/*---------------------------------------------------------------------------------------------
 *  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 { Event, Emitter } from 'vs/base/common/event';
import { Throttler, timeout } from 'vs/base/common/async';
import { IConfigurationService } from 'vs/platform/configuration/common/configuration';
import { ILifecycleService } from 'vs/platform/lifecycle/electron-main/lifecycleMain';
import product from 'vs/platform/node/product';
import { TPromise } from 'vs/base/common/winjs.base';
import { IUpdateService, State, StateType, AvailableForDownload, UpdateType } from 'vs/platform/update/common/update';
import { IEnvironmentService } from 'vs/platform/environment/common/environment';
import { ILogService } from 'vs/platform/log/common/log';
import { IRequestService } from 'vs/platform/request/node/request';
import { CancellationToken } from 'vs/base/common/cancellation';

export function createUpdateURL(platform: string, quality: string): string {
	return `${product.updateUrl}/api/update/${platform}/${quality}/${product.commit}`;
}

export abstract class AbstractUpdateService implements IUpdateService {

	_serviceBrand: any;

	protected readonly url: string | undefined;

	private _state: State = State.Uninitialized;
	private throttler: Throttler = new Throttler();

	private _onStateChange = new Emitter<State>();
	get onStateChange(): Event<State> { return this._onStateChange.event; }

	get state(): State {
		return this._state;
	}

	protected setState(state: State): void {
		this.logService.info('update#setState', state.type);
		this._state = state;
		this._onStateChange.fire(state);
	}

	constructor(
		@ILifecycleService private lifecycleService: ILifecycleService,
		@IConfigurationService protected configurationService: IConfigurationService,
		@IEnvironmentService private environmentService: IEnvironmentService,
		@IRequestService protected requestService: IRequestService,
		@ILogService protected logService: ILogService,
	) {
		if (this.environmentService.disableUpdates) {
			this.logService.info('update#ctor - updates are disabled');
			return;
		}

		if (!product.updateUrl || !product.commit) {
			this.logService.info('update#ctor - updates are disabled');
			return;
		}

		const quality = this.getProductQuality();

		if (!quality) {
			this.logService.info('update#ctor - updates are disabled');
			return;
		}

		this.url = this.buildUpdateFeedUrl(quality);
		if (!this.url) {
			this.logService.info('update#ctor - updates are disabled');
			return;
		}

		this.setState(State.Idle(this.getUpdateType()));

		// Start checking for updates after 30 seconds
		this.scheduleCheckForUpdates(30 * 1000).then(null, err => this.logService.error(err));
	}

	private getProductQuality(): string {
		const quality = this.configurationService.getValue<string>('update.channel');
		return quality === 'none' ? null : product.quality;
	}

	private scheduleCheckForUpdates(delay = 60 * 60 * 1000): Thenable<void> {
		return timeout(delay)
			.then(() => this.checkForUpdates(null))
			.then(update => {
				// TODO: TS 3.1 upgrade. Why are we checking against void?
				if (update as any) {
					// Update found, no need to check more
					return TPromise.as(null);
				}

				// Check again after 1 hour
				return this.scheduleCheckForUpdates(60 * 60 * 1000);
			});
	}

	checkForUpdates(context: any): TPromise<void> {
		this.logService.trace('update#checkForUpdates, state = ', this.state.type);

		if (this.state.type !== StateType.Idle) {
			return TPromise.as(null);
		}

		return this.throttler.queue(() => TPromise.as(this.doCheckForUpdates(context)));
	}

	downloadUpdate(): TPromise<void> {
		this.logService.trace('update#downloadUpdate, state = ', this.state.type);

		if (this.state.type !== StateType.AvailableForDownload) {
			return TPromise.as(null);
		}

		return this.doDownloadUpdate(this.state);
	}

	protected doDownloadUpdate(state: AvailableForDownload): TPromise<void> {
		return TPromise.as(null);
	}

	applyUpdate(): TPromise<void> {
		this.logService.trace('update#applyUpdate, state = ', this.state.type);

		if (this.state.type !== StateType.Downloaded) {
			return TPromise.as(null);
		}

		return this.doApplyUpdate();
	}

	protected doApplyUpdate(): TPromise<void> {
		return TPromise.as(null);
	}

	quitAndInstall(): TPromise<void> {
		this.logService.trace('update#quitAndInstall, state = ', this.state.type);

		if (this.state.type !== StateType.Ready) {
			return TPromise.as(null);
		}

		this.logService.trace('update#quitAndInstall(): before lifecycle quit()');

		this.lifecycleService.quit(true /* from update */).then(vetod => {
			this.logService.trace(`update#quitAndInstall(): after lifecycle quit() with veto: ${vetod}`);
			if (vetod) {
				return;
			}

			this.logService.trace('update#quitAndInstall(): running raw#quitAndInstall()');
			this.doQuitAndInstall();
		});

		return TPromise.as(null);
	}

	isLatestVersion(): TPromise<boolean | undefined> {
		if (!this.url) {
			return TPromise.as(undefined);
		}
		return this.requestService.request({ url: this.url }, CancellationToken.None).then(context => {
			// The update server replies with 204 (No Content) when no
			// update is available - that's all we want to know.
			if (context.res.statusCode === 204) {
				return true;
			} else {
				return false;
			}
		});
	}

	protected getUpdateType(): UpdateType {
		return UpdateType.Archive;
	}

	protected doQuitAndInstall(): void {
		// noop
	}

	protected abstract buildUpdateFeedUrl(quality: string): string | undefined;
	protected abstract doCheckForUpdates(context: any): void;
}