import NoteResource from '../models/NoteResource';
import BaseModel from '../BaseModel';
import BaseService from './BaseService';
import Setting from '../models/Setting';
import shim from '../shim';
import ItemChange from '../models/ItemChange';
import Note from '../models/Note';
import Resource from '../models/Resource';
import SearchEngine from './search/SearchEngine';
import ItemChangeUtils from './ItemChangeUtils';
import time from '../time';
import eventManager, { EventName } from '../eventManager';
const { sprintf } = require('sprintf-js');

export default class ResourceService extends BaseService {

	public static isRunningInBackground_ = false;
	private isIndexing_ = false;

	private maintenanceCalls_: boolean[] = [];
	private maintenanceTimer1_: any = null;
	private maintenanceTimer2_: any = null;

	public async indexNoteResources() {
		this.logger().info('ResourceService::indexNoteResources: Start');

		if (this.isIndexing_) {
			this.logger().info('ResourceService::indexNoteResources: Already indexing - waiting for it to finish');
			await time.waitTillCondition(() => !this.isIndexing_);
			return;
		}

		this.isIndexing_ = true;

		try {
			await ItemChange.waitForAllSaved();

			let foundNoteWithEncryption = false;

			while (true) {
				const changes = await ItemChange.modelSelectAll(`
					SELECT id, item_id, type
					FROM item_changes
					WHERE item_type = ?
					AND id > ?
					ORDER BY id ASC
					LIMIT 10
					`, [BaseModel.TYPE_NOTE, Setting.value('resourceService.lastProcessedChangeId')],
				);

				if (!changes.length) break;

				const noteIds = changes.map((a: any) => a.item_id);
				const notes = await Note.modelSelectAll(`SELECT id, title, body, encryption_applied FROM notes WHERE id IN ("${noteIds.join('","')}")`);

				const noteById = (noteId: string) => {
					for (let i = 0; i < notes.length; i++) {
						if (notes[i].id === noteId) return notes[i];
					}
					// The note may have been deleted since the change was recorded. For example in this case:
					// - Note created (Some Change object is recorded)
					// - Note is deleted
					// - ResourceService indexer runs.
					// In that case, there will be a change for the note, but the note will be gone.
					return null;
				};

				for (let i = 0; i < changes.length; i++) {
					const change = changes[i];

					if (change.type === ItemChange.TYPE_CREATE || change.type === ItemChange.TYPE_UPDATE) {
						const note = noteById(change.item_id);

						if (note) {
							if (note.encryption_applied) {
								// If we hit an encrypted note, abort processing for now.
								// Note will eventually get decrypted and processing can resume then.
								// This is a limitation of the change tracking system - we cannot skip a change
								// and keep processing the rest since we only keep track of "lastProcessedChangeId".
								foundNoteWithEncryption = true;
								break;
							}

							await this.setAssociatedResources(note.id, note.body);
						} else {
							this.logger().warn(`ResourceService::indexNoteResources: A change was recorded for a note that has been deleted: ${change.item_id}`);
						}
					} else if (change.type === ItemChange.TYPE_DELETE) {
						await NoteResource.remove(change.item_id);
					} else {
						throw new Error(`Invalid change type: ${change.type}`);
					}

					Setting.setValue('resourceService.lastProcessedChangeId', change.id);
				}

				if (foundNoteWithEncryption) break;
			}

			await Setting.saveAll();

			await NoteResource.addOrphanedResources();

			await ItemChangeUtils.deleteProcessedChanges();
		} catch (error) {
			this.logger().error('ResourceService::indexNoteResources:', error);
		}

		this.isIndexing_ = false;

		eventManager.emit(EventName.NoteResourceIndexed);

		this.logger().info('ResourceService::indexNoteResources: Completed');
	}

	public async setAssociatedResources(noteId: string, noteBody: string) {
		const resourceIds = await Note.linkedResourceIds(noteBody);
		await NoteResource.setAssociatedResources(noteId, resourceIds);
	}

	public async deleteOrphanResources(expiryDelay: number = null) {
		if (expiryDelay === null) expiryDelay = Setting.value('revisionService.ttlDays') * 24 * 60 * 60 * 1000;
		const resourceIds = await NoteResource.orphanResources(expiryDelay);
		this.logger().info('ResourceService::deleteOrphanResources:', resourceIds);
		for (let i = 0; i < resourceIds.length; i++) {
			const resourceId = resourceIds[i];
			const results = await SearchEngine.instance().search(resourceId);
			if (results.length) {
				const note = await Note.load(results[0].id);
				if (note) {
					this.logger().info(sprintf('ResourceService::deleteOrphanResources: Skipping deletion of resource %s because it is still referenced in note %s. Re-indexing note content to fix the issue.', resourceId, note.id));
					await this.setAssociatedResources(note.id, note.body);
				}
			} else {
				await Resource.delete(resourceId);
			}
		}
	}

	private static async autoSetFileSize(resourceId: string, filePath: string, waitTillExists = true) {
		const itDoes = await shim.fsDriver().waitTillExists(filePath, waitTillExists ? 10000 : 0);
		if (!itDoes) {
			// this.logger().warn('Trying to set file size on non-existent resource:', resourceId, filePath);
			return;
		}
		const fileStat = await shim.fsDriver().stat(filePath);
		await Resource.setFileSizeOnly(resourceId, fileStat.size);
	}

	public static async autoSetFileSizes() {
		const resources = await Resource.needFileSizeSet();

		for (const r of resources) {
			await this.autoSetFileSize(r.id, Resource.fullPath(r), false);
		}
	}

	public async maintenance() {
		this.maintenanceCalls_.push(true);
		try {
			await this.indexNoteResources();
			await this.deleteOrphanResources();
		} finally {
			this.maintenanceCalls_.pop();
		}
	}

	public static runInBackground() {
		if (this.isRunningInBackground_) return;

		this.isRunningInBackground_ = true;
		const service = this.instance();

		service.maintenanceTimer1_ = shim.setTimeout(() => {
			void service.maintenance();
		}, 1000 * 30);

		service.maintenanceTimer2_ = shim.setInterval(() => {
			void service.maintenance();
		}, 1000 * 60 * 60 * 4);
	}

	public async cancelTimers() {
		if (this.maintenanceTimer1_) {
			shim.clearTimeout(this.maintenanceTimer1_);
			this.maintenanceTimer1_ = null;
		}
		if (this.maintenanceTimer2_) {
			shim.clearInterval(this.maintenanceTimer2_);
			this.maintenanceTimer2_ = null;
		}

		return new Promise((resolve) => {
			const iid = shim.setInterval(() => {
				if (!this.maintenanceCalls_.length) {
					shim.clearInterval(iid);
					resolve(null);
				}
			}, 100);
		});
	}

	public static instance_: ResourceService = null;

	public static instance() {
		if (this.instance_) return this.instance_;
		this.instance_ = new ResourceService();
		return this.instance_;
	}

}