/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the Source EULA. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import { IUserDataSyncService, SyncStatus, ISynchroniser, IUserDataSyncStoreService, SyncSource } from 'vs/platform/userDataSync/common/userDataSync';
import { Disposable } from 'vs/base/common/lifecycle';
import { IInstantiationService } from 'vs/platform/instantiation/common/instantiation';
import { SettingsSynchroniser } from 'vs/platform/userDataSync/common/settingsSync';
import { Emitter, Event } from 'vs/base/common/event';
import { IConfigurationService } from 'vs/platform/configuration/common/configuration';
import { timeout } from 'vs/base/common/async';

export class UserDataSyncService extends Disposable implements IUserDataSyncService {

	_serviceBrand: any;

	private readonly synchronisers: ISynchroniser[];

	private _status: SyncStatus = SyncStatus.Uninitialized;
	get status(): SyncStatus { return this._status; }
	private _onDidChangeStatus: Emitter<SyncStatus> = this._register(new Emitter<SyncStatus>());
	readonly onDidChangeStatus: Event<SyncStatus> = this._onDidChangeStatus.event;

	readonly onDidChangeLocal: Event<void>;

	private _conflictsSource: SyncSource | null = null;
	get conflictsSource(): SyncSource | null { return this._conflictsSource; }

	constructor(
		@IUserDataSyncStoreService private readonly userDataSyncStoreService: IUserDataSyncStoreService,
		@IInstantiationService private readonly instantiationService: IInstantiationService,
	) {
		super();
		this.synchronisers = [
			this.instantiationService.createInstance(SettingsSynchroniser)
		];
		this.updateStatus();
		this._register(Event.any(...this.synchronisers.map(s => Event.map(s.onDidChangeStatus, () => undefined)))(() => this.updateStatus()));
		this.onDidChangeLocal = Event.any(...this.synchronisers.map(s => s.onDidChangeLocal));
	}

	async sync(_continue?: boolean): Promise<boolean> {
		if (!this.userDataSyncStoreService.enabled) {
			throw new Error('Not enabled');
		}
		for (const synchroniser of this.synchronisers) {
			if (!await synchroniser.sync(_continue)) {
				return false;
			}
		}
		return true;
	}

	private updateStatus(): void {
		this._conflictsSource = this.computeConflictsSource();
		this.setStatus(this.computeStatus());
	}

	private setStatus(status: SyncStatus): void {
		if (this._status !== status) {
			this._status = status;
			this._onDidChangeStatus.fire(status);
		}
	}

	private computeStatus(): SyncStatus {
		if (!this.userDataSyncStoreService.enabled) {
			return SyncStatus.Uninitialized;
		}
		if (this.synchronisers.some(s => s.status === SyncStatus.HasConflicts)) {
			return SyncStatus.HasConflicts;
		}
		if (this.synchronisers.some(s => s.status === SyncStatus.Syncing)) {
			return SyncStatus.Syncing;
		}
		return SyncStatus.Idle;
	}

	private computeConflictsSource(): SyncSource | null {
		const source = this.synchronisers.filter(s => s.status === SyncStatus.HasConflicts)[0];
		if (source) {
			if (source instanceof SettingsSynchroniser) {
				return SyncSource.Settings;
			}
		}
		return null;
	}

}

export class UserDataAutoSync extends Disposable {

	constructor(
		@IConfigurationService private readonly configurationService: IConfigurationService,
		@IUserDataSyncService private readonly userDataSyncService: IUserDataSyncService,
		@IUserDataSyncStoreService userDataSyncStoreService: IUserDataSyncStoreService,
	) {
		super();
		if (userDataSyncStoreService.enabled) {
			this.sync(true);
			this._register(Event.filter(this.configurationService.onDidChangeConfiguration, e => e.affectsConfiguration('userConfiguration.enableSync'))(() => this.sync(true)));

			// Sync immediately if there is a local change.
			this._register(Event.debounce(this.userDataSyncService.onDidChangeLocal, () => undefined, 500)(() => this.sync(false)));
		}
	}

	private async sync(loop: boolean): Promise<void> {
		if (this.isSyncEnabled()) {
			try {
				await this.userDataSyncService.sync();
			} catch (e) {
				// Ignore errors
			}
			if (loop) {
				await timeout(1000 * 5); // Loop sync for every 5s.
				this.sync(loop);
			}
		}
	}

	private isSyncEnabled(): boolean {
		const { user: userLocal } = this.configurationService.inspect<boolean>('userConfiguration.enableSync');
		return userLocal === undefined || userLocal;
	}

}