Support Space explore pagination

changelog.d/3693.feature

@@ -0,0 +1 @@
+Space summary pagination

matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/room/model/SpaceChildInfo.kt

@@ -27,7 +27,7 @@ data class SpaceChildInfo(
         val avatarUrl: String?,
         val order: String?,
         val activeMemberCount: Int?,
-        val autoJoin: Boolean,
+//        val autoJoin: Boolean,
         val viaServers: List<String>,
         val parentRoomId: String?,
         val suggested: Boolean?,

matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/space/Space.kt

@@ -36,7 +36,7 @@ interface Space {
     suspend fun addChildren(roomId: String,
                             viaServers: List<String>?,
                             order: String?,
-                            autoJoin: Boolean = false,
+//                            autoJoin: Boolean = false,
                             suggested: Boolean? = false)
 
     fun getChildInfo(roomId: String): SpaceChildContent?
@@ -46,8 +46,8 @@ interface Space {
     @Throws
     suspend fun setChildrenOrder(roomId: String, order: String?)
 
-    @Throws
+//    @Throws
-    suspend fun setChildrenAutoJoin(roomId: String, autoJoin: Boolean)
+//    suspend fun setChildrenAutoJoin(roomId: String, autoJoin: Boolean)
 
     @Throws
     suspend fun setChildrenSuggested(roomId: String, suggested: Boolean)

matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/space/SpaceService.kt

@@ -18,9 +18,10 @@ package org.matrix.android.sdk.api.session.space
 
 import android.net.Uri
 import androidx.lifecycle.LiveData
+import org.matrix.android.sdk.api.session.events.model.Event
 import org.matrix.android.sdk.api.session.room.RoomSummaryQueryParams
 import org.matrix.android.sdk.api.session.room.model.RoomSummary
-import org.matrix.android.sdk.api.session.room.model.SpaceChildInfo
+import org.matrix.android.sdk.internal.session.space.SpaceHierarchySummary
 import org.matrix.android.sdk.internal.session.space.peeking.SpacePeekResult
 
 typealias SpaceSummaryQueryParams = RoomSummaryQueryParams
@@ -58,10 +59,18 @@ interface SpaceService {
 
     /**
      * Get's information of a space by querying the server
+     * @param suggestedOnly If true, return only child events and rooms where the m.space.child event has suggested: true.
+     * @param limit a client-defined limit to the maximum number of rooms to return per page. Must be a non-negative integer.
+     * @param maxDepth: Optional: The maximum depth in the tree (from the root room) to return.
+     * @param from: Optional. Pagination token given to retrieve the next set of rooms. Note that if a pagination token is provided,
+     * then the parameters given for suggested_only and max_depth must be the same.
      */
     suspend fun querySpaceChildren(spaceId: String,
                                    suggestedOnly: Boolean? = null,
-                                   autoJoinedOnly: Boolean? = null): Pair<RoomSummary, List<SpaceChildInfo>>
+                                   limit: Int? = null,
+                                   from: String? = null,
+                                   // when paginating, pass back the m.space.child state events
+                                   knownStateList: List<Event>? = null): SpaceHierarchySummary
 
     /**
      * Get a live list of space summaries. This list is refreshed as soon as the data changes.

matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/space/model/SpaceChildContent.kt

@@ -40,12 +40,12 @@ data class SpaceChildContent(
          * or consist of more than 50 characters, are forbidden and should be ignored if received.)
          */
         @Json(name = "order") val order: String? = null,
-        /**
+//        /**
-         * The auto_join flag on a child listing allows a space admin to list the sub-spaces and rooms in that space which should
+//         * The auto_join flag on a child listing allows a space admin to list the sub-spaces and rooms in that space which should
-         * be automatically joined by members of that space.
+//         * be automatically joined by members of that space.
-         * (This is not a force-join, which are descoped for a future MSC; the user can subsequently part these room if they desire.)
+//         * (This is not a force-join, which are descoped for a future MSC; the user can subsequently part these room if they desire.)
-         */
+//         */
-        @Json(name = "auto_join") val autoJoin: Boolean? = false,
+//        @Json(name = "auto_join") val autoJoin: Boolean? = false,
 
         /**
          * If `suggested` is set to `true`, that indicates that the child should be advertised to

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/database/mapper/RoomSummaryMapper.kt

@@ -88,7 +88,7 @@ internal class RoomSummaryMapper @Inject constructor(private val timelineEventMa
                             avatarUrl = it.childSummaryEntity?.avatarUrl,
                             activeMemberCount = it.childSummaryEntity?.joinedMembersCount,
                             order = it.order,
-                            autoJoin = it.autoJoin ?: false,
+//                            autoJoin = it.autoJoin ?: false,
                             viaServers = it.viaServers.toList(),
                             parentRoomId = roomSummaryEntity.roomId,
                             suggested = it.suggested,

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/relationship/RoomChildRelationInfo.kt

@@ -43,7 +43,7 @@ internal class RoomChildRelationInfo(
     data class SpaceChildInfo(
             val roomId: String,
             val order: String?,
-            val autoJoin: Boolean,
+//            val autoJoin: Boolean,
             val viaServers: List<String>
     )
 
@@ -71,7 +71,7 @@ internal class RoomChildRelationInfo(
                             SpaceChildInfo(
                                     roomId = it.stateKey,
                                     order = scc.validOrder(),
-                                    autoJoin = scc.autoJoin ?: false,
+//                                    autoJoin = scc.autoJoin ?: false,
                                     viaServers = via
                             )
                         }

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/summary/RoomSummaryUpdater.kt

@@ -220,7 +220,7 @@ internal class RoomSummaryUpdater @Inject constructor(
                                     this.childRoomId = child.roomId
                                     this.childSummaryEntity = RoomSummaryEntity.where(realm, child.roomId).findFirst()
                                     this.order = child.order
-                                    this.autoJoin = child.autoJoin
+//                                    this.autoJoin = child.autoJoin
                                     this.viaServers.addAll(child.viaServers)
                                 }
                         )

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/space/DefaultSpace.kt

@@ -51,7 +51,7 @@ internal class DefaultSpace(
     override suspend fun addChildren(roomId: String,
                                      viaServers: List<String>?,
                                      order: String?,
-                                     autoJoin: Boolean,
+//                                     autoJoin: Boolean,
                                      suggested: Boolean?) {
         // Find best via
         val bestVia = viaServers
@@ -69,7 +69,6 @@ internal class DefaultSpace(
                 stateKey = roomId,
                 body = SpaceChildContent(
                         via = bestVia,
-                        autoJoin = autoJoin,
                         order = order,
                         suggested = suggested
                 ).toContent()
@@ -90,7 +89,7 @@ internal class DefaultSpace(
                 body = SpaceChildContent(
                         order = null,
                         via = null,
-                        autoJoin = null,
+//                        autoJoin = null,
                         suggested = null
                 ).toContent()
         )
@@ -115,35 +114,35 @@ internal class DefaultSpace(
                 body = SpaceChildContent(
                         order = order,
                         via = existing.via,
-                        autoJoin = existing.autoJoin,
+//                        autoJoin = existing.autoJoin,
                         suggested = existing.suggested
                 ).toContent()
         )
     }
 
