BP_XProfile_Field::get_fields_for_member_type( string|array $member_types )

	public static function get_fields_for_member_type( $member_types ) {
		global $wpdb;

		$fields = array();

		if ( empty( $member_types ) ) {
			$member_types = array( 'any' );
		} elseif ( ! is_array( $member_types ) ) {
			$member_types = array( $member_types );
		}

		$bp = buddypress();

		// Pull up all recorded field profile type data.
		$mt_meta = wp_cache_get( 'field_member_types', 'bp_xprofile' );
		if ( false === $mt_meta ) {
			$mt_meta = $wpdb->get_results( "SELECT object_id, meta_value FROM {$bp->profile->table_name_meta} WHERE meta_key = 'member_type' AND object_type = 'field'" );
			wp_cache_set( 'field_member_types', $mt_meta, 'bp_xprofile' );
		}

		// Keep track of all fields with recorded member_type metadata.
		$all_recorded_field_ids = wp_list_pluck( $mt_meta, 'object_id' );

		// Sort member_type matches in arrays, keyed by field_id.
		foreach ( $mt_meta as $_mt_meta ) {
			if ( ! isset( $fields[ $_mt_meta->object_id ] ) ) {
				$fields[ $_mt_meta->object_id ] = array();
			}

			$fields[ $_mt_meta->object_id ][] = $_mt_meta->meta_value;
		}

		/*
		 * Filter out fields that don't match any passed types, or those marked '_none'.
		 * The 'any' type is implicitly handled here: it will match no types.
		 */
		foreach ( $fields as $field_id => $field_types ) {
			if ( ! array_intersect( $field_types, $member_types ) ) {
				unset( $fields[ $field_id ] );
			}
		}

		// Any fields with no member_type metadata are available to all profile types.
		if ( ! in_array( '_none', $member_types ) ) {
			if ( ! empty( $all_recorded_field_ids ) ) {
				$all_recorded_field_ids_sql = implode( ',', array_map( 'absint', $all_recorded_field_ids ) );
				$unrestricted_field_ids     = $wpdb->get_col( "SELECT id FROM {$bp->profile->table_name_fields} WHERE id NOT IN ({$all_recorded_field_ids_sql})" );
			} else {
				$unrestricted_field_ids = $wpdb->get_col( "SELECT id FROM {$bp->profile->table_name_fields}" );
			}

			// Append the 'null' pseudo-type.
			$all_member_types   = bp_get_member_types();
			$all_member_types   = array_values( $all_member_types );
			$all_member_types[] = 'null';

			foreach ( $unrestricted_field_ids as $unrestricted_field_id ) {
				$fields[ $unrestricted_field_id ] = $all_member_types;
			}
		}

		return $fields;
	}