import { coursePlayer } from './player.svelte.js';
import { scormState } from '$core/scorm/index.js';
import { course } from '../../course.js';
import type { CourseSlide } from './types.js';

function countCompleted(slides: CourseSlide[]): number {
	return slides.filter((s) => scormState.store.isSlideCompleted(s.lessonId, s.id)).length;
}

const PERCENT_MAX = 100;
const TICK_INTERVAL_MS = 1000;

type PlayerBuiltinsAccessors = {
	getSlideEnterTime: () => number;
};

export class PlayerBuiltins {
	readonly #accessors: PlayerBuiltinsAccessors;
	#now = $state(Date.now());
	#intervalId: ReturnType<typeof setInterval> | undefined;

	constructor(accessors: PlayerBuiltinsAccessors) {
		this.#accessors = accessors;
	}

	#lessonSlides(lessonId: string): CourseSlide[] {
		return coursePlayer.slides.filter((s) => s.lessonId === lessonId);
	}

	#lessonIndex(lessonId: string): number {
		return course.lessons.findIndex((l) => l.id === lessonId);
	}

	get course() {
		const active = coursePlayer.activeSlide;
		const total = coursePlayer.slides.length;
		const completed = countCompleted(coursePlayer.slides);
		const lessonIndex = active ? this.#lessonIndex(active.lessonId) : -1;
		return {
			slideNumber: active ? active.index + 1 : 0,
			totalSlides: total,
			slidesCompleted: completed,
			progress: total > 0 ? Math.round((completed / total) * PERCENT_MAX) : 0,
			lessonNumber: lessonIndex + 1,
			totalLessons: course.lessons.length
		};
	}

	get lesson() {
		const active = coursePlayer.activeSlide;
		if (!active)
			return {
				title: '',
				slideNumber: 0,
				totalSlides: 0,
				slidesCompleted: 0,
				progress: 0
			};
		const slides = this.#lessonSlides(active.lessonId);
		const completed = countCompleted(slides);
		return {
			id: active.lessonId,
			title: active.lessonTitle,
			slideNumber: slides.findIndex((s) => s.pathname === active.pathname) + 1,
			totalSlides: slides.length,
			slidesCompleted: completed,
			progress: slides.length > 0 ? Math.round((completed / slides.length) * PERCENT_MAX) : 0
		};
	}

	get slide() {
		const active = coursePlayer.activeSlide;
		return {
			id: active?.id ?? '',
			title: active?.title ?? '',
			elapsedMs: active ? this.#now - this.#accessors.getSlideEnterTime() : 0
		};
	}

	get session() {
		return { elapsedMs: this.#now - scormState.sessionStartTime };
	}

	startTicking(): void {
		this.#intervalId = setInterval(() => {
			this.#now = Date.now();
		}, TICK_INTERVAL_MS);
	}

	stopTicking(): void {
		clearInterval(this.#intervalId);
		this.#intervalId = undefined;
	}
}