import {ConnectedPosition} from '@angular/cdk/overlay';
import {isArray} from 'rxjs/internal-compatibility';

export declare type Placement = 'auto' | 'top' | 'bottom' | 'left' | 'right' | 'top-left' | 'top-right' | 'bottom-left' | 'bottom-right' | 'left-top' | 'left-bottom' | 'right-top' | 'right-bottom';
export declare type PlacementArray = Placement | Array<Placement>;

export class ArOverlayPosition {

  private static readonly _offsetYVal = 7;

  public static TOP_LEFT: ConnectedPosition = {
    originX: 'end',
    originY: 'top',
    overlayX: 'end',
    overlayY: 'bottom',
    offsetY: -ArOverlayPosition._offsetYVal
  };

  public static TOP_RIGHT: ConnectedPosition = {
    originX: 'start',
    originY: 'top',
    overlayX: 'start',
    overlayY: 'bottom',
    offsetY: -ArOverlayPosition._offsetYVal
  };

  public static BOTTOM_LEFT: ConnectedPosition = {
    originX: 'end',
    originY: 'bottom',
    overlayX: 'end',
    overlayY: 'top',
    offsetY: ArOverlayPosition._offsetYVal
  };

  public static BOTTOM_RIGHT: ConnectedPosition = {
    originX: 'start',
    originY: 'bottom',
    overlayX: 'start',
    overlayY: 'top',
    offsetY: ArOverlayPosition._offsetYVal
  };

  public static LEFT_TOP: ConnectedPosition = {
    originX: 'start',
    originY: 'top',
    overlayX: 'end',
    overlayY: 'top',
    offsetX: -ArOverlayPosition._offsetYVal
  };

  public static LEFT_BOTTOM: ConnectedPosition = {
    originX: 'start',
    originY: 'bottom',
    overlayX: 'end',
    overlayY: 'bottom',
    offsetX: -ArOverlayPosition._offsetYVal
  };

  public static RIGHT_TOP: ConnectedPosition = {
    originX: 'end',
    originY: 'top',
    overlayX: 'start',
    overlayY: 'top',
    offsetX: ArOverlayPosition._offsetYVal
  };

  public static RIGHT_BOTTOM: ConnectedPosition = {
    originX: 'end',
    originY: 'bottom',
    overlayX: 'start',
    overlayY: 'bottom',
    offsetX: ArOverlayPosition._offsetYVal
  };

  public static getConnectedPosition(position: PlacementArray): ConnectedPosition[] {
    if (isArray(position)) {
      return Array.from(position).map(pos => this.getPosition(pos as Placement));
    } else if (position === 'auto') {
      return this.getAutoPosition();
    } else {
      return [this.getPosition(position as Placement)];
    }
  }

  private static getPosition(position: Placement) {
    switch (position) {
      case 'top':
        return ArOverlayPosition.TOP_RIGHT;
      case 'bottom':
        return ArOverlayPosition.BOTTOM_RIGHT;
      case 'left':
        return ArOverlayPosition.LEFT_TOP;
      case 'right':
        return ArOverlayPosition.RIGHT_TOP;
      case 'top-left':
        return ArOverlayPosition.TOP_LEFT;
      case 'top-right':
        return ArOverlayPosition.TOP_RIGHT;
      case 'bottom-left':
        return ArOverlayPosition.BOTTOM_LEFT;
      case 'bottom-right':
        return ArOverlayPosition.BOTTOM_RIGHT;
      case 'left-top':
        return ArOverlayPosition.LEFT_TOP;
      case 'left-bottom':
        return ArOverlayPosition.LEFT_BOTTOM;
      case 'right-top':
        return ArOverlayPosition.RIGHT_TOP;
      case 'right-bottom':
        return ArOverlayPosition.RIGHT_BOTTOM;
    }
  }

  private static getAutoPosition(): ConnectedPosition[] {
    return [ArOverlayPosition.TOP_LEFT, ArOverlayPosition.TOP_RIGHT,
      ArOverlayPosition.BOTTOM_LEFT, ArOverlayPosition.BOTTOM_RIGHT,
      ArOverlayPosition.LEFT_TOP, ArOverlayPosition.LEFT_BOTTOM,
      ArOverlayPosition.RIGHT_TOP, ArOverlayPosition.RIGHT_BOTTOM
    ];
  }
}