tridactyl/src/logging.ts

/**
 * Helper functions for logging
 */

import * as Config from "./config"

export enum LEVEL {
    NEVER = 0,      // don't use this in calls to log()
    ERROR = 1,
    WARNING = 2,
    INFO = 3,
    DEBUG = 4,
}

export class Logger {
    /**
     * Config-aware Logger class.
     *
     * @param logModule     the logging module name: this is ued to look up the
     *                      configured/default level in the user config
     */
    constructor(private logModule) {}

    /**
     * Config-aware logging function.
     *
     * @param level         the level of the logging - if <= configured, the message
     *                      will be shown
     *
     * @return              logging function: this is returned as a function to
     *                      retain the call site
     */
    private log(level: LEVEL) {
        let configedLevel = Config.get("logging", this.logModule) || LEVEL.WARNING

        if (level <= configedLevel) {
            // hand over to console.log, error or debug as needed
            switch (level) {

                case LEVEL.ERROR:
                    return console.error
                case LEVEL.WARNING:
                    return console.warn
                case LEVEL.INFO:
                    return console.log
                case LEVEL.DEBUG:
                    return console.debug
            }
        }

        // do nothing with the message
        return function(...args) {}
    }

    // These are all getters so that logger.debug = console.debug and
    // logger.debug('blah') translates into console.debug('blah') with the
    // filename and line correct.
    public get debug() {
        return this.log(LEVEL.DEBUG)
    }
    public get info() {
        return this.log(LEVEL.INFO)
    }
    public get warning() {
        return this.log(LEVEL.WARNING)
    }
    public get error() {
        return this.log(LEVEL.ERROR)
    }
}

export default Logger