How to get AutoRefreshingAuthClient from AuthClient without any service account (Google Auth) - flutter

Question

I need an AutoRefreshingAuthClient to use gsheet to play with authenticated users Google Sheet. I can get AuthClient using google_sign_in package.
So, How can I get AutoRefreshingAuthClient from AuthClient in a flutter application without any service account?
The reason I don't want to use a Service Account is,
If I use a Service Account, all files are saved into this Service Account. But, I want to read, write and use Google Sheet from the authenticated user's account.

Answer 1

I ended up using googleapis instead. Seems like gsheets was made to work specifically with Service Accounts so even if you create a valid AutoRefreshingAuthClient it'll check to see if it's a Service Account.
Here's how I did it with the SheetsApi (The GoogleAuthClient class was found after a lot of searching on GitHub and multiple users had the same thing):
import 'package:http/http.dart' as http;
class GoogleAuthClient extends http.BaseClient {
final Map<String, String> _headers;
final http.Client _client = new http.Client();
GoogleAuthClient(this._headers);
Future<http.StreamedResponse> send(http.BaseRequest request) {
return _client.send(request..headers.addAll(_headers));
}
}
final client = GoogleAuthClient((await _googleSignIn.currentUser.authHeaders));
_SheetApi = sheets.SheetsApi(client);
There is as decent amount of overhead on our side with SheetsApi compared to GSheets. Like appending rows or simply naming your Spreadsheet requires more lines of code and/or objects:
// Sheet creation
sheets.Spreadsheet request = sheets.Spreadsheet.fromJson({
'properties': {
'title': "$title",
},
});
sheets.Spreadsheet sh = getSheetApi().spreadsheets.create(request));
// Add first row
List<String> row = [...];
getSheetApi().spreadsheets.values.append(createSheetRows([columns]), sh.spreadsheetId, "Sheet1!$startLetter:$endLetter",
valueInputOption: 'USER_ENTERED');
...
static sheets.ValueRange createSheetRows(List<List<String>> row){
return sheets.ValueRange.fromJson({
"values": row,
"majorDimension": "ROWS"
});
}
static sheets.ValueRange createSheetRow(List<String> row){
return createSheetRows([row]);
}