nope/lib/logger/fileLogging.ts

/**
 * @author Martin Karkowski
 * @email m.karkowski@zema.de
 * @create date 2021-05-21 16:44:59
 * @modify date 2021-07-29 16:06:13
 * @desc [description]
 */

import { writeFile } from "fs";
import { join } from "path";
import { createFile } from "../helpers/fileMethods";
import { replaceAll } from "../helpers/stringMethods";
import { getCentralNopeLogger, getNopeLogger } from "./getLogger";

export const CURRENT_DATE = _parsableISOString();
export const DEFAULT_LOG_LOCATION = join(process.cwd(), "logs");
const DEFAULT_FILE = join(DEFAULT_LOG_LOCATION, CURRENT_DATE + ".log");

function _parsableISOString(date = new Date()) {
  let isoString = date.toISOString();
  isoString = replaceAll(isoString, ":", "-");
  isoString = replaceAll(isoString, ".", "-");
  return isoString;
}

/**
 * Generates a Log-File Path based on the given name with the following format:
 * /logs/{name}_{date}.log
 *
 * @export
 * @param {string} name Name of the File.
 * @return {*}  {string}
 */
export function generateLogfilePath(name: string): string {
  return join(DEFAULT_LOG_LOCATION, name + "_" + _parsableISOString() + ".log");
}

/**
 * Function to use a log file instead of the console log.
 *
 * @export
 */
export function useLogFile(pathToFile = DEFAULT_FILE, bufferSize = 100): void {
  const logger = getCentralNopeLogger();

  // Define a function, that will write the content of the Buffer to our
  // file.
  const writeBufferToFile = function (cb: () => void = null) {
    const textToStore = buffer.join("\n");

    readyToWrite = false;

    // Now lets start to write the Fil.e
    writeFile(
      pathToFile,
      textToStore,
      {
        encoding: "utf-8",
        flag: "a"
      },
      (err) => {
        if (err) {
          console.error(err);
        } else {
          readyToWrite = true;

          if (typeof (cb) == "function") {
            cb();
          }
        }
      }
    );

    buffer = [];
  };

  let buffer: string[] = [];
  let readyToWrite = false;

  // Now every thing, is defined, so we are able to
  // define our file.

  const consoleLogger = getNopeLogger("file-logger");

  createFile(pathToFile, "", { encoding: "utf-8" }).then(
    // If our file has been created,
    (_) => {
      readyToWrite = true;

      // Now make shure, that our inital buffer has been written
      if (buffer.length > 0) {
        writeBufferToFile();
      }
    }
  );

  logger.setHandler((msg, context) => {
    if (bufferSize < buffer.length && readyToWrite) {
      // Now if the Data is ready, lets write the
      // buffer to the File.
      writeBufferToFile();
    } else {
      // Else we extend our buffer:
      const logAsString = [
        context.filterLevel.name,
        "-",
        context.name,
        ":",
        Object.values(msg).join(" ")
      ].join(" ");
      buffer.push(logAsString);
    }
  });

  if (bufferSize > 0) {
    const clearBufferAtEnd = function () {
      consoleLogger.info("Shutdown detected! Trying to Write the Buffer");

      if (readyToWrite) {
        // Now if the Data is ready, lets write the
        // buffer to the File.
        writeBufferToFile(() => process.exit(0));
      } else {
        setTimeout(clearBufferAtEnd, 50);
      }
    };

    process.on("SIGINT", clearBufferAtEnd);
    process.on("SIGTERM", clearBufferAtEnd);
  }
}