<?php
if (!class_exists('SimpleUserAvatar_Public')) {

  /**
   * PHP class SimpleUserAvatar_Public
   *
   * @since 2.8
   */
  class SimpleUserAvatar_Public {

    public function __construct() {

      // Override WordPress function get_avatar();
      add_filter('get_avatar', [$this, 'get_avatar_filter'], 5, 5);

    }


    public static function init() {

      new self;

    }


    /**
     * Override of the original WordPress function get_avatar();
     *
     * @since  1.0
     * @return string
     */
    public function get_avatar_filter($avatar, $id_or_email, $size, $default_value, $alt) {

      // Global $pagenow
      global $pagenow;

      // If pagenow is "Discussion" in WP Admin return default avatar
      if ($pagenow === 'options-discussion.php') {
        return $avatar;
      }

      // Get user ID, if is numeric
      if (is_numeric($id_or_email)) {

        $user_id = (int)$id_or_email;

      // If is string, maybe the user email
      } elseif (is_string($id_or_email)) {

        // Find user by email
        $user = get_user_by('email', $id_or_email);

        // If user doesn't exists or this is not an ID
        if (!isset($user->ID) || !is_numeric($user->ID)) {
          return $avatar;
        }

        $user_id = (int)$user->ID;

      // If is an object
      } elseif (is_object($id_or_email)) {
      
        // If is an ID
        if (isset($id_or_email->ID) && is_numeric($id_or_email->ID)) {

          $user_id = (int)$id_or_email->ID;
        
          // If this is an Comment Object
        } elseif (isset($id_or_email->comment_author_email)) {

          // Get user by Email
          $user = get_user_by('email', $id_or_email->comment_author_email);

          // If user doesn't exists or this is not an ID
          if (!isset($user->ID) || !is_numeric($user->ID)) {
            return $avatar;
          }

          $user_id = (int)$user->ID;
        } else {
          return $avatar;
        }
      }

      // Get attachment ID from user meta
      $attachment_id = get_user_meta($user_id, SUA_USER_META_KEY, true);
      if (empty($attachment_id) || !is_numeric($attachment_id)) {
        return $avatar;
      }

      // Get attachment image src
      $attachment_src = wp_get_attachment_image_src($attachment_id, 'medium');

      // Override WordPress src
      if ($attachment_src !== false) {
        $avatar = preg_replace('/src=("|\').*?("|\')/', "src='{$attachment_src[0]}'", $avatar);
      }

      // Get attachment image srcset
      $attachment_srcset = wp_get_attachment_image_srcset($attachment_id);

      // Override WordPress srcset
      $avatar = preg_replace('/srcset=("|\').*?("|\')/', $attachment_srcset !== false ? "srcset='{$attachment_srcset}'" : '', $avatar);

      return $avatar;

    }

  }

  add_action('plugins_loaded', ['SimpleUserAvatar_Public', 'init']);

}