<?php
// Wrapper around setcookie that auto-sets samesite, and deals with older versions of php
function zm_setcookie($cookie, $value, $options=array()) {
  if (!isset($options['expires'])) {
    $options['expires'] = time()+3600*24*30*12*10; // 10 years?!
  }
  if (!isset($options['samesite'])) {
    $options['samesite'] = 'Strict';
  }

  if (version_compare(phpversion(), '7.3.0', '>=')) {
    setcookie($cookie, $value, $options);
  } else {
    setcookie($cookie, $value, $options['expires'], '/; samesite=strict');
  }
  ZM\Debug("Setting cookie for $cookie to $value");
}

// ZM session start function support timestamp management
function zm_session_start() {
  if (ini_get('session.name') != 'ZMSESSID') {
    // Make sure use_strict_mode is enabled.
    // use_strict_mode is mandatory for security reasons.
    ini_set('session.use_strict_mode', 1);

    $currentCookieParams = session_get_cookie_params(); 
    $currentCookieParams['lifetime'] = ZM_COOKIE_LIFETIME;
    $currentCookieParams['httponly'] = true;
    if ( version_compare(phpversion(), '7.3.0', '<') ) {
      session_set_cookie_params(
        $currentCookieParams['lifetime'],
        $currentCookieParams['path'].'; samesite=strict',
        $currentCookieParams['domain'],
        $currentCookieParams['secure'],
        $currentCookieParams['httponly']
      );
    } else {
      # samesite was introduced in 7.3.0
      $currentCookieParams['samesite'] = 'Strict';
      session_set_cookie_params($currentCookieParams);
    }

    ini_set('session.name', 'ZMSESSID');
    ZM\Debug('Setting cookie parameters to '.print_r($currentCookieParams, true));
  }
  session_start();
  $_SESSION['remoteAddr'] = $_SERVER['REMOTE_ADDR']; // To help prevent session hijacking
  $now = time();
  // Do not allow to use expired session ID
  if ( !empty($_SESSION['last_time']) && ($_SESSION['last_time'] < ($now - 180)) ) {
    ZM\Info('Destroying session due to timeout.');
    session_destroy();
    session_start();
  } else if ( !empty($_SESSION['generated_at']) ) {
    if ( $_SESSION['generated_at']<($now-(ZM_COOKIE_LIFETIME/2)) ) {
      ZM\Debug('Regenerating session because generated_at ' . $_SESSION['generated_at'] . ' < ' . $now . '-'.ZM_COOKIE_LIFETIME.'/2 = '.($now-ZM_COOKIE_LIFETIME/2));
      zm_session_regenerate_id();
    }
  }
} // function zm_session_start()

// session regenerate id function
// Assumes that zm_session_start has been called previously
function zm_session_regenerate_id() {
  if (!is_session_started()) session_start();

  // Set deleted timestamp. Session data must not be deleted immediately for reasons.
  $_SESSION['last_time'] = time();
  // Finish session
  session_write_close();

  session_start();
  
  ZM\Debug("Regenerating session. Old id was " . session_id());
  session_regenerate_id();
  ZM\Debug("Regenerating session. New id was " . session_id());
  unset($_SESSION['last_time']);
  $_SESSION['generated_at'] = time();
} // function zm_session_regenerate_id()

function is_session_started() {
  if ( php_sapi_name() !== 'cli' ) {
    if ( version_compare(phpversion(), '5.4.0', '>=') ) {
      return session_status() === PHP_SESSION_ACTIVE ? TRUE : FALSE;
    } else {
      return session_id() === '' ? FALSE : TRUE;
    }
  } else {
    Warning("php_sapi_name === 'cli'");
  }
  return FALSE;
} // function is_session_started()

function zm_session_clear() {
  if (!is_session_started()) session_start();
  $_SESSION = array();
  if ( ini_get('session.use_cookies') ) {
    $p = session_get_cookie_params();
    # Update the cookie to expire in the past.
    $p['expires'] = time() - 31536000;
    unset($p['lifetime']); // Not valid for a cookie
    zm_setcookie(session_name(), '', $p);
  }
  session_unset();
  session_destroy();
  session_write_close();
} // function zm_session_clear()

class ZMSessionHandler implements SessionHandlerInterface {
  private $db;
  public function __construct() {
    global $dbConn;
    $this->db = $dbConn;

    // Set handler to overide SESSION
    /*
    session_set_save_handler(
      array($this, '_open'),
      array($this, '_close'),
      array($this, '_read'),
      array($this, '_write'),
      array($this, '_destroy'),
      array($this, '_gc'),
      array($this, '_create_sid'),
      array($this, '_validate_sid')
    );
*/
  }
  public function open($path, $name): bool {
    ZM\Debug("Session::open ".($this->db?true:false));
    return $this->db ? true : false;
  }
  public function close() : bool {
    ZM\Debug("Session::close ");
    // The example code closed the db connection.. I don't think we care to.
    return true;
  }
  #[\ReturnTypeWillChange]
  public function read($id){
    ZM\Debug("Session::read ");
    $sth = $this->db->prepare('SELECT data FROM Sessions WHERE id = :id');
    if (!$sth->bindParam(':id', $id, PDO::PARAM_STR, 32)) {
      ZM\Error("Failed to bind param");
      if (!$sth->bindParam(':id', $id, PDO::PARAM_STR)) {
        ZM\Error("Failed to bind param");
      }
    }

    if ( $sth->execute() ) {
      if (( $row = $sth->fetch(PDO::FETCH_ASSOC) ) ) {
        return $row['data'];
      } 
      ZM\Debug("Exeuted but no row for $id");
    }
    ZM\Error("No session for id $id?");
    // Return an empty string
    return '';
  }
  public function write($id, $data) : bool {
    ZM\Debug("Session::write $id $data");
    // Create time stamp
    $access = time();

    $sth = $this->db->prepare('REPLACE INTO Sessions VALUES (:id, :access, :data)');

    $sth->bindParam(':id', $id, PDO::PARAM_STR, 32);
    $sth->bindParam(':access', $access, PDO::PARAM_INT);
    $sth->bindParam(':data', $data);

    if ($sth->execute()) {
      ZM\Debug("sucess");
      return true;
    } else {
      ZM\Debug("failss");
      return false;
    }
    #return $sth->execute() ? true : false;
  }
  public function destroy($id) : bool {
    ZM\Debug("Session::destroy $id");
    $sth = $this->db->prepare('DELETE FROM Sessions WHERE Id = :id');
    $sth->bindParam(':id', $id, PDO::PARAM_STR, 32);
    return $sth->execute() ? true : false;
  }
  #[\ReturnTypeWillChange]
  public function gc($max) {
    // Calculate what is to be deemed old
    $now = time();
    $old = $now - $max;
    ZM\Debug('doing session gc ' . $now . '-' . $max. '='.$old);
    $sth = $this->db->prepare('DELETE FROM Sessions WHERE access < :old');
    $sth->bindParam(':old', $old, PDO::PARAM_INT);
    return $sth->execute() ? true : false;
  }
  public function validateId($key) : bool {return true;}
} # end class Session

$session = new ZMSessionHandler;
session_set_save_handler($session, true);
?>