/// <summary>
/// An extenstion method on HttpClient that sends a request to <c>client</c>, using
/// the request type (Get, Put, Post) specified by <c>invocation</c>.
/// </summary>
/// <param name="client">The target client.</param>
/// <param name="invocation">A delegate that issues the required request type.</param>
/// <param name="requestUrn">The URN representing the request.</param>
/// <returns>The client's response as a <see cref="HttpResponseMessage"/>.</returns>
///
public static Task <HttpResponseMessage> Invoke(this HttpClient client,
HttpClientHelpers.EndPointInvocation invocation,
string requestUrn,
StringContent content = null)
{
return(invocation(client, requestUrn, content));
}
/// <summary>
/// Makes a call to the specified endpoint of Accounts API, using the specified Invocation (Get, Put or Post).
/// Content can be passed for Put and Post as <see cref="StringContent"/>.
/// </summary>
/// <param name="httpClient">The HttpClient instance serving as <c>this</c>.</param>
/// <param name="invocation">A delegate that will pass the </param>
/// <param name="requestUrn">The URN to be appended to the Accounts API URL in order to
/// obtain the full request URL.</param>
/// <param name="content">The content, if any. Only used if <c>invocation</c> is
/// <see cref="HttpClientHelpers.Put"/> or <see cref="HttpClientHelpers.Post"/></param>
/// <returns>An object representing the response by the Accounts API.</returns>
/// <example>
/// var response = InvokeManagementApi(Put, "accounts/credit/1234?sum=100");
///
/// Where "1234" is an account number and "100" is the sum to be credited to that account.
/// </example>
public static async Task <HttpResponseMessage> InvokeApiAsync(this HttpClient httpClient,
HttpClientHelpers.EndPointInvocation invocation,
string requestUrn,
StringContent content = null)
{
var response = await httpClient.Invoke(invocation, requestUrn, content);
return(response);
}
/// <summary>
/// Makes a call to the specified endpoint of Accounts API, using the specified Invocation (Get, Put or Post).
/// This call only supports requests that can be fully encoded in the URL.
/// </summary>
/// <param name="invocation">A delegate that will pass the </param>
/// <param name="requestUrn">The URN to be appended to the Accounts API URL in order to
/// obtain the full request URL.</param>
/// <returns>An object representing the response by the Accounts API.</returns>
/// <example>
/// var response = await InvokeApiAsync(Put, "accounts/credit/1234?sum=100");
///
/// Where "1234" is an account number and "100" is the sum to be credited to that account.
/// </example>
private async Task <HttpResponseMessage> InvokeApiAsync(HttpClientHelpers.EndPointInvocation invocation, string requestUrn)
{
HttpResponseMessage response;
var accessToken = TokenManager.GetAccessTokens().AccessToken;
using (var apiClient = new AccountsApiClient(_accountsApiUrl, accessToken))
{
response = await apiClient.Invoke(invocation, requestUrn);
}
return(response);
}
/// <summary>
/// Submits a request URL to the Accounts API. Contains the retry logic required in order to
/// deal with expired Access/Refresh Tokens.
/// </summary>
/// <param name="invocation">The calling method (Get, Put, or Post).</param>
/// <param name="requestUrn">The request to be submitted to the Accounts API.
/// See: <see cref="InvokeApiAsync(HttpClientHelpers.EndPointInvocation,string)"/>
/// </param>
/// <param name="userCredentialsCallback">
/// A delegate that can be invoked to obtain username/password credentials from the user.
/// </param>
/// <returns>The response from the Accounts API.</returns>
///
private async Task <HttpResponseMessage> InvokeApiAsync(HttpClientHelpers.EndPointInvocation invocation,
string requestUrn,
UserCredentialsCallback userCredentialsCallback)
{
// ReSharper disable once NotAccessedVariable
AccessTokenPair accessTokens;
//--------------------------------------------------------------------------------------------
// Have we been authenticated? Check the Token Manager for an Access Token. If we don't have
// one, go get one.
//--------------------------------------------------------------------------------------------
// ReSharper disable once RedundantAssignment
if ((accessTokens = TokenManager.GetAccessTokens()).IsNull())
{
var(username, password) = await userCredentialsCallback();
await GetAndStoreApiAccessTokens(username, password);
}
// TODO handle failure
//--------------------------------------------------------------------------------------------
// We have an Access Token; issue the request to the Accounts API.
//--------------------------------------------------------------------------------------------
var response = await InvokeApiAsync(invocation, requestUrn);
//--------------------------------------------------------------------------------------------
// Did the request fail?
//--------------------------------------------------------------------------------------------
if (!response.IsSuccessStatusCode)
{
Console.WriteLine(response.StatusCode);
//------------------------------------------------------------------------------------------
// Failed. Was it because our access token timed out?
//------------------------------------------------------------------------------------------
if (response.IsAccessTokenExpired())
{
//----------------------------------------------------------------------------------------
// Yes. Use our refresh token to get a new access token.
//----------------------------------------------------------------------------------------
// ReSharper disable once NotAccessedVariable
var accessToken = await GetAndStoreApiAccessTokens();
//----------------------------------------------------------------------------------------
// Re-submit the original request with the new access token.
//----------------------------------------------------------------------------------------
response = await InvokeApiAsync(invocation, requestUrn);
//----------------------------------------------------------------------------------------
// Is the Accounts API still reporting an expired token?
//----------------------------------------------------------------------------------------
if (response.IsAccessTokenExpired())
{
//--------------------------------------------------------------------------------------
// Yes. Apparently, our refresh token has expired too. At this point we must ask the
// user to re-authenticate with their username/password. Use the caller-provided
// callback to obtain them.
//--------------------------------------------------------------------------------------
var(username, password) = await userCredentialsCallback();
//--------------------------------------------------------------------------------------
// Try to get a new access token one more time, using the user's credentials.
//--------------------------------------------------------------------------------------
// ReSharper disable once RedundantAssignment
accessToken = await GetAndStoreApiAccessTokens(username, password);
//--------------------------------------------------------------------------------------
// Either that worked, or it didn't. Either way, we're done here. Return the final
// response to the caller.
//--------------------------------------------------------------------------------------
response = await InvokeApiAsync(invocation, requestUrn);
}
}
}
return(response);
}
