import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

import '../debug/log_store.dart';
import '../theme/tokens.dart';

/// Beta-testing console: shows the app's captured `print`/`debugPrint` output
/// and uncaught errors (see [LogStore], wired up in `main`). Read-only view
/// with copy-all / clear / follow controls — no debugger needed on-device.
class DebugScreen extends StatefulWidget {
  const DebugScreen({super.key});

  @override
  State<DebugScreen> createState() => _DebugScreenState();
}

class _DebugScreenState extends State<DebugScreen> {
  static const _errorColor = Color(0xFFE06C75);

  final _controller = ScrollController();

  /// When true, new lines keep the view pinned to the bottom (tail -f style).
  /// Flipped off automatically when the user scrolls up to read history.
  bool _follow = true;

  @override
  void initState() {
    super.initState();
    _controller.addListener(_onScroll);
    LogStore.instance.addListener(_onLog);
  }

  @override
  void dispose() {
    LogStore.instance.removeListener(_onLog);
    _controller.removeListener(_onScroll);
    _controller.dispose();
    super.dispose();
  }

  void _onScroll() {
    if (!_controller.hasClients) return;
    final atBottom =
        _controller.offset >= _controller.position.maxScrollExtent - 24;
    if (atBottom != _follow) setState(() => _follow = atBottom);
  }

  void _