diff --git a/platform/platform-api/src/com/intellij/util/io/HttpRequests.java b/platform/platform-api/src/com/intellij/util/io/HttpRequests.java
index bb8051d2bac9..e0beb322fba6 100644
--- a/platform/platform-api/src/com/intellij/util/io/HttpRequests.java
+++ b/platform/platform-api/src/com/intellij/util/io/HttpRequests.java
@@ -173,6 +173,11 @@ public final class HttpRequests {
     return new RequestBuilderImpl(url, connection -> ((HttpURLConnection)connection).setRequestMethod("DELETE"));
   }
 
+  @NotNull
+  public static RequestBuilder delete(@NotNull String url, @Nullable String contentType) {
+    return requestWithBody(url, "DELETE", contentType, null);
+  }
+
   @NotNull
   public static RequestBuilder post(@NotNull String url, @Nullable String contentType) {
     return requestWithBody(url, "POST", contentType, null);
@@ -525,8 +530,8 @@ public final class HttpRequests {
 
       if (builder.myThrowStatusCodeException) {
         URLConnection connection = request.myConnection;
-        if (connection instanceof HttpURLConnection && ((HttpURLConnection)connection).getRequestMethod().equals("POST")) {
-          // getResponseCode is not checked on connect for POST, because write must be performed before read
+        if (connection.getDoOutput()) {
+          // getResponseCode is not checked on connect, because write must be performed before read
           HttpURLConnection urlConnection = (HttpURLConnection)connection;
           int responseCode = urlConnection.getResponseCode();
           if (responseCode >= 400) {
@@ -596,12 +601,13 @@ public final class HttpRequests {
         return connection;
       }
 
-      HttpURLConnection httpURLConnection = (HttpURLConnection)connection;
-      String method = httpURLConnection.getRequestMethod();
-      if (method.equals("POST") || method.equals("PUT")) {
+      if (connection.getDoOutput()) {
         return connection;
       }
 
+      HttpURLConnection httpURLConnection = (HttpURLConnection)connection;
+      String method = httpURLConnection.getRequestMethod();
+
       LOG.assertTrue(method.equals("GET") || method.equals("HEAD") || method.equals("DELETE"),
                      "'" + method + "' not supported; please use GET, HEAD, DELETE, PUT or POST");
 
diff --git a/plugins/github/src/org/jetbrains/plugins/github/api/GithubApiRequest.kt b/plugins/github/src/org/jetbrains/plugins/github/api/GithubApiRequest.kt
index 0480abd25b4e..b47805bf3273 100644
--- a/plugins/github/src/org/jetbrains/plugins/github/api/GithubApiRequest.kt
+++ b/plugins/github/src/org/jetbrains/plugins/github/api/GithubApiRequest.kt
@@ -48,9 +48,6 @@ sealed class GithubApiRequest<T>(val url: String) {
       inline fun <reified T> json(url: String, acceptMimeType: String? = null): Get<T> =
         Json(url, T::class.java, acceptMimeType)
 
-      inline fun <reified T> jsonList(url: String, acceptMimeType: String? = null): Get<List<T>> =
-        JsonList(url, T::class.java, acceptMimeType)
-
       inline fun <reified T> jsonPage(url: String, acceptMimeType: String? = null): Get<GithubResponsePage<T>> =
         JsonPage(url, T::class.java, acceptMimeType)
 
@@ -133,6 +130,8 @@ sealed class GithubApiRequest<T>(val url: String) {
 
     companion object {
       inline fun <reified T> json(url: String, body: Any? = null): Put<T> = Json(url, body, T::class.java)
+
+      inline fun <reified T> jsonList(url: String, body: Any): Put<List<T>> = JsonList(url, T::class.java, body)
     }
 
     open class Json<T>(url: String, body: Any?, clazz: Class<T>) : Put<T>(body?.let { GithubApiContentHelper.toJson(it) },
@@ -143,6 +142,17 @@ sealed class GithubApiRequest<T>(val url: String) {
 
       override fun extractResult(response: GithubApiResponse): T = parseJsonResponse(response, typeToken)
     }
+
+    open class JsonList<T>(url: String, clazz: Class<T>, body: Any?)
+      : Put<List<T>>(body?.let { GithubApiContentHelper.toJson(it) },
+                     GithubApiContentHelper.JSON_MIME_TYPE,
+                     url,
+                     GithubApiContentHelper.V3_JSON_MIME_TYPE) {
+
+      private val typeToken = TypeToken.getParameterized(List::class.java, clazz) as TypeToken<List<T>>
+
+      override fun extractResult(response: GithubApiResponse): List<T> = parseJsonResponse(response, typeToken)
+    }
   }
 
   abstract class Patch<T> @JvmOverloads constructor(override val body: String,
@@ -163,10 +173,23 @@ sealed class GithubApiRequest<T>(val url: String) {
     }
   }
 
-  open class Delete(url: String) : GithubApiRequest<Unit>(url) {
-    override val acceptMimeType: String? = null
+  abstract class Delete<T> @JvmOverloads constructor(override val body: String?,
+                                                     override val bodyMimeType: String,
+                                                     url: String,
+                                                     override val acceptMimeType: String? = null) : GithubApiRequest.WithBody<T>(url) {
 
-    override fun extractResult(response: GithubApiResponse) {}
+    companion object {
+      inline fun <reified T> json(url: String, body: Any? = null): Delete<T> = Json(url, body, T::class.java)
+    }
+
+    open class Json<T>(url: String, body: Any? = null, clazz: Class<T>) : Delete<T>(body?.let { GithubApiContentHelper.toJson(it) },
+                                                                                    GithubApiContentHelper.JSON_MIME_TYPE,
+                                                                                    url,
+                                                                                    GithubApiContentHelper.V3_JSON_MIME_TYPE) {
+      private val typeToken = TypeToken.get(clazz)
+
+      override fun extractResult(response: GithubApiResponse): T = parseJsonResponse(response, typeToken)
+    }
   }
 
   companion object {
diff --git a/plugins/github/src/org/jetbrains/plugins/github/api/GithubApiRequestExecutor.kt b/plugins/github/src/org/jetbrains/plugins/github/api/GithubApiRequestExecutor.kt
index a0d8cdf4cd4e..2f988245ea35 100644
--- a/plugins/github/src/org/jetbrains/plugins/github/api/GithubApiRequestExecutor.kt
+++ b/plugins/github/src/org/jetbrains/plugins/github/api/GithubApiRequestExecutor.kt
@@ -149,7 +149,9 @@ sealed class GithubApiRequestExecutor {
         is GithubApiRequest.Put -> HttpRequests.put(request.url, request.bodyMimeType)
         is GithubApiRequest.Patch -> HttpRequests.patch(request.url, request.bodyMimeType)
         is GithubApiRequest.Head -> HttpRequests.head(request.url)
-        is GithubApiRequest.Delete -> HttpRequests.delete(request.url)
+        is GithubApiRequest.Delete -> {
+          if (request.body == null) HttpRequests.delete(request.url) else HttpRequests.delete(request.url, request.bodyMimeType)
+        }
         else -> throw UnsupportedOperationException("${request.javaClass} is not supported")
       }
         .connectTimeout(githubSettings.connectionTimeout)
diff --git a/plugins/github/src/org/jetbrains/plugins/github/api/GithubApiRequests.kt b/plugins/github/src/org/jetbrains/plugins/github/api/GithubApiRequests.kt
index e94577a520d8..b77dd9f91157 100644
--- a/plugins/github/src/org/jetbrains/plugins/github/api/GithubApiRequests.kt
+++ b/plugins/github/src/org/jetbrains/plugins/github/api/GithubApiRequests.kt
@@ -100,7 +100,7 @@ object GithubApiRequests {
       delete(getUrl(server, urlSuffix, "/$username/$repoName")).withOperationName("delete repository $username/$repoName")
 
