From 929bfbc88259ddf08f2ad0bc13c6c63b8ab1c37b Mon Sep 17 00:00:00 2001
From: Tulir Asokan <tulir@maunium.net>
Date: Mon, 7 Oct 2024 22:18:06 +0300
Subject: [PATCH] web/roomview: add history pagination button

---
 go.mod                       |  2 +-
 go.sum                       |  4 ++--
 web/src/api/client.ts        | 19 ++++++++++++++++---
 web/src/api/statestore.ts    | 11 +++++++++++
 web/src/api/types/hitypes.ts |  5 +++++
 web/src/ui/RoomView.tsx      |  1 +
 6 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/go.mod b/go.mod
index fb82b31..fed43bd 100644
--- a/go.mod
+++ b/go.mod
@@ -11,7 +11,7 @@ require (
 	go.mau.fi/util v0.8.1-0.20241003092848-3b49d3e0b9ee
 	go.mau.fi/zeroconfig v0.1.3
 	maunium.net/go/mauflag v1.0.0
-	maunium.net/go/mautrix v0.21.1-0.20241006181705-64692eb06e11
+	maunium.net/go/mautrix v0.21.1-0.20241007191346-1d8891fdb40e
 )
 
 require (
diff --git a/go.sum b/go.sum
index 2b1713b..545d4b2 100644
--- a/go.sum
+++ b/go.sum
@@ -58,5 +58,5 @@ gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 maunium.net/go/mauflag v1.0.0 h1:YiaRc0tEI3toYtJMRIfjP+jklH45uDHtT80nUamyD4M=
 maunium.net/go/mauflag v1.0.0/go.mod h1:nLivPOpTpHnpzEh8jEdSL9UqO9+/KBJFmNRlwKfkPeA=
-maunium.net/go/mautrix v0.21.1-0.20241006181705-64692eb06e11 h1:XhBqRfWg75OCsXxmb4uFJtHs6feq4MG9xaBWZKcMhFg=
-maunium.net/go/mautrix v0.21.1-0.20241006181705-64692eb06e11/go.mod h1:+fF5qsmXRCEXQZgW5ececC0PI3c7gISHTLcyftP4Bh0=
+maunium.net/go/mautrix v0.21.1-0.20241007191346-1d8891fdb40e h1:/R+hxB3+o+6iWxhBP/ibzooMF3OU0r3WRCu5m7FeKNs=
+maunium.net/go/mautrix v0.21.1-0.20241007191346-1d8891fdb40e/go.mod h1:+fF5qsmXRCEXQZgW5ececC0PI3c7gISHTLcyftP4Bh0=
diff --git a/web/src/api/client.ts b/web/src/api/client.ts
index 649bdc8..4a77cb1 100644
--- a/web/src/api/client.ts
+++ b/web/src/api/client.ts
@@ -15,7 +15,7 @@
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 import { CachedEventDispatcher } from "../util/eventdispatcher.ts"
 import type {
-	ClientWellKnown, DBEvent, EventID, EventRowID, EventType, RoomID, TimelineRowID, UserID,
+	ClientWellKnown, DBEvent, EventID, EventRowID, EventType, PaginationResponse, RoomID, TimelineRowID, UserID,
 } from "./types/hitypes.ts"
 import { ClientState, RPCEvent } from "./types/hievents.ts"
 import { RPCClient } from "./rpc.ts"
@@ -59,11 +59,24 @@ export default class Client {
 		return this.request("get_events_by_row_ids", { row_ids })
 	}
 
-	paginate(room_id: RoomID, max_timeline_id: TimelineRowID, limit: number): Promise<DBEvent[]> {
+	async loadMoreHistory(roomID: RoomID): Promise<void> {
+		const room = this.store.rooms.get(roomID)
+		if (!room) {
+			throw new Error("Room not found")
+		}
+		const oldestRowID = room.timeline.current[0]?.timeline_rowid
+		const resp = await this.paginate(roomID, oldestRowID ?? 0, 100)
+		if (room.timeline.current[0]?.timeline_rowid !== oldestRowID) {
+			throw new Error("Timeline changed while loading history")
+		}
+		room.applyPagination(resp.events)
+	}
+
+	paginate(room_id: RoomID, max_timeline_id: TimelineRowID, limit: number): Promise<PaginationResponse> {
 		return this.request("paginate", { room_id, max_timeline_id, limit })
 	}
 
-	paginateServer(room_id: RoomID, limit: number): Promise<DBEvent[]> {
+	paginateServer(room_id: RoomID, limit: number): Promise<PaginationResponse> {
 		return this.request("paginate_server", { room_id, limit })
 	}
 
diff --git a/web/src/api/statestore.ts b/web/src/api/statestore.ts
index 2dccac9..a637312 100644
--- a/web/src/api/statestore.ts
+++ b/web/src/api/statestore.ts
@@ -67,6 +67,17 @@ export class RoomStateStore {
 		this.meta = new NonNullCachedEventDispatcher(meta)
 	}
 
+	applyPagination(history: DBEvent[]) {
+		// Pagination comes in newest to oldest, timeline is in the opposite order
+		history.reverse()
+		const newTimeline = history.map(evt => {
+			this.eventsByRowID.set(evt.rowid, evt)
+			this.eventsByID.set(evt.event_id, evt)
+			return { timeline_rowid: evt.timeline_rowid, event_rowid: evt.rowid }
+		})
+		this.timeline.emit([...newTimeline, ...this.timeline.current])
+	}
+
 	applySync(sync: SyncRoom) {
 		if (visibleMetaIsEqual(this.meta.current, sync.meta)) {
 			this.meta.current = sync.meta
diff --git a/web/src/api/types/hitypes.ts b/web/src/api/types/hitypes.ts
index 190aebe..38e3a86 100644
--- a/web/src/api/types/hitypes.ts
+++ b/web/src/api/types/hitypes.ts
@@ -110,6 +110,11 @@ export interface DBEvent {
 	last_edit_rowid?: EventRowID
 }
 
+export interface PaginationResponse {
+	events: DBEvent[]
+	has_more: boolean
+}
+
 export interface EventUnsigned {
 	prev_content?: unknown
 	prev_sender?: UserID
diff --git a/web/src/ui/RoomView.tsx b/web/src/ui/RoomView.tsx
index eabf1d7..e00b7a7 100644
--- a/web/src/ui/RoomView.tsx
+++ b/web/src/ui/RoomView.tsx
@@ -29,6 +29,7 @@ const RoomView = ({ client, room }: RoomViewProps) => {
 	const timeline = useNonNullEventAsState(room.timeline)
 	return <div className="room-view">
 		{roomMeta.room_id}
+		<button onClick={() => client.loadMoreHistory(roomMeta.room_id)}>Load history</button>
 		{timeline.map(entry => <TimelineEvent
 			key={entry.event_rowid} client={client} room={room} eventRowID={entry.event_rowid}
 		/>)}