<?php

/**
 * Class that encapsulates everything that can be done with a user
 */
class User
{
  private $id;
  private $name;
  private $surname;
  private $username;
  private $email;
  private $rank;
  private $active;

  /**
   * Gets user data from database and creates the class
   * @param int $id user ID
   */
  function __construct($id)
  {
    global $mysqli;
    $stmt = $mysqli->prepare("SELECT * FROM users WHERE id=?");
    $stmt->bind_param("d", $id);
    $stmt->execute();
    $query = $stmt->get_result();

    if (!$query->num_rows) {
      throw new Exception("User doesn't exist.");
      return;
    }

    $result = $query->fetch_array();
    $this->id = $id;
    $this->active = $result['active'];
    $this->name = $result['name'];
    $this->email = $result['email'];
    $this->surname = $result['surname'];
    $this->username = $result['username'];
    $this->rank = $result['permission'];
  }

  /**
   * Returns username of this user
   * @return String username
   */
  public function get_username()
  {
    return $this->username;
  }

  /**
   * Returns whether this user is active
   * @return Boolean user active status
   */
  public function is_active()
  {
    return $this->active;
  }

  /**
   * Returns rank of this user
   * @return int rank
   */
  public function get_rank()
  {
    return $this->rank;
  }

  /**
   * Returns full name of this user
   * @return String name in "Name Surname" format
   */
  public function get_name()
  {
    return $this->name . " " . $this->surname;
  }

  /**
   * Toggles active status of this user. First checks if the user
   * making the change has permission to do that.
   * @return void
   */
  public function toggle()
  {
    global $mysqli, $message, $user;

    $id = $_GET['id'];
    if ($this->id != $_SESSION['user'] && $user->get_rank() <= 1 && ($user->get_rank() < $this->rank)) {
      $stmt = $mysqli->prepare("UPDATE users SET active = !active WHERE id=?");
      $stmt->bind_param("i", $this->id);
      $stmt->execute();
      $stmt->close();
      header("Location: " . WEB_URL . "/admin/?do=user&id=" . $id);
    } else {
      $message = _("You don't have the permission to do that!");
    }
  }

  /**
   * Processes submitted form and adds user unless problem is encountered, 
   * calling this is possible only for Superadmin (other ranks cannot add users)
   * or when the installation script is being run. Also checks requirements
   * for username and email being unique and char limits.
   * @return void
   */
  public static function add()
  {
    global $user, $message, $mysqli;
    if (INSTALL_OVERRIDE || $user->get_rank() == 0) {
      if (strlen(trim($_POST['name'])) == 0) {
        $messages[] = _("Name");
      }
      if (strlen(trim($_POST['surname'])) == 0) {
        $messages[] = _("Surname");
      }
      if (strlen(trim($_POST['email'])) == 0) {
        $messages[] = _("Email");
      }
      if (strlen(trim($_POST['password'])) == 0) {
        $messages[] = _("Password");
      }
      if (!isset($_POST['permission'])) {
        $messages[] = _("Rank");
      }

      if (isset($messages)) {
        $message = "Please enter " . implode(", ", $messages);
        return;
      }

      $name = $_POST['name'];
      $surname = $_POST['surname'];
      $username = $_POST['username'];
      $email = $_POST['email'];
      $pass = $_POST['password'];

      if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        $message = "Invalid email!";
        return;
      }

      $variables = array();
      if (strlen($name) > 50) {
        $variables[] = 'name: 50';
      }
      if (strlen($surname) > 50) {
        $variables[] = 'surname: 50';
      }
      if (strlen($username) > 50) {
        $variables[] = 'username: 50';
      }
      if (strlen($email) > 60) {
        $variables[] = 'email: 60';
      }


      if (!empty($variables)) {
        $message = _("Please mind the following character limits: ");
        $message .= implode(", ", $variables);
        return;
      }

      $salt = uniqid(mt_rand(), true);
      $hash = hash('sha256', $pass . $salt);
      $permission = $_POST['permission'];


