import 'package:flutter/material.dart';

import '../proto/messages.pb.dart';
import '../session/session_controller.dart';

typedef LogFilter = bool Function(LogPacket entry);

/// Reusable log viewer with auto-scroll-to-newest and disengage-on-manual-scroll.
class LogListView extends StatefulWidget {
  const LogListView({
    super.key,
    required this.session,
    required this.filter,
  });

  final SessionController session;
  final LogFilter filter;

  @override
  State<LogListView> createState() => _LogListViewState();
}

class _LogListViewState extends State<LogListView> {
  final ScrollController _ctrl = ScrollController();
  bool _autoScroll = true;

  @override
  void initState() {
    super.initState();
    _ctrl.addListener(_onScroll);
    widget.session.logTick.addListener(_onNewLog);
  }

  @override
  void dispose() {
    widget.session.logTick.removeListener(_onNewLog);
    _ctrl.dispose();
    super.dispose();
  }

  void _onScroll() {
    if (!_ctrl.hasClients) return;
    final atBottom = _ctrl.offset >=
        _ctrl.position.maxScrollExtent - 4;
    if (_autoScroll != atBottom) {
      setState(() => _autoScroll = atBottom);
    }
  }

  void _onNewLog() {
    if (!_autoScroll || !_ctrl.hasClients) return;
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!_ctrl.hasClients) return;
      _ctrl.jumpTo(_ctrl.position.maxScrollExtent);
    });
  }

  @override
  Widget build(BuildContext context) {
    return ValueListenableBuilder<int>(
      valueListenable: widget.session.logTick,
      builder: (_, __, ___) {
        final entries = widget.session.logs
            .iterate()
            .where(widget.filter)
            .toList(growable: false);
        return ListView.builder(
          controller: _ctrl,
          itemCount: entries.length,
          itemBuilder: (_, i) => _LogRow(entry: entries[i]),
        );
      },
    );
  }
}

class _LogRow extends StatelessWidget {
  const _LogRow({required this.entry});
  final LogPacket entry;

  @override
  Widget build(BuildContext context) {
    final ts = entry.hasTimestampUs()
        ? _fmtTime(entry.timestampUs.toInt())
        : '';
    final sev = entry.hasSeverity() ? entry.severity.name : '';
    final err = entry.hasErrorNumber()
        ? '[${entry.errorNumber.toString().padLeft(4, '0')}]'
        : '';
    final desc = entry.hasDescription() ? entry.description : '';
    final sevColor = switch (sev) {
      'WARN' => Colors.amber.shade800,
      'ERROR' || 'FATAL' => Colors.red.shade800,
      _ => Colors.grey.shade700,
    };
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 1),
      child: DefaultTextStyle(
        style: const TextStyle(fontFamily: 'monospace', fontSize: 11),
        child: Row(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(ts, style: const TextStyle(color: Colors.grey)),
            const SizedBox(width: 8),
            SizedBox(
              width: 50,
              child: Text(sev, style: TextStyle(color: sevColor)),
            ),
            const SizedBox(width: 6),
            Text(err, style: const TextStyle(color: Colors.grey)),
            const SizedBox(width: 8),
            Expanded(child: Text(desc, overflow: TextOverflow.ellipsis)),
          ],
        ),
      ),
    );
  }

  String _fmtTime(int us) {
    final d = DateTime.fromMicrosecondsSinceEpoch(us);
    return '${d.hour.toString().padLeft(2, '0')}:'
        '${d.minute.toString().padLeft(2, '0')}:'
        '${d.second.toString().padLeft(2, '0')}.'
        '${d.millisecond.toString().padLeft(3, '0')}';
  }
}