import {Collection} from "@extollo/util"
import {Cache} from "./Cache"

/**
 * An in-memory implementation of the Cache.
 * This is the default implementation for compatibility, but applications should switch to a persistent-backed cache driver.
 */
export class MemoryCache extends Cache {
    /** Static collection of in-memory cache items. */
    private static cacheItems: Collection<{key: string, value: string, expires?: Date}> = new Collection<{key: string; value: string, expires?: Date}>()

    public fetch(key: string): string | Promise<string | undefined> | undefined {
        const now = new Date()
        return MemoryCache.cacheItems
            .where('key', '=', key)
            .firstWhere(item => {
                return !item.expires || now < item.expires
            })?.value
    }

    public put(key: string, value: string, expires?: Date): void | Promise<void> {
        const existing = MemoryCache.cacheItems.firstWhere('key', '=', key)
        if ( existing ) {
            existing.value = value
            existing.expires = expires
        } else {
            MemoryCache.cacheItems.push({ key, value, expires })
        }
    }

    public has(key: string): boolean | Promise<boolean> {
        const now = new Date()
        return !!MemoryCache.cacheItems
            .where('key', '=', key)
            .firstWhere(item => {
                return !item.expires || now < item.expires
            })
    }

    public drop(key: string): void | Promise<void> {
        MemoryCache.cacheItems = MemoryCache.cacheItems.where('key', '!=', key)
    }
}