import type { Scorm12API, Scorm2004API } from './types.js';

const MAX_SEARCH_DEPTH = 10;

type WindowRecord = Record<string, unknown>;

function isScorm12API(value: unknown): value is Scorm12API {
	return (
		typeof value === 'object' &&
		value !== null &&
		'LMSInitialize' in value &&
		'LMSGetValue' in value &&
		'LMSSetValue' in value
	);
}

function isScorm2004API(value: unknown): value is Scorm2004API {
	return (
		typeof value === 'object' &&
		value !== null &&
		'Initialize' in value &&
		'GetValue' in value &&
		'SetValue' in value
	);
}

function readScorm12Candidate(targetWindow: Window): unknown {
	return (targetWindow as unknown as WindowRecord).API;
}

function readScorm2004Candidate(targetWindow: Window): unknown {
	return (targetWindow as unknown as WindowRecord).API_1484_11;
}

type CandidateReader = (targetWindow: Window) => unknown;

function traverseParents(
	startWindow: Window,
	read: CandidateReader,
	test: (candidate: unknown) => boolean
): unknown {
	let currentWindow = startWindow;
	let depth = 0;

	while (depth < MAX_SEARCH_DEPTH) {
		try {
			const candidate = read(currentWindow);
			if (test(candidate)) return candidate;
		} catch {
			break;
		}

		if (currentWindow.parent === currentWindow) break;
		currentWindow = currentWindow.parent;
		depth++;
	}

	return undefined;
}

function findAPI(read: CandidateReader, test: (candidate: unknown) => boolean): unknown {
	const rootWindow = globalThis as unknown as Window;

	const fromParents = traverseParents(rootWindow, read, test);
	if (fromParents !== undefined) return fromParents;

	try {
		const openerWindow = rootWindow.opener as Window | null;
		if (openerWindow !== null && openerWindow !== undefined) {
			return traverseParents(openerWindow, read, test);
		}
	} catch {
		return undefined;
	}

	return undefined;
}

export function findScorm12API(): Scorm12API | undefined {
	const result = findAPI(readScorm12Candidate, isScorm12API);
	return isScorm12API(result) ? result : undefined;
}

export function findScorm2004API(): Scorm2004API | undefined {
	const result = findAPI(readScorm2004Candidate, isScorm2004API);
	return isScorm2004API(result) ? result : undefined;
}