-    override suspend fun setChildrenAutoJoin(roomId: String, autoJoin: Boolean) {
+//    override suspend fun setChildrenAutoJoin(roomId: String, autoJoin: Boolean) {
-        val existing = room.getStateEvents(setOf(EventType.STATE_SPACE_CHILD), QueryStringValue.Equals(roomId))
+//        val existing = room.getStateEvents(setOf(EventType.STATE_SPACE_CHILD), QueryStringValue.Equals(roomId))
-                .firstOrNull()
+//                .firstOrNull()
-                ?.content.toModel<SpaceChildContent>()
+//                ?.content.toModel<SpaceChildContent>()
-                ?: throw IllegalArgumentException("$roomId is not a child of this space")
+//                ?: throw IllegalArgumentException("$roomId is not a child of this space")
-
+//
-        if (existing.autoJoin == autoJoin) {
+//        if (existing.autoJoin == autoJoin) {
-            // nothing to do?
+//            // nothing to do?
-            return
+//            return
-        }
+//        }
-
+//
-        // edit state event and set via to null
+//        // edit state event and set via to null
-        room.sendStateEvent(
+//        room.sendStateEvent(
-                eventType = EventType.STATE_SPACE_CHILD,
+//                eventType = EventType.STATE_SPACE_CHILD,
-                stateKey = roomId,
+//                stateKey = roomId,
-                body = SpaceChildContent(
+//                body = SpaceChildContent(
-                        order = existing.order,
+//                        order = existing.order,
-                        via = existing.via,
+//                        via = existing.via,
-                        autoJoin = autoJoin,
+//                        autoJoin = autoJoin,
-                        suggested = existing.suggested
+//                        suggested = existing.suggested
-                ).toContent()
+//                ).toContent()
-        )
+//        )
-    }
+//    }
 
     override suspend fun setChildrenSuggested(roomId: String, suggested: Boolean) {
         val existing = room.getStateEvents(setOf(EventType.STATE_SPACE_CHILD), QueryStringValue.Equals(roomId))
@@ -162,7 +161,7 @@ internal class DefaultSpace(
                 body = SpaceChildContent(
                         order = existing.order,
                         via = existing.via,
-                        autoJoin = existing.autoJoin,
+//                        autoJoin = existing.autoJoin,
                         suggested = suggested
                 ).toContent()
         )

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/space/DefaultSpaceService.kt

@@ -19,6 +19,7 @@ package org.matrix.android.sdk.internal.session.space
 import android.net.Uri
 import androidx.lifecycle.LiveData
 import org.matrix.android.sdk.api.query.QueryStringValue
+import org.matrix.android.sdk.api.session.events.model.Event
 import org.matrix.android.sdk.api.session.events.model.EventType
 import org.matrix.android.sdk.api.session.events.model.toContent
 import org.matrix.android.sdk.api.session.events.model.toModel
@@ -27,6 +28,7 @@ import org.matrix.android.sdk.api.session.room.model.Membership
 import org.matrix.android.sdk.api.session.room.model.PowerLevelsContent
 import org.matrix.android.sdk.api.session.room.model.RoomDirectoryVisibility
 import org.matrix.android.sdk.api.session.room.model.RoomHistoryVisibility
+import org.matrix.android.sdk.api.session.room.model.RoomJoinRules
 import org.matrix.android.sdk.api.session.room.model.RoomSummary
 import org.matrix.android.sdk.api.session.room.model.SpaceChildInfo
 import org.matrix.android.sdk.api.session.room.model.create.CreateRoomPreset
@@ -108,53 +110,65 @@ internal class DefaultSpaceService @Inject constructor(
 
     override suspend fun querySpaceChildren(spaceId: String,
                                             suggestedOnly: Boolean?,
-                                            autoJoinedOnly: Boolean?): Pair<RoomSummary, List<SpaceChildInfo>> {
+                                            limit: Int?,
-        return resolveSpaceInfoTask.execute(ResolveSpaceInfoTask.Params.withId(spaceId, suggestedOnly, autoJoinedOnly)).let { response ->
+                                            from: String?,
+                                            knownStateList: List<Event>?): SpaceHierarchySummary {
+        return resolveSpaceInfoTask.execute(
+                ResolveSpaceInfoTask.Params(
+                        spaceId = spaceId, limit = limit, maxDepth = 1, from = from, suggestedOnly = suggestedOnly
+                )
+        ).let { response ->
             val spaceDesc = response.rooms?.firstOrNull { it.roomId == spaceId }
-            Pair(
+            val root = RoomSummary(
-                    first = RoomSummary(
+                    roomId = spaceDesc?.roomId ?: spaceId,
-                            roomId = spaceDesc?.roomId ?: spaceId,
+                    roomType = spaceDesc?.roomType,
-                            roomType = spaceDesc?.roomType,
+                    name = spaceDesc?.name ?: "",
-                            name = spaceDesc?.name ?: "",
+                    displayName = spaceDesc?.name ?: "",
-                            displayName = spaceDesc?.name ?: "",
+                    topic = spaceDesc?.topic ?: "",
-                            topic = spaceDesc?.topic ?: "",
+                    joinedMembersCount = spaceDesc?.numJoinedMembers,
-                            joinedMembersCount = spaceDesc?.numJoinedMembers,
+                    avatarUrl = spaceDesc?.avatarUrl ?: "",
-                            avatarUrl = spaceDesc?.avatarUrl ?: "",
+                    encryptionEventTs = null,
-                            encryptionEventTs = null,
+                    typingUsers = emptyList(),
-                            typingUsers = emptyList(),
+                    isEncrypted = false,
-                            isEncrypted = false,
+                    flattenParentIds = emptyList(),
-                            flattenParentIds = emptyList()
+                    canonicalAlias = spaceDesc?.canonicalAlias,
-                    ),
+                    joinRules = RoomJoinRules.PUBLIC.takeIf { spaceDesc?.worldReadable == true }
-                    second = response.rooms
+            )
-                            ?.filter { it.roomId != spaceId }
+            val children = response.rooms
-                            ?.flatMap { childSummary ->
+                    ?.filter { it.roomId != spaceId }
-                                response.events
+                    ?.flatMap { childSummary ->
-                                        ?.filter { it.stateKey == childSummary.roomId && it.type == EventType.STATE_SPACE_CHILD }
+                        (spaceDesc?.childrenState ?: knownStateList)
-                                        ?.mapNotNull { childStateEv ->
+                                ?.filter { it.stateKey == childSummary.roomId && it.type == EventType.STATE_SPACE_CHILD }
-                                            // create a child entry for everytime this room is the child of a space
+                                ?.mapNotNull { childStateEv ->
-                                            // beware that a room could appear then twice in this list
+                                    // create a child entry for everytime this room is the child of a space
-                                            childStateEv.content.toModel<SpaceChildContent>()?.let { childStateEvContent ->
+                                    // beware that a room could appear then twice in this list
-                                                SpaceChildInfo(
+                                    childStateEv.content.toModel<SpaceChildContent>()?.let { childStateEvContent ->
-                                                        childRoomId = childSummary.roomId,
+                                        SpaceChildInfo(
-                                                        isKnown = true,
+                                                childRoomId = childSummary.roomId,
-                                                        roomType = childSummary.roomType,
+                                                isKnown = true,
-                                                        name = childSummary.name,
+                                                roomType = childSummary.roomType,
-                                                        topic = childSummary.topic,
+                                                name = childSummary.name,
-                                                        avatarUrl = childSummary.avatarUrl,
+                                                topic = childSummary.topic,
-                                                        order = childStateEvContent.order,
+                                                avatarUrl = childSummary.avatarUrl,
-                                                        autoJoin = childStateEvContent.autoJoin ?: false,
+                                                order = childStateEvContent.order,
-                                                        viaServers = childStateEvContent.via.orEmpty(),
+//                                                        autoJoin = childStateEvContent.autoJoin ?: false,
-                                                        activeMemberCount = childSummary.numJoinedMembers,
+                                                viaServers = childStateEvContent.via.orEmpty(),
-                                                        parentRoomId = childStateEv.roomId,
+                                                activeMemberCount = childSummary.numJoinedMembers,
-                                                        suggested = childStateEvContent.suggested,
+                                                parentRoomId = childStateEv.roomId,
-                                                        canonicalAlias = childSummary.canonicalAlias,
+                                                suggested = childStateEvContent.suggested,
-                                                        aliases = childSummary.aliases,
+                                                canonicalAlias = childSummary.canonicalAlias,
-                                                        worldReadable = childSummary.worldReadable
+                                                aliases = childSummary.aliases,
-                                                )
+                                                worldReadable = childSummary.worldReadable
-                                            }
+                                        )
-                                        }.orEmpty()
+                                    }
-                            }
+                                }.orEmpty()
-                            .orEmpty()
+                    }
+                    .orEmpty()
+            SpaceHierarchySummary(
+                    rootSummary = root,
+                    children = children,
+                    childrenState = spaceDesc?.childrenState.orEmpty(),
+                    nextToken = response.nextBatch
             )
         }
     }

