import { AlienClass } from '../aliens/alien/alien.class';
import { AssetClass } from '../asset/asset.class';
import { BoundarySetupModel } from '../model/boundary-set.model';
import { GameService } from './game.service';
export declare class InvasionService extends AssetClass {
    private alienBoss;
    private aliens;
    private isAlienCreepLeft;
    private xAlienDelta;
    private isBossing;
    private timerId;
    private displayElapseTime;
    private isGameStarted;
    constructor(gameService: GameService, ctx: CanvasRenderingContext2D, boundary: BoundarySetupModel);
    protected spawn(): void;
    private setup;
    private toggleScore;
    private findNextBombingAlien;
    aliensDestroyed(): boolean;
    setupInvasion(yStart: number): void;
    splat(): boolean;
    getAllActiveAliens(): AlienClass[];
    private getActiveAliens;
    increaseInvasionSpeed(creepSpeed: number): boolean;
    private dropAliens;
    private moveAliens;
    animate(now: number, creepSpeedLevel: number): void;
    resetAlienCreep(): void;
    private setAlienBossDisplayElapseTime;
}