index.js

var optimist = require('optimist')
  , argv = optimist.argv;

// optimist provides these, we don't want them.
delete argv['_'];
delete argv['$0'];

// Load a js or json file
var getFile = function(filename) {
  var file;
  try {
    file = require(filename);
  } catch (e) {
    if (e instanceof SyntaxError) {
      throw new Error("Confrodo: Syntax error in file '" + filename + "': " + e.message);
    } else if (e.message.match(/^Cannot find module/)) {
      throw new Error("Confrodo: Can't find file '" + filename + "'");
    } else {
      throw e;
    }
  }
  return file;
};

// Get the enviroment.
// env will be "local" unless `env` is passed as a command
// line argument, or the NODE_ENV environment variable is set.
var getEnvironment = function() {
  var env;
  if (argv.hasOwnProperty('env')) {
    env = argv.env;
  } else if (typeof process.env.NODE_ENV === 'string') {
    env = process.env.NODE_ENV;
  } else {
    env = 'local';
  }
  return env;
};

// Merge two objects together.
// The second object wins if the both have
// the same property.
var mergeConfig = function(configA, configB, mergeStrategy) {
  if (mergeStrategy) {
    return mergeStrategy(configA, configB);
  }
  var merged = {}
    , hop = Object.prototype.hasOwnProperty;
  for (var i in configA) {
    if (hop.call(configA, i)) {
      merged[i] = configA[i];
    }
  }
  for (var i in configB) {
    if (hop.call(configB, i)) {
      merged[i] = configB[i];
    }
  }
  return merged;
};

// The magic we export.
// This funcion combines everything into one object.
// It is the essence of awesomeness.
var frodo = function() {
  var args = Array.prototype.slice.call(arguments);
  var mergeStrategy = null;
  if (typeof args[args.length - 1] === "function") {
    mergeStrategy = args.pop();
  }
  var config = {};
  config.env = getEnvironment();
  for (var i = 0; i < args.length; ++i) {
    if (typeof args[i] === "string") {
      if (args[i] === "ENV") {
        config = mergeConfig(config, process.env, mergeStrategy);
      } else if (args[i] === "ARGV") {
        config = mergeConfig(config, argv, mergeStrategy);
      } else {
        config = mergeConfig(config, getFile(args[i]), mergeStrategy);
      }
    } else if (typeof args[i] === "object") {
      config = mergeConfig(config, args[i], mergeStrategy);
    }
  }
  return config;
};

// attach env to confrodo
frodo.env = getEnvironment();

// set NODE_ENV, in case we got it from somwhere else
process.env['NODE_ENV'] = frodo.env;

module.exports = frodo;