/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/
'use strict';

import { LanguageServiceDefaultsImpl } from './monaco.contribution';
import { TypeScriptWorker } from './tsWorker';

import IDisposable = monaco.IDisposable;
import Uri = monaco.Uri;

export class WorkerManager {

	private _modeId: string;
	private _defaults: LanguageServiceDefaultsImpl;
	private _idleCheckInterval: number;
	private _lastUsedTime: number;
	private _configChangeListener: IDisposable;
	private _updateExtraLibsToken: number;
	private _extraLibsChangeListener: IDisposable;

	private _worker: monaco.editor.MonacoWebWorker<TypeScriptWorker> | null;
	private _client: Promise<TypeScriptWorker> | null;

	constructor(modeId: string, defaults: LanguageServiceDefaultsImpl) {
		this._modeId = modeId;
		this._defaults = defaults;
		this._worker = null;
		this._client = null;
		this._idleCheckInterval = setInterval(() => this._checkIfIdle(), 30 * 1000);
		this._lastUsedTime = 0;
		this._configChangeListener = this._defaults.onDidChange(() => this._stopWorker());
		this._updateExtraLibsToken = 0;
		this._extraLibsChangeListener = this._defaults.onDidExtraLibsChange(() => this._updateExtraLibs());
	}

	private _stopWorker(): void {
		if (this._worker) {
			this._worker.dispose();
			this._worker = null;
		}
		this._client = null;
	}

	dispose(): void {
		clearInterval(this._idleCheckInterval);
		this._configChangeListener.dispose();
		this._extraLibsChangeListener.dispose();
		this._stopWorker();
	}

	private async _updateExtraLibs(): Promise<void> {
		if (!this._worker) {
			return;
		}
		const myToken = ++this._updateExtraLibsToken;
		const proxy = await this._worker.getProxy();
		if (this._updateExtraLibsToken !== myToken) {
			// avoid multiple calls
			return;
		}
		proxy.updateExtraLibs(this._defaults.getExtraLibs());
	}

	private _checkIfIdle(): void {
		if (!this._worker) {
			return;
		}
		const maxIdleTime = this._defaults.getWorkerMaxIdleTime();
		const timePassedSinceLastUsed = Date.now() - this._lastUsedTime;
		if (maxIdleTime > 0 && timePassedSinceLastUsed > maxIdleTime) {
			this._stopWorker();
		}
	}

	private _getClient(): Promise<TypeScriptWorker> {
		this._lastUsedTime = Date.now();

		if (!this._client) {
			this._worker = monaco.editor.createWebWorker<TypeScriptWorker>({

				// module that exports the create() method and returns a `TypeScriptWorker` instance
				moduleId: 'vs/language/typescript/tsWorker',

				label: this._modeId,

				// passed in to the create() method
				createData: {
					compilerOptions: this._defaults.getCompilerOptions(),
					extraLibs: this._defaults.getExtraLibs()
				}
			});

			let p = <Promise<TypeScriptWorker>>this._worker.getProxy();

			if (this._defaults.getEagerModelSync()) {
				p = p.then(worker => {
					if (this._worker) {
						return this._worker.withSyncedResources(monaco.editor.getModels()
							.filter(model => model.getModeId() === this._modeId)
							.map(model => model.uri)
						);
					}
					return worker;
				});
			}

			this._client = p;
		}

		return this._client;
	}

	getLanguageServiceWorker(...resources: Uri[]): Promise<TypeScriptWorker> {
		let _client: TypeScriptWorker;
		return this._getClient().then((client) => {
			_client = client
		}).then(_ => {
			if (this._worker) {
				return this._worker.withSyncedResources(resources)
			}
		}).then(_ => _client);
	}
}