     @JvmStatic
-    fun delete(url: String) = Delete(url).withOperationName("delete repository at $url")
+    fun delete(url: String) = Delete.json<Unit>(url).withOperationName("delete repository at $url")
 
     object Branches : Entity("/branches") {
       @JvmStatic
@@ -136,8 +136,50 @@ object GithubApiRequests {
       fun get(url: String) = Get.jsonPage<GithubRepo>(url).withOperationName("get forks")
     }
 
+    object Assignees : Entity("/assignees") {
+
+      @JvmStatic
+      fun pages(server: GithubServerPath, username: String, repoName: String) =
+        GithubApiPagesLoader.Request(get(server, username, repoName), ::get)
+
+      @JvmOverloads
+      @JvmStatic
+      fun get(server: GithubServerPath, username: String, repoName: String, pagination: GithubRequestPagination? = null) =
+        get(getUrl(server, Repos.urlSuffix, "/$username/$repoName", urlSuffix, getQuery(pagination?.toString().orEmpty())))
+
+      @JvmStatic
+      fun get(url: String) = Get.jsonPage<GithubUser>(url).withOperationName("get assignees")
+    }
+
+    object Labels : Entity("/labels") {
+
+      @JvmStatic
+      fun pages(server: GithubServerPath, username: String, repoName: String) =
+        GithubApiPagesLoader.Request(get(server, username, repoName), ::get)
+
+      @JvmOverloads
+      @JvmStatic
+      fun get(server: GithubServerPath, username: String, repoName: String, pagination: GithubRequestPagination? = null) =
+        get(getUrl(server, Repos.urlSuffix, "/$username/$repoName", urlSuffix, getQuery(pagination?.toString().orEmpty())))
+
+      @JvmStatic
+      fun get(url: String) = Get.jsonPage<GithubIssueLabel>(url).withOperationName("get assignees")
+    }
+
     object Collaborators : Entity("/collaborators") {
 
+      @JvmStatic
+      fun pages(server: GithubServerPath, username: String, repoName: String) =
+        GithubApiPagesLoader.Request(get(server, username, repoName), ::get)
+
+      @JvmOverloads
+      @JvmStatic
+      fun get(server: GithubServerPath, username: String, repoName: String, pagination: GithubRequestPagination? = null) =
+        get(getUrl(server, Repos.urlSuffix, "/$username/$repoName", urlSuffix, getQuery(pagination?.toString().orEmpty())))
+
+      @JvmStatic
+      fun get(url: String) = Get.jsonPage<GithubUserWithPermissions>(url).withOperationName("get collaborators")
+
       @JvmStatic
       fun add(server: GithubServerPath, username: String, repoName: String, collaborator: String) =
         Put.json<Any>(getUrl(server, Repos.urlSuffix, "/$username/$repoName", urlSuffix, "/", collaborator))
@@ -180,6 +222,11 @@ object GithubApiRequests {
         Patch.json<GithubIssue>(getUrl(server, Repos.urlSuffix, "/$username/$repoName", urlSuffix, "/", id),
                                 GithubChangeIssueStateRequest(if (open) "open" else "closed"))
 
+      @JvmStatic
+      fun updateAssignees(server: GithubServerPath, username: String, repoName: String, id: String, assignees: Collection<String>) =
+        Patch.json<GithubIssue>(getUrl(server, Repos.urlSuffix, "/$username/$repoName", urlSuffix, "/", id),
+                                GithubAssigneesCollectionRequest(assignees))
+
       object Comments : Entity("/comments") {
         @JvmStatic
         fun create(server: GithubServerPath, username: String, repoName: String, issueId: String, body: String) =
@@ -203,6 +250,13 @@ object GithubApiRequests {
         fun get(url: String) = Get.jsonPage<GithubIssueCommentWithHtml>(url, GithubApiContentHelper.V3_HTML_JSON_MIME_TYPE)
           .withOperationName("get comments for issue")
       }
+
+      object Labels : Entity("/labels") {
+        @JvmStatic
+        fun replace(server: GithubServerPath, username: String, repoName: String, issueId: String, labels: Collection<String>) =
+          Put.jsonList<GithubIssueLabel>(getUrl(server, Repos.urlSuffix, "/$username/$repoName", Issues.urlSuffix, "/", issueId, urlSuffix),
+                                         GithubLabelsCollectionRequest(labels))
+      }
     }
 
     object PullRequests : Entity("/pulls") {
@@ -265,6 +319,18 @@ object GithubApiRequests {
           .withOperationName("rebase and merge pull request ${pullRequest.number}")
 
       private fun getMergeUrl(pullRequest: GithubPullRequest) = pullRequest.url + "/merge"
+
+      object Reviewers : Entity("/requested_reviewers") {
+        @JvmStatic
+        fun add(server: GithubServerPath, username: String, repoName: String, number: Long, reviewers: Collection<String>) =
+          Post.json<Unit>(getUrl(server, Repos.urlSuffix, "/$username/$repoName", PullRequests.urlSuffix, "/$number", urlSuffix),
+                          GithubReviewersCollectionRequest(reviewers, listOf<String>()))
+
+        @JvmStatic
+        fun remove(server: GithubServerPath, username: String, repoName: String, number: Long, reviewers: Collection<String>) =
+          Delete.json<Unit>(getUrl(server, Repos.urlSuffix, "/$username/$repoName", PullRequests.urlSuffix, "/$number", urlSuffix),
+                            GithubReviewersCollectionRequest(reviewers, listOf<String>()))
+      }
     }
   }
 
@@ -280,7 +346,7 @@ object GithubApiRequests {
       .withOperationName("get gist $id")
 
     @JvmStatic
-    fun delete(server: GithubServerPath, id: String) = Delete(getUrl(server, urlSuffix, "/$id"))
+    fun delete(server: GithubServerPath, id: String) = Delete.json<Unit>(getUrl(server, urlSuffix, "/$id"))
       .withOperationName("delete gist $id")
   }
 
