/// <reference path="inputEventCoordinate.ts" />

namespace com.keyman.osk {
  export type InputHandler = (coord: InputEventCoordinate) => void;

  export interface InputEventEngineConfig {
    /**
     * Specifies the element that input listeners should be attached to.
     */
    readonly eventRoot: HTMLElement;
    /**
     * Specifies the most specific common ancestor element of any event target
     * that the InputEventEngine should consider.
     */
    readonly targetRoot: HTMLElement;

    readonly coordConstrainedWithinInteractiveBounds: (coord: InputEventCoordinate) => boolean;

    readonly inputStartHandler?:      InputHandler;
    readonly inputMoveHandler?:       InputHandler;
    readonly inputMoveCancelHandler?: InputHandler;
    readonly inputEndHandler?:        InputHandler;
  }

  export abstract class InputEventEngine {
    protected readonly config: InputEventEngineConfig;

    public constructor(config: InputEventEngineConfig) {
      this.config = config;
    }

    abstract registerEventHandlers();
    abstract unregisterEventHandlers();

    onInputStart(coord: InputEventCoordinate) {
      if(this.config.inputStartHandler) {
        this.config.inputStartHandler(coord);
      }
    }

    onInputMove(coord: InputEventCoordinate) {
      if(this.config.inputMoveHandler) {
        this.config.inputMoveHandler(coord);
      }
    }

    onInputMoveCancel(coord: InputEventCoordinate) {
      if(this.config.inputMoveCancelHandler) {
        this.config.inputMoveCancelHandler(coord);
      }
    }

    onInputEnd(coord: InputEventCoordinate) {
      if(this.config.inputEndHandler) {
        this.config.inputEndHandler(coord);
      }
    }
  }
}