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/space/JoinSpaceTask.kt

@@ -19,7 +19,6 @@ package org.matrix.android.sdk.internal.session.space
 import io.realm.RealmConfiguration
 import kotlinx.coroutines.TimeoutCancellationException
 import org.matrix.android.sdk.api.session.room.model.Membership
-import org.matrix.android.sdk.api.session.room.model.RoomType
 import org.matrix.android.sdk.api.session.space.JoinSpaceResult
 import org.matrix.android.sdk.internal.database.awaitNotEmptyResult
 import org.matrix.android.sdk.internal.database.model.RoomSummaryEntity
@@ -84,39 +83,39 @@ internal class DefaultJoinSpaceTask @Inject constructor(
         // after that i should have the children (? do I need to paginate to get state)
         val summary = roomSummaryDataSource.getSpaceSummary(params.roomIdOrAlias)
         Timber.v("## Space: Found space summary Name:[${summary?.name}] children: ${summary?.spaceChildren?.size}")
-        summary?.spaceChildren?.forEach {
+//        summary?.spaceChildren?.forEach {
 //            val childRoomSummary = it.roomSummary ?: return@forEach
-            Timber.v("## Space: Processing child :[${it.childRoomId}] autoJoin:${it.autoJoin}")
+//            Timber.v("## Space: Processing child :[${it.childRoomId}] suggested:${it.suggested}")
-            if (it.autoJoin) {
+//            if (it.autoJoin) {
-                // I should try to join as well
+//                // I should try to join as well
-                if (it.roomType == RoomType.SPACE) {
+//                if (it.roomType == RoomType.SPACE) {
-                    // recursively join auto-joined child of this space?
+//                    // recursively join auto-joined child of this space?
-                    when (val subspaceJoinResult = execute(JoinSpaceTask.Params(it.childRoomId, null, it.viaServers))) {
+//                    when (val subspaceJoinResult = execute(JoinSpaceTask.Params(it.childRoomId, null, it.viaServers))) {
-                        JoinSpaceResult.Success           -> {
+//                        JoinSpaceResult.Success           -> {
-                            // nop
+//                            // nop
-                        }
+//                        }
-                        is JoinSpaceResult.Fail           -> {
+//                        is JoinSpaceResult.Fail           -> {
-                            errors[it.childRoomId] = subspaceJoinResult.error
+//                            errors[it.childRoomId] = subspaceJoinResult.error
-                        }
+//                        }
-                        is JoinSpaceResult.PartialSuccess -> {
+//                        is JoinSpaceResult.PartialSuccess -> {
-                            errors.putAll(subspaceJoinResult.failedRooms)
+//                            errors.putAll(subspaceJoinResult.failedRooms)
-                        }
+//                        }
-                    }
+//                    }
-                } else {
+//                } else {
-                    try {
+//                    try {
-                        Timber.v("## Space: Joining room child ${it.childRoomId}")
+//                        Timber.v("## Space: Joining room child ${it.childRoomId}")
-                        joinRoomTask.execute(JoinRoomTask.Params(
+//                        joinRoomTask.execute(JoinRoomTask.Params(
-                                roomIdOrAlias = it.childRoomId,
+//                                roomIdOrAlias = it.childRoomId,
-                                reason = "Auto-join parent space",
+//                                reason = "Auto-join parent space",
-                                viaServers = it.viaServers
+//                                viaServers = it.viaServers
-                        ))
+//                        ))
-                    } catch (failure: Throwable) {
+//                    } catch (failure: Throwable) {
-                        errors[it.childRoomId] = failure
+//                        errors[it.childRoomId] = failure
-                        Timber.e("## Space: Failed to join room child ${it.childRoomId}")
+//                        Timber.e("## Space: Failed to join room child ${it.childRoomId}")
-                    }
+//                    }
-                }
+//                }
-            }
+//            }
-        }
+//        }
 
         return if (errors.isEmpty()) {
             JoinSpaceResult.Success

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/space/ResolveSpaceInfoTask.kt

@@ -24,23 +24,24 @@ import javax.inject.Inject
 internal interface ResolveSpaceInfoTask : Task<ResolveSpaceInfoTask.Params, SpacesResponse> {
     data class Params(
             val spaceId: String,
-            val maxRoomPerSpace: Int?,
+//            val maxRoomPerSpace: Int?,
-            val limit: Int,
+            val limit: Int?,
-            val batchToken: String?,
+            val maxDepth: Int?,
-            val suggestedOnly: Boolean?,
+            val from: String?,
-            val autoJoinOnly: Boolean?
+            val suggestedOnly: Boolean?
+//            val autoJoinOnly: Boolean?
     ) {
-        companion object {
+//        companion object {
-            fun withId(spaceId: String, suggestedOnly: Boolean?, autoJoinOnly: Boolean?) =
+//            fun withId(spaceId: String, suggestedOnly: Boolean?) =
-                    Params(
+//                    Params(
-                            spaceId = spaceId,
+//                            spaceId = spaceId,
-                            maxRoomPerSpace = 10,
+// //                            maxRoomPerSpace = 10,
-                            limit = 20,
+//                            limit = 20,
-                            batchToken = null,
+//                            from = null,
-                            suggestedOnly = suggestedOnly,
+//                            suggestedOnly = suggestedOnly
-                            autoJoinOnly = autoJoinOnly
+// //                            autoJoinOnly = autoJoinOnly
-                    )
+//                    )
-        }
+//        }
     }
 }
 