diff --git a/plugins/github/src/org/jetbrains/plugins/github/api/data/GithubIssueLabel.java b/plugins/github/src/org/jetbrains/plugins/github/api/data/GithubIssueLabel.java
index bb33066d9192..67f200d6a135 100644
--- a/plugins/github/src/org/jetbrains/plugins/github/api/data/GithubIssueLabel.java
+++ b/plugins/github/src/org/jetbrains/plugins/github/api/data/GithubIssueLabel.java
@@ -19,7 +19,7 @@ import org.jetbrains.io.mandatory.RestModel;
 @RestModel
 @SuppressWarnings("UnusedDeclaration")
 public class GithubIssueLabel {
-  private Long id;
+  @Mandatory private Long id;
   private String nodeId;
   private String url;
   @Mandatory private String name;
@@ -35,4 +35,21 @@ public class GithubIssueLabel {
   public String getColor() {
     return color;
   }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) return true;
+    if (!(o instanceof GithubIssueLabel)) return false;
+
+    GithubIssueLabel label = (GithubIssueLabel)o;
+
+    if (!id.equals(label.id)) return false;
+
+    return true;
+  }
+
+  @Override
+  public int hashCode() {
+    return id.hashCode();
+  }
 }
diff --git a/plugins/github/src/org/jetbrains/plugins/github/api/data/GithubPermissions.java b/plugins/github/src/org/jetbrains/plugins/github/api/data/GithubPermissions.java
new file mode 100644
index 000000000000..94d34567b8e9
--- /dev/null
+++ b/plugins/github/src/org/jetbrains/plugins/github/api/data/GithubPermissions.java
@@ -0,0 +1,24 @@
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package org.jetbrains.plugins.github.api.data;
+
+import org.jetbrains.io.mandatory.Mandatory;
+import org.jetbrains.io.mandatory.RestModel;
+
+@RestModel
+public class GithubPermissions {
+  @Mandatory private Boolean admin;
+  @Mandatory private Boolean pull;
+  @Mandatory private Boolean push;
+
+  public boolean isAdmin() {
+    return admin;
+  }
+
+  public boolean isPull() {
+    return pull;
+  }
+
+  public boolean isPush() {
+    return push;
+  }
+}
\ No newline at end of file
diff --git a/plugins/github/src/org/jetbrains/plugins/github/api/data/GithubRepoWithPermissions.java b/plugins/github/src/org/jetbrains/plugins/github/api/data/GithubRepoWithPermissions.java
index e35a9f3086f4..738149843d28 100644
--- a/plugins/github/src/org/jetbrains/plugins/github/api/data/GithubRepoWithPermissions.java
+++ b/plugins/github/src/org/jetbrains/plugins/github/api/data/GithubRepoWithPermissions.java
@@ -5,33 +5,13 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.io.mandatory.Mandatory;
 import org.jetbrains.io.mandatory.RestModel;
 
-//example/GithubRepoWithPermissions.json
 @RestModel
 @SuppressWarnings("UnusedDeclaration")
 public class GithubRepoWithPermissions extends GithubRepo {
-  @Mandatory private Permissions permissions;
+  @Mandatory private GithubPermissions permissions;
 
   @NotNull
-  public Permissions getPermissions() {
+  public GithubPermissions getPermissions() {
     return permissions;
   }
-
-  @RestModel
-  public static class Permissions {
-    @Mandatory private Boolean admin;
-    @Mandatory private Boolean pull;
-    @Mandatory private Boolean push;
-
-    public boolean isAdmin() {
-      return admin;
-    }
-
-    public boolean isPull() {
-      return pull;
-    }
-
-    public boolean isPush() {
-      return push;
-    }
-  }
 }
diff --git a/plugins/github/src/org/jetbrains/plugins/github/api/data/GithubUserWithPermissions.java b/plugins/github/src/org/jetbrains/plugins/github/api/data/GithubUserWithPermissions.java
new file mode 100644
index 000000000000..978524c8936c
--- /dev/null
+++ b/plugins/github/src/org/jetbrains/plugins/github/api/data/GithubUserWithPermissions.java
@@ -0,0 +1,17 @@
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package org.jetbrains.plugins.github.api.data;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.io.mandatory.Mandatory;
+import org.jetbrains.io.mandatory.RestModel;
+
+@RestModel
+@SuppressWarnings("UnusedDeclaration")
+public class GithubUserWithPermissions extends GithubUser {
+  @Mandatory private GithubPermissions permissions;
+
+  @NotNull
+  public GithubPermissions getPermissions() {
+    return permissions;
+  }
+}
diff --git a/plugins/github/src/org/jetbrains/plugins/github/api/requests/GithubAssigneesCollectionRequest.java b/plugins/github/src/org/jetbrains/plugins/github/api/requests/GithubAssigneesCollectionRequest.java
new file mode 100644
index 000000000000..d4147cfb17fb
--- /dev/null
+++ b/plugins/github/src/org/jetbrains/plugins/github/api/requests/GithubAssigneesCollectionRequest.java
@@ -0,0 +1,15 @@
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package org.jetbrains.plugins.github.api.requests;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Collection;
+
+@SuppressWarnings({"FieldCanBeLocal", "UnusedDeclaration"})
+public class GithubAssigneesCollectionRequest {
+  @NotNull private final Collection<String> assignees;
+
+  public GithubAssigneesCollectionRequest(@NotNull Collection<String> assignees) {
+    this.assignees = assignees;
+  }
+}
diff --git a/plugins/github/src/org/jetbrains/plugins/github/api/requests/GithubLabelsCollectionRequest.java b/plugins/github/src/org/jetbrains/plugins/github/api/requests/GithubLabelsCollectionRequest.java
new file mode 100644
index 000000000000..4f2184393db4
--- /dev/null
+++ b/plugins/github/src/org/jetbrains/plugins/github/api/requests/GithubLabelsCollectionRequest.java
@@ -0,0 +1,15 @@
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package org.jetbrains.plugins.github.api.requests;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Collection;
+
+@SuppressWarnings({"FieldCanBeLocal", "UnusedDeclaration"})
+public class GithubLabelsCollectionRequest {
+  @NotNull private final Collection<String> labels;
+
+  public GithubLabelsCollectionRequest(@NotNull Collection<String> labels) {
+    this.labels = labels;
+  }
+}
diff --git a/plugins/github/src/org/jetbrains/plugins/github/api/requests/GithubReviewersCollectionRequest.java b/plugins/github/src/org/jetbrains/plugins/github/api/requests/GithubReviewersCollectionRequest.java
new file mode 100644
index 000000000000..7e1376553ba7
--- /dev/null
+++ b/plugins/github/src/org/jetbrains/plugins/github/api/requests/GithubReviewersCollectionRequest.java
@@ -0,0 +1,18 @@
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package org.jetbrains.plugins.github.api.requests;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Collection;
+
+@SuppressWarnings({"FieldCanBeLocal", "UnusedDeclaration"})
+public class GithubReviewersCollectionRequest {
+  @NotNull private final Collection<String> reviewers;
+  @NotNull private final Collection<String> team_reviewers;
+
+  public GithubReviewersCollectionRequest(@NotNull Collection<String> reviewers,
+                                          @NotNull Collection<String> team_reviewers) {
+    this.reviewers = reviewers;
+    this.team_reviewers = team_reviewers;
+  }
+}
diff --git a/plugins/github/src/org/jetbrains/plugins/github/pullrequest/GithubPullRequestsComponentFactory.kt b/plugins/github/src/org/jetbrains/plugins/github/pullrequest/GithubPullRequestsComponentFactory.kt
index d93acf134087..4c12a3e3c57c 100644
--- a/plugins/github/src/org/jetbrains/plugins/github/pullrequest/GithubPullRequestsComponentFactory.kt
+++ b/plugins/github/src/org/jetbrains/plugins/github/pullrequest/GithubPullRequestsComponentFactory.kt
@@ -25,6 +25,7 @@ import org.jetbrains.plugins.github.pullrequest.config.GithubPullRequestsProject
 import org.jetbrains.plugins.github.pullrequest.data.GithubPullRequestsBusyStateTrackerImpl
 import org.jetbrains.plugins.github.pullrequest.data.GithubPullRequestsDataLoader
 import org.jetbrains.plugins.github.pullrequest.data.GithubPullRequestsLoader
+import org.jetbrains.plugins.github.pullrequest.data.service.GithubPullRequestsMetadataServiceImpl
 import org.jetbrains.plugins.github.pullrequest.data.service.GithubPullRequestsSecurityServiceImpl
 import org.jetbrains.plugins.github.pullrequest.data.service.GithubPullRequestsStateServiceImpl
 import org.jetbrains.plugins.github.pullrequest.ui.GithubPullRequestChangesComponent
@@ -73,13 +74,16 @@ internal class GithubPullRequestsComponentFactory(private val project: Project,
     private val securityService = GithubPullRequestsSecurityServiceImpl(sharedProjectSettings, accountDetails, repoDetails)
     private val busyStateTracker = GithubPullRequestsBusyStateTrackerImpl()
 
