Function to download a file from Supabase storage and track download progress

supabase_file_download.dart

import 'dart:io';
import 'package:http/http.dart' as http;

import 'package:supabase_flutter/supabase_flutter.dart';

Future<void> _downloadFileWithProgress(Map<String, String> headers,
      String bucketId, String path, File downloadPath) async {
    try {
      setState(() {
        _downloading = true;
      });

      final _path = _getFinalPath(bucketId, path);
      final options = FetchOptions(headers: headers, noResolveJson: true);

      final url = '${supabase.storage.url}/object/$_path';

      final request = http.Request('GET', Uri.parse(url))
        ..headers.addAll(headers)
        ..body = json.encode({});

      final response = request.send();

      List<List<int>> chunks = [];
      int downloaded = 0;

      response.asStream().listen((event) {
        event.stream.listen(
          (value) {
            // Display perecentage of completion
            debugPrint(
                'downloadPercentage: ${downloaded / (event.contentLength ?? 0) * 100}');

            chunks.add(value);
            downloaded += value.length;

            setState(() {
              _downloadProgress = downloaded / (event.contentLength ?? 0);
            });
          },
          onDone: () async {
            // Display perecentage of completion
            debugPrint(
                'downloadPercentage: ${downloaded / (event.contentLength ?? 0) * 100}');

            // Save the file
            final Uint8List bytes = Uint8List(event.contentLength ?? 0);
            int offset = 0;

            for (List<int> chunk in chunks) {
              bytes.setRange(offset, offset + chunk.length, chunk);
              offset += chunk.length;
            }

            await downloadPath.create(recursive: true);
            await downloadPath.writeAsBytes(bytes);

            setState(() {
              _downloading = false;
            });
          },
        );
      });
    } catch (e) {
      debugPrint(e.toString());
    }
  }