/// <summary>
/// Begins an asynchronous request for the country-specific Alexa ranking.
/// </summary>
/// <param name="callback">The callback method.</param>
/// <param name="country">The country.</param>
/// <param name="pages">The number of pages to return.</param>
/// <param name="ranking">The ranking list.</param>
/// <param name="userState">The user state.</param>
public IAsyncResult BeginGetCountryRanking(AsyncCallback callback, AlexaCountry country, int pages, AlexaRanking ranking = null, object userState = null)
{
// Create the request state.
AlexaRankingRequestState asyncState = new AlexaRankingRequestState(callback, country, pages, ranking, userState);
// Call the internal request method.
this.BeginGetRankingInternal(asyncState, this.GetUriCountryRanking);
// Return the request state.
return asyncState;
}
/// <summary>
/// Computes the request URI for the Alexa country ranking.
/// </summary>
/// <param name="asyncState">The request state</param>
/// <param name="uri">The request URI.</param>
/// <param name="country">The request country.</param>
private void GetUriCountryRanking(AlexaRankingRequestState asyncState, out Uri uri, out AlexaCountry country)
{
// Set the URI.
uri = new Uri(AlexaRequest.urlRankingCountry.FormatWith(asyncState.Page++, asyncState.Country.Code));
// Set the country.
country = asyncState.Country;
}
/// <summary>
/// Computes the request URI for the Alexa global ranking.
/// </summary>
/// <param name="asyncState">The request state</param>
/// <param name="uri">The request URI.</param>
/// <param name="country">The request country.</param>
private void GetUriGlobalRanking(AlexaRankingRequestState asyncState, out Uri uri, out AlexaCountry country)
{
// Set the URI.
uri = new Uri(AlexaRequest.urlRankingGlobal.FormatWith(asyncState.Page++));
// Set the country.
country = AlexaCountry.Global;
}
/// <summary>
/// Begins an asynchronous request for the Alexa ranking.
/// </summary>
/// <param name="asyncState">The asynchronous state.</param>
private void BeginGetRankingInternal(AlexaRankingRequestState asyncState, AlexaRankingAction actionUri)
{
// The URI.
Uri uri;
// The country.
AlexaCountry country;
// Call the ranking action.
actionUri(asyncState, out uri, out country);
// Begin an asynchronous request for the Alexa ranking.
asyncState.Result = base.Begin(uri, (AsyncWebResult asyncResult) =>
{
try
{
// The request data.
string data;
// Complete the request.
AsyncWebResult result = base.End(asyncResult, out data);
// Parse the list of countries.
asyncState.Ranking.Parse(data, country);
// If there are more pages.
if (asyncState.Page < asyncState.Pages)
{
// Begin a new request.
this.BeginGetRankingInternal(asyncState, actionUri);
}
else
{
// Complete the request.
asyncState.Complete();
// Call the callback method.
if (null != asyncState.Callback) asyncState.Callback(asyncState);
// Dispose the state.
asyncState.Dispose();
}
}
catch (Exception exception)
{
// Set the exception.
asyncState.Exception = exception;
// Complete the request.
asyncState.Complete();
// Call the callback method.
if (null != asyncState.Callback) asyncState.Callback(asyncState);
// Dispose the state.
asyncState.Dispose();
}
}, asyncState);
}
