import { Cache } from './Cache'
import { Collection } from '../collection/Collection'

/**
 * Base interface for an item stored in a memory cache.
 */
export interface InMemCacheItem {
    key: string,
    item: string,
}

/**
 * A cache implementation stored in memory.
 * @extends Cache
 */
export class InMemCache extends Cache {
    /**
     * The stored cache items.
     * @type Collection<InMemCacheItem>
     */
    protected items: Collection<InMemCacheItem> = new Collection<InMemCacheItem>()

    public async fetch(key: string): Promise<string | undefined> {
        const item = this.items.firstWhere('key', '=', key)
        if ( item ) {
            return item.item
        }
    }

    public async put(key: string, item: string): Promise<void> {
        const existing = this.items.firstWhere('key', '=', key)
        if ( existing ) {
            existing.item = item
        } else {
            this.items.push({ key,
                item })
        }
    }

    public async has(key: string): Promise<boolean> {
        return this.items.where('key', '=', key).length > 0
    }

    public async drop(key: string): Promise<void> {
        this.items = this.items.whereNot('key', '=', key)
    }
}