      $stmt = $mysqli->prepare("INSERT INTO users values (NULL, ?, ?, ?, ?, ?, ?, ?, 1)");
      $stmt->bind_param("ssssssi", $email, $username, $name, $surname, $hash, $salt, $permission);
      $stmt->execute();

      if ($stmt->affected_rows == 0) {
        $message = _("Username or email already used");
        return;
      }

      $to      = $email;
      $subject = _('User account created') . ' - ' . NAME;
      $msg = sprintf(_("Hi %s!<br>" . "Your account has been created. You can login with your email address at <a href=\"%s\">%s</a> with password %s - please change it as soon as possible."), $name . " " . $surname, WEB_URL . "/admin", WEB_URL . "/admin", $pass);
      $headers = "Content-Type: text/html; charset=utf-8 " . PHP_EOL;
      $headers .= "MIME-Version: 1.0 " . PHP_EOL;
      $headers .= "From: " . MAILER_NAME . ' <' . MAILER_ADDRESS . '>' . PHP_EOL;
      $headers .= "Reply-To: " . MAILER_NAME . ' <' . MAILER_ADDRESS . '>' . PHP_EOL;

      mail($to, $subject, $msg, $headers);
      if (!INSTALL_OVERRIDE) {
        header("Location: " . WEB_URL . "/admin/?do=settings");
      }
    } else {
      $message = _("You don't have the permission to do that!");
    }
  }

  /**
   * Processes submitted form and logs user in, unless the user is deactivated or wrong
   * password or email has been submitted. The script doesn't let anyone know which
   * field was wrong as it is not possible to verify email address from outside admin panel,
   * so this actually helps with security :)
   * @return void
   */
  public static function login()
  {
    global $message, $mysqli;
    if (!isset($_POST['email']) && !isset($_POST['email'])) {
      return;
    }

    if ((!isset($_POST['email']) || !isset($_POST['email']))) {
      $message = _("Please fill in your email and password!");
      return;
    }
    $email = $_POST['email'];
    $pass = $_POST['pass'];

    $stmt = $mysqli->prepare("SELECT id,password_salt as salt,active FROM users WHERE email=?");
    $stmt->bind_param("s", $email);
    $stmt->execute();
    $query = $stmt->get_result();

    if ($query->num_rows < 1) {
      $message = _("Wrong email or password");
      return;
    }

    $result = $query->fetch_assoc();
    $salt = $result["salt"];
    $id =  $result["id"];
    $active =  $result["active"];

    if (!$active) {
      $message = _("Your account has been disabled. Please contact administrator.");
      return;
    }

    $hash = hash('sha256', $pass . $salt);
    $stmt = $mysqli->prepare("SELECT count(*) as count FROM users WHERE id=? AND password_hash=?");
    $stmt->bind_param("is", $id, $hash);
    $stmt->execute();
    $query = $stmt->get_result();

    if (!$query->fetch_assoc()['count']) {
      $message = _("Wrong email or password");
      return;
    }

    if (isset($_POST['remember']) && $_POST['remember']) {
      $year = strtotime('+356 days', time());
      $token = Token::add($id, 'remember', $year);
      setcookie('token', $token, $year, "/");
      setcookie('user', $id, $year, "/");
    }

    $_SESSION['user'] = $id;
    header("Location: " . WEB_URL . "/admin");
  }

  /**
   * Checks whether token is valid (this means is in database and associated
   * with the user) and sets session data if it is, so user remains logged in.
   * The script deletes the token either way.
   * @return void
   */
  public static function restore_session()
  {
    global $message;
    $id = $_COOKIE['user'];
    $token = $_COOKIE['token'];

    if (Token::validate($token, $id, "remember")) {
      $year = strtotime('+356 days', time());
      unset($_COOKIE['token']);
      $_SESSION['user'] = $id;
      $new_token = Token::add($id, 'remember', $year);
      setcookie('token', $new_token, $year, "/");
      setcookie('user', $id, $year, "/");
    } else {
      unset($_COOKIE['user']);
      unset($_COOKIE['token']);
      setcookie('user', null, -1, '/');
      setcookie('token', null, -1, '/');
      $message = _("Invalid token detected, please login again!");
    }

