import 'dart:collection';

import 'package:flutter/foundation.dart';

/// Small in-memory log the client can copy from the Debug screen and send
/// back with a bug report. Keeps the newest [_capacity] lines only.
class AppLog {
  AppLog._();

  static const int _capacity = 400;
  static final ListQueue<String> _lines = ListQueue<String>();

  static void i(String msg) => _add('I', msg);
  static void w(String msg) => _add('W', msg);
  static void e(String msg, [Object? error, StackTrace? stack]) {
    final b = StringBuffer(msg);
    if (error != null) b.write(' | $error');
    if (stack != null) {
      // First few frames are enough to locate a crash.
      final frames = stack.toString().split('\n').take(8).join('\n    ');
      b.write('\n    $frames');
    }
    _add('E', b.toString());
  }

  static void _add(String level, String msg) {
    final t = DateTime.now();
    String two(int v) => v.toString().padLeft(2, '0');
    final ts = '${two(t.hour)}:${two(t.minute)}:${two(t.second)}.'
        '${t.millisecond.toString().padLeft(3, '0')}';
    final line = '$ts $level $msg';
    _lines.addLast(line);
    while (_lines.length > _capacity) {
      _lines.removeFirst();
    }
    debugPrint(line);
  }

  static String dump() => _lines.join('\n');

  static int get length => _lines.length;
}