// Copyright (c) Microsoft Corporation. All rights reserved.

// Licensed under the MIT License.

'use strict';

const globalCacheStore = new Map<string, { expiry: number; data: any }>();

/**

* Gets a cache store to be used to store return values of methods or any other.

*

* @returns

*/

export function getGlobalCacheStore() {

return globalCacheStore;

}

export function getCacheKeyFromFunctionArgs(keyPrefix: string, fnArgs: any[]): string {

const argsKey = fnArgs.map((arg) => `${JSON.stringify(arg)}`).join('-Arg-Separator-');

return `KeyPrefix=${keyPrefix}-Args=${argsKey}`;

}

export function clearCache() {

globalCacheStore.clear();

}

type CacheData<T> = {

value: T;

expiry: number;

};

/**

* InMemoryCache caches a single value up until its expiry.

*/

export class InMemoryCache<T> {

private cacheData?: CacheData<T>;

constructor(protected readonly expiryDurationMs: number) {}

public get hasData() {

if (!this.cacheData || this.hasExpired(this.cacheData.expiry)) {

this.cacheData = undefined;

return false;

}

return true;

}

/**

* Returns undefined if there is no data.

* Uses `hasData` to determine whether any cached data exists.

*

* @readonly

* @type {(T | undefined)}

* @memberof InMemoryCache

*/

public get data(): T | undefined {

if (!this.hasData) {

return;

}

return this.cacheData?.value;

}

public set data(value: T | undefined) {

if (value !== undefined) {

this.cacheData = {

expiry: this.calculateExpiry(),

value,

};

} else {

this.cacheData = undefined;

}

}

public clear() {

this.cacheData = undefined;

}

/**

* Has this data expired?

* (protected class member to allow for reliable non-data-time-based testing)

*

* @param expiry The date to be tested for expiry.

* @returns true if the data expired, false otherwise.

*/

protected hasExpired(expiry: number): boolean {

return expiry <= Date.now();

}

/**

* When should this data item expire?

* (protected class method to allow for reliable non-data-time-based testing)

*

* @returns number representing the expiry time for this item.

*/

protected calculateExpiry(): number {

return Date.now() + this.expiryDurationMs;

}

}