场景教程：消息搜索与本地存储

IMClient client = IMClient.init(context, new IMClientOptions("demo", "http://127.0.0.1:8080"));
client.connect(token, new ConnectCallback() {
    @Override public void onSuccess(String userId) { /* 已连接 */ }
    @Override public void onError(IMError error) { /* 1002/3002 */ }
});

// 搜索：回调在主线程投递；result.total 为命中总数。
client.searchMessages(new SearchMessagesOptions("你好", 20), new ResultCallback<MessageSearchResult>() {
    @Override public void onSuccess(MessageSearchResult result) {
        boolean truncated = result.getMessages().size() < result.getTotal();
        render(result.getMessages(), result.getTotal(), truncated);
    }
    @Override public void onError(IMError error) {
        // 1001 参数错误；1003 无权限
        toast("搜索失败：" + error.getCode() + " " + error.getMessage());
    }
});

final engine = await RCIMIWEngine.create(
  'YOUR_APP_KEY',
  RCIMIWEngineOptions.create(naviServer: 'https://im.example.com'),
);
final code = await engine.connect(token, 10);
if (code != 0) throw Exception('connect failed: $code');

Future<List<Message>> search(String keyword) async {
  final res = await engine.searchMessages(keyword: keyword, limit: 20);
  if (res.code != 0) {
    // 1001 参数错误 / 1003 无权限
    throw Exception("[${res.code}] ${res.msg}");
  }
  final result = res.data!;
  return result.messages; // result.total 为命中总数
}

// 注意：分页是“单会话”的；Web/Android 的 IMLib 不提供本地全文索引，
// 这里只是把已加载的页在内存里过滤，不要直接读 SDK 的私有 SQLite 文件。
void loadOlder(IMClient client, ConversationType type, String targetId, String keyword) {
    client.getHistoryMessages(type, targetId, new HistoryOptions(50, null),
        new ResultCallback<HistoryPage>() {
            @Override public void onSuccess(HistoryPage page) {
                for (Message m : page.getMessages()) {
                    String text = m.getContent() == null ? "" : m.getContent().getText();
                    if (text != null && text.toLowerCase().contains(keyword.toLowerCase())) {
                        appendHit(m);
                    }
                }
                // page.getHasMore() 为 false 时已经到头
            }
            @Override public void onError(IMError error) { /* 1001/1003/3002 */ }
        });
}

Future<List<Message>> searchOlder(String keyword, int conversationType, String targetId) async {
  final hits = <Message>[];
  int? beforeSeq;
  for (var page = 0; page < 5; page++) {
    final res = await client.getHistoryMessages(
      conversationType,
      targetId,
      limit: 50,
      beforeSeq: beforeSeq,
    );
    if (res.code != 0) throw Exception("[${res.code}] ${res.msg}");
    final data = res.data!;
    for (final m in data.messages) {
      final text = m.content.text ?? "";
      if (text.toLowerCase().contains(keyword.toLowerCase())) hits.add(m);
    }
    if (!data.hasMore || data.messages.isEmpty) break;
    beforeSeq = data.messages.last.seq;
  }
  return hits;
}