/// <summary>
/// Creates a new instance based on an <see cref="AgencyResponse"/>.
/// </summary>
/// <param name="agencyResponse">The response from an Agency query.</param>
public AgencyQueryException(AgencyResponse agencyResponse)
: base(agencyResponse.status_txt)
{
StatusCode = agencyResponse.status_code;
}
/// <summary>
/// Creates a new instance based on an <see cref="AgencyResponse"/>.
/// </summary>
/// <param name="agencyResponse">The response from an Agency query.</param>
public AgencyQueryException(AgencyResponse agencyResponse)
: base(agencyResponse.status_txt)
{
StatusCode = agencyResponse.status_code;
}
/// <summary>
/// Retrieves GTFS data for a specified agency.
/// Data will be retrieved from an in-memory list if available and up-to-date.
/// Otherwise the GTFS data will be requested from the GTFS Data Exchange website
/// and stored for future use.
/// </summary>
/// <param name="agencyId">The GTFS-Data-Exchange agency identifier.</param>
/// <param name="lastModified">If an "If-Modified-Since" header is present, that value can be used here. Otherwise omit.</param>
/// <param name="etags">If the HTTP request contains "If-None-Match", it can be passed in here. Otherwise it can be omitted.</param>
/// <returns>Returns a <see cref="FeedRequestResponse"/>.</returns>
/// <exception cref="ArgumentException">Thrown if <paramref name="agencyId"/> is <see langword="null"/> or consists only of whitespace.</exception>
/// <exception cref="AgencyQueryException">Thrown if the query to gtfs-data-exchange for information fails.</exception>
public FeedRequestResponse GetGtfs(string agencyId,
DateTimeOffset?lastModified = default(DateTimeOffset?),
IEnumerable <EntityTagHeaderValue> etags = null)
{
if (string.IsNullOrWhiteSpace(agencyId))
{
throw new ArgumentException("The agencyId was not provided.");
}
// Get the record with the matching agency ID.
var feedRecord = _feedList.FirstOrDefault(r => string.Compare(r.AgencyId, agencyId, true) == 0);
// Check to see if there are matching Etags...
if (feedRecord != null && feedRecord.Etag != null && etags != null)
{
var match = etags.FirstOrDefault(et => et == feedRecord.Etag);
if (match != null)
{
return(new FeedRequestResponse {
NotModified = true
});
}
}
HttpClient client = null;
GtfsFeed gtfs = feedRecord != null ? feedRecord.GtfsData : null;
EntityTagHeaderValue outEtag = null;
AgencyResponse agencyResponse = null;
FeedRequestResponse output = null;
try
{
// Check for an existing record...
// Check online to see if there is a newer feed available.
// This will be skipped if there is no matching GTFS feed stored for the specified agency.
const string urlFmt = "http://www.gtfs-data-exchange.com/api/agency?agency={0}";
Uri uri = new Uri(string.Format(urlFmt, agencyId));
client = new HttpClient();
client.DefaultRequestHeaders.IfModifiedSince = lastModified;
if (etags != null)
{
foreach (var etag in etags)
{
client.DefaultRequestHeaders.IfNoneMatch.Add(etag);
}
}
client.GetAsync(uri).ContinueWith((t) =>
{
outEtag = t.Result.Headers.ETag;
if (t.Result.StatusCode == HttpStatusCode.NotModified)
{
output = new FeedRequestResponse
{
NotModified = true
};
}
else if (t.Result.StatusCode == HttpStatusCode.OK)
{
t.Result.Content.ReadAsStreamAsync().ContinueWith(streamTask => {
using (var streamReader = new StreamReader(streamTask.Result))
using (var jsonReader = new JsonTextReader(streamReader))
{
var serializer = JsonSerializer.Create();
agencyResponse = serializer.Deserialize <AgencyResponse>(jsonReader);
}
}).Wait();
}
}).Wait();
// If the request for GTFS info returned a "Not Modified" response, return now.
if (output == null)
{
if (agencyResponse.status_code != 200)
{
throw new AgencyQueryException(agencyResponse);
}
if (lastModified.HasValue && lastModified.Value >= agencyResponse.data.agency.date_last_updated.FromJSDateToDateTimeOffset())
{
if (feedRecord == null)
{
feedRecord = new FeedRecord
{
DateLastUpdated = lastModified.Value,
Etag = outEtag
};
}
}
else
{
if (feedRecord == null || (agencyResponse.data.agency.date_last_updated.FromJSDateToDateTimeOffset() > feedRecord.DateLastUpdated))
{
// Get the GTFS file...
Uri zipUri = new Uri(String.Join("/", agencyResponse.data.agency.dataexchange_url.TrimEnd('/'), "latest.zip"));
// TODO: make the request and parse the GTFS...
if (client == null)
{
client = new HttpClient();
}
else
{
client.DefaultRequestHeaders.Clear();
}
client.GetStreamAsync(zipUri).ContinueWith(t =>
{
t.Result.ReadGtfsAsync().ContinueWith(gtfsTask => {
gtfs = gtfsTask.Result;
// Delete the existing feedRecord.
if (feedRecord != null)
{
_feedList.Remove(feedRecord);
}
feedRecord = new FeedRecord
{
GtfsData = gtfs,
AgencyId = agencyId,
DateLastUpdated = agencyResponse.data.agency.date_last_updated.FromJSDateToDateTimeOffset(),
Etag = outEtag
};
// Add the new GTFS feed data to the in-memory collection.
_feedList.Add(feedRecord);
}).Wait();
}).Wait();
}
}
}
}
finally
{
if (client != null)
{
client.Dispose();
}
}
return(new FeedRequestResponse
{
FeedRecord = feedRecord
});
}