log.ts

/*!
 * Copyright (c) Microsoft Corporation. All rights reserved.
 * Licensed under the MIT License.
 */

import debug from 'debug';

class Log {

	private loggers: { [area: string]: debug.IDebugger } = {};

	public enable(facility?: string, severity?: string) {
		const area = this.area(facility, severity);
		this.enableArea(area);
	}

	public disable(facility?: string, severity?: string) {
		const area = this.area(facility, severity);
		this.disableArea(area);
	}

	public enabled(facility?: string, severity?: string) {
		const area = this.area(facility, severity);
		return this.areaEnabled(area);
	}

	private logger(facility: string, severity: string): debug.IDebugger {
		return this.loggers[this.area(facility, severity)];
	}

	public debug(facility: string, formatter: any, ...args: any[]) {
		this.log(facility, 'debug', formatter, ...args);
	}

	public warning(facility: string, formatter: any, ...args: any[]) {
		this.log(facility, 'warning', formatter, ...args);
	}

	public error(facility: string, formatter: any, ...args: any[]) {
		this.log(facility, 'error', formatter, ...args);
	}

	public info(facility: string, formatter: any, ...args: any[]) {
		this.log(facility, 'info', formatter, ...args);
	}

	public verbose(facility: string, formatter: any, ...args: any[]) {
		this.log(facility, 'verbose', formatter, ...args);
	}

	public log(facility: string, severity: string, formatter: any, ...args: any[]) {
		this.checkInitialize();
		if (formatter) {
			facility = this.cleanupFacility(facility);
			severity = this.cleanupSeverity(severity);
			const logger = this.logger(null, null) || this.logger(facility, null) || this.logger(facility, severity);
			if (logger) {
				logger(formatter, ...args);
			}
		}
	}

	private area(facility: string, severity: string): string {
		facility = this.cleanupFacility(facility);
		severity = this.cleanupSeverity(severity);
		let area = '';
		if (facility) {
			area = `${facility}`;
		}
		if (severity) {
			area = `${area}:${severity}`;
		}
		return area;
	}

	private enableArea(area: string) {
		if (!this.loggers[area]) {
			this.loggers[area] = debug(area);
			const areas = Object.keys(this.loggers).join(',');
			debug.enable(areas);
		}
	}

	private disableArea(area: string) {
		delete this.loggers[area];
		const areas = Object.keys(this.loggers).join(',');
		debug.enable(areas);
	}

	private areaEnabled(area: string) {
		return !!this.loggers[area];
	}

	private cleanupFacility(facility: string) {
		switch (facility) {
			case '': return null;
			default: return facility;
		}
	}

	private cleanupSeverity(severity: string) {
		switch (severity) {
			case 'success': return 'info';
			case '': return null;
			default: return severity;
		}
	}

	private checkInitialize = () => {
		this.enable('app');
		this.enable('client');
		const logging = process.env.MRE_LOGGING || '';
		if (logging && logging.length) {
			const parts = logging.split(',').map(s => s.trim());
			for (const part of parts) {
				/* eslint-disable-next-line prefer-const */
				let [facility, severity] = part.split(':').map(s => s.trim());
				const disable = facility.startsWith('-');
				facility = facility.replace(/^-/u, '');
				if (disable) {
					this.disable(facility, severity);
				} else {
					this.enable(facility, severity);
				}
			}
		}
		this.checkInitialize = () => { };
	};
}

export const log = new Log();