@@ -49,15 +50,13 @@ internal class DefaultResolveSpaceInfoTask @Inject constructor(
         private val globalErrorReceiver: GlobalErrorReceiver
 ) : ResolveSpaceInfoTask {
     override suspend fun execute(params: ResolveSpaceInfoTask.Params): SpacesResponse {
-        val body = SpaceSummaryParams(
-                maxRoomPerSpace = params.maxRoomPerSpace,
-                limit = params.limit,
-                batch = params.batchToken ?: "",
-                autoJoinedOnly = params.autoJoinOnly,
-                suggestedOnly = params.suggestedOnly
-        )
         return executeRequest(globalErrorReceiver) {
-            spaceApi.getSpaces(params.spaceId, body)
+            spaceApi.getSpaceHierarchy(
+                    spaceId = params.spaceId,
+                    suggestedOnly = params.suggestedOnly,
+                    limit = params.limit,
+                    maxDepth = params.maxDepth,
+                    from = params.from)
         }
     }
 }

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/space/SpaceApi.kt

@@ -17,9 +17,9 @@
 package org.matrix.android.sdk.internal.session.space
 
 import org.matrix.android.sdk.internal.network.NetworkConstants
-import retrofit2.http.Body
+import retrofit2.http.GET
-import retrofit2.http.POST
 import retrofit2.http.Path
+import retrofit2.http.Query
 
 internal interface SpaceApi {
 
@@ -37,7 +37,23 @@ internal interface SpaceApi {
      * - MSC 2946 https://github.com/matrix-org/matrix-doc/blob/kegan/spaces-summary/proposals/2946-spaces-summary.md
      * - https://hackmd.io/fNYh4tjUT5mQfR1uuRzWDA
      */
-    @POST(NetworkConstants.URI_API_PREFIX_PATH_UNSTABLE + "org.matrix.msc2946/rooms/{roomId}/spaces")
+//    @POST(NetworkConstants.URI_API_PREFIX_PATH_UNSTABLE + "org.matrix.msc2946/rooms/{roomId}/spaces")
-    suspend fun getSpaces(@Path("roomId") spaceId: String,
+//    suspend fun getSpaces(@Path("roomId") spaceId: String,
-                  @Body params: SpaceSummaryParams): SpacesResponse
+//                          @Body params: SpaceSummaryParams): SpacesResponse
+
+    /**
+     * @param limit: Optional: a client-defined limit to the maximum number of rooms to return per page. Must be a non-negative integer.
+     * @param max_depth: Optional: The maximum depth in the tree (from the root room) to return.
+     * The deepest depth returned will not include children events. Defaults to no-limit. Must be a non-negative integer.
+     *
+     * @param from: Optional. Pagination token given to retrieve the next set of rooms.
+     * Note that if a pagination token is provided, then the parameters given for suggested_only and max_depth must be the same.
+     */
+    @GET(NetworkConstants.URI_API_PREFIX_PATH_UNSTABLE + "org.matrix.msc2946/rooms/{roomId}/hierarchy")
+    suspend fun getSpaceHierarchy(
+            @Path("roomId") spaceId: String,
+            @Query("suggested_only") suggestedOnly: Boolean?,
+            @Query("limit") limit: Int?,
+            @Query("max_depth") maxDepth: Int?,
+            @Query("from") from: String?): SpacesResponse
 }

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/space/SpaceChildSummaryResponse.kt

@@ -18,14 +18,21 @@ package org.matrix.android.sdk.internal.session.space
 
 import com.squareup.moshi.Json
 import com.squareup.moshi.JsonClass
+import org.matrix.android.sdk.api.session.events.model.Event
 
+/**
+ * The fields are the same as those returned by /publicRooms (see spec), with the addition of:
+ *       room_type: the value of the m.type field from the room's m.room.create event, if any.
+ *       children_state: The m.space.child events of the room. For each event, only the following fields are included1: type, state_key, content, room_id, sender, with the addition of:
+ *       origin_server_ts: This is required for sorting of rooms as specified below.
+ */
 @JsonClass(generateAdapter = true)
 internal data class SpaceChildSummaryResponse(
-        /**
+//        /**
-         * The total number of state events which point to or from this room (inbound/outbound edges).
+//         * The total number of state events which point to or from this room (inbound/outbound edges).
-         * This includes all m.space.child events in the room, in addition to m.room.parent events which point to this room as a parent.
+//         * This includes all m.space.child events in the room, in addition to m.room.parent events which point to this room as a parent.
-         */
+//         */
-        @Json(name = "num_refs") val numRefs: Int? = null,
+//        @Json(name = "num_refs") val numRefs: Int? = null,
 
         /**
          * The room type, which is m.space for subspaces.
@@ -33,6 +40,11 @@ internal data class SpaceChildSummaryResponse(
          */
         @Json(name = "room_type") val roomType: String? = null,
 
+        /**  The m.space.child events of the room. For each event, only the following fields are included:
+         *  type, state_key, content, room_id, sender, with the addition of origin_server_ts: This is required for sorting of rooms as specified below.
+         */
+        @Json(name = "children_state") val childrenState: List<Event>? = null,
+
         /**
          * Aliases of the room. May be empty.
          */

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/space/SpaceHierarchySummary.kt

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2021 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.matrix.android.sdk.internal.session.space
+
+import org.matrix.android.sdk.api.session.events.model.Event
+import org.matrix.android.sdk.api.session.room.model.RoomSummary
+import org.matrix.android.sdk.api.session.room.model.SpaceChildInfo
+
+data class SpaceHierarchySummary(
+        val rootSummary: RoomSummary,
+        val children: List<SpaceChildInfo>,
+        val childrenState: List<Event>,
+        val nextToken: String? = null
+)

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/space/SpaceSummaryParams.kt

@@ -1,34 +0,0 @@
-/*
- * Copyright 2020 The Matrix.org Foundation C.I.C.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.matrix.android.sdk.internal.session.space
-
-import com.squareup.moshi.Json
-import com.squareup.moshi.JsonClass
-
-@JsonClass(generateAdapter = true)
-internal data class SpaceSummaryParams(
-        /**  The maximum number of rooms/subspaces to return for a given space, if negative unbounded. default: -1 */
-        @Json(name = "max_rooms_per_space") val maxRoomPerSpace: Int?,
-        /** The maximum number of rooms/subspaces to return, server can override this, default: 100 */
-        @Json(name = "limit") val limit: Int?,
-        /** A token to use if this is a subsequent HTTP hit, default: "". */
-        @Json(name = "batch") val batch: String = "",
-        /** whether we should only return children with the "suggested" flag set. */
-        @Json(name = "suggested_only") val suggestedOnly: Boolean?,
-        /** whether we should only return children with the "suggested" flag set. */
-        @Json(name = "auto_join_only") val autoJoinedOnly: Boolean?
-)

