import async from "async";
import BaseModule from "./BaseModule";
import Job from "./Job";
import JobContext from "./JobContext";
import JobQueue from "./JobQueue";
import LogBook from "./LogBook";
import { JobOptions } from "./types/JobOptions";
import { Jobs, Modules, ModuleStatus, ModuleClass } from "./types/Modules";

export default class ModuleManager {
	private modules?: Modules;

	public logBook: LogBook;

	private jobQueue: JobQueue;

	/**
	 * Module Manager
	 *
	 * @param logBook - Logbook
	 */
	public constructor(logBook: LogBook) {
		this.logBook = logBook;
		this.jobQueue = new JobQueue();
	}

	/**
	 * getStatus - Get status of modules
	 *
	 * @returns Module statuses
	 */
	public getStatus() {
		const status: Record<string, ModuleStatus> = {};
		Object.entries(this.modules || {}).forEach(([name, module]) => {
			status[name] = module.getStatus();
		});
		return status;
	}

	/**
	 * getJobsStats - Get statistics of job queue
	 *
	 * @returns Job queue statistics
	 */
	public getJobsStats() {
		return this.jobQueue.getStats();
	}

	/**
	 * getJobsStatus - Get status of job queue
	 *
	 * @returns Job queue status
	 */
	public getJobsStatus() {
		return this.jobQueue.getStatus();
	}

	/**
	 * getQueueStatus - Get status of queued jobs
	 *
	 * @returns Job statuses
	 */
	public getQueueStatus() {
		return this.jobQueue.getQueueStatus();
	}

	/**
	 * loadModule - Load and initialize module
	 *
	 * @param moduleName - Name of the module
	 * @returns Module
	 */
	private loadModule<T extends keyof Modules>(
		moduleName: T
	): Promise<Modules[T]> {
		return new Promise(resolve => {
			const mapper = {
				stations: "StationModule",
				others: "OtherModule",
				data: "DataModule"
			};
			import(`./modules/${mapper[moduleName]}`).then(
				({ default: Module }: { default: ModuleClass<Modules[T]> }) => {
					const module = new Module(this);
					resolve(module);
				}
			);
		});
	}

	/**
	 * loadModules - Load and initialize all modules
	 *
	 * @returns Promise
	 */
	private loadModules(): Promise<void> {
		return new Promise((resolve, reject) => {
			const fetchModules = async () => ({
				data: await this.loadModule("data"),
				others: await this.loadModule("others"),
				stations: await this.loadModule("stations")
			});
			fetchModules()
				.then(modules => {
					this.modules = modules;
					resolve();
				})
				.catch(err => {
					reject(new Error(err));
				});
		});
	}

	/**
	 * startup - Handle startup
	 */
	public async startup(): Promise<void> {
		await this.loadModules().catch(async err => {
			await this.shutdown();
			throw err;
		});
		if (!this.modules) throw new Error("No modules were loaded");
		await async
			.each(Object.values(this.modules), async module => {
				await module.startup().catch(async err => {
					module.setStatus("ERROR");
					throw err;
				});
			})
			.catch(async err => {
				await this.shutdown();
				throw err;
			});
		this.jobQueue.resume();
	}

	/**
	 * shutdown - Handle shutdown
	 */
	public async shutdown(): Promise<void> {
		// TODO: await jobQueue completion/handle shutdown
		if (this.modules)
			await async.each(Object.values(this.modules), async module => {
				if (
					module.getStatus() === "STARTED" ||
					module.getStatus() === "STARTING" || // TODO: Handle better
					module.getStatus() === "ERROR"
				)
					await module.shutdown();
			});
	}

	/**
	 * runJob - Run a job
	 *
	 * @param moduleName - Module name
	 * @param jobName - Job name
	 * @param params - Params
	 */
	public runJob<
		ModuleNameType extends keyof Jobs & keyof Modules,
		JobNameType extends keyof Jobs[ModuleNameType] &
			keyof Omit<Modules[ModuleNameType], keyof BaseModule>,
		PayloadType extends "payload" extends keyof Jobs[ModuleNameType][JobNameType]
			? Jobs[ModuleNameType][JobNameType]["payload"] extends undefined
				? void
				: Jobs[ModuleNameType][JobNameType]["payload"]
			: void,
		ReturnType = "returns" extends keyof Jobs[ModuleNameType][JobNameType]
			? Jobs[ModuleNameType][JobNameType]["returns"]
			: never
	>(
		moduleName: ModuleNameType,
		jobName: JobNameType,
		payload: PayloadType,
		options?: JobOptions
	): Promise<ReturnType> {
		return new Promise<ReturnType>((resolve, reject) => {
			const module = this.modules && this.modules[moduleName];
			if (!module) reject(new Error("Module not found."));
			else {
				const jobFunction = module[jobName];
				if (!jobFunction || typeof jobFunction !== "function")
					reject(new Error("Job not found."));
				else if (
					Object.prototype.hasOwnProperty.call(BaseModule, jobName)
				)
					reject(new Error("Illegal job function."));
				else {
					const job = new Job(
						jobName.toString(),
						module,
						(job, resolveJob, rejectJob) => {
							const jobContext = new JobContext(
								this,
								this.logBook,
								job
							);
							jobFunction
								.apply(jobContext, [payload])
								.then((response: ReturnType) => {
									this.logBook.log({
										message: "Job completed successfully",
										type: "success",
										category: "jobs",
										data: {
											jobName: job.getName(),
											jobId: job.getUuid()
										}
									});
									resolveJob();
									resolve(response);
								})
								.catch((err: any) => {
									this.logBook.log({
										message: `Job failed with error "${err}"`,
										type: "error",
										category: "jobs",
										data: {
											jobName: job.getName(),
											jobId: job.getUuid()
										}
									});
									rejectJob();
									reject(err);
								});
						},
						{
							priority: (options && options.priority) || 10
						}
					);

					// If a job options.runDirectly is set to true, skip the queue and run a job directly
					if (options && options.runDirectly)
						this.jobQueue.runJob(job);
					else this.jobQueue.add(job);
				}
			}
		});
	}
}