export interface QuickLink {
	id: string;
	score: number;
	lastAccessed: number;
}

const RETURNED_LENGTH: number = 6;
const MAX_SCORE: number = 50;
const MAX_ENTRIES: number = RETURNED_LENGTH * 4;

class QuickLinksService {
	#links = $state<QuickLink[]>([]);

	constructor() {
		if (typeof window !== 'undefined') {
			const saved = localStorage.getItem('ql');
			if (saved) {
				try {
					this.#links = JSON.parse(saved);
				} catch {
					this.#links = [];
				}
			}
		}
	}

	get list(): QuickLink[] {
		return this.#links.slice(0, RETURNED_LENGTH);
	}

	recordVisit(id: string) {
		if (id == '') return;
		const existing = this.#links.find((l) => l.id === id);

		if (existing) {
			existing.score += 1;
			existing.lastAccessed = Date.now();
		} else {
			this.#links.push({
				id: id,
				score: 1,
				lastAccessed: Date.now()
			});
		}

		// Score decay - if MAX_SCORE reached, divide all by two
		if (this.#links.some((l) => l.score > MAX_SCORE)) {
			this.#links.forEach((l) => {
				l.score = Math.max(1, Math.floor(l.score / 2));
			});
		}

		// Sort & Prune
		const sorted = [...this.#links].sort(
			(a, b) => b.score - a.score || b.lastAccessed - a.lastAccessed
		);

		this.#links = sorted.slice(0, MAX_ENTRIES);

		if (typeof window !== 'undefined') {
			localStorage.setItem('ql', JSON.stringify(this.#links));
		}
	}

	reset() {
		this.#links = [];
		if (typeof window !== 'undefined') {
			localStorage.removeItem('ql');
		}
	}
}

export const quickLinks = new QuickLinksService();