bp_email_unsubscribe_handler()

function bp_email_unsubscribe_handler() {
	$emails         = bp_email_get_unsubscribe_type_schema();
	$raw_email_type = ! empty( $_GET['nt'] ) ? $_GET['nt'] : '';
	$raw_hash       = ! empty( $_GET['nh'] ) ? $_GET['nh'] : '';
	$raw_user_id    = ! empty( $_GET['uid'] ) ? absint( $_GET['uid'] ) : 0;
	$new_hash       = hash_hmac( 'sha1', "{$raw_email_type}:{$raw_user_id}", bp_email_get_salt() );

	// Check required values.
	if ( ! $raw_user_id || ! $raw_email_type || ! $raw_hash || ! array_key_exists( $raw_email_type, $emails ) ) {
		$redirect_to = wp_login_url();
		$result_msg  = __( 'Something has gone wrong.', 'buddyboss' );
		$unsub_msg   = __( 'Please log in and go to your settings to unsubscribe from notification emails.', 'buddyboss' );

	// Check valid hash.
	} elseif ( ! hash_equals( $new_hash, $raw_hash ) ) {
		$redirect_to = wp_login_url();
		$result_msg  = __( 'Something has gone wrong.', 'buddyboss' );
		$unsub_msg   = __( 'Please log in and go to your settings to unsubscribe from notification emails.', 'buddyboss' );

	// Don't let authenticated users unsubscribe other users' email notifications.
	} elseif ( is_user_logged_in() && get_current_user_id() !== $raw_user_id ) {
		$result_msg  = __( 'Something has gone wrong.', 'buddyboss' );
		$unsub_msg   = __( 'Please go to your notifications settings to unsubscribe from emails.', 'buddyboss' );

		if ( bp_is_active( 'settings' ) ) {
			$redirect_to = sprintf(
				'%s%s/notifications/',
				bp_core_get_user_domain( get_current_user_id() ),
				bp_get_settings_slug()
			);
		} else {
			$redirect_to = bp_core_get_user_domain( get_current_user_id() );
		}

	} else {
		if ( bp_is_active( 'settings' ) ) {
			$redirect_to = sprintf(
				'%s%s/notifications/',
				bp_core_get_user_domain( $raw_user_id ),
				bp_get_settings_slug()
			);
		} else {
			$redirect_to = bp_core_get_user_domain( $raw_user_id );
		}

		// Unsubscribe.
		$meta_key = $emails[ $raw_email_type ]['unsubscribe']['meta_key'];
		bp_update_user_meta( $raw_user_id, $meta_key, 'no' );

		$result_msg = $emails[ $raw_email_type ]['unsubscribe']['message'];
		$unsub_msg  = __( 'You can change this or any other email notification preferences in your email settings.', 'buddyboss' );
	}

	$message = sprintf(
		'%1$s <a href="%2$s">%3$s</a>',
		$result_msg,
		esc_url( $redirect_to ),
		esc_html( $unsub_msg )
	);

	bp_core_add_message( $message );
	bp_core_redirect( bp_core_get_user_domain( $raw_user_id ) );

	exit;
}