120 lines
3.3 KiB
Dart
120 lines
3.3 KiB
Dart
import 'dart:async';
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import 'dart:typed_data';
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import 'datalog_db.dart';
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enum PlaybackStatus { idle, playing, paused }
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/// Loads stored frames from SQLite and replays them through a stream
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/// at configurable speed. Consumers watch [frameStream] exactly like
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/// the live BT stream — the parser layer is unaware of the difference.
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class DatalogPlayer {
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final DatalogDb _db;
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List<StoredFrame> _frames = [];
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int _position = 0; // index into _frames
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double _speed = 1.0; // 1.0 = real-time, 2.0 = 2× faster
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PlaybackStatus _status = PlaybackStatus.idle;
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PlaybackStatus get status => _status;
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int get position => _position;
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int get totalFrames => _frames.length;
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double get speed => _speed;
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set speed(double v) => _speed = v.clamp(0.25, 8.0);
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final StreamController<Uint8List> _controller =
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StreamController<Uint8List>.broadcast();
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Stream<Uint8List> get frameStream => _controller.stream;
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/// Callback fired on each tick — lets UI update a progress indicator.
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void Function(int position, int total)? onProgress;
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Timer? _timer;
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DatalogPlayer(this._db);
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/// Load all frames for [sessionId] into memory.
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Future<void> load(int sessionId) async {
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await stop();
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_frames = await _db.getFrames(sessionId);
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_position = 0;
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_status = PlaybackStatus.idle;
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}
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/// Start or resume playback.
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void play() {
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if (_status == PlaybackStatus.playing) return;
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if (_frames.isEmpty) return;
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_status = PlaybackStatus.playing;
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_scheduleNext();
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}
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void pause() {
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_timer?.cancel();
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_timer = null;
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if (_status == PlaybackStatus.playing) {
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_status = PlaybackStatus.paused;
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}
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}
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Future<void> stop() async {
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_timer?.cancel();
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_timer = null;
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_position = 0;
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_status = PlaybackStatus.idle;
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}
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/// Jump to a specific frame index.
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void seek(int index) {
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_position = index.clamp(0, _frames.length - 1);
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onProgress?.call(_position, _frames.length);
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}
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void _scheduleNext() {
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if (_position >= _frames.length) {
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_status = PlaybackStatus.idle;
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onProgress?.call(_frames.length, _frames.length);
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return;
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}
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// Calculate delay to next frame using original timestamps
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Duration delay = const Duration(milliseconds: 100); // default 10 Hz
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if (_position + 1 < _frames.length) {
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final gap = _frames[_position + 1].timestamp
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.difference(_frames[_position].timestamp);
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delay = Duration(
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microseconds: (gap.inMicroseconds / _speed).round(),
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);
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// Clamp to 10ms–2s to handle gaps from pauses/reconnects
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delay = delay.clamp(
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const Duration(milliseconds: 10),
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const Duration(seconds: 2),
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);
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}
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_timer = Timer(delay, () {
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if (_status != PlaybackStatus.playing) return;
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if (_position < _frames.length) {
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_controller.add(_frames[_position].data);
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onProgress?.call(_position, _frames.length);
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_position++;
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}
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_scheduleNext();
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});
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}
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void dispose() {
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_timer?.cancel();
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_controller.close();
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}
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}
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extension on Duration {
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Duration clamp(Duration min, Duration max) {
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if (this < min) return min;
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if (this > max) return max;
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return this;
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}
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}
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