    Token::delete($token);
  }
  /**
   * Renders settings for this user so it can be displayed in admin panel.
   * @return void
   */
  public function render_user_settings()
  {
    global $permissions, $user;
?>
    <div class="row user">
      <div class="col-md-2 col-md-offset-2"><img src="https://www.gravatar.com/avatar/<?php echo md5(strtolower(trim($this->email))); ?>?s=160" alt="<?php echo _("Profile picture"); ?>"></div>
      <div class="col-md-6">
        <?php if ($this->id == $_SESSION['user'] || $user->get_rank() < 1) {
        ?>
          <form action="<?php echo WEB_URL; ?>/admin/?do=user&amp;id=<?php echo $this->id; ?>" method="POST">
            <div class="input-group">
              <div class="col-md-12">
                <div class="row">
                  <label class="form-name" for="name"><?php echo _("Name"); ?></label>
                  <label class="form-name" for="surname"><?php echo _("Surname"); ?></label>
                </div>
                <div class="row">
                  <input type="text" name="name" placeholder="<?php echo _("Name"); ?>" title="<?php echo _("Name"); ?>" class="form-control form-name" value=<?php echo htmlspecialchars($this->name, ENT_QUOTES); ?>>
                  <input type="text" name="surname" placeholder="<?php echo _("Surname"); ?>" title="<?php echo _("Surname"); ?>" class="form-control form-name" value=<?php echo htmlspecialchars($this->surname, ENT_QUOTES); ?>>
                </div>
              </div>
            </div>
            <button type="submit" class="btn btn-primary float-end"><?php echo _("Change name"); ?></button>
          </form>
        <?php
        } else {
        ?>
          <h3><?php echo $this->name . " " . $this->surname; ?></h3>
        <?php
        } ?>
      </div>
    </div>
    <form action="<?php echo WEB_URL; ?>/admin/?do=user&amp;id=<?php echo $this->id; ?>" method="POST">
      <div class="row user">
        <div class="col-md-2 col-md-offset-2"><strong><?php echo _("Username"); ?></strong></div>
        <div class="col-md-6">
          <?php
          if ($this->id == $_SESSION['user'] || $user->get_rank() < 1) { ?>
            <div class="input-group">
              <input type="text" class="form-control" name="username" required value="<?php echo htmlspecialchars($this->username, ENT_QUOTES); ?>">
              <span class="input-group-btn">
                <button type="submit" class="btn btn-primary float-end"><?php echo _("Change username"); ?></button>
              </span>
            </div>
            <?php
          } else { ?><?php echo $this->username . " ";
                      if ($user->get_rank() >= 1) {
                        echo "<i class='fa fa-" . ($this->active ? "check success" : "times danger") . "'></i>";
                      }
                    }
                      ?>
        </div>
      </div>
    </form>

    <form action="<?php echo WEB_URL; ?>/admin/?do=user&id=<?php echo $this->id; ?>" method="POST">
      <div class="row user">
        <div class="col-md-2 col-md-offset-2"><strong><?php echo _("Role"); ?></strong></div>
        <div class="col-md-6"><?php if ($user->get_rank() == 0 && $this->id != $_SESSION['user']) { ?>
            <div class="input-group"><select class="form-control" name="permission">
                <?php foreach ($permissions as $key => $value) {
                                  echo "<option value='$key' " . ($key == $this->rank ? "selected" : "") . ">$value</option>";
                                } ?>
              </select><span class="input-group-btn">
                <button type="submit" class="btn btn-primary float-end"><?php echo _("Change role"); ?></button>
              </span>
            </div><?php } else {
                                echo $permissions[$this->rank];
                              } ?>
        </div>
      </div>
    </form>

