google_drive_search.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_samples/show_dialog.dart';
import 'package:googleapis/drive/v3.dart' as drive;
import 'package:google_sign_in/google_sign_in.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:http/http.dart' as http;

class GoogleDriveSearch extends StatefulWidget {
  @override
  _GoogleDriveSearch createState() => _GoogleDriveSearch();
}

const _folderType = "application/vnd.google-apps.folder";

class _GoogleDriveSearch extends State<GoogleDriveSearch> {
  final googleSignIn = GoogleSignIn.standard(scopes: [
    drive.DriveApi.driveAppdataScope,
    // drive.DriveApi.driveFileScope,
    drive.DriveApi.driveReadonlyScope
  ]);

  @override
  Widget build(BuildContext context) {
    return SafeArea(
      child: Scaffold(
        appBar: AppBar(
          title: Text("Google Drive Search"),
        ),
        body: _createBody(context),
      ),
    );
  }

  Widget _createBody(BuildContext context) {
    return Column(
      children: [
        Center(child: _createButton("All file list", _allFileList)),
        Center(child: _createButton("Root list", _root)),
        Center(child: _createButton("Text files", _txt)),
        Center(child: _createButton("Files in temp1 folder", _filesInFolder)),
        Center(
            child: _createButton("Files owned by other", _filesOwnedByOther)),
        Center(child: _createButton("Shared files", _sharedFiles)),
      ],
    );
  }

  Future<drive.FileList> _allFileList(drive.DriveApi driveApi) {
    return driveApi.files.list(
      spaces: 'drive',
    );
  }

  Future<drive.FileList> _root(drive.DriveApi driveApi) {
    return driveApi.files.list(
      spaces: 'drive',
      q: "'root' in parents",
    );
  }

  Future<drive.FileList> _txt(drive.DriveApi driveApi) {
    return driveApi.files.list(
      spaces: 'drive',
      q: "name contains '.txt'",
    );
  }

  Future<drive.FileList> _filesInFolder(drive.DriveApi driveApi) async {
    final folderId = await _getFolderId(driveApi, "temp1");
    return driveApi.files.list(
      spaces: 'drive',
      q: "'$folderId' in parents",
    );
  }

  Future<drive.FileList> _filesOwnedByOther(drive.DriveApi driveApi) async {
    return driveApi.files.list(
      spaces: 'drive',
      q: "not 'me' in owners",
    );
  }

  Future<drive.FileList> _sharedFiles(drive.DriveApi driveApi) async {
    final list = await driveApi.files.list(
      spaces: 'drive',
      q: "'me' in owners",
      $fields: "files(name, mimeType, shared)",
    );

    list.files?.removeWhere((element) => element.shared == false);
    return list;
  }

  Future<drive.DriveApi?> _getDriveApi() async {
    final googleUser = await googleSignIn.signIn();

    if (googleUser != null) {
      final googleAuth = await googleUser.authentication;
      final credential = GoogleAuthProvider.credential(
        accessToken: googleAuth.accessToken,
        idToken: googleAuth.idToken,
      );
      final UserCredential loginUser =
          await FirebaseAuth.instance.signInWithCredential(credential);

      assert(loginUser.user?.uid == FirebaseAuth.instance.currentUser?.uid);
    }

    final headers = await googleUser?.authHeaders;
    if (headers == null) {
      await showMessage(context, "Sign-in first", "Error");
      return null;
    }

    final client = GoogleAuthClient(headers);
    final driveApi = drive.DriveApi(client);
    return driveApi;
  }

  Future<String?> _getFolderId(
    drive.DriveApi driveApi,
    String folderName,
  ) async {
    try {
      final found = await driveApi.files.list(
        q: "mimeType = '$_folderType' and name = '$folderName'",
        $fields: "files(id)",
      );
      final files = found.files;
      if (files == null) {
        return null;
      }

      if (files.isNotEmpty) {
        return files.first.id;
      }
    } catch (e) {
      print(e);
    }
    return null;
  }

  Widget _createButton(String title, Function(drive.DriveApi driveApi) query) {
    return ElevatedButton(
      onPressed: () async {
        final driveApi = await _getDriveApi();
        if (driveApi == null) {
          return;
        }

        final fileList = await query(driveApi);
        final files = fileList.files;
        if (files == null) {
          return showMessage(context, "Data not found", "");
        }
        await _showList(files);
      },
      child: Text(title),
    );
  }

  Future<void> _showList(List<drive.File> files) {
    return showDialog(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: Text("List"),
          content: Container(
            width: MediaQuery.of(context).size.height - 50,
            height: MediaQuery.of(context).size.height,
            child: ListView.builder(
              itemCount: files.length,
              itemBuilder: (context, index) {
                final isFolder = files[index].mimeType == _folderType;

                return ListTile(
                  leading: Icon(isFolder
                      ? Icons.folder
                      : Icons.insert_drive_file_outlined),
                  title: Text(files[index].name ?? ""),
                );
              },
            ),
          ),
        );
      },
    );
  }
}

class GoogleAuthClient extends http.BaseClient {
  final Map<String, String> _headers;
  final _client = new http.Client();

  GoogleAuthClient(this._headers);

  @override
  Future<http.StreamedResponse> send(http.BaseRequest request) {
    request.headers.addAll(_headers);
    return _client.send(request);
  }
}