/**
 * Forecast - Weather Info for Node.js
 * By James Wyse <james@jameswyse.net>
 *
 * https://github.com/jameswyse/forecast/
 */

var crypto = require('crypto');
var moment = require('moment');
var assign = require('object-assign');
var providers = require('./providers');


/**
 * Forecast Constructor
 * @param {Object} options Options
 */
var Forecast = module.exports = function (options) {
  this.providers = providers;
  this.cache = {};

  this.options = assign({}, {
    service: 'darksky',
    units: 'celcius',
    cache: true,
    ttl: {
      minutes: 30
    }
  }, options || {});

  if (this.options.key === 'your-api-key') {
    this.options.key = null;
  }

  this.options.ttl = moment.duration(this.options.ttl);
};


/**
 * Expired - Checks if the given `key` has expired.
 * @param  {String} key Cache key
 * @return {Boolean}    `true` if expired, `false` otherwise.
 */
Forecast.prototype.expired = function (key) {

  if (this.cache[key] === undefined) {
    return true;
  }

  if (this.cache[key].expires < (new Date().getTime())) {
    delete this.cache[key];
    return true;
  }

  return false;
};


/**
 * Get the current weather conditions
 * @param  {Array}    apiParams    Accepts a latitude and longitude pair and optionally a unix timestamp as an `Array`
 * @param  {Boolean}  ignoreCache  If true then the cache will be ignored
 * @param  {Function} callback     Callback, signature: callback(err, result)
 */
Forecast.prototype.get = function (apiParams, ignoreCache, callback) {
  var self = this;
  var key  = crypto.createHash('md5')
    .update(this.options + apiParams)
    .digest('hex');

  if (typeof ignoreCache === 'function') {
    callback = ignoreCache;
    ignoreCache = false;
  }

  if (typeof ignoreCache !== 'boolean') {
    ignoreCache = false;
  }

  if (!ignoreCache && this.options.cache && this.cache[key] && !this.expired(key)) {
    return callback(null, this.cache[key]);
  }

  var Service = this.providers(this.options.service.toLowerCase());
  var service = new Service(this.options);

  return service.get(apiParams, function (err, result) {
    if (err) {
      return callback(err);
    }

    if (result !== undefined && self.options.cache) {
      self.cache[key] = result;
      self.cache[key].expires = new Date().getTime() + self.options.ttl.asMilliseconds();
    }

    return callback(null, result);
  });
};