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/space/SpacesResponse.kt

@@ -18,14 +18,11 @@ package org.matrix.android.sdk.internal.session.space
 
 import com.squareup.moshi.Json
 import com.squareup.moshi.JsonClass
-import org.matrix.android.sdk.api.session.events.model.Event
 
 @JsonClass(generateAdapter = true)
 internal data class SpacesResponse(
         /** Its presence indicates that there are more results to return. */
         @Json(name = "next_batch") val nextBatch: String? = null,
         /** Rooms information like name/avatar/type ... */
-        @Json(name = "rooms") val rooms: List<SpaceChildSummaryResponse>? = null,
+        @Json(name = "rooms") val rooms: List<SpaceChildSummaryResponse>? = null
-        /** These are the edges of the graph. The objects in the array are complete (or stripped?) m.room.parent or m.space.child events. */
-        @Json(name = "events") val events: List<Event>? = null
 )

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/space/peeking/PeekSpaceTask.kt

@@ -103,7 +103,7 @@ internal class DefaultPeekSpaceTask @Inject constructor(
                     // can't peek :/
                     spaceChildResults.add(
                             SpaceChildPeekResult(
-                                    childId, childPeek, entry.second?.autoJoin, entry.second?.order
+                                    childId, childPeek, entry.second?.order
                             )
                     )
                     // continue to next child
@@ -116,7 +116,7 @@ internal class DefaultPeekSpaceTask @Inject constructor(
                             SpaceSubChildPeekResult(
                                     childId,
                                     childPeek,
-                                    entry.second?.autoJoin,
+//                                    entry.second?.autoJoin,
                                     entry.second?.order,
                                     peekChildren(childStateEvents, depth + 1, maxDepth)
                             )
@@ -127,7 +127,7 @@ internal class DefaultPeekSpaceTask @Inject constructor(
                     Timber.v("## SPACE_PEEK: room child $entry")
                     spaceChildResults.add(
                             SpaceChildPeekResult(
-                                    childId, childPeek, entry.second?.autoJoin, entry.second?.order
+                                    childId, childPeek, entry.second?.order
                             )
                     )
                 }

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/space/peeking/SpacePeekResult.kt

@@ -28,21 +28,21 @@ data class SpacePeekSummary(
 interface ISpaceChild {
     val id: String
     val roomPeekResult: PeekResult
-    val default: Boolean?
+//    val default: Boolean?
     val order: String?
 }
 
 data class SpaceChildPeekResult(
         override val id: String,
         override val roomPeekResult: PeekResult,
-        override val default: Boolean? = null,
+//        override val default: Boolean? = null,
         override val order: String? = null
 ) : ISpaceChild
 
 data class SpaceSubChildPeekResult(
         override val id: String,
         override val roomPeekResult: PeekResult,
-        override val default: Boolean?,
+//        override val default: Boolean?,
         override val order: String?,
         val children: List<ISpaceChild>
 ) : ISpaceChild

vector/src/main/java/im/vector/app/features/home/room/detail/upgrade/UpgradeRoomViewModelTask.kt

@@ -80,7 +80,7 @@ class UpgradeRoomViewModelTask @Inject constructor(
                                 roomId = updatedRoomId,
                                 viaServers = currentInfo.via,
                                 order = currentInfo.order,
-                                autoJoin = currentInfo.autoJoin ?: false,
+//                                autoJoin = currentInfo.autoJoin ?: false,
                                 suggested = currentInfo.suggested
                         )
 

vector/src/main/java/im/vector/app/features/home/room/list/RoomListSectionBuilderSpace.kt

@@ -230,8 +230,11 @@ class RoomListSectionBuilderSpace(
                                 Observable.just(emptyList())
                             } else {
                                 liveData(context = viewModelScope.coroutineContext + Dispatchers.IO) {
-                                    val spaceSum = tryOrNull { session.spaceService().querySpaceChildren(selectedSpace.roomId, suggestedOnly = true) }
+                                    val spaceSum = tryOrNull {
-                                    val value = spaceSum?.second.orEmpty().distinctBy { it.childRoomId }
+                                        session.spaceService()
+                                                .querySpaceChildren(selectedSpace.roomId, suggestedOnly = true, null, null)
+                                    }
+                                    val value = spaceSum?.children.orEmpty().distinctBy { it.childRoomId }
                                     // i need to check if it's already joined.
                                     val filtered = value.filter {
                                         session.getRoomSummary(it.childRoomId)?.membership?.isActive() != true

vector/src/main/java/im/vector/app/features/matrixto/SpaceCardRenderer.kt

@@ -62,7 +62,7 @@ class SpaceCardRenderer @Inject constructor(
                 inCard.matrixToAccessImage.isVisible = true
                 inCard.matrixToAccessImage.setImageResource(R.drawable.ic_room_private)
             }
-            val memberCount = spaceSummary.otherMemberIds.size
+            val memberCount = spaceSummary.joinedMembersCount?.let { it - 1 } ?: 0
             if (memberCount != 0) {
                 inCard.matrixToMemberPills.isVisible = true
                 inCard.spaceChildMemberCountText.text = stringProvider.getQuantityString(R.plurals.room_title_members, memberCount, memberCount)

vector/src/main/java/im/vector/app/features/spaces/create/CreateSpaceViewModelTask.kt

@@ -134,7 +134,7 @@ class CreateSpaceViewModelTask @Inject constructor(
                             timeout.roomID
                         }
                         val via = session.sessionParams.homeServerHost?.let { listOf(it) } ?: emptyList()
-                        createdSpace!!.addChildren(roomId, via, null, autoJoin = false, suggested = true)
+                        createdSpace!!.addChildren(roomId, via, null, suggested = true)
                         // set canonical
                         session.spaceService().setSpaceParent(
                                 roomId,

vector/src/main/java/im/vector/app/features/spaces/explore/SpaceDirectoryController.kt