    <?php if ($this->id == $_SESSION['user'] || $user->get_rank() < 1) { ?>
      <form action="<?php echo WEB_URL; ?>/admin/?do=user&amp;id=<?php echo $this->id; ?>" method="POST">
        <div class="row user">
          <div class="col-md-2 col-md-offset-2"><strong>Email</strong></div>
          <div class="col-md-6">
            <div class="input-group">
              <input type="email" class="form-control" name="email" value="<?php echo $this->email; ?>">
              <span class="input-group-btn">
                <button type="submit" class="btn btn-primary float-end"><?php echo _("Change email"); ?></button>
              </span>
            </div>
          </div>
        </div>
      </form>
    <?php } else {
    ?>
      <div class="row user">
        <div class="col-md-2 col-md-offset-2"><strong><?php echo _("Email"); ?></strong></div>
        <div class="col-md-6">
          <a href="mailto:<?php echo $this->email; ?>"><?php echo $this->email; ?></a>
        </div>
      </div>
    <?php
    }

    if ($this->id == $_SESSION['user']) {
    ?>

      <form action="<?php echo WEB_URL; ?>/admin/?do=user" method="POST">
        <div class="row">
          <div class="col-md-2 col-md-offset-2"><strong><?php echo _("Password"); ?></strong></div>
          <div class="col-md-6">
            <label for="password"><?php echo _("Old password"); ?></label>
            <input id="password" placeholder="<?php echo _("Old password"); ?>" type="password" class="form-control" name="old_password">
            <label for="new_password"><?php echo _("New password"); ?></label>
            <input id="new_password" placeholder="<?php echo _("New password"); ?>" type="password" class="form-control" name="password">
            <label for="new_password_check"><?php echo _("Repeat password"); ?></label>
            <input id="new_password_check" placeholder="<?php echo _("Repeat password"); ?>" type="password" class="form-control" name="password_repeat">
            <button type="submit" class="btn btn-primary float-end margin-top"><?php echo _("Change password"); ?></button>
          </div>
        </div>
      </form>
    <?php
    }

    if ($this->id != $_SESSION['user'] && $user->get_rank() <= 1 && ($user->get_rank() < $this->rank)) { ?>
      <div class="row">
        <div class="col-md-2 col-md-offset-2"></div>
        <div class="col-md-6">
          <?php
          if ($this->active) {
            echo '<a href="' . WEB_URL . '/admin/?do=user&id=' . $this->id . '&what=toggle" class="btn btn-danger">' . _("Deactivate user") . "</a>";
          } else {
            echo '<a href="' . WEB_URL . '/admin/?do=user&id=' . $this->id . '&what=toggle" class="btn btn-success">' . _("Activate user") . "</a>";
          }
          ?>
        </div>
      </div>
<?php }
  }

  /**
   * Changes username of user by POST[ID].
   * @return void
   */
  public function change_username()
  {
    global $mysqli, $message, $user;
    $id = $this->id;

    $stmt = $mysqli->prepare("SELECT count(*) FROM users WHERE username LIKE ?");
    $stmt->bind_param("s", $_POST["username"]);
    $stmt->execute();
    if ($stmt->num_rows > 0) {
      $message = _("This username is already taken.");
      return;
    }
    $stmt->close();

    if ($_SESSION['user'] != $id && $user->get_rank() > 0) {
      $message = _("Cannot change username of other users!");
    } else {
      $stmt = $mysqli->prepare("UPDATE users SET username = ? WHERE id=?");
      $stmt->bind_param("si", $_POST["username"], $id);
      $stmt->execute();
      $stmt->close();
      header("Location:  " . WEB_URL . "/admin/?do=user&id=" . $id);
    }
  }

  /**
   * Changes name and surname of user by POST[ID].
   * @return void
   */
  public function change_name()
  {
    global $mysqli, $message, $user;
    if (strlen(trim($_POST['name'])) == 0) {
      $messages[] = _("Name");
    }
    if (strlen(trim($_POST['surname'])) == 0) {
      $messages[] = _("Surname");
    }

    if (!empty($messages)) {
      $message = "Please enter " . implode(", ", $messages);
      return;
    }

