stream browser resource

Author: thefringeninja

src/SqlStreamStore.HAL/Constants.cs

@@ -60,6 +60,7 @@ public static class Relations
             public const string DeleteStream = StreamStorePrefix + ":delete-stream";
             public const string DeleteMessage = StreamStorePrefix + ":delete-message";
             public const string Find = StreamStorePrefix + ":find";
+            public const string ListStreams = StreamStorePrefix + ":list-streams";
         }
 
         public static class Streams
@@ -71,6 +72,7 @@ public static class Streams
             public static PathString AllStreamPath = new PathString($"/{All}");
             public static PathString StreamsPath = new PathString($"/{Stream}");
             public static PathString IndexPath = new PathString("/");
+            public static PathString StreamBrowserPath = AllStreamPath.Add("/list");
         }
 
         public static class ReadDirection

src/SqlStreamStore.HAL/SqlStreamStoreHalMiddleware.cs

@@ -11,6 +11,8 @@
     using SqlStreamStore.HAL.Docs;
     using SqlStreamStore.HAL.Index;
     using SqlStreamStore.HAL.Logging;
+    using SqlStreamStore.HAL.Resources;
+    using SqlStreamStore.HAL.StreamBrowser;
     using SqlStreamStore.HAL.StreamMessage;
     using SqlStreamStore.HAL.StreamMetadata;
     using SqlStreamStore.HAL.Streams;
@@ -62,6 +64,7 @@ public static IApplicationBuilder UseSqlStreamStoreHal(
             var index = new IndexResource(streamStore);
             var allStream = new AllStreamResource(streamStore, options.UseCanonicalUrls);
             var allStreamMessages = new AllStreamMessageResource(streamStore);
+            var streamBrowser = new StreamBrowserResource(streamStore);
             var streams = new StreamResource(streamStore);
             var streamMetadata = new StreamMetadataResource(streamStore);
             var streamMessages = new StreamMessageResource(streamStore);
@@ -83,6 +86,7 @@ public static IApplicationBuilder UseSqlStreamStoreHal(
                 .UseIndex(index)
                 .UseAllStream(allStream)
                 .UseAllStreamMessage(allStreamMessages)
+                .UseStreamBrowser(streamBrowser)
                 .UseStreams(streams)
                 .UseStreamMetadata(streamMetadata)
                 .UseStreamMessages(streamMessages);

src/SqlStreamStore.HAL/StreamBrowser/ListStreamsMiddleware.cs

@@ -0,0 +1,42 @@
+namespace SqlStreamStore.HAL.StreamBrowser
+{
+    using System;
+    using System.Net.Http;
+    using Microsoft.AspNetCore.Builder;
+    using Microsoft.AspNetCore.Http;
+    using SqlStreamStore.HAL.Resources;
+    using MidFunc = System.Func<
+        Microsoft.AspNetCore.Http.HttpContext,
+        System.Func<System.Threading.Tasks.Task>,
+        System.Threading.Tasks.Task
+    >;
+
+    internal static class StreamBrowserMiddleware
+    {
+        public static IApplicationBuilder UseStreamBrowser(
+            this IApplicationBuilder builder,
+            StreamBrowserResource streamBrowser)
+            => builder.MapWhen(IsMatch, Configure(streamBrowser));
+        
+        private static bool IsMatch(HttpContext context)
+            => context.Request.Path.IsStreamBrowser();
+
+        public static bool IsStreamBrowser(this PathString requestPath)
+            => requestPath == Constants.Streams.StreamBrowserPath;
+
+        private static Action<IApplicationBuilder> Configure(StreamBrowserResource streamBrowser)
+            => builder => builder
+                .UseMiddlewareLogging(typeof(StreamBrowserMiddleware))
+                .MapWhen(HttpMethod.Get, inner => inner.Use(BrowseStreams(streamBrowser)));
+
+        private static MidFunc BrowseStreams(StreamBrowserResource streamBrowser)
+            => async (context, next) =>
+            {
+                var response = await streamBrowser.Get(
+                    new ListStreamsOperation(context.Request),
+                    context.RequestAborted);
+
+                await context.WriteResponse(response);
+            };
+    }
+}

