/// <summary>Serch Yelp (API v1)</summary>
/// <see cref="http://www.yelp.com/developers/documentation/search_api">Yelp v1 API for develoeprs web site</see>
public class YelpV1Helper
{
    private string YelpKey;
    public YelpV1Helper(string YelpKey)
    {
        this.YelpKey = YelpKey;
    }
 
    /// <summary>
    /// Enables searching for business review information within a certain radius of a particular location.
    /// </summary>
    /// <param name="query">String representing the name of business or search term being requested. (E.G. "bars") </param>
    /// <param name="latitude">Latitude of geo-point to search near. </param>
    /// <param name="longitude">Longitude of geo-point to search near. </param>
    /// <param name="limit">Specifies the number of businesses to return in the result set. Default is 10. Minimum value is 1 and maximum value is 20 </param>
    /// <param name="radius">Radius to use while searching around specified geo-point. Maximum value = 25. If a radius is not specified, it will be chosen based on the specificity of the location.</param>
    /// <param name="category">This parameter allows filtering of result set by a particular category. You can search in multiple categories by separating them with a plus character, e.g category=bars+poolhalls </param>
    /// <returns></returns>
    public async Task<List<Business>> SearchAsync(string query, double latitude, double longitude, string category = null, int limit = 50, int radius = 25)
    {
        var _Url = "http://api.yelp.com/business_review_search?";
        _Url += string.Format("ywsid={0}&", YelpKey);
        _Url += string.Format("lat={0}&", latitude);
        _Url += string.Format("long={0}&", longitude);
        _Url += string.Format("limit={0}&", limit);
        _Url += string.Format("radius={0}&", radius);
        _Url += string.Format("term={0}&", System.Uri.EscapeDataString(query));
        _Url = _Url.TrimEnd('&');
 
        string _JsonString = string.Empty;
        try
        {
            // fetch from rest service
            var _HttpClient = new System.Net.Http.HttpClient();
            var _HttpResponse = await _HttpClient.GetAsync(_Url);
            _JsonString = await _HttpResponse.Content.ReadAsStringAsync();
 
            // check for error
            if (_JsonString.Contains("{\"Error\":"))
                throw new InvalidResultException { JSON = _JsonString };
 
            // deserialize json to objects
            var _JsonBytes = Encoding.Unicode.GetBytes(_JsonString);
            using (MemoryStream _MemoryStream = new MemoryStream(_JsonBytes))
            {
                var _JsonSerializer = new DataContractJsonSerializer(typeof(RootObject));
                var _Result = (RootObject)_JsonSerializer.ReadObject(_MemoryStream);
                return _Result.businesses;
            }
        }
        catch (InvalidSomethingException) { throw; }
        catch (Exception e) { throw new InvalidSomethingException(e) { JSON = _JsonString }; }
    }
 
    public class InvalidSomethingException : Exception
    {
        public InvalidSomethingException() { }
        public InvalidSomethingException(Exception e) : base(string.Empty, e) { }
        public string JSON { get; set; }
    }
    public class InvalidResultException : InvalidSomethingException { }
 
    // JSON
 
    public class Message
    {
        public string text { get; set; }
        public int code { get; set; }
        public string version { get; set; }
    }
 
    public class Category
    {
        public string category_filter { get; set; }
        public string search_url { get; set; }
        public string name { get; set; }
    }
 
    public class Review
    {
        public string rating_img_url_small { get; set; }
        public string user_photo_url_small { get; set; }
        public string rating_img_url { get; set; }
        public int rating { get; set; }
        public string user_url { get; set; }
        public string url { get; set; }
        public string mobile_uri { get; set; }
        public string text_excerpt { get; set; }
        public string user_photo_url { get; set; }
        public string date { get; set; }
        public string user_name { get; set; }
        public string id { get; set; }
    }
 
    public class Business
    {
        public string rating_img_url { get; set; }
        public string country_code { get; set; }
        public string id { get; set; }
        public bool is_closed { get; set; }
        public string city { get; set; }
        public string mobile_url { get; set; }
        public int review_count { get; set; }
        public string zip { get; set; }
        public string state { get; set; }
        public double latitude { get; set; }
        public string rating_img_url_small { get; set; }
        public string address1 { get; set; }
        public string address2 { get; set; }
        public string address3 { get; set; }
        public string phone { get; set; }
        public string state_code { get; set; }
        public List<Category> categories { get; set; }
        public string photo_url { get; set; }
        public double distance { get; set; }
        public string name { get; set; }
        public List<object> neighborhoods { get; set; }
        public string url { get; set; }
        public string country { get; set; }
        public double avg_rating { get; set; }
        public double longitude { get; set; }
        public string nearby_url { get; set; }
        public List<Review> reviews { get; set; }
        public string photo_url_small { get; set; }
    }
 
    public class RootObject
    {
        public Message message { get; set; }
        public List<Business> businesses { get; set; }
    }
}