const MINUTE = 1000 * 60;
const DEFAULT_TTL = 5 * MINUTE;

export interface TtlCacheOptions {
    ttlMs?: number;
}

export class TtlCache<T = any> {
    private readonly data: Map<string, T>;
    private readonly timers: Map<string, ReturnType<typeof setTimeout>>;
    private readonly ttl: number;

    constructor({ ttlMs = DEFAULT_TTL }: TtlCacheOptions = {}) {
        if (ttlMs < 0) {
            throw new Error('default TTL must be zero or greater');
        }

        this.data = new Map();
        this.timers = new Map();
        this.ttl = ttlMs;
    }

    set(key: string, value: T, ttl?: number) {
        this.setTimeout(key, ttl ?? this.ttl);
        this.data.set(key, value);
    }

    get(key: string) {
        return this.data.get(key);
    }

    has(key: string) {
        return this.data.has(key);
    }

    delete(key: string) {
        this.cancelTimeout(key);
        this.data.delete(key);
    }

    clear() {
        this.data.clear();
        this.timers.forEach(value => clearTimeout(value));
        this.timers.clear();
    }

    private cancelTimeout(key: string) {
        const id = this.timers.get(key);
        if (id) {
            clearTimeout(id);
            this.timers.delete(key);
        }
    }

    private setTimeout(key: string, ttl: number) {
        this.cancelTimeout(key);
        if (ttl < 0) {
            return;
        }

        const id = setTimeout(() => this.delete(key), ttl);
        this.timers.set(key, id);
    }
}