@@ -18,8 +18,10 @@ package im.vector.app.features.spaces.explore
 
 import android.view.View
 import com.airbnb.epoxy.TypedEpoxyController
+import com.airbnb.epoxy.VisibilityState
 import com.airbnb.mvrx.Fail
 import com.airbnb.mvrx.Incomplete
+import com.airbnb.mvrx.Uninitialized
 import im.vector.app.R
 import im.vector.app.core.epoxy.ClickListener
 import im.vector.app.core.epoxy.errorWithRetryItem
@@ -54,13 +56,15 @@ class SpaceDirectoryController @Inject constructor(
         fun onRoomClick(spaceChildInfo: SpaceChildInfo)
         fun retry()
         fun addExistingRooms(spaceId: String)
+        fun loadAdditionalItemsIfNeeded()
     }
 
     var listener: InteractionListener? = null
 
     override fun buildModels(data: SpaceDirectoryState?) {
         val host = this
-        val results = data?.spaceSummaryApiResult
+        val currentRootId = data?.hierarchyStack?.lastOrNull() ?: data?.spaceId ?: return
+        val results = data?.apiResults?.get(currentRootId)
 
         if (results is Incomplete) {
             loadingItem {
@@ -94,7 +98,9 @@ class SpaceDirectoryController @Inject constructor(
                 }
             }
         } else {
-            val flattenChildInfo = results?.invoke()
+            val hierarchySummary = results?.invoke()
+            val flattenChildInfo = hierarchySummary
+                    ?.children
                     ?.filter {
                         it.parentRoomId == (data.hierarchyStack.lastOrNull() ?: data.spaceId)
                     }
@@ -132,6 +138,7 @@ class SpaceDirectoryController @Inject constructor(
                     // if it's known use that matrixItem because it would have a better computed name
                     val matrixItem = data?.knownRoomSummaries?.find { it.roomId == info.childRoomId }?.toMatrixItem()
                             ?: info.toMatrixItem()
+
                     spaceChildInfoItem {
                         id(info.childRoomId)
                         matrixItem(matrixItem)
@@ -162,6 +169,28 @@ class SpaceDirectoryController @Inject constructor(
                     }
                 }
             }
+            if (hierarchySummary?.nextToken != null) {
+                val paginationStatus = data.paginationStatus[currentRootId] ?: Uninitialized
+                if (paginationStatus is Fail) {
+                    errorWithRetryItem {
+                        id("error_${currentRootId}_${hierarchySummary.nextToken}")
+                        text(host.errorFormatter.toHumanReadable(paginationStatus.error))
+                        listener { host.listener?.retry() }
+                    }
+                } else {
+                    loadingItem {
+                        id("pagination_${currentRootId}_${hierarchySummary.nextToken}")
+                        showLoader(true)
+                        onVisibilityStateChanged { _, _, visibilityState ->
+                            // Do something with the new visibility state
+                            if (visibilityState == VisibilityState.VISIBLE) {
+                                // we can trigger a seamless load of additional items
+                                host.listener?.loadAdditionalItemsIfNeeded()
+                            }
+                        }
+                    }
+                }
+            }
         }
     }
 }

vector/src/main/java/im/vector/app/features/spaces/explore/SpaceDirectoryFragment.kt

@@ -25,6 +25,7 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.core.text.toSpannable
 import androidx.core.view.isVisible
+import com.airbnb.epoxy.EpoxyVisibilityTracker
 import com.airbnb.mvrx.activityViewModel
 import com.airbnb.mvrx.withState
 import com.google.android.material.dialog.MaterialAlertDialogBuilder
@@ -72,6 +73,7 @@ class SpaceDirectoryFragment @Inject constructor(
             FragmentSpaceDirectoryBinding.inflate(layoutInflater, container, false)
 
     private val viewModel by activityViewModel(SpaceDirectoryViewModel::class)
+    private val epoxyVisibilityTracker = EpoxyVisibilityTracker()
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
@@ -84,6 +86,7 @@ class SpaceDirectoryFragment @Inject constructor(
         }
         epoxyController.listener = this
         views.spaceDirectoryList.configureWith(epoxyController)
+        epoxyVisibilityTracker.attach(views.spaceDirectoryList)
 
         viewModel.selectSubscribe(this, SpaceDirectoryState::canAddRooms) {
             invalidateOptionsMenu()
@@ -95,6 +98,7 @@ class SpaceDirectoryFragment @Inject constructor(
 
     override fun onDestroyView() {
         epoxyController.listener = null
+        epoxyVisibilityTracker.detach(views.spaceDirectoryList)
         views.spaceDirectoryList.cleanup()
         super.onDestroyView()
     }
@@ -102,21 +106,20 @@ class SpaceDirectoryFragment @Inject constructor(
     override fun invalidate() = withState(viewModel) { state ->
         epoxyController.setData(state)
 
-        val currentParent = state.hierarchyStack.lastOrNull()?.let { currentParent ->
+        val currentParentId = state.hierarchyStack.lastOrNull()
-            state.spaceSummaryApiResult.invoke()?.firstOrNull { it.childRoomId == currentParent }
-        }
 
-        if (currentParent == null) {
+        if (currentParentId == null) {
+            // it's the root
             val title = getString(R.string.space_explore_activity_title)
             views.toolbar.title = title
-
-            spaceCardRenderer.render(state.spaceSummary.invoke(), emptyList(), this, views.spaceCard)
         } else {
-            val title = currentParent.name ?: currentParent.canonicalAlias ?: getString(R.string.space_explore_activity_title)
+            val title = state.currentRootSummary?.name
+                    ?: state.currentRootSummary?.canonicalAlias
+                    ?: getString(R.string.space_explore_activity_title)
             views.toolbar.title = title
-
-            spaceCardRenderer.render(currentParent, emptyList(), this, views.spaceCard)
         }
+
+        spaceCardRenderer.render(state.currentRootSummary, emptyList(), this, views.spaceCard)
     }
 
     override fun onPrepareOptionsMenu(menu: Menu) = withState(viewModel) { state ->
@@ -170,6 +173,10 @@ class SpaceDirectoryFragment @Inject constructor(
         addExistingRoomActivityResult.launch(SpaceManageActivity.newIntent(requireContext(), spaceId, ManageType.AddRooms))
     }
 
+    override fun loadAdditionalItemsIfNeeded() {
+        viewModel.handle(SpaceDirectoryViewAction.LoadAdditionalItemsIfNeeded)
+    }
+
     override fun onUrlClicked(url: String, title: String): Boolean {
         permalinkHandler
                 .launch(requireActivity(), url, null)
@@ -206,7 +213,5 @@ class SpaceDirectoryFragment @Inject constructor(
         // nothing?
         return false
     }
-//    override fun navigateToRoom(roomId: String) {
+
-//        viewModel.handle(SpaceDirectoryViewAction.NavigateToRoom(roomId))
-//    }
 }

vector/src/main/java/im/vector/app/features/spaces/explore/SpaceDirectoryState.kt

