import 'package:flutter/foundation.dart';

/// Severity of a captured log line, used only to tint it in the Debug tab.
enum LogLevel { info, error }

/// A single captured console line, stamped with the wall-clock time it arrived.
@immutable
class LogEntry {
  const LogEntry(this.time, this.text, this.level);

  final DateTime time;
  final String text;
  final LogLevel level;

  /// `HH:MM:SS.mmm` — enough resolution to correlate bursts while streaming.
  String get timeLabel {
    String two(int n) => n.toString().padLeft(2, '0');
    return '${two(time.hour)}:${two(time.minute)}:${two(time.second)}'
        '.${time.millisecond.toString().padLeft(3, '0')}';
  }
}

/// In-memory ring buffer of console/system output, surfaced in the Debug tab so
/// the app's logs can be read (and copied) on-device during beta testing —
/// there's no attached debugger on a TestFlight/sideloaded build.
///
/// A process-wide singleton because the capture hooks (the zone `print`
/// override and `FlutterError.onError`) are installed in `main()`, outside the
/// widget/provider tree. The UI listens via [ListenableBuilder].
class LogStore extends ChangeNotifier {
  LogStore._();
  static final LogStore instance = LogStore._();

  /// Keep the tail bounded so a chatty session can't grow memory without limit.
  static const int _maxEntries = 3000;

  final List<LogEntry> _entries = <LogEntry>[];

  /// Newest-last, read-only view for the UI.
  List<LogEntry> get entries => List.unmodifiable(_entries);

  int get length => _entries.length;

  void add(String text, {LogLevel level = LogLevel.info}) {
    // A single print can carry embedded newlines; split so each shows as its
    // own row (and the timestamp lines up per line).
    final now = DateTime.now();
    for (final line in text.split('\n')) {
      _entries.add(LogEntry(now, line, level));
    }
    final overflow = _entries.length - _maxEntries;
    if (overflow > 0) _entries.removeRange(0, overflow);
    notifyListeners();
  }

  void clear() {
    _entries.clear();
    notifyListeners();
  }

  /// The whole buffer as plain text, for copy-to-clipboard / sharing.
  String asText() =>
      _entries.map((e) => '${e.timeLabel}  ${e.text}').join('\n');
}