+    private val metadataService = GithubPullRequestsMetadataServiceImpl(project, progressManager, dataLoader, busyStateTracker,
+                                                                        requestExecutor,
+                                                                        avatarIconsProviderFactory, account.server, repoDetails.fullPath)
     private val stateService = GithubPullRequestsStateServiceImpl(project, progressManager, dataLoader, busyStateTracker, requestExecutor,
                                                                   account.server, repoDetails.fullPath)
 
     private val changes = GithubPullRequestChangesComponent(project, pullRequestUiSettings).apply {
       diffAction.registerCustomShortcutSet(this@GithubPullRequestsComponent, this@GithubPullRequestsComponent)
     }
-    private val details = GithubPullRequestDetailsComponent(dataLoader, securityService, busyStateTracker, stateService,
+    private val details = GithubPullRequestDetailsComponent(dataLoader, securityService, busyStateTracker, metadataService, stateService,
                                                             avatarIconsProviderFactory)
     private val preview = GithubPullRequestPreviewComponent(changes, details)
 
diff --git a/plugins/github/src/org/jetbrains/plugins/github/pullrequest/data/service/GithubPullRequestsMetadataService.kt b/plugins/github/src/org/jetbrains/plugins/github/pullrequest/data/service/GithubPullRequestsMetadataService.kt
new file mode 100644
index 000000000000..bd15b36b0907
--- /dev/null
+++ b/plugins/github/src/org/jetbrains/plugins/github/pullrequest/data/service/GithubPullRequestsMetadataService.kt
@@ -0,0 +1,16 @@
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package org.jetbrains.plugins.github.pullrequest.data.service
+
+import org.jetbrains.annotations.CalledInAwt
+import javax.swing.JComponent
+
+interface GithubPullRequestsMetadataService {
+  @CalledInAwt
+  fun adjustReviewers(pullRequest: Long, parentComponent: JComponent)
+
+  @CalledInAwt
+  fun adjustAssignees(pullRequest: Long, parentComponent: JComponent)
+
+  @CalledInAwt
+  fun adjustLabels(pullRequest: Long, parentComponent: JComponent)
+}
\ No newline at end of file
diff --git a/plugins/github/src/org/jetbrains/plugins/github/pullrequest/data/service/GithubPullRequestsMetadataServiceImpl.kt b/plugins/github/src/org/jetbrains/plugins/github/pullrequest/data/service/GithubPullRequestsMetadataServiceImpl.kt
new file mode 100644
index 000000000000..4f952d4f6215
--- /dev/null
+++ b/plugins/github/src/org/jetbrains/plugins/github/pullrequest/data/service/GithubPullRequestsMetadataServiceImpl.kt
@@ -0,0 +1,311 @@
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package org.jetbrains.plugins.github.pullrequest.data.service
+
+import com.intellij.icons.AllIcons
+import com.intellij.openapi.Disposable
+import com.intellij.openapi.progress.EmptyProgressIndicator
+import com.intellij.openapi.progress.ProgressIndicator
+import com.intellij.openapi.progress.ProgressManager
+import com.intellij.openapi.progress.Task
+import com.intellij.openapi.project.Project
+import com.intellij.openapi.ui.popup.JBPopupListener
+import com.intellij.openapi.ui.popup.LightweightWindowEvent
+import com.intellij.openapi.ui.popup.PopupChooserBuilder
+import com.intellij.openapi.util.Disposer
+import com.intellij.openapi.util.text.StringUtil
+import com.intellij.ui.CollectionListModel
+import com.intellij.ui.ColorUtil
+import com.intellij.ui.SimpleTextAttributes
+import com.intellij.ui.components.JBList
+import com.intellij.util.ui.ColorIcon
+import com.intellij.util.ui.JBUI
+import com.intellij.util.ui.StatusText
+import com.intellij.util.ui.UIUtil
+import com.intellij.util.ui.components.BorderLayoutPanel
+import org.jetbrains.plugins.github.api.GithubApiRequestExecutor
+import org.jetbrains.plugins.github.api.GithubApiRequests
+import org.jetbrains.plugins.github.api.GithubFullPath
+import org.jetbrains.plugins.github.api.GithubServerPath
+import org.jetbrains.plugins.github.api.data.GithubIssueLabel
+import org.jetbrains.plugins.github.api.data.GithubPullRequestDetailed
+import org.jetbrains.plugins.github.api.data.GithubPullRequestDetailedWithHtml
+import org.jetbrains.plugins.github.api.data.GithubUser
+import org.jetbrains.plugins.github.api.util.GithubApiPagesLoader
+import org.jetbrains.plugins.github.pullrequest.avatars.CachingGithubAvatarIconsProvider
+import org.jetbrains.plugins.github.pullrequest.data.GithubPullRequestsBusyStateTracker
+import org.jetbrains.plugins.github.pullrequest.data.GithubPullRequestsDataLoader
+import org.jetbrains.plugins.github.util.*
+import java.awt.Component
+import java.util.concurrent.CompletableFuture
+import java.util.function.Consumer
+import java.util.function.Function
+import javax.swing.*
+
+class GithubPullRequestsMetadataServiceImpl internal constructor(private val project: Project,
+                                                                 private val progressManager: ProgressManager,
+                                                                 private val dataLoader: GithubPullRequestsDataLoader,
+                                                                 private val busyStateTracker: GithubPullRequestsBusyStateTracker,
+                                                                 private val requestExecutor: GithubApiRequestExecutor,
+                                                                 private val avatarIconsProviderFactory: CachingGithubAvatarIconsProvider.Factory,
+                                                                 private val serverPath: GithubServerPath,
+                                                                 private val repoPath: GithubFullPath)
+  : GithubPullRequestsMetadataService {
+
+  private val repoCollaboratorsWithPushAccess: List<GithubUser> by lazy {
+    GithubApiPagesLoader
+      .loadAll(requestExecutor, progressManager.progressIndicator,
+               GithubApiRequests.Repos.Collaborators.pages(serverPath, repoPath.user, repoPath.repository))
+      .filter { it.permissions.isPush }
+  }
+
+  private val repoIssuesAssignees: List<GithubUser> by lazy {
+    GithubApiPagesLoader.loadAll(requestExecutor, progressManager.progressIndicator,
+                                 GithubApiRequests.Repos.Assignees.pages(serverPath, repoPath.user, repoPath.repository))
+  }
+
+  private val repoIssuesLabels: List<GithubIssueLabel> by lazy {
+    GithubApiPagesLoader.loadAll(requestExecutor, progressManager.progressIndicator,
+                                 GithubApiRequests.Repos.Labels.pages(serverPath, repoPath.user, repoPath.repository))
+  }
+
+  override fun adjustReviewers(pullRequest: Long, parentComponent: JComponent) {
+    showUsersChooser(pullRequest, "Reviewers", parentComponent,
+                     { _, details -> repoCollaboratorsWithPushAccess.filter { details.user != it } }) { it.requestedReviewers }
+      .handleOnEdt(getAdjustmentHandler(pullRequest, "reviewer") { delta, indicator ->
+        if (delta.removedItems.isNotEmpty()) {
+          indicator.text2 = "Removing reviewers"
+          requestExecutor.execute(indicator,
+                                  GithubApiRequests.Repos.PullRequests.Reviewers
+                                    .remove(serverPath, repoPath.user, repoPath.repository, pullRequest,
+                                            delta.removedItems.map { it.login }))
+        }
+        if (delta.newItems.isNotEmpty()) {
+          indicator.text2 = "Adding reviewers"
+          requestExecutor.execute(indicator,
+                                  GithubApiRequests.Repos.PullRequests.Reviewers
+                                    .add(serverPath, repoPath.user, repoPath.repository, pullRequest,
+                                         delta.newItems.map { it.login }))
+        }
+      })
+  }
+
+  override fun adjustAssignees(pullRequest: Long, parentComponent: JComponent) {
+    showUsersChooser(pullRequest, "Assignees", parentComponent, { _, _ -> repoIssuesAssignees }) { it.assignees }
+      .handleOnEdt(getAdjustmentHandler(pullRequest, "assignee") { delta, indicator ->
+        requestExecutor.execute(indicator,
+                                GithubApiRequests.Repos.Issues
+                                  .updateAssignees(serverPath, repoPath.user, repoPath.repository, pullRequest.toString(),
+                                                   delta.newCollection.map { it.login }))
+      })
+  }
+
+  override fun adjustLabels(pullRequest: Long, parentComponent: JComponent) {
+    showChooser(pullRequest, "Labels", parentComponent,
+                { SelectionListCellRenderer.Labels() }, { it.name },
+                { _, _ -> repoIssuesLabels }, { it.labels.orEmpty() })
+      .handleOnEdt(getAdjustmentHandler(pullRequest, "label") { delta, indicator ->
+        requestExecutor.execute(indicator,
+                                GithubApiRequests.Repos.Issues.Labels
+                                  .replace(serverPath, repoPath.user, repoPath.repository, pullRequest.toString(),
+                                           delta.newCollection.map { it.name }))
+      })
+  }
+
+  private fun showUsersChooser(pullRequest: Long,
+                               popupTitle: String,
+                               parentComponent: JComponent,
+                               availableListProvider: (ProgressIndicator, GithubPullRequestDetailed) -> List<GithubUser>,
