import deprecated from '@wordpress/deprecated';

const internalsKey = '_reactInternals';

// HostComponent fiber tag, represents a DOM element like <div>.
const HostComponent = 5;
const HostText = 6;

function findCurrentFiber( fiber: any ): any {
	if ( ! fiber.alternate ) {
		// First mount — only one version exists, and it's current.
		return fiber;
	}

	// Walk up to the HostRoot to figure out which tree this fiber is on.
	let node = fiber;
	while ( node.return ) {
		node = node.return;
	}

	// The root's stateNode.current points to the current tree's root fiber.
	if ( node.stateNode.current === node ) {
		// We walked up the current tree, so `fiber` is already current.
		return fiber;
	}

	// We walked up the alternate tree — switch to the current version.
	return fiber.alternate;
}

function findHostFiber( fiber: any ): any {
	const current = findCurrentFiber( fiber );
	if ( ! current ) {
		return null;
	}
	return findHostFiberImpl( current );
}

function findHostFiberImpl( fiber: any ): any {
	if ( fiber.tag === HostComponent || fiber.tag === HostText ) {
		return fiber;
	}

	let child = fiber.child;
	while ( child ) {
		const hostFiber = findHostFiberImpl( child );
		if ( hostFiber ) {
			return hostFiber;
		}
		child = child.sibling;
	}

	return null;
}

/**
 * Finds the DOM node of a React component instance.
 *
 * @deprecated since WordPress 7.1.0. Use DOM refs instead.
 * @see https://react.dev/reference/react-dom/findDOMNode
 *
 * @param      instance Component's instance.
 */
export default function findDOMNode( instance: any ): Element | Text | null {
	deprecated( 'wp.element.findDOMNode', {
		since: '7.1',
		alternative: 'DOM refs',
		link: 'https://react.dev/reference/react-dom/findDOMNode',
	} );

	if ( instance === null || instance === undefined ) {
		return null;
	}

	if ( instance.nodeType !== undefined ) {
		return instance as Element | Text;
	}

	const fiber = instance[ internalsKey ];
	if ( fiber === undefined ) {
		if ( typeof instance.render === 'function' ) {
			throw new Error( 'Unable to find node on an unmounted component.' );
		}
		const keys = Object.keys( instance ).join( ',' );
		throw new Error(
			`Argument appears to not be a ReactComponent. Keys: ${ keys }`
		);
	}

	const hostFiber = findHostFiber( fiber );
	return hostFiber?.stateNode ?? null;
}