@@ -18,28 +18,27 @@ package im.vector.app.features.spaces.explore
 
 import com.airbnb.mvrx.Async
 import com.airbnb.mvrx.MvRxState
-import com.airbnb.mvrx.Uninitialized
 import org.matrix.android.sdk.api.session.room.members.ChangeMembershipState
 import org.matrix.android.sdk.api.session.room.model.RoomSummary
 import org.matrix.android.sdk.api.session.room.model.SpaceChildInfo
+import org.matrix.android.sdk.internal.session.space.SpaceHierarchySummary
 
 data class SpaceDirectoryState(
         // The current filter
         val spaceId: String,
         val currentFilter: String = "",
-        val spaceSummary: Async<RoomSummary> = Uninitialized,
+        val apiResults: Map<String, Async<SpaceHierarchySummary>> = emptyMap(),
-        val spaceSummaryApiResult: Async<List<SpaceChildInfo>> = Uninitialized,
+        val currentRootSummary: RoomSummary? = null,
         val childList: List<SpaceChildInfo> = emptyList(),
         val hierarchyStack: List<String> = emptyList(),
-        // True if more result are available server side
-        val hasMore: Boolean = false,
         // Set of joined roomId / spaces,
         val joinedRoomsIds: Set<String> = emptySet(),
         // keys are room alias or roomId
         val changeMembershipStates: Map<String, ChangeMembershipState> = emptyMap(),
         val canAddRooms: Boolean = false,
-        // cached room summaries of known rooms
+        // cached room summaries of known rooms, we use it because computed room name would be better using it
-        val knownRoomSummaries : List<RoomSummary> = emptyList()
+        val knownRoomSummaries : List<RoomSummary> = emptyList(),
+        val paginationStatus: Map<String, Async<Unit>> = emptyMap()
 ) : MvRxState {
     constructor(args: SpaceDirectoryArgs) : this(
             spaceId = args.spaceId

vector/src/main/java/im/vector/app/features/spaces/explore/SpaceDirectoryViewAction.kt

@@ -26,4 +26,5 @@ sealed class SpaceDirectoryViewAction : VectorViewModelAction {
     data class NavigateToRoom(val roomId: String) : SpaceDirectoryViewAction()
     object HandleBack : SpaceDirectoryViewAction()
     object Retry : SpaceDirectoryViewAction()
+    object LoadAdditionalItemsIfNeeded : SpaceDirectoryViewAction()
 }

vector/src/main/java/im/vector/app/features/spaces/explore/SpaceDirectoryViewModel.kt

@@ -23,6 +23,7 @@ import com.airbnb.mvrx.FragmentViewModelContext
 import com.airbnb.mvrx.Loading
 import com.airbnb.mvrx.MvRxViewModelFactory
 import com.airbnb.mvrx.Success
+import com.airbnb.mvrx.Uninitialized
 import com.airbnb.mvrx.ViewModelContext
 import dagger.assisted.Assisted
 import dagger.assisted.AssistedFactory
@@ -34,6 +35,8 @@ import kotlinx.coroutines.launch
 import org.matrix.android.sdk.api.session.Session
 import org.matrix.android.sdk.api.session.events.model.EventType
 import org.matrix.android.sdk.api.session.room.model.Membership
+import org.matrix.android.sdk.api.session.room.model.RoomJoinRules
+import org.matrix.android.sdk.api.session.room.model.RoomSummary
 import org.matrix.android.sdk.api.session.room.model.RoomType
 import org.matrix.android.sdk.api.session.room.model.SpaceChildInfo
 import org.matrix.android.sdk.api.session.room.powerlevels.PowerLevelsHelper
@@ -67,11 +70,11 @@ class SpaceDirectoryViewModel @AssistedInject constructor(
         setState {
             copy(
                     childList = spaceSum?.spaceChildren ?: emptyList(),
-                    spaceSummary = spaceSum?.let { Success(spaceSum) } ?: Loading()
+                    currentRootSummary = spaceSum
             )
         }
 
-        refreshFromApi()
+        refreshFromApi(initialState.spaceId)
         observeJoinedRooms()
         observeMembershipChanges()
         observePermissions()
@@ -93,29 +96,44 @@ class SpaceDirectoryViewModel @AssistedInject constructor(
                 .disposeOnClear()
     }
 
-    private fun refreshFromApi() {
+    private fun refreshFromApi(rootId: String?) = withState { state ->
+        val spaceId = rootId ?: initialState.spaceId
         setState {
             copy(
-                    spaceSummaryApiResult = Loading()
+                    apiResults = state.apiResults.toMutableMap().apply {
+                        this[spaceId] = Loading()
+                    }.toMap()
             )
         }
         viewModelScope.launch(Dispatchers.IO) {
+            val cachedResults = state.apiResults.toMutableMap()
             try {
-                val query = session.spaceService().querySpaceChildren(initialState.spaceId)
+                val query = session.spaceService().querySpaceChildren(
-                val knownSummaries = query.second.mapNotNull {
+                        spaceId,
+                        limit = 10
+                )
+                val knownSummaries = query.children.mapNotNull {
                     session.getRoomSummary(it.childRoomId)
                             ?.takeIf { it.membership == Membership.JOIN } // only take if joined because it will be up to date (synced)
-                }
+                }.distinctBy { it.roomId }
                 setState {
                     copy(
-                            spaceSummaryApiResult = Success(query.second),
+                            apiResults = cachedResults.apply {
-                            knownRoomSummaries = knownSummaries
+                                this[spaceId] = Success(query)
+                            },
+                            currentRootSummary = query.rootSummary,
+                            paginationStatus = state.paginationStatus.toMutableMap().apply {
+                                this[spaceId] = Uninitialized
+                            }.toMap(),
+                            knownRoomSummaries = (state.knownRoomSummaries + knownSummaries).distinctBy { it.roomId },
                     )
                 }
             } catch (failure: Throwable) {
                 setState {
                     copy(
-                            spaceSummaryApiResult = Fail(failure)
+                            apiResults = cachedResults.apply {
+                                this[spaceId] = Fail(failure)
+                            }
                     )
                 }
             }
@@ -149,39 +167,143 @@ class SpaceDirectoryViewModel @AssistedInject constructor(
 