+                               currentListExtractor: (GithubPullRequestDetailed) -> List<GithubUser>)
+    : CompletableFuture<CollectionDelta<GithubUser>> {
+    return showChooser(pullRequest, popupTitle, parentComponent, { list ->
+      val avatarIconsProvider = avatarIconsProviderFactory.create(JBUI.uiIntValue("GitHub.Avatars.Size", 20), list)
+      SelectionListCellRenderer.Users(avatarIconsProvider)
+    }, { it.login }, availableListProvider, currentListExtractor)
+  }
+
+  private fun <T> showChooser(pullRequest: Long,
+                              popupTitle: String,
+                              parentComponent: JComponent,
+                              cellRendererFactory: (JList<SelectableWrapper<T>>) -> ListCellRenderer<SelectableWrapper<T>>,
+                              speedSearchNamer: (T) -> String,
+                              availableListProvider: (ProgressIndicator, GithubPullRequestDetailed) -> List<T>,
+                              currentListExtractor: (GithubPullRequestDetailed) -> List<T>)
+    : CompletableFuture<CollectionDelta<T>> {
+
+    val listModel = CollectionListModel<SelectableWrapper<T>>()
+    val list = JBList<SelectableWrapper<T>>(listModel)
+
+    val builder = PopupChooserBuilder<SelectableWrapper<T>>(list)
+      .setTitle(popupTitle)
+      .setResizable(true)
+      .setMovable(true)
+      .setNamerForFiltering { speedSearchNamer(it.value) }
+      .setAutoSelectIfEmpty(false)
+      .setCloseOnEnter(false)
+      .setRenderer(cellRendererFactory(list))
+      .setItemsChosenCallback {
+        for (item in it) {
+          item.selected = !item.selected
+        }
+        list.repaint()
+      }
+    val popup = builder.createPopup()
+
+    val updater = builder.backgroundUpdater
+    updater.paintBusy(true)
+    list.emptyText.text = "Loading..."
+
+    var originalSelection: Set<T> = setOf()
+
+    val progressIndicator = EmptyProgressIndicator()
+    Disposer.register(popup, Disposable { progressIndicator.cancel() })
+
+    val loadingFuture = GithubAsyncUtil
+      .futureOfMutable { dataLoader.getDataProvider(pullRequest).detailsRequest }
+      .thenComposeAsync(Function { details: GithubPullRequestDetailedWithHtml ->
+        originalSelection = currentListExtractor(details).toHashSet()
+        progressManager.submitBackgroundTask(project, "Load List Of Possibilities", true, progressIndicator) {
+          availableListProvider(it, details)
+        }
+      })
+      .thenAcceptAsync(Consumer { possibilities ->
+        listModel.replaceAll(possibilities
+                               .map { SelectableWrapper(it, originalSelection.contains(it)) }
+                               .sortedBy { !it.selected })
+
+        updater.paintBusy(false)
+        list.emptyText.text = StatusText.DEFAULT_EMPTY_TEXT
+
+        popup.pack(true, true)
+      }, EDT_EXECUTOR)
+      .exceptionally {
+        updater.paintBusy(false)
+        list.emptyText.clear()
+        list.emptyText.appendText("Can't load the list", SimpleTextAttributes.ERROR_ATTRIBUTES)
+        list.emptyText.appendSecondaryText(it.message.orEmpty(), SimpleTextAttributes.ERROR_ATTRIBUTES, null)
+        throw it
+      }
+
+    Disposer.register(popup, Disposable {
+      loadingFuture.cancel(true)
+    })
+
+    val result = CompletableFuture<CollectionDelta<T>>()
+    popup.addListener(object : JBPopupListener {
+      override fun onClosed(event: LightweightWindowEvent) {
+        if (!loadingFuture.isDone || loadingFuture.isCancelled || loadingFuture.isCompletedExceptionally) {
+          result.cancel(true)
+          return
+        }
+
+        val selected = listModel.items.filter { it.selected }.map { it.value }
+        result.complete(CollectionDelta(originalSelection, selected))
+      }
+    })
+    popup.showUnderneathOf(parentComponent)
+    return result
+  }
+
+  private fun <T> getAdjustmentHandler(pullRequest: Long,
+                                       entityName: String,
+                                       adjuster: (CollectionDelta<T>, ProgressIndicator) -> Unit): (CollectionDelta<T>?, Throwable?) -> Unit {
+    return handler@{ delta, error ->
+      if (error != null) {
+        if (!GithubAsyncUtil.isCancellation(error))
+          GithubNotifications.showError(project, "Failed to adjust list of ${StringUtil.pluralize(entityName)}", error)
+        return@handler
+      }
+      if (delta == null || delta.isEmpty) {
+        return@handler
+      }
+
+      if (!busyStateTracker.acquire(pullRequest)) return@handler
+      progressManager.run(object : Task.Backgroundable(project, "Adjusting List Of ${StringUtil.pluralize(entityName).capitalize()}",
+                                                       true) {
+        override fun run(indicator: ProgressIndicator) {
+          adjuster(delta, indicator)
+        }
+
+        override fun onThrowable(error: Throwable) {
+          GithubNotifications.showError(project, "Failed to adjust list of ${StringUtil.pluralize(entityName)}", error)
+        }
+
+        override fun onFinished() {
+          busyStateTracker.release(pullRequest)
+          dataLoader.reloadDetails(pullRequest)
+        }
+      })
+    }
+  }
+
+  private data class SelectableWrapper<T>(val value: T, var selected: Boolean = false)
+
+  private sealed class SelectionListCellRenderer<T>
+    : ListCellRenderer<SelectableWrapper<T>>, BorderLayoutPanel() {
+
+    private val mainLabel = JLabel()
+    private val checkIconLabel = JLabel()
+
+    init {
+      checkIconLabel.iconTextGap = JBUI.scale(UIUtil.DEFAULT_VGAP)
+
+      addToLeft(checkIconLabel)
+      addToCenter(mainLabel)
+
+      border = JBUI.Borders.empty(2)
+    }
+
+    override fun getListCellRendererComponent(list: JList<out SelectableWrapper<T>>,
+                                              value: SelectableWrapper<T>,
+                                              index: Int,
+                                              isSelected: Boolean,
+                                              cellHasFocus: Boolean): Component {
+      font = list.font
+      foreground = UIUtil.getListForeground(isSelected, list.hasFocus())
+      background = UIUtil.getListBackground(isSelected, list.hasFocus())
+
+      mainLabel.foreground = foreground
+      mainLabel.font = font
+
+      mainLabel.text = getText(value.value)
+      mainLabel.icon = getIcon(value.value)
+
+      if (value.selected) {
+        checkIconLabel.icon = AllIcons.Actions.Checked
+        checkIconLabel.border = JBUI.Borders.empty(0, 4)
+      }
+      else {
+        checkIconLabel.icon = null
+        checkIconLabel.border = JBUI.Borders.empty(0, 10)
+      }
+
+      return this
+    }
+
+    abstract fun getText(value: T): String
+    abstract fun getIcon(value: T): Icon
+
+    class Users(private val iconsProvider: CachingGithubAvatarIconsProvider)
+      : SelectionListCellRenderer<GithubUser>() {
+
+      override fun getText(value: GithubUser) = value.login
+      override fun getIcon(value: GithubUser) = iconsProvider.getIcon(value)
+
+    }
+
+    class Labels
+      : SelectionListCellRenderer<GithubIssueLabel>() {
+
+      override fun getText(value: GithubIssueLabel) = value.name
+      override fun getIcon(value: GithubIssueLabel) = ColorIcon(16, ColorUtil.fromHex(value.color))
+
+    }
+  }
+
+  private class CollectionDelta<out T>(oldCollection: Collection<T>, val newCollection: Collection<T>) {
+    val newItems: Collection<T> = newCollection - oldCollection
+    val removedItems: Collection<T> = oldCollection - newCollection
+
+    val isEmpty = newItems.isEmpty() && removedItems.isEmpty()
+  }
+}
\ No newline at end of file
diff --git a/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/GithubPullRequestDetailsComponent.kt b/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/GithubPullRequestDetailsComponent.kt
index fe687c033d70..7386df0ed1da 100644
--- a/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/GithubPullRequestDetailsComponent.kt
+++ b/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/GithubPullRequestDetailsComponent.kt
@@ -14,6 +14,7 @@ import org.jetbrains.plugins.github.api.data.GithubPullRequestDetailedWithHtml
 import org.jetbrains.plugins.github.pullrequest.avatars.CachingGithubAvatarIconsProvider
 import org.jetbrains.plugins.github.pullrequest.data.GithubPullRequestsBusyStateTracker
 import org.jetbrains.plugins.github.pullrequest.data.GithubPullRequestsDataLoader
+import org.jetbrains.plugins.github.pullrequest.data.service.GithubPullRequestsMetadataService
 import org.jetbrains.plugins.github.pullrequest.data.service.GithubPullRequestsSecurityService
 import org.jetbrains.plugins.github.pullrequest.data.service.GithubPullRequestsStateService
 import org.jetbrains.plugins.github.pullrequest.ui.details.GithubPullRequestDetailsModel
@@ -23,12 +24,13 @@ import java.awt.BorderLayout
 internal class GithubPullRequestDetailsComponent(private val dataLoader: GithubPullRequestsDataLoader,
                                                  securityService: GithubPullRequestsSecurityService,
                                                  busyStateTracker: GithubPullRequestsBusyStateTracker,
+                                                 metadataService: GithubPullRequestsMetadataService,
                                                  stateService: GithubPullRequestsStateService,
                                                  iconProviderFactory: CachingGithubAvatarIconsProvider.Factory)
   : GithubDataLoadingComponent<GithubPullRequestDetailedWithHtml>(), Disposable {
 