src/SqlStreamStore.HAL/StreamBrowser/ListStreamsOperation.cs

@@ -0,0 +1,58 @@
+namespace SqlStreamStore.HAL.StreamBrowser
+{
+    using System.Threading;
+    using System.Threading.Tasks;
+    using Microsoft.AspNetCore.Http;
+    using SqlStreamStore.Streams;
+
+    internal class ListStreamsOperation : IStreamStoreOperation<ListStreamsPage>
+    {
+        public Pattern Pattern { get; }
+        public string ContinuationToken { get; }
+        public int MaxCount { get; }
+        public string PatternType { get; }
+        public PathString Path { get; }
+
+        public ListStreamsOperation(HttpRequest request)
+        {
+            Path = request.Path;
+            if(request.Query.TryGetValueCaseInsensitive('t', out var patternType))
+            {
+                PatternType = patternType;
+            }
+
+            if(!request.Query.TryGetValueCaseInsensitive('p', out var pattern))
+            {
+                Pattern = Pattern.Anything();
+            }
+            else
+            {
+                switch(PatternType)
+                {
+                    case "s":
+                        Pattern = Pattern.StartsWith(pattern);
+                        break;
+                    case "e":
+                        Pattern = Pattern.EndsWith(pattern);
+                        break;
+                    default:
+                        Pattern = Pattern.Anything();
+                        break;
+                }
+            }
+
+            if(request.Query.TryGetValueCaseInsensitive('c', out var continuationToken))
+            {
+                ContinuationToken = continuationToken;
+            }
+
+            MaxCount = request.Query.TryGetValueCaseInsensitive('m', out var m)
+                       && int.TryParse(m, out var maxCount)
+                ? maxCount
+                : 100;
+        }
+
+        public Task<ListStreamsPage> Invoke(IStreamStore streamStore, CancellationToken cancellationToken)
+            => streamStore.ListStreams(Pattern, MaxCount, ContinuationToken, cancellationToken);
+    }
+}

src/SqlStreamStore.HAL/StreamBrowser/StreamBrowserResource.cs

@@ -0,0 +1,51 @@
+namespace SqlStreamStore.HAL.Resources
+{
+    using System;
+    using System.Threading;
+    using System.Threading.Tasks;
+    using Halcyon.HAL;
+    using SqlStreamStore.HAL.StreamBrowser;
+
+    internal class StreamBrowserResource
+    {
+        private readonly IStreamStore _streamStore;
+
+        public StreamBrowserResource(IStreamStore streamStore)
+        {
+            _streamStore = streamStore;
+        }
+
+        public async Task<Response> Get(ListStreamsOperation operation, CancellationToken cancellationToken)
+        {
+            var listStreamsPage = await operation.Invoke(_streamStore, cancellationToken);
+
+            var halResponse = new HALResponse(new
+                {
+                    listStreamsPage.ContinuationToken
+                })
+                .AddEmbeddedCollection(
+                    Constants.Relations.Feed,
+                    Array.ConvertAll(
+                        listStreamsPage.StreamIds,
+                        streamId =>
+                        {
+                            var href = $"../../streams/{streamId}";
+                            return new HALResponse(null)
+                                .AddLinks(
+                                    new Link(Constants.Relations.Self, href, streamId),
+                                    new Link(Constants.Relations.Feed, href, streamId));
+                        }
+                    ));
+
+            if(listStreamsPage.ContinuationToken != null)
+            {
+                halResponse.AddLinks(
+                    new Link(
+                        Constants.Relations.Next,
+                        $"browser?p={operation.Pattern.Value}&t={operation.PatternType}&c={listStreamsPage.ContinuationToken}&m={operation.MaxCount}"));
+            }
+
+            return new HalJsonResponse(halResponse);
+        }
+    }
+}