Add asAppScopedClient() function for convenience

src/main/java/com/spotify/github/async/Async.java

@@ -20,6 +20,8 @@
 
 package com.spotify.github.async;
 
+import java.util.concurrent.CompletableFuture;
+import java.util.function.Function;
 import java.util.stream.Stream;
 
 import static java.util.stream.StreamSupport.stream;
@@ -34,4 +36,19 @@ public static <T> Stream<T> streamFromPaginatingIterable(final Iterable<AsyncPag
         return stream(iterable.spliterator(), false)
                    .flatMap(page -> stream(page.spliterator(), false));
     }
+
+    public static <T> CompletableFuture<T> exceptionallyCompose(
+            final CompletableFuture<T> future, final Function<Throwable, CompletableFuture<T>> handler) {
+
+        return future
+                .handle(
+                        (result, throwable) -> {
+                            if (throwable != null) {
+                                return handler.apply(throwable);
+                            } else {
+                                return CompletableFuture.completedFuture(result);
+                            }
+                        })
+                .thenCompose(Function.identity());
+    }
 }

src/main/java/com/spotify/github/v3/clients/GitHubClient.java

@@ -25,10 +25,12 @@
 
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.spotify.github.Tracer;
+import com.spotify.github.async.Async;
 import com.spotify.github.jackson.Json;
 import com.spotify.github.v3.Team;
 import com.spotify.github.v3.User;
 import com.spotify.github.v3.checks.AccessToken;
+import com.spotify.github.v3.checks.Installation;
 import com.spotify.github.v3.comment.Comment;
 import com.spotify.github.v3.exceptions.ReadOnlyRepositoryException;
 import com.spotify.github.v3.exceptions.RequestNotOkException;
@@ -53,6 +55,7 @@
 import java.util.Objects;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionStage;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Consumer;
@@ -71,6 +74,7 @@
 public class GitHubClient {
 
   private static final int EXPIRY_MARGIN_IN_MINUTES = 5;
+  private static final int HTTP_NOT_FOUND = 404;
 
   private Tracer tracer = NoopTracer.INSTANCE;
 
@@ -367,6 +371,37 @@ public GitHubClient withScopeForInstallationId(final int installationId) {
         installationId);
   }
 
+    /**
+     * This is for clients authenticated as a GitHub App: when performing operations,
+     * the "installation" of the App must be specified.
+     * This returns a {@code GitHubClient} that has been scoped to the
+     * user's/organization's installation of the app, if any.
+     */
+    public CompletionStage<Optional<GitHubClient>> asAppScopedClient(final String owner) {
+        return Async.exceptionallyCompose(this
+                        .createOrganisationClient(owner)
+                        .createGithubAppClient()
+                        .getInstallation()
+                        .thenApply(Installation::id), e -> {
+                    if (e.getCause() instanceof RequestNotOkException && ((RequestNotOkException) e.getCause()).statusCode() == HTTP_NOT_FOUND) {
+                        return this
+                                .createUserClient(owner)
+                                .createGithubAppClient()
+                                .getUserInstallation()
+                                .thenApply(Installation::id);
+                    }
+                    return CompletableFuture.failedFuture(e);
+                })
+                .thenApply(id -> Optional.of(this.withScopeForInstallationId(id)))
+                .exceptionally(
+                        e -> {
+                            if (e.getCause() instanceof RequestNotOkException && ((RequestNotOkException) e.getCause()).statusCode() == HTTP_NOT_FOUND) {
+                                return Optional.empty();
+                            }
+                            throw new RuntimeException(e);
+                        });
+    }
+
   public GitHubClient withTracer(final Tracer tracer) {
     this.tracer = tracer;
     return this;

