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

// Licensed under the MIT License.

import { cloneDeep } from 'lodash';

import { getGlobalPersistentStore, IPersistentStore } from '../common/externalDependencies';

import { PythonEnvInfo } from './info';

import { areSameEnv } from './info/env';

/**

* Represents the environment info cache to be used by the cache locator.

*/

export interface IEnvsCache {

/**

* Initialization logic to be done outside of the constructor, for example reading from persistent storage.

*/

initialize(): void;

/**

* Return all environment info currently in memory for this session.

*

* @return An array of cached environment info, or `undefined` if there are none.

*/

getAllEnvs(): PythonEnvInfo[] | undefined;

/**

* Replace all environment info currently in memory for this session.

*

* @param envs The array of environment info to store in the in-memory cache.

*/

setAllEnvs(envs: PythonEnvInfo[]): void;

/**

* If the cache has been initialized, return environmnent info objects that match a query object.

* If none of the environments in the cache match the query data, return an empty array.

* If the in-memory cache has not been initialized prior to calling `filterEnvs`, return `undefined`.

*

* @param env The environment info data that will be used to look for

* environment info objects in the cache, or a unique environment key.

* If passing an environment info object, it may contain incomplete environment info.

* @return The environment info objects matching the `env` param,

* or `undefined` if the in-memory cache is not initialized.

*/

filterEnvs(env: PythonEnvInfo | string): PythonEnvInfo[] | undefined;

/**

* Writes the content of the in-memory cache to persistent storage.

*/

flush(): Promise<void>;

}

type CompleteEnvInfoFunction = (envInfo: PythonEnvInfo) => boolean;

/**

* Environment info cache using persistent storage to save and retrieve pre-cached env info.

*/

export class PythonEnvInfoCache implements IEnvsCache {

private initialized = false;

private envsList: PythonEnvInfo[] | undefined;

private persistentStorage: IPersistentStore<PythonEnvInfo[]> | undefined;

constructor(private readonly isComplete: CompleteEnvInfoFunction) {}

public initialize(): void {

if (this.initialized) {

return;

}

this.initialized = true;

this.persistentStorage = getGlobalPersistentStore<PythonEnvInfo[]>('PYTHON_ENV_INFO_CACHE');

this.envsList = this.persistentStorage?.get();

}

public getAllEnvs(): PythonEnvInfo[] | undefined {

return cloneDeep(this.envsList);

}

public setAllEnvs(envs: PythonEnvInfo[]): void {

this.envsList = cloneDeep(envs);

}

public filterEnvs(env: PythonEnvInfo | string): PythonEnvInfo[] | undefined {

const result = this.envsList?.filter((info) => areSameEnv(info, env));

if (result) {

return cloneDeep(result);

}

return undefined;

}

public async flush(): Promise<void> {

const completeEnvs = this.envsList?.filter(this.isComplete);

if (completeEnvs?.length) {

await this.persistentStorage?.set(completeEnvs);

}

}

}