import { ownerWindow } from "../../internals/dom/owner-window.ts";

export interface ViewportRect {
	x: number;
	y: number;
	width: number;
	height: number;
}

/**
 * Calculates the viewport rect for the virtual cursor. Mirrors React
 * `packages/react/src/number-field/utils/getViewportRect.ts`.
 */
export function getViewportRect(
	teleportDistance: number | undefined,
	scrubAreaEl: HTMLElement,
): ViewportRect {
	const win = ownerWindow(scrubAreaEl);
	const rect = scrubAreaEl.getBoundingClientRect();

	if (rect && teleportDistance != null) {
		return {
			x: rect.left - teleportDistance / 2,
			y: rect.top - teleportDistance / 2,
			width: rect.right + teleportDistance / 2,
			height: rect.bottom + teleportDistance / 2,
		};
	}

	const vV = win.visualViewport;

	if (vV) {
		return {
			x: vV.offsetLeft,
			y: vV.offsetTop,
			width: vV.offsetLeft + vV.width,
			height: vV.offsetTop + vV.height,
		};
	}

	return {
		x: 0,
		y: 0,
		width: win.document.documentElement.clientWidth,
		height: win.document.documentElement.clientHeight,
	};
}