   private val detailsModel = GithubPullRequestDetailsModel()
-  private val detailsPanel = GithubPullRequestDetailsPanel(detailsModel, securityService, busyStateTracker, stateService,
+  private val detailsPanel = GithubPullRequestDetailsPanel(detailsModel, securityService, busyStateTracker, metadataService, stateService,
                                                            iconProviderFactory)
 
   private val loadingPanel = JBLoadingPanel(BorderLayout(), this, ProgressWindow.DEFAULT_PROGRESS_DIALOG_POSTPONE_TIME_MILLIS).apply {
@@ -62,6 +64,8 @@ internal class GithubPullRequestDetailsComponent(private val dataLoader: GithubP
         dataLoader.reloadDetails(result.number)
       }
     }
+    validate()
+    repaint()
   }
 
   override fun handleError(error: Throwable) {
diff --git a/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/details/GithubPullRequestDetailsPanel.kt b/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/details/GithubPullRequestDetailsPanel.kt
index 6300a32df779..95aaab807dee 100644
--- a/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/details/GithubPullRequestDetailsPanel.kt
+++ b/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/details/GithubPullRequestDetailsPanel.kt
@@ -17,6 +17,7 @@ import net.miginfocom.layout.LC
 import net.miginfocom.swing.MigLayout
 import org.jetbrains.plugins.github.pullrequest.avatars.CachingGithubAvatarIconsProvider
 import org.jetbrains.plugins.github.pullrequest.data.GithubPullRequestsBusyStateTracker
+import org.jetbrains.plugins.github.pullrequest.data.service.GithubPullRequestsMetadataService
 import org.jetbrains.plugins.github.pullrequest.data.service.GithubPullRequestsSecurityService
 import org.jetbrains.plugins.github.pullrequest.data.service.GithubPullRequestsStateService
 import java.awt.Graphics
@@ -28,6 +29,7 @@ import javax.swing.JPanel
 internal class GithubPullRequestDetailsPanel(model: GithubPullRequestDetailsModel,
                                              securityService: GithubPullRequestsSecurityService,
                                              busyStateTracker: GithubPullRequestsBusyStateTracker,
+                                             metadataService: GithubPullRequestsMetadataService,
                                              stateService: GithubPullRequestsStateService,
                                              iconProviderFactory: CachingGithubAvatarIconsProvider.Factory)
   : JPanel(), ComponentWithEmptyText, Disposable {
@@ -37,7 +39,7 @@ internal class GithubPullRequestDetailsPanel(model: GithubPullRequestDetailsMode
   }
   private val iconsProvider = iconProviderFactory.create(JBValue.UIInteger("Profile.Icon.Size", 20), this)
 
