class BP_Nouveau_Group_Invite_Query extends BP_User_Query {
	/**
	 * Array of group member ids, cached to prevent redundant lookups
	 *
	 * @var null|array Null if not yet defined, otherwise an array of ints
	 * @since 3.0.0
	 */
	protected $group_member_ids;

	/**
	 * Set up action hooks
	 *
	 * @since 3.0.0
	 */
	public function setup_hooks() {
		add_action( 'bp_pre_user_query_construct', array( $this, 'build_exclude_args' ) );
		add_action( 'bp_pre_user_query', array( $this, 'build_meta_query' ) );
	}

	/**
	 * Exclude group members from the user query as it's not needed to invite members to join the group.
	 *
	 * @since 3.0.0
	 */
	public function build_exclude_args() {
		$this->query_vars = bp_parse_args(
			$this->query_vars,
			array(
				'group_id'     => 0,
				'is_confirmed' => true,
			),
			'nouveau_group_invite_query_exlude_args'
		);

		$group_member_ids = $this->get_group_member_ids();

		/**
		 * We want to exclude users who are already members or who have been
		 * invited by **any** of the group members to join it.
		 */
		$type = 'exclude';

		// We want to get the invited users who did not confirmed yet.
		if ( false === $this->query_vars['is_confirmed'] ) {
			$type = 'include';
		}

		if ( ! empty( $group_member_ids ) ) {
			$this->query_vars[ $type ] = $group_member_ids;
		}
	}

	/**
	 * Get the members of the queried group
	 *
	 * @since 3.0.0
	 *
	 * @return array $ids User IDs of relevant group member ids
	 */
	protected function get_group_member_ids() {
		global $wpdb;

		if ( is_array( $this->group_member_ids ) ) {
			return $this->group_member_ids;
		}

		// Fetch **all** invited users.
		$pending_invites = groups_get_invites( array(
			'item_id'     => $this->query_vars['group_id'],
			'invite_sent' => 'sent',
			'fields'      => 'user_ids'
		) );

		// This is a clue that we only want the invitations.
		if ( false === $this->query_vars['is_confirmed'] ) {
			return $pending_invites;
		}

		/**
		 * Otherwise, we want group members _and_ users with outstanding invitations,
		 * because we're doing an "exclude" query.
		 */
		$bp  = buddypress();
		$sql = array(
			'select'  => "SELECT user_id FROM {$bp->groups->table_name_members}",
			'where'   => array(),
			'orderby' => '',
			'order'   => '',
			'limit'   => '',
		);

		/** WHERE clauses *****************************************************/

		// Group id
		$sql['where'][] = $wpdb->prepare( 'group_id = %d', $this->query_vars['group_id'] );

		// Join the query part
		$sql['where'] = ! empty( $sql['where'] ) ? 'WHERE ' . implode( ' AND ', $sql['where'] ) : '';

		/** ORDER BY clause ***************************************************/
		$sql['orderby'] = 'ORDER BY date_modified';
		$sql['order']   = 'DESC';

		/** LIMIT clause ******************************************************/
		$this->group_member_ids = $wpdb->get_col( "{$sql['select']} {$sql['where']} {$sql['orderby']} {$sql['order']} {$sql['limit']}" );

		return array_merge( $this->group_member_ids, $pending_invites );
	}

	/**
	 * @since 3.0.0
	 */
	public function build_meta_query( BP_User_Query $bp_user_query ) {
		if ( isset( $this->query_vars['scope'] ) && 'members' === $this->query_vars['scope'] && isset( $this->query_vars['meta_query'] ) ) {

			$invites_meta_query = new WP_Meta_Query( $this->query_vars['meta_query'] );
			$meta_sql           = $invites_meta_query->get_sql( 'user', 'u', 'ID' );

			if ( empty( $meta_sql['join'] ) || empty( $meta_sql['where'] ) ) {
				return;
			}

			$bp_user_query->uid_clauses['select'] .= ' ' . $meta_sql['join'];
			$bp_user_query->uid_clauses['where']  .= ' ' . $meta_sql['where'];
		}
	}

	/**
	 * @since 3.0.0
	 */
	public static function get_inviter_ids( $user_id = 0, $group_id = 0 ) {
		global $wpdb;

		if ( empty( $group_id ) || empty( $user_id ) ) {
			return array();
		}

		return groups_get_invites( array(
			'user_id'     => $user_id,
			'item_id'     => $group_id,
			'invite_sent' => 'sent',
			'fields'      => 'inviter_ids'
		) );
	}
}