/**
 * Export the current Environment.
**/
exports.env = null;


/**
 * Export the last error that occured, if any.
**/
exports._lastError = null;


/**
 * Storage for current settings object.
**/
var SETTINGS;


/**
 * These are the various environment based settings.
 *
 * @return  {Object}              The loaded settings object.
 * @throws  {Error}               If the settings file cannot be found.
**/
var environments = {
  development: function() {
    return require('./settings/development').settings;
  },

  production: function() {
    return require('./settings/production').settings;
  },

  local: function() {
    return require('./settings/local').settings;
  }
};


/**
 * Cache for cache()
**/
var _cache = {};


/**
 * Takes a given key and stores it in the cache
 * for faster lookup times.
 *
 * @param   {String}    key       The key name.
 * @param   {Mixed}     value     The value for the key.
 * @return  {Mixed}               If value: the value; Else key exists boolean.
**/
function cache(key, value) {
  if (!value) {
    return _cache[key];
  } else {
    return _cache[key] = value;
  }
}


/**
 * Parses a string to figure out its value within an object
 *
 * @param   {Object}    settings  The settings object to search within.
 * @param   {String}    key       The key to search for.
 * @param   {Mixed}     value     If acting as a Setter, the value to set.
 * @return  {Mixed}               The current value of object at key.
**/
function resolve(settings, key, value) {
  if (_cache[key] === undefined || arguments.length === 3) {
    var current = settings;
    for (var node, parts = key.split('.');
        parts.length && (node = parts.shift()); ) {
      if (parts.length !== 0) {
        current = current[node] = (current[node] || {});
      } else {
        current = (value ? (current[node] = value) : current[node]);
      }
    }
    return cache(key, current);
  } else {
    return cache(key);
  }
}


/**
 * Sets the current environment and loads up the corresponding settings.
 *
 * @param   {String}    env       The environment to switch to.
 * @return  {Boolean}             The environment was successfully switched.
**/
exports.setEnv = function(env) {
  if (typeof environments[env] === 'function') {
    try {
      SETTINGS = environments[env]();
      exports.env = env;
      return true;
    } catch (e) {
      exports._lastError = e;
      return false;
    }
  } else {
    return false;
  }
};


/**
 * Returns the currently loaded environment.
 *
 * @return  {String}              The currently loaded environment.
 * @this                          The `settings` object.
**/
exports.getEnv = function() {
  return exports.env;
};


/**
 * Set the current environment to that defined in process.env.SERVER_ENV;
 *
 * Defaults to 'local' environment.
 *
 * @return  {Boolean}             The environment was successfully switched.
**/
exports.setAutoEnv = function() {
  if (process.env.SERVER_ENV) {
    return exports.setEnv(process.env.SERVER_ENV);
  } else {
    return exports.setEnv('local');
  }
};


/**
 * Returns the value of the setting at `key`.
 *
 * If only we had proxies, of well, here's to ES Harmony
 *
 * @param   {String}    key       An object tree, levels separated by a period.
 * @return  {Mixed}               The value for the key.
**/
exports.get = function(key) {
  if (!SETTINGS) {
    throw new Error('setEnv must be called before settings can be accessed');
  }

  return resolve(SETTINGS, key);
};


/**
 * Sets the value of the setting at key with `value`.
 *
 * @param   {String}    key       An object tree, levels separated by a period.
 * @param   {Mixed}     value     The value to set the key to.
**/
exports.set = function(key, value) {
  if (!SETTINGS) {
    throw new Error('setEnv must be called before settings can be changed');
  }

  resolve(SETTINGS, key, value);
};


/**
 * The toJSON method for JSON.stringify
 *
 * @return  {String}              The JSON encoded `SETTINGS` object.
**/
exports.toJSON = function() {
  return SETTINGS;
};