using System;

using System.Collections.Generic;

using System.Threading.Tasks;

using ServiceStack.Caching;

using ServiceStack.Web;

namespace ServiceStack

{

public static class AutoQueryDataServiceSource

{

public static QueryDataSource<T> ServiceSource<T>(this QueryDataContext ctx, object requestDto, ICacheClient cache, TimeSpan? expiresIn=null, string cacheKey=null)

{

if (cacheKey == null)

cacheKey = "aqd:" + requestDto.ToGetUrl();

var cachedResults = cache.Get<List<T>>(cacheKey);

if (cachedResults != null)

return new MemoryDataSource<T>(ctx, cachedResults);

var response = ServiceSource<T>(ctx, requestDto);

return response.CacheMemorySource(cache, cacheKey, expiresIn);

}

internal static QueryDataSource<T> CacheMemorySource<T>(this MemoryDataSource<T> response, ICacheClient cache, string cacheKey, TimeSpan? expiresIn)

{

if (expiresIn != null)

cache.Set(cacheKey, response.Data, expiresIn.Value);

else

cache.Set(cacheKey, response.Data);

return response;

}

public static MemoryDataSource<T> ServiceSource<T>(this QueryDataContext ctx, object requestDto)

{

var response = HostContext.AppHost.GetServiceGateway(ctx.Request).Send<object>(requestDto);

var results = GetResults<T>(response);

if (results == null)

throw new NotSupportedException(

$"IEnumerable<{typeof(T).Name}> could not be derived from Response {response.GetType().Name} from Request {requestDto.GetType().Name}");

return new MemoryDataSource<T>(ctx, results);

}

public static IEnumerable<T> GetResults<T>(object response)

{

var task = response as Task;

if (task != null)

response = task.GetResult();

var httpResult = response as IHttpResult;

if (httpResult != null)

response = httpResult.Response;

var result = response as IEnumerable<T>;

if (result != null)

return result;

foreach (var pi in response.GetType().GetPublicProperties())

{

if (typeof(IEnumerable<T>).IsAssignableFromType(pi.PropertyType))

{

return (IEnumerable<T>)pi.GetGetMethod().Invoke(response, TypeConstants.EmptyObjectArray);

}

}

return null;

}

}

}