wip: add message fetcher

Author: nakasyou

packages/linejs/client/features/chat/fetcher.ts

@@ -0,0 +1,39 @@
+import type { Client } from "../../client.ts";
+import type { Chat } from "./mod.ts";
+import type * as line from '@evex/linejs-types'
+import { TalkMessage } from '../message/mod.ts'
+
+export interface MessageFetcher {
+  fetch: (limit: number) => Promise<TalkMessage[]>
+}
+export const createMessageFetcher = async (client: Client, chat: Chat) => {
+  const boxes = await client.base.talk.getMessageBoxes({
+    messageBoxListRequest: {},
+  });
+  const box = boxes.messageBoxes.find((box) => box.id === chat.mid);
+  if (!box) {
+    throw new Error("Message box not found.");
+  }
+
+  let lastMessageId: line.MessageBoxV2MessageId = box.lastDeliveredMessageId
+  return {
+    async fetch(limit: number) {
+      const messages = await client.base.talk.getPreviousMessagesV2WithRequest({
+        request: {
+          messageBoxId: box.id,
+          endMessageId: lastMessageId,
+					messagesCount: limit,
+        },
+      });
+      const lastMessage = messages.at(-1)!
+      lastMessageId = {
+        deliveredTime: lastMessage.deliveredTime,
+        messageId: parseInt(lastMessage.id)
+      }
+
+      return await Promise.all(
+        messages.map((message) => TalkMessage.fromRawTalk(message, client)),
+      );
+    }
+  }
+};

packages/linejs/client/features/chat/mod.ts

@@ -1,6 +1,7 @@
 import type { Client } from "../../mod.ts";
 import type * as line from "@evex/linejs-types";
 import { TalkMessage } from "../message/talk.ts";
+import { createMessageFetcher, type MessageFetcher } from './fetcher.ts'
 
 interface ChatInit {
 	client: Client;
@@ -147,6 +148,10 @@ export class Chat {
 		);
 	}
 
+	messageFetcher(): Promise<MessageFetcher> {
+		return createMessageFetcher(this.#client, this)
+	}
+
 	/**
 	 * Create a Chat instance from raw message.
 	 * @param raw Raw message