src/test/java/com/spotify/github/v3/clients/GitHubClientTest.java

@@ -22,6 +22,8 @@
 
 import static com.google.common.io.Resources.getResource;
 import static java.nio.charset.Charset.defaultCharset;
+import static java.util.concurrent.CompletableFuture.completedFuture;
+import static java.util.concurrent.CompletableFuture.failedFuture;
 import static org.hamcrest.CoreMatchers.containsString;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.collection.IsMapContaining.hasEntry;
@@ -33,6 +35,7 @@
 import com.google.common.io.Resources;
 import com.spotify.github.Tracer;
 import com.spotify.github.v3.checks.CheckSuiteResponseList;
+import com.spotify.github.v3.checks.Installation;
 import com.spotify.github.v3.exceptions.ReadOnlyRepositoryException;
 import com.spotify.github.v3.exceptions.RequestNotOkException;
 import com.spotify.github.v3.repos.CommitItem;
@@ -42,6 +45,7 @@
 import java.io.IOException;
 import java.net.URI;
 import java.net.URISyntaxException;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
@@ -228,4 +232,59 @@ public void testGetCheckSuites() throws Throwable {
     assertThat(result.checkSuites().get(0).app().get().slug().get(), is("octoapp"));
 
   }
+
+  @Test
+  void asAppScopedClientGetsUserClientIfOrgClientNotFound() {
+    var appGithub = GitHubClient.create(client, URI.create("http://bogus"), new byte[] {}, 1);
+    var githubSpy = spy(appGithub);
+
+    var orgClientMock = mock(OrganisationClient.class);
+    when(githubSpy.createOrganisationClient("owner")).thenReturn(orgClientMock);
+
+    var appClientMock = mock(GithubAppClient.class);
+    when(orgClientMock.createGithubAppClient()).thenReturn(appClientMock);
+    when(appClientMock.getInstallation()).thenReturn(failedFuture(new RequestNotOkException("", "", 404, "", new HashMap<>())));
+
+    var userClientMock = mock(UserClient.class);
+    when(githubSpy.createUserClient("owner")).thenReturn(userClientMock);
+
+    var appClientMock2 = mock(GithubAppClient.class);
+    when(userClientMock.createGithubAppClient()).thenReturn(appClientMock2);
+
+    var installationMock = mock(Installation.class);
+    when(appClientMock2.getUserInstallation()).thenReturn(completedFuture(installationMock));
+    when(installationMock.id()).thenReturn(1);
+
+    var maybeScopedClient = githubSpy.asAppScopedClient("owner").toCompletableFuture().join();
+
+    Assertions.assertTrue(maybeScopedClient.isPresent());
+    verify(githubSpy, times(1)).createOrganisationClient("owner");
+    verify(githubSpy, times(1)).createUserClient("owner");
+  }
+
+  @Test
+  void asAppScopedClientReturnsEmptyIfNoInstallation() {
+    var appGithub = GitHubClient.create(client, URI.create("http://bogus"), new byte[] {}, 1);
+    var githubSpy = spy(appGithub);
+
+    var orgClientMock = mock(OrganisationClient.class);
+    when(githubSpy.createOrganisationClient("owner")).thenReturn(orgClientMock);
+
+    var appClientMock = mock(GithubAppClient.class);
+    when(orgClientMock.createGithubAppClient()).thenReturn(appClientMock);
+    when(appClientMock.getInstallation()).thenReturn(failedFuture(new RequestNotOkException("", "", 404, "", new HashMap<>())));
+
+    var userClientMock = mock(UserClient.class);
+    when(githubSpy.createUserClient("owner")).thenReturn(userClientMock);
+
+    var appClientMock2 = mock(GithubAppClient.class);
+    when(userClientMock.createGithubAppClient()).thenReturn(appClientMock2);
+
+    var installationMock = mock(Installation.class);
+    when(appClientMock2.getUserInstallation()).thenReturn(failedFuture(new RequestNotOkException("", "", 404, "", new HashMap<>())));
+    when(installationMock.id()).thenReturn(1);
+
+    var maybeScopedClient = githubSpy.asAppScopedClient("owner").toCompletableFuture().join();
+    Assertions.assertTrue(maybeScopedClient.isEmpty());
+  }
 }