'use strict';
var _ = require('lodash');
var preconditions = require('preconditions').singleton();

function LocalStorage() {
  this.type = 'DB';

  preconditions.checkState(typeof localStorage !== 'undefined',
                           'localstorage not available, cannot run plugin');
};

LocalStorage.prototype.init = function() {
};

LocalStorage.prototype.setCredentials = function(email, password, opts) {
  this.email = email;
  this.password = password;
};

LocalStorage.prototype.getItem = function(k,cb) {
  return cb(null, localStorage.getItem(k));
};

/**
 * Same as setItem, but fails if an item already exists
 */
LocalStorage.prototype.createItem = function(name, value, callback) {
  if (localStorage.getItem(name)) {
    return callback('EEXISTS');
  }
  return this.setItem(name, value, callback);
};

LocalStorage.prototype.setItem = function(k,v,cb) {
  localStorage.setItem(k,v);
  return cb();
};

LocalStorage.prototype.removeItem = function(k,cb) { 
  localStorage.removeItem(k);
  return cb();
};

LocalStorage.prototype.clear = function(cb) { 
  localStorage.clear();
  return cb();
};

LocalStorage.prototype.allKeys = function(cb) {
  var l = localStorage.length;
  var ret = [];

  for(var i=0; i<l; i++)
    ret.push(localStorage.key(i));

  return cb(null, ret);    
};

LocalStorage.prototype.getFirst = function(prefix, opts, cb) {
  opts = opts || {};
  var that = this;

  this.allKeys(function(err, allKeys) {
    var keys = _.filter(allKeys, function(k) {
      if ((k === prefix) || k.indexOf(prefix) === 0) return true;
    });

    if (keys.length === 0)
      return cb(new Error('not found'));

    if (opts.onlyKey)
      return cb(null, null, keys[0]);

    that.getItem(keys[0], function(err, data) {
      if (err) {
        return cb(err);
      }
      return cb(null, data, keys[0]);
    });
  });
};

module.exports = LocalStorage;