Log formatter

log-formatter.js

#!/usr/bin/env node

const EventEmitter = require("events");

const stdin = new EventEmitter();
stdin.on("line", console.error);


let buff = "";

process.stdin.resume();


process.once("SIGINT", function () {

  if (buff.length > 0) {
    processLines([buff]);
  };

  process.on("SIGINT", function () {
    process.exit(0);
  });
});


process.stdin
  .on("data", function (data) {

    buff += data;
    let lines = buff.split(/\r\n|\n/);

    // Remove trailing newline
    buff = lines.pop();

    processLines(lines);
  })
  .on("end", function () {
    if (buff.length > 0) {
      processLines([buff]);
    };
  });


function processLines(lines) {
  lines.map(formatToJSON).filter(logFilter).map(customFormatter).forEach(function (line) {
    stdin.emit("line", line);
  });
}


function formatToJSON(line) {
  try {
    return JSON.parse(line);
  }
  catch (err) {
    //console.error(">", err);
    //console.error(">", line);
    return line;
  }
}


function logFilter(log) {
  let filterEnabled = true;

  //  Accept all logs if no custom log filter is enabled
  return (filterEnabled ? customLogFilter(log) : true);
}


//
// @todo Load from somewhere else
//
function customLogFilter(log) {
  if (true) {
    return true;
  }

  if (typeof log !== "object") {
    return false;
  }
  //console.log("FILTER", log);
  if (log.one === "first") {
    return true;
  }

  return false;
}


function customFormatter(x) {
  if (false) {
    return `[${x.time}]`;
  }

  return x;
}