import { scormState } from '$core/scorm/index.js';
import type { SlideObjectiveStatus } from '$core/scorm/persistent-store.svelte.js';
import { coursePlayer } from './player.svelte.js';

function getSlideOrThrow() {
	const slide = coursePlayer.activeSlide;
	if (!slide) {
		throw new Error(
			'useSlideCompletion() must be called inside a component rendered by the course player'
		);
	}
	return slide;
}

function canChangeScore(currentScore: number | undefined, newScore: number): boolean {
	if (typeof newScore !== 'number' || Number.isNaN(newScore) || newScore < 0) {
		console.warn('Invalid score value. Score must be a non-negative number.', {
			newScore
		});
		return false;
	}
	return typeof currentScore === 'number' && newScore < currentScore ? false : true;
}

export type SlideCompletionHandle = {
	readonly status: SlideObjectiveStatus;
	readonly isPassed: boolean;
	readonly isFailed: boolean;
	readonly score: number | undefined;
	markPassed: () => void;
	markFailed: () => void;
	markPassedWithScore: (score: number) => void;
	setScore: (score: number) => boolean;
};

export function useSlideCompletion(): SlideCompletionHandle {
	const slide = getSlideOrThrow();

	const statusObject = $derived.by(() => {
		return {
			status: scormState.store.getSlideStatus(slide.lessonId, slide.id),
			isPassed: scormState.store.isSlideCompleted(slide.lessonId, slide.id),
			isFailed: scormState.store.getSlideStatus(slide.lessonId, slide.id) === 'failed',
			score: scormState.store.getSlideScore(slide.lessonId, slide.id)
		};
	});

	function updateObjective(status: SlideObjectiveStatus, score?: number) {
		scormState.store.updateSlideObjective({
			lessonId: slide.lessonId,
			slideId: slide.id,
			status,
			score
		});
	}

	return {
		get status(): SlideObjectiveStatus {
			return statusObject.status;
		},
		get isPassed(): boolean {
			return statusObject.isPassed;
		},
		get isFailed(): boolean {
			return statusObject.isFailed;
		},
		get score(): number | undefined {
			return statusObject.score;
		},
		setScore(score: number): boolean {
			if (!canChangeScore(statusObject.score, score)) return false;
			updateObjective(statusObject.status, score);
			return true;
		},
		markPassed(): void {
			updateObjective('passed');
		},
		markFailed(): void {
			updateObjective('failed');
		},
		markPassedWithScore(score: number): void {
			updateObjective('passed', score);
		}
	};
}