node-redis-rate-limiter/lib/options.js

var assert  = require('assert');
var moment  = require('moment');

var getMatches =  function(opts){
  return getRate(opts).match(/^(\d+)\s*\/\s*([a-z]+)$/);
};

var keyShorthands = {
  'ip': function(req) {
    return req.connection.remoteAddress;
  }
};

var getRate = function(opts){
  if(typeof opts.rate === 'function') return opts.rate();
  return opts.rate;
};

var getLimit = function(opts){
  if(getRate(opts)) return parseInt(getMatches(opts)[1], 10);
  if(typeof opts.limit === 'function') return opts.limit();
  return opts.limit;
};

var getWindow = function(opts){
  if(getRate(opts)) return moment.duration(1, getMatches(opts)[2]) / 1000;
  if(typeof opts.window === 'function') return opts.window();
  return opts.window;
};

var getStatus = function(opts){
  if (!("status" in opts)) {
    opts.status = 429;
  }
  return opts.status;
};

var getKey = function(opts){
  if(typeof opts.key === 'function') return opts.key;
  return keyShorthands[opts.key];
};

var validate = function(opts){
  assert.equal(typeof opts.redis, 'object', 'Invalid redis client');
  assert.equal(typeof getKey(opts), 'function', 'Invalid key: ' + opts.key);
  if(opts.rate) assert.ok(getMatches(opts), 'Invalid rate: ' + getRate(opts));
  assert.equal(typeof getLimit(opts), 'number', 'Invalid limit: ' + getLimit(opts));
  assert.equal(typeof getWindow(opts), 'number', 'Invalid window: ' + getWindow(opts));
  assert.notEqual(getLimit(opts), 0,  'Invalid rate limit: ' + getRate(opts));
  assert.notEqual(getWindow(opts), 0, 'Invalid rate window: ' + getRate(opts));
  assert.equal(typeof getStatus(opts), 'number', 'Invalid status response type: ' + typeof getStatus(opts));
  var validStatuses = new Set([200,429]);
  assert.ok(validStatuses.has(getStatus(opts)),
    'Invalid status response code, must one of ' + validStatuses + ' found ' + getStatus(opts));
};

canonical = function(opts) {
  validate(opts);
  return {
    redis: opts.redis,
    key: getKey(opts),
    rate: getRate.bind(null, opts),
    limit: getLimit.bind(null, opts),
    window: getWindow.bind(null, opts),
    status: getStatus.bind(null, opts),
    deleteImmediatelyIfRaceCondition: opts.deleteImmediatelyIfRaceCondition,
    onPossibleRaceCondition: opts.onPossibleRaceCondition
  };
};

module.exports = {
  canonical: canonical
};