-  private val metaPanel = GithubPullRequestMetadataPanel(model, iconsProvider).apply {
+  private val metaPanel = GithubPullRequestMetadataPanel(model, securityService, busyStateTracker, metadataService, iconsProvider).apply {
     border = JBUI.Borders.empty(4, 8, 4, 8)
   }
   private val descriptionPanel = GithubPullRequestDescriptionPanel(model).apply {
diff --git a/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/details/GithubPullRequestMetadataPanel.kt b/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/details/GithubPullRequestMetadataPanel.kt
index c96dd05974a0..b6a8d98c946f 100644
--- a/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/details/GithubPullRequestMetadataPanel.kt
+++ b/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/details/GithubPullRequestMetadataPanel.kt
@@ -2,6 +2,7 @@
 package org.jetbrains.plugins.github.pullrequest.ui.details
 
 import com.intellij.openapi.Disposable
+import com.intellij.openapi.util.Disposer
 import com.intellij.ui.components.panels.Wrapper
 import com.intellij.util.ui.JBUI
 import com.intellij.util.ui.UIUtil
@@ -9,21 +10,28 @@ import net.miginfocom.layout.CC
 import net.miginfocom.layout.LC
 import net.miginfocom.swing.MigLayout
 import org.jetbrains.plugins.github.api.data.GithubIssueLabel
+import org.jetbrains.plugins.github.api.data.GithubPullRequestDetailed
 import org.jetbrains.plugins.github.api.data.GithubUser
 import org.jetbrains.plugins.github.pullrequest.avatars.CachingGithubAvatarIconsProvider
+import org.jetbrains.plugins.github.pullrequest.data.GithubPullRequestsBusyStateTracker
+import org.jetbrains.plugins.github.pullrequest.data.service.GithubPullRequestsMetadataService
+import org.jetbrains.plugins.github.pullrequest.data.service.GithubPullRequestsSecurityService
 import org.jetbrains.plugins.github.util.GithubUIUtil
 import javax.swing.JLabel
 import javax.swing.JPanel
 import javax.swing.SwingConstants
 
 internal class GithubPullRequestMetadataPanel(private val model: GithubPullRequestDetailsModel,
+                                              private val securityService: GithubPullRequestsSecurityService,
+                                              private val busyStateTracker: GithubPullRequestsBusyStateTracker,
+                                              private val metadataService: GithubPullRequestsMetadataService,
                                               private val iconsProvider: CachingGithubAvatarIconsProvider)
   : JPanel(), Disposable {
 
   private val directionPanel = GithubPullRequestDirectionPanel()
-  private val reviewersHandle = LabeledListPanelHandle.create("No Reviewers", "Reviewers:", ::createUserLabel)
-  private val assigneesHandle = LabeledListPanelHandle.create("Unassigned", "Assignees:", ::createUserLabel)
-  private val labelsHandle = LabeledListPanelHandle.create("No Labels", "Labels:", ::createLabelLabel)
+  private val reviewersHandle = ReviewersListPanelHandle()
+  private val assigneesHandle = AssigneesListPanelHandle()
+  private val labelsHandle = LabelsListPanelHandle()
 
   init {
     isOpaque = false
@@ -42,10 +50,11 @@ internal class GithubPullRequestMetadataPanel(private val model: GithubPullReque
 
     model.addDetailsChangedListener(this) {
       directionPanel.direction = model.details?.let { it.head to it.base }
-      reviewersHandle.list = model.details?.requestedReviewers
-      assigneesHandle.list = model.details?.assignees
-      labelsHandle.list = model.details?.labels
     }
+
+    Disposer.register(this, reviewersHandle)
+    Disposer.register(this, assigneesHandle)
+    Disposer.register(this, labelsHandle)
   }
 
   private fun addListPanel(handle: LabeledListPanelHandle<*>) {
@@ -53,13 +62,48 @@ internal class GithubPullRequestMetadataPanel(private val model: GithubPullReque
     add(handle.panel, CC().minWidth("0").growX().pushX().wrap())
   }
 
+  override fun dispose() {}
+
+  private inner class ReviewersListPanelHandle
+    : LabeledListPanelHandle<GithubUser>(model, securityService, busyStateTracker, "No Reviewers", "Reviewers:") {
+    override fun extractItems(details: GithubPullRequestDetailed): List<GithubUser> = details.requestedReviewers
+
+    override fun getItemComponent(item: GithubUser) = createUserLabel(item)
+
+    override fun editList() {
+      model.details?.run { metadataService.adjustReviewers(number, editButton) }
+    }
+  }
+
+  private inner class AssigneesListPanelHandle
+    : LabeledListPanelHandle<GithubUser>(model, securityService, busyStateTracker, "Unassigned", "Assignees:") {
+
+    override fun extractItems(details: GithubPullRequestDetailed): List<GithubUser> = details.assignees
+
+    override fun getItemComponent(item: GithubUser) = createUserLabel(item)
+
+    override fun editList() {
+      model.details?.run { metadataService.adjustAssignees(number, editButton) }
+    }
+  }
+
   private fun createUserLabel(user: GithubUser) = JLabel(user.login, iconsProvider.getIcon(user), SwingConstants.LEFT).apply {
     border = JBUI.Borders.empty(UIUtil.DEFAULT_VGAP, UIUtil.DEFAULT_HGAP / 2, UIUtil.DEFAULT_VGAP, UIUtil.DEFAULT_HGAP / 2)
   }
 
+  private inner class LabelsListPanelHandle
+    : LabeledListPanelHandle<GithubIssueLabel>(model, securityService, busyStateTracker, "No Labels", "Labels:") {
+
+    override fun extractItems(details: GithubPullRequestDetailed): List<GithubIssueLabel>? = details.labels
+
+    override fun getItemComponent(item: GithubIssueLabel) = createLabelLabel(item)
+
+    override fun editList() {
+      model.details?.run { metadataService.adjustLabels(number, editButton) }
+    }
+  }
+
   private fun createLabelLabel(label: GithubIssueLabel) = Wrapper(GithubUIUtil.createIssueLabelLabel(label)).apply {
     border = JBUI.Borders.empty(UIUtil.DEFAULT_VGAP + 1, UIUtil.DEFAULT_HGAP / 2, UIUtil.DEFAULT_VGAP + 2, UIUtil.DEFAULT_HGAP / 2)
   }
-
-  override fun dispose() {}
 }
\ No newline at end of file
diff --git a/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/details/LabeledListPanelHandle.kt b/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/details/LabeledListPanelHandle.kt
index cd6386a31705..c1cd96191e6e 100644
--- a/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/details/LabeledListPanelHandle.kt
+++ b/plugins/github/src/org/jetbrains/plugins/github/pullrequest/ui/details/LabeledListPanelHandle.kt
@@ -1,39 +1,96 @@
 // Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.plugins.github.pullrequest.ui.details
 
+import com.intellij.icons.AllIcons
+import com.intellij.openapi.Disposable
+import com.intellij.openapi.ui.popup.IconButton
+import com.intellij.ui.InplaceButton
 import com.intellij.ui.components.panels.NonOpaquePanel
+import com.intellij.util.IconUtil
 import com.intellij.util.ui.JBUI
+import com.intellij.util.ui.JBUI.Panels.simplePanel
 import com.intellij.util.ui.UIUtil
+import org.jetbrains.plugins.github.api.data.GithubPullRequestDetailed
+import org.jetbrains.plugins.github.pullrequest.data.GithubPullRequestsBusyStateTracker
+import org.jetbrains.plugins.github.pullrequest.data.service.GithubPullRequestsSecurityService
 import org.jetbrains.plugins.github.pullrequest.ui.WrapLayout
 import org.jetbrains.plugins.github.util.GithubUtil.Delegates.equalVetoingObservable
+import java.awt.Cursor
 import java.awt.FlowLayout
+import java.awt.event.ActionListener
+import javax.swing.Icon
 import javax.swing.JComponent
 import javax.swing.JLabel
 