     override fun handle(action: SpaceDirectoryViewAction) {
         when (action) {
-            is SpaceDirectoryViewAction.ExploreSubSpace -> {
+            is SpaceDirectoryViewAction.ExploreSubSpace          -> {
-                setState {
+                handleExploreSubSpace(action)
-                    copy(hierarchyStack = hierarchyStack + listOf(action.spaceChildInfo.childRoomId))
-                }
             }
-            SpaceDirectoryViewAction.HandleBack         -> {
+            SpaceDirectoryViewAction.HandleBack                  -> {
-                withState {
+                handleBack()
-                    if (it.hierarchyStack.isEmpty()) {
-                        _viewEvents.post(SpaceDirectoryViewEvents.Dismiss)
-                    } else {
-                        setState {
-                            copy(
-                                    hierarchyStack = hierarchyStack.dropLast(1)
-                            )
-                        }
-                    }
-                }
             }
-            is SpaceDirectoryViewAction.JoinOrOpen      -> {
+            is SpaceDirectoryViewAction.JoinOrOpen               -> {
                 handleJoinOrOpen(action.spaceChildInfo)
             }
-            is SpaceDirectoryViewAction.NavigateToRoom  -> {
+            is SpaceDirectoryViewAction.NavigateToRoom           -> {
                 _viewEvents.post(SpaceDirectoryViewEvents.NavigateToRoom(action.roomId))
             }
-            is SpaceDirectoryViewAction.ShowDetails     -> {
+            is SpaceDirectoryViewAction.ShowDetails              -> {
                 // This is temporary for now to at least display something for the space beta
                 // It's not ideal as it's doing some peeking that is not needed.
                 session.permalinkService().createRoomPermalink(action.spaceChildInfo.childRoomId)?.let {
                     _viewEvents.post(SpaceDirectoryViewEvents.NavigateToMxToBottomSheet(it))
                 }
             }
-            SpaceDirectoryViewAction.Retry              -> {
+            SpaceDirectoryViewAction.Retry                       -> {
-                refreshFromApi()
+                handleRetry()
+            }
+            SpaceDirectoryViewAction.LoadAdditionalItemsIfNeeded -> {
+                loadAdditionalItemsIfNeeded()
+            }
+        }
+    }
+
+    private fun handleBack() = withState { state ->
+        if (state.hierarchyStack.isEmpty()) {
+            _viewEvents.post(SpaceDirectoryViewEvents.Dismiss)
+        } else {
+            val newStack = state.hierarchyStack.dropLast(1)
+            val newRootId = newStack.lastOrNull() ?: initialState.spaceId
+            val rootSummary = state.apiResults[newRootId]?.invoke()?.rootSummary
+            setState {
+                copy(
+                        hierarchyStack = hierarchyStack.dropLast(1),
+                        currentRootSummary = rootSummary
+                )
+            }
+        }
+    }
+
+    private fun handleRetry() = withState { state ->
+        refreshFromApi(state.hierarchyStack.lastOrNull() ?: initialState.spaceId)
+    }
+
+    private fun handleExploreSubSpace(action: SpaceDirectoryViewAction.ExploreSubSpace) = withState { state ->
+        val newRootId = action.spaceChildInfo.childRoomId
+        val curSum = RoomSummary(
+                roomId = action.spaceChildInfo.childRoomId,
+                roomType = action.spaceChildInfo.roomType,
+                name = action.spaceChildInfo.name ?: "",
+                canonicalAlias = action.spaceChildInfo.canonicalAlias,
+                topic = action.spaceChildInfo.topic ?: "",
+                joinedMembersCount = action.spaceChildInfo.activeMemberCount,
+                avatarUrl = action.spaceChildInfo.avatarUrl ?: "",
+                isEncrypted = false,
+                joinRules = if (action.spaceChildInfo.worldReadable) RoomJoinRules.PUBLIC else RoomJoinRules.PRIVATE,
+                encryptionEventTs = 0,
+                typingUsers = emptyList()
+        )
+        setState {
+            copy(
+                    hierarchyStack = hierarchyStack + listOf(newRootId),
+                    currentRootSummary = curSum
+            )
+        }
+        val shouldLoad = when (state.apiResults[newRootId]) {
+            Uninitialized -> true
+            is Loading    -> false
+            is Success    -> false
+            is Fail       -> true
+            null          -> true
+        }
+
+        if (shouldLoad) {
+            refreshFromApi(newRootId)
+        }
+    }
+
+    private fun loadAdditionalItemsIfNeeded() = withState { state ->
+        val currentRootId = state.hierarchyStack.lastOrNull() ?: initialState.spaceId
+        val mutablePaginationStatus = state.paginationStatus.toMutableMap().apply {
+            if (this[currentRootId] == null) {
+                this[currentRootId] = Uninitialized
+            }
+        }
+
+        if (mutablePaginationStatus[currentRootId] is Loading) return@withState
+
+        setState {
+            copy(paginationStatus = mutablePaginationStatus.toMap())
+        }
+
+        viewModelScope.launch(Dispatchers.IO) {
+            val cachedResults = state.apiResults.toMutableMap()
+            try {
+                val currentResponse = cachedResults[currentRootId]?.invoke()
+                if (currentResponse == null) {
+                    // nothing to paginate through...
+                    setState {
+                        copy(paginationStatus = mutablePaginationStatus.apply { this[currentRootId] = Uninitialized }.toMap())
+                    }
+                    return@launch
+                }
+                val query = session.spaceService().querySpaceChildren(
+                        currentRootId,
+                        limit = 10,
+                        from = currentResponse.nextToken,
+                        knownStateList = currentResponse.childrenState
+                )
+                val knownSummaries = query.children.mapNotNull {
+                    session.getRoomSummary(it.childRoomId)
+                            ?.takeIf { it.membership == Membership.JOIN } // only take if joined because it will be up to date (synced)
+                }.distinctBy { it.roomId }
+
+                cachedResults[currentRootId] = Success(
+                        currentResponse.copy(
+                                children = currentResponse.children + query.children,
+                                nextToken = query.nextToken,
+                        )
+                )
+                setState {
+                    copy(
+                            apiResults = cachedResults.toMap(),
+                            paginationStatus = mutablePaginationStatus.apply { this[currentRootId] = Success(Unit) }.toMap(),
+                            knownRoomSummaries = (state.knownRoomSummaries + knownSummaries).distinctBy { it.roomId }
+                    )
+                }
+            } catch (failure: Throwable) {
+                setState {
+                    copy(
+                            paginationStatus = mutablePaginationStatus.apply { this[currentRootId] = Fail(failure) }.toMap()
+                    )
+                }
             }
         }
     }

vector/src/main/java/im/vector/app/features/spaces/manage/SpaceManageRoomsViewModel.kt

@@ -50,7 +50,7 @@ class SpaceManageRoomsViewModel @AssistedInject constructor(
 
         viewModelScope.launch(Dispatchers.IO) {
             val apiResult = runCatchingToAsync {
-                session.spaceService().querySpaceChildren(spaceId = initialState.spaceId).second
+                session.spaceService().querySpaceChildren(spaceId = initialState.spaceId).children
             }
             setState {
                 copy(
@@ -131,8 +131,8 @@ class SpaceManageRoomsViewModel @AssistedInject constructor(
                             roomId = info.childRoomId,
                             viaServers = info.viaServers,
                             order = info.order,
-                            suggested = suggested,
+                            suggested = suggested
-                            autoJoin = info.autoJoin
+//                            autoJoin = info.autoJoin
                     )
                 } catch (failure: Throwable) {
                     errorList.add(failure)
@@ -156,7 +156,7 @@ class SpaceManageRoomsViewModel @AssistedInject constructor(
         }
         viewModelScope.launch(Dispatchers.IO) {
             val apiResult = runCatchingToAsync {
-                session.spaceService().querySpaceChildren(spaceId = initialState.spaceId).second
+                session.spaceService().querySpaceChildren(spaceId = initialState.spaceId).children
             }
             setState {
                 copy(

vector/src/main/java/im/vector/app/features/spaces/preview/SpacePreviewViewModel.kt

@@ -151,7 +151,7 @@ class SpacePreviewViewModel @AssistedInject constructor(
         setState {
             copy(
                     spaceInfo = Success(
-                            resolveResult.first.let {
+                            resolveResult.rootSummary.let {
                                 ChildInfo(
                                         roomId = it.roomId,
                                         avatarUrl = it.avatarUrl,
@@ -165,7 +165,7 @@ class SpacePreviewViewModel @AssistedInject constructor(
                             }
                     ),
                     childInfoList = Success(
-                            resolveResult.second.map {
+                            resolveResult.children.map {
                                 ChildInfo(
                                         roomId = it.childRoomId,
                                         avatarUrl = it.avatarUrl,