/// <summary>
/// Executes the router to find an appropriate processor for the incoming message
/// </summary>
/// <param name="type">The type of incoming message from Slack.</param>
/// <param name="context">The <see cref="HttpContext"/> for the current request.</param>
/// <param name="httpClient">The <see cref="HttpClient"/> instance to use for any network calls (to promote reuse)</param>
/// <returns>A task that represents the execution of the router.</returns>
/// <exception cref="ArgumentNullException">Throws when <paramref name="context"/> or <paramref name="httpClient"/> is <c>null</c>.</exception>
public async Task ProcessAsync(IncomingMessageType type, HttpContext context, HttpClient httpClient)
{
_ = context ?? throw new ArgumentNullException(nameof(context));
_ = httpClient ?? throw new ArgumentNullException(nameof(httpClient));
// Ensure it's a POST coming from Slack
if (context.Request.Method != "POST")
{
context.Response.StatusCode = 404;
return;
}
AppResponse response = null;
var isRespondable = false;
try
{
switch (type)
{
case IncomingMessageType.Command:
isRespondable = true;
response = await ProcessCommandAsync(context);
break;
case IncomingMessageType.Action:
isRespondable = true;
response = await ProcessActionAsync(context);
break;
case IncomingMessageType.Event:
await ProcessEventAsync(context);
break;
}
}
catch (Exception e)
{
var message = $"An exception occurred while processing this {type}";
_logger.LogError(e, message, null);
if (isRespondable)
{
if (response == null)
{
response = new AppResponse();
}
response.ImmediateMessage = SlackMessage.CreateErrorMessage($"message: {e.Message}");
response.ResponseUrlMessages.Clear();
context.Response.StatusCode = 200;
}
else
{
context.Response.StatusCode = 500;
}
}
if (!isRespondable)
{
return;
}
if (response.ImmediateMessage != null)
{
// Respond immediately with a message
// Per Slack docs, this keeps the original message in the channel
// See https://api.slack.com/slash-commands#delayed_responses_and_multiple_responses
context.Response.ContentType = "application/json";
await context.Response.WriteAsync(response.ImmediateMessage.ToJson());
}
if (response.ResponseUrlMessages.Count > 0 && !string.IsNullOrEmpty(response.response_url))
{
foreach (var message in response.ResponseUrlMessages)
{
// Send the message back to the response_url
// Per Slack docs, this replaces the original message in the channel
// See https://api.slack.com/slash-commands#delayed_responses_and_multiple_responses
var requestMessage = new HttpRequestMessage(HttpMethod.Post, new Uri(response.response_url))
{
Content = new StringContent(message.ToJson(), Encoding.UTF8, "application/json")
};
try
{
var result = await httpClient.SendAsync(requestMessage);
if (!result.IsSuccessStatusCode)
{
throw new Exception($"Failed to post to Slack: Status Code \"{result.StatusCode}\" ({(int)result.StatusCode}).");
}
}
catch (Exception e)
{
// Something happened posting back to the response_url, so log the error
_logger.LogError(e, "An exception occurred while sending a message to the response_url", null);
}
}
}
}
