'use strict';
const Raven = require('raven');
const throttle = require('lodash.throttle');

const listeners = [];

// Zero-pad a number in a string.
// eg. 4 becomes 04 but 17 stays 17.
function pad(string) {
  string = String(string);
  return (string.length < 2) ? ('0' + string) : string;
}

// Compact date representation.
// eg. 0611093840 for June 11, 9:38:40 UTC.
function date() {
  const date = new Date();
  return pad(date.getUTCMonth() + 1) +
    pad(date.getUTCDate()) +
    pad(date.getUTCHours()) +
    pad(date.getUTCMinutes()) +
    pad(date.getUTCSeconds());
}

module.exports = function log(...msg) {
  const d = date();
  listeners.forEach(f => f(d, ...msg))
  console.log(d, ...msg);
};

const throttledConsoleError = throttle(console.error, 10000, { trailing: false });

module.exports.error = function error(...msg) {
  const d = date();
  listeners.forEach(f => f(d, ...msg));
  Raven.captureException(msg, function (sendErr) {
    if (sendErr) {
      throttledConsoleError('Failed to send captured exception to Sentry', sendErr.message);
    }
  });
  console.error(d, ...msg);
};

module.exports.addListener = function addListener(func) {
  listeners.push(func);
};

module.exports.removeListener = function removeListener(func) {
  const index = listeners.indexOf(func);
  if (index < 0) { return; }
  listeners.splice(index, 1);
};