    $id = $this->id;

    if ($_SESSION['user'] != $id && $user->get_rank() > 0) {
      $message = _("Cannot change names of other users!");
    } else {
      $stmt = $mysqli->prepare("UPDATE users SET `name` = ?, `surname` = ?  WHERE id=?");
      $stmt->bind_param("ssi", $_POST["name"], $_POST["surname"], $id);
      $stmt->execute();
      $stmt->close();
      header("Location:  " . WEB_URL . "/admin/?do=user&id=" . $id);
    }
  }

  /**
   * Changes user password and deletes all remember tokens so all other sessions 
   * won't stay logged in without knowing new pass. Uses token when reseting password.
   * @param String $token
   * @return void
   */
  public function change_password($token = false)
  {
    global $mysqli, $message;
    $id = $this->id;
    if ($_POST['password'] != $_POST['password_repeat']) {
      $message = _("Passwords do not match!");
      return;
    }

    if (!$token) {
      if ($_SESSION['user'] != $id) {
        $message = _("Cannot change password of other users!");
      } else {
        $stmt = $mysqli->prepare("SELECT password_salt as salt FROM users WHERE id=?");
        $stmt->bind_param("i", $id);
        $stmt->execute();
        $query = $stmt->get_result();
        $result = $query->fetch_assoc();

        $salt = $result['salt'];
        $pass = $_POST['old_password'];
        $hash = hash('sha256', $pass . $salt);

        $stmt = $mysqli->prepare("SELECT count(*) as count FROM users WHERE id=? AND password_hash = ?");
        $stmt->bind_param("is", $id, $hash);
        $stmt->execute();

        if ($stmt->get_result()->fetch_assoc()['count']) {
          $pass = $_POST['password'];
          $hash = hash('sha256', $pass . $salt);
          $stmt = $mysqli->prepare("UPDATE users SET password_hash = ? WHERE id=?");
          $stmt->bind_param("si", $hash, $id);
          $stmt->execute();
          $stmt->close();

          $stmt = $mysqli->prepare("DELETE FROM tokens WHERE user = ? AND data = 'remember'");
          $stmt->bind_param("d", $id);
          $stmt->execute();
          $stmt->get_result();

          User::logout();
        } else {
          $message = _("Wrong password!");
        }
      }
    } else {
      if (Token::validate($token, $id, "passwd")) {
        $stmt = $mysqli->prepare("SELECT password_salt as salt FROM users WHERE id=?");
        $stmt->bind_param("i", $id);
        $stmt->execute();
        $query = $stmt->get_result();
        $result = $query->fetch_assoc();

        $salt = $result['salt'];
        $pass = $_POST['password'];
        $hash = hash('sha256', $pass . $salt);

        $stmt = $mysqli->prepare("UPDATE users SET password_hash = ? WHERE id=?");
        $stmt->bind_param("si", $hash, $id);
        $stmt->execute();
        $stmt->close();

        $stmt = $mysqli->prepare("DELETE FROM tokens WHERE user = ? AND data = 'remember'");
        $stmt->bind_param("d", $id);
        $stmt->execute();
        $stmt->get_result();
      } else {
        $message = _("Invalid token detected, please retry your request from start!");
      }
      Token::delete($token);
    }
  }

  /**
   * Sends email with link for password reset, link is token protected and valid only once.
   * @return void
   */
  public static function password_link()
  {
    global $mysqli;
    $email = $_POST['email'];

    $stmt = $mysqli->prepare("SELECT id FROM users WHERE email=?");
    $stmt->bind_param("s", $email);
    $stmt->execute();
    $query = $stmt->get_result();

    $id = $query->fetch_assoc()['id'];
    $time = strtotime('+1 day', time());

    $token = Token::add($id, 'passwd', $time);

