site.com"; // email from
  private $each = 10; // get 10 subscribers each send cycle
  private $pause = 1; // 1 sec pause between each cycle

  // (B) CONSTRUCTOR - CONNECT TO DATABASE
  function __construct () {
    $this->pdo = new PDO(
      "mysql:host=".DB_HOST.";dbname=".DB_NAME.";charset=".DB_CHARSET, 
      DB_USER, DB_PASSWORD, [
      PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
      PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC
    ]);
  }

  // (C) DESTRUCTOR - CLOSE DATABASE CONNECTION
  function __destruct () {
    if ($this->stmt!==null) { $this->stmt = null; }
    if ($this->pdo!==null) { $this->pdo = null; }
  }

  // (D) COUNT TOTAL NUMBER OF SUBSCRIBERS
  function count () {
    $this->stmt = $this->pdo->prepare("SELECT COUNT(*) `cnt` FROM `newsletter`");
    $this->stmt->execute();
    return $this->stmt->fetchColumn();
  }

  // (E) GET SUBSCRIBERS
  function get ($start=0, $end=10) {
    $this->stmt = $this->pdo->prepare("SELECT * FROM `newsletter` LIMIT $x, $y");
    $this->stmt->execute();
    return $this->stmt->fetchAll();
  }
 
  // (F) SEND NEWSLETTER
  function send ($subject, $template, $replace=null) {
    // (F1) EMAIL HEADERS
    $header = implode("\r\n", [
      "From: " . $this->from,
      "MIME-Version: 1.0",
      "Content-Type: text/html; charset=utf-8",
    ]);
 
    // (F2) LOAD TEMPLATE
    if (!file_exists($template)) {
      $this->error = "$template not found";
      return false;
    }
    $template = file_get_contents($template);
 
    // (F3) SEND BATCH BY BATCH
    for ($i=0; $i<$this->count(); $i+=$this->each) {
      $subs = $this->get($i, $this->each);
      foreach ($subs as $s) {
        // (F3-1) EMAIL TEMPLATE REPLACE
        $msg = $template;
        if ($replace != null) { foreach ($replace as $from=>$to) {
          $msg = str_replace($from, $s[$to], $msg);
        }}
 
        // (F3-2) SEND - SAVE THE SEND STATUS HERE IF YOU WANT
        if (@mail($s["email"], $subject, $msg, $header)) {
          // OK
        } else {
          // NOT OK
        }
      }
 
      // (F3-3) NEXT CYCLE
      sleep($this->pause);
    }
  }
}
 
// (G) DATABASE SETTINGS - CHANGE TO YOUR OWN!
define("DB_HOST", "localhost");
define("DB_NAME", "globalpunch_lb-newsletter");
define("DB_CHARSET", "utf8mb4");
define("DB_USER", "globalpunch_lb-user");
define("DB_PASSWORD", "Burney20**##");
 
// (H) NEWSLETTER OBJECT
$_NEWS = new Newsletter();