import type { PositionAnchor } from "./types";

/**
 * @remarks \@since 5.1.6
 * @internal
 */
export interface TransformOriginOptions extends PositionAnchor {
  transformOriginY?: number;
}

/**
 * This is a simple util that'll generate a css `transform-origin` string so
 * that the fixed element can animate from the correct point based on the
 * provided anchor.
 *
 * @param options - The anchor that should be used to create the transform origin
 * for.
 * @returns the transform origin string
 * @internal
 */
export function getTransformOrigin(options: TransformOriginOptions): string {
  const { transformOriginY: yPosition } = options;

  let x = "0";
  switch (options.x) {
    case "right":
    case "inner-left":
      x = "0";
      break;
    case "center":
      x = "50%";
      break;
    case "left":
    case "inner-right":
      x = "100%";
      break;
    default:
      x = "0";
  }

  let y = "0";
  if (typeof yPosition === "number") {
    y = `${yPosition}px`;
  } else {
    switch (options.y) {
      case "above":
      case "bottom":
        y = "100%";
        break;
      case "center":
        y = "50%";
        break;
      case "below":
      case "top":
        y = "0";
        break;
      default:
        y = "0";
    }
  }

  return `${x} ${y}`;
}