    $link = WEB_URL . "/admin/?do=lost-password&id=$id&token=$token";
    $to      = $email;
    $user = new User($id);
    $subject = _('Reset password') . ' - ' . NAME;
    $msg = sprintf(_("Hi %s!<br>Below you will find link to change your password. The link is valid for 24hrs. If you didn't request this, feel free to ignore it. <br><br><a href=\"%s\">RESET PASSWORD</a><br><br>If the link doesn't work, copy &amp; paste it into your browser: <br>%s"), $user->get_name(), $link, $link);
    $headers = "Content-Type: text/html; charset=utf-8 " . PHP_EOL;
    $headers .= "MIME-Version: 1.0 " . PHP_EOL;
    $headers .= "From: " . MAILER_NAME . ' <' . MAILER_ADDRESS . '>' . PHP_EOL;
    $headers .= "Reply-To: " . MAILER_NAME . ' <' . MAILER_ADDRESS . '>' . PHP_EOL;

    mail($to, $subject, $msg, $headers);
  }

  /**
   * Sends email with link for email change confirmation (security reasons), link is token protected and valid only once.
   * @return void
   */
  public function email_link()
  {
    global $user, $mysqli;

    $email = $_POST['email'];
    $id = $this->id;

    if ($user->get_rank() < 1 && $id != $_SESSION['user']) {
      $stmt = $mysqli->prepare("UPDATE users SET email = ? WHERE id=?");
      $stmt->bind_param("sd", $email, $id);
      $stmt->execute();
      $stmt->get_result();
      header("Location: " . WEB_URL . "/admin/?do=user&id=" . $id);
      return;
    }

    $time = strtotime('+1 day', time());

    $token = Token::add($id, 'email;$email', $time);

    $link = WEB_URL . "/admin/?do=change-email&id=$id&token=$token";
    $to      = $email;
    $subject = _('Email change') . ' - ' . NAME;
    $msg = sprintf(_("Hi %s!<br>Below you will find link to change your email. The link is valid for 24hrs. If you didn't request this, feel free to ignore it. <br><br><a href=\"%s\">CHANGE EMAIL</a><br><br>If the link doesn't work, copy &amp; paste it into your browser: <br>%s"), $user->get_name(), $link, $link);
    $headers = "Content-Type: text/html; charset=utf-8 " . PHP_EOL;
    $headers .= "MIME-Version: 1.0 " . PHP_EOL;
    $headers .= "From: " . MAILER_NAME . ' <' . MAILER_ADDRESS . '>' . PHP_EOL;
    $headers .= "Reply-To: " . MAILER_NAME . ' <' . MAILER_ADDRESS . '>' . PHP_EOL;

    mail($to, $subject, $msg, $headers);
    return _('Confirmation email sent!');
  }

  /**
   * Changes email.
   * @return void
   */
  public function change_email()
  {
    global $mysqli, $message;
    $token = $_GET['token'];
    $id = $_GET['id'];

    if (Token::validate($token, $id, "email;%")) {
      $data = explode(";", Token::get_data($token, $id));

      $email = $data[1];

      $stmt = $mysqli->prepare("UPDATE users SET email = ? WHERE id=?");
      $stmt->bind_param("sd", $email, $id);
      $stmt->execute();
      $stmt->get_result();
      Token::delete($token);
      header("Location: " . WEB_URL . "/admin/");
    } else {
      $message = _("Invalid token detected, please retry your request from start!");
    }

    Token::delete($token);
  }

  /**
   * Logs current user out.
   * @return void
   */
  public static function logout()
  {
    session_unset();
    if (isset($_COOKIE['token'])) {
      $token = $_COOKIE['token'];
      Token::delete($token);
      unset($_COOKIE['user']);
      unset($_COOKIE['token']);
      setcookie('user', null, -1, '/');
      setcookie('token', null, -1, '/');
    }
    header("Location: " . WEB_URL . "/admin");
  }

  /**
   * Changes permissions of current user - only super admin can do this, so it checks permission first.
   * @return void
   */
  public function change_permission()
  {
    global $mysqli, $message, $user;
    if ($user->get_rank() == 0) {
      $permission = $_POST['permission'];
      $id = $_GET['id'];
      $stmt = $mysqli->prepare("UPDATE users SET permission=? WHERE id=?");
      $stmt->bind_param("si", $permission, $id);
      $stmt->execute();
      header("Location: " . WEB_URL . "/admin/?do=user&id=" . $id);
    } else {
      $message = _("You don't have permission to do that!");
    }
  }
}
