Source Code added

mobile/lib/utils/upload_speed_calculator.dart

@@ -0,0 +1,182 @@
+/// A class to calculate upload speed based on progress updates.
+///
+/// Tracks bytes transferred over time and calculates average speed
+/// using a sliding window approach to smooth out fluctuations.
+class UploadSpeedCalculator {
+  /// Creates an UploadSpeedCalculator with the given window size.
+  ///
+  /// [windowSize] determines how many recent samples to use for
+  /// calculating the average speed. Default is 5 samples.
+  UploadSpeedCalculator({this.windowSize = 5});
+
+  /// The number of samples to keep in the sliding window.
+  final int windowSize;
+
+  /// List of recent speed samples (bytes per second).
+  final List<double> _speedSamples = [];
+
+  /// The timestamp of the last progress update.
+  DateTime? _lastUpdateTime;
+
+  /// The bytes transferred at the last progress update.
+  int _lastBytes = 0;
+
+  /// The total file size being uploaded.
+  int _totalBytes = 0;
+
+  /// Resets the calculator for a new upload.
+  void reset() {
+    _speedSamples.clear();
+    _lastUpdateTime = null;
+    _lastBytes = 0;
+    _totalBytes = 0;
+  }
+
+  /// Updates the calculator with the current progress.
+  ///
+  /// [currentBytes] is the number of bytes transferred so far.
+  /// [totalBytes] is the total size of the file being uploaded.
+  ///
+  /// Returns the calculated speed in MB/s, or -1 if not enough data.
+  double update(int currentBytes, int totalBytes) {
+    final now = DateTime.now();
+    _totalBytes = totalBytes;
+
+    if (_lastUpdateTime == null) {
+      _lastUpdateTime = now;
+      _lastBytes = currentBytes;
+      return -1;
+    }
+
+    final elapsed = now.difference(_lastUpdateTime!);
+
+    // Only calculate if at least 100ms has passed to avoid division by very small numbers
+    if (elapsed.inMilliseconds < 100) {
+      return _currentSpeed;
+    }
+
+    final bytesTransferred = currentBytes - _lastBytes;
+    final elapsedSeconds = elapsed.inMilliseconds / 1000.0;
+
+    // Calculate bytes per second, then convert to MB/s
+    final bytesPerSecond = bytesTransferred / elapsedSeconds;
+    final mbPerSecond = bytesPerSecond / (1024 * 1024);
+
+    // Add to sliding window
+    _speedSamples.add(mbPerSecond);
+    if (_speedSamples.length > windowSize) {
+      _speedSamples.removeAt(0);
+    }
+
+    _lastUpdateTime = now;
+    _lastBytes = currentBytes;
+
+    return _currentSpeed;
+  }
+
+  /// Returns the current calculated speed in MB/s.
+  ///
+  /// Returns -1 if no valid speed has been calculated yet.
+  double get _currentSpeed {
+    if (_speedSamples.isEmpty) {
+      return -1;
+    }
+    // Calculate average of all samples in the window
+    final sum = _speedSamples.fold(0.0, (prev, speed) => prev + speed);
+    return sum / _speedSamples.length;
+  }
+
+  /// Returns the current speed in MB/s, or -1 if not available.
+  double get speed => _currentSpeed;
+
+  /// Returns a human-readable string representation of the current speed.
+  ///
+  /// Returns '-- MB/s' if N/A, otherwise in MB/s or kB/s format.
+  String get speedAsString {
+    final s = _currentSpeed;
+    return switch (s) {
+      <= 0 => '-- MB/s',
+      >= 1 => '${s.round()} MB/s',
+      _ => '${(s * 1000).round()} kB/s',
+    };
+  }
+
+  /// Returns the estimated time remaining as a Duration.
+  ///
+  /// Returns Duration with negative seconds if not calculable.
+  Duration get timeRemaining {
+    final s = _currentSpeed;
+    if (s <= 0 || _totalBytes <= 0 || _lastBytes >= _totalBytes) {
+      return const Duration(seconds: -1);
+    }
+
+    final remainingBytes = _totalBytes - _lastBytes;
+    final bytesPerSecond = s * 1024 * 1024;
+    final secondsRemaining = remainingBytes / bytesPerSecond;
+
+    return Duration(seconds: secondsRemaining.round());
+  }
+
+  /// Returns a human-readable string representation of time remaining.
+  ///
+  /// Returns '--:--' if N/A, otherwise HH:MM:SS or MM:SS format.
+  String get timeRemainingAsString {
+    final remaining = timeRemaining;
+    return switch (remaining.inSeconds) {
+      <= 0 => '--:--',
+      < 3600 =>
+        '${remaining.inMinutes.toString().padLeft(2, "0")}'
+            ':${remaining.inSeconds.remainder(60).toString().padLeft(2, "0")}',
+      _ =>
+        '${remaining.inHours}'
+            ':${remaining.inMinutes.remainder(60).toString().padLeft(2, "0")}'
+            ':${remaining.inSeconds.remainder(60).toString().padLeft(2, "0")}',
+    };
+  }
+}
+
+/// Manager for tracking upload speeds for multiple concurrent uploads.
+///
+/// Each upload is identified by a unique task ID.
+class UploadSpeedManager {
+  /// Map of task IDs to their speed calculators.
+  final Map<String, UploadSpeedCalculator> _calculators = {};
+
+  /// Gets or creates a speed calculator for the given task ID.
+  UploadSpeedCalculator getCalculator(String taskId) {
+    return _calculators.putIfAbsent(taskId, () => UploadSpeedCalculator());
+  }
+
+  /// Updates progress for a specific task and returns the speed string.
+  ///
+  /// [taskId] is the unique identifier for the upload task.
+  /// [currentBytes] is the number of bytes transferred so far.
+  /// [totalBytes] is the total size of the file being uploaded.
+  ///
+  /// Returns the human-readable speed string.
+  String updateProgress(String taskId, int currentBytes, int totalBytes) {
+    final calculator = getCalculator(taskId);
+    calculator.update(currentBytes, totalBytes);
+    return calculator.speedAsString;
+  }
+
+  /// Gets the current speed string for a specific task.
+  String getSpeedAsString(String taskId) {
+    return _calculators[taskId]?.speedAsString ?? '-- MB/s';
+  }
+
+  /// Gets the time remaining string for a specific task.
+  String getTimeRemainingAsString(String taskId) {
+    return _calculators[taskId]?.timeRemainingAsString ?? '--:--';
+  }
+
+  /// Removes a task from tracking.
+  void removeTask(String taskId) {
+    _calculators.remove(taskId);
+  }
+
+  /// Clears all tracked tasks.
+  void clear() {
+    _calculators.clear();
+  }
+}