-internal abstract class LabeledListPanelHandle<T>(emptyText: String, notEmptyText: String) {
+internal abstract class LabeledListPanelHandle<T>(private val model: GithubPullRequestDetailsModel,
+                                                  private val securityService: GithubPullRequestsSecurityService,
+                                                  private val busyStateTracker: GithubPullRequestsBusyStateTracker,
+                                                  emptyText: String, notEmptyText: String)
+  : Disposable {
+
   val label = JLabel().apply {
     foreground = UIUtil.getContextHelpForeground()
     border = JBUI.Borders.empty(UIUtil.DEFAULT_VGAP + 2, 0, UIUtil.DEFAULT_VGAP + 2, UIUtil.DEFAULT_HGAP / 2)
   }
   val panel = NonOpaquePanel(WrapLayout(FlowLayout.LEADING, 0, 0))
 
-  var list: List<T>? by equalVetoingObservable<List<T>?>(null) { newList ->
+  protected val editButton = InplaceButton(IconButton(null,
+                                                      resizeSquareIcon(AllIcons.General.Inline_edit),
+                                                      resizeSquareIcon(AllIcons.General.Inline_edit_hovered)),
+                                           ActionListener { (::editList)() }).apply {
+    cursor = Cursor.getPredefinedCursor(Cursor.HAND_CURSOR)
+    isVisible = securityService.isCurrentUserWithPushAccess()
+  }
+
+  private fun resizeSquareIcon(icon: Icon): Icon {
+    val scale = 20f / icon.iconHeight
+    return IconUtil.scale(icon, editButton, scale)
+  }
+
+  private var list: List<T>? by equalVetoingObservable<List<T>?>(null) { newList ->
     label.text = newList?.let { if (it.isEmpty()) emptyText else notEmptyText }
     label.isVisible = newList != null
 
     panel.removeAll()
     panel.isVisible = newList != null
-    if (newList != null) for (item in newList) {
-      panel.add(getListItemComponent(item))
+    if (newList != null) {
+      if (newList.isEmpty()) {
+        panel.add(editButton)
+      }
+      else {
+        for (item in newList.dropLast(1)) {
+          panel.add(getListItemComponent(item))
+        }
+        panel.add(getListItemComponent(newList.last(), true))
+      }
     }
   }
 
-  abstract fun getListItemComponent(item: T): JComponent
-
-  companion object {
-    inline fun <T> create(emptyText: String, notEmptyText: String, crossinline componentProvider: (T) -> JComponent) =
-      object : LabeledListPanelHandle<T>(emptyText, notEmptyText) {
-        override fun getListItemComponent(item: T) = componentProvider(item)
-      }
+  init {
+    model.addDetailsChangedListener(this) {
+      list = model.details?.let(::extractItems)
+      updateButton()
+    }
+    busyStateTracker.addPullRequestBusyStateListener(this) {
+      updateButton()
+    }
   }
+
+  private fun updateButton() {
+    editButton.isEnabled = !(model.details?.number?.let(busyStateTracker::isBusy) ?: true)
+  }
+
+  private fun getListItemComponent(item: T, last: Boolean = false) =
+    if (!last) getItemComponent(item)
+    else simplePanel(getItemComponent(item)).addToRight(editButton).apply {
+      isOpaque = false
+    }
+
+  abstract fun extractItems(details: GithubPullRequestDetailed): List<T>?
+
+  abstract fun getItemComponent(item: T): JComponent
+
+  abstract fun editList()
+
+  override fun dispose() {}
 }
\ No newline at end of file
diff --git a/plugins/github/src/org/jetbrains/plugins/github/util/GithubAsyncUtil.kt b/plugins/github/src/org/jetbrains/plugins/github/util/GithubAsyncUtil.kt
index 187ef60c073f..612ab57960ca 100644
--- a/plugins/github/src/org/jetbrains/plugins/github/util/GithubAsyncUtil.kt
+++ b/plugins/github/src/org/jetbrains/plugins/github/util/GithubAsyncUtil.kt
@@ -4,6 +4,9 @@ package org.jetbrains.plugins.github.util
 import com.intellij.openapi.application.runInEdt
 import com.intellij.openapi.progress.ProcessCanceledException
 import com.intellij.openapi.progress.ProgressIndicator
+import com.intellij.openapi.progress.ProgressManager
+import com.intellij.openapi.progress.Task
+import com.intellij.openapi.project.Project
 import java.util.concurrent.*
 import java.util.function.BiFunction
 
@@ -33,6 +36,23 @@ object GithubAsyncUtil {
     return result
   }
 
+  @JvmStatic
+  fun <T> futureOfMutable(futureSupplier: () -> CompletableFuture<T>): CompletableFuture<T> {
+    val result = CompletableFuture<T>()
+    handleToOtherIfCancelled(futureSupplier, result)
+    return result
+  }
+
+  private fun <T> handleToOtherIfCancelled(futureSupplier: () -> CompletableFuture<T>, other: CompletableFuture<T>) {
+    futureSupplier().handle { result, error ->
+      if (result != null) other.complete(result)
+      if (error != null) {
+        if (isCancellation(error)) handleToOtherIfCancelled(futureSupplier, other)
+        other.completeExceptionally(error.cause)
+      }
+    }
+  }
+
   fun isCancellation(error: Throwable): Boolean {
     return error is ProcessCanceledException
            || error is CancellationException
@@ -41,6 +61,28 @@ object GithubAsyncUtil {
   }
 }
 
+fun <T> ProgressManager.submitBackgroundTask(project: Project,
+                                             title: String,
+                                             canBeCancelled: Boolean,
+                                             progressIndicator: ProgressIndicator,
+                                             process: (indicator: ProgressIndicator) -> T): CompletableFuture<T> {
+  val future = CompletableFuture<T>()
+  runProcessWithProgressAsynchronously(object : Task.Backgroundable(project, title, canBeCancelled) {
+    override fun run(indicator: ProgressIndicator) {
+      future.complete(process(indicator))
+    }
+
+    override fun onCancel() {
+      future.cancel(true)
+    }
+
+    override fun onThrowable(error: Throwable) {
+      future.completeExceptionally(error)
+    }
+  }, progressIndicator)
+  return future
+}
+
 fun <T> CompletableFuture<T>.handleOnEdt(handler: (T?, Throwable?) -> Unit): CompletableFuture<Unit> =
   handleAsync(BiFunction<T?, Throwable?, Unit> { result: T?, error: Throwable? ->
     handler(result, error)
diff --git a/plugins/github/src/org/jetbrains/plugins/github/util/GithubUIUtil.kt b/plugins/github/src/org/jetbrains/plugins/github/util/GithubUIUtil.kt
index 12f7149375f1..048d1ae8e684 100644
--- a/plugins/github/src/org/jetbrains/plugins/github/util/GithubUIUtil.kt
+++ b/plugins/github/src/org/jetbrains/plugins/github/util/GithubUIUtil.kt
@@ -41,7 +41,7 @@ object GithubUIUtil {
     }
   }
 
-  fun createIssueLabelLabel(label: GithubIssueLabel): JBLabel = JBLabel(" ${label.name} ", UIUtil.ComponentStyle.MINI).apply {
+  fun createIssueLabelLabel(label: GithubIssueLabel): JBLabel = JBLabel(" ${label.name} ", UIUtil.ComponentStyle.SMALL).apply {
     val apiColor = ColorUtil.fromHex(label.color)
     background = JBColor(apiColor, ColorUtil.darker(apiColor, 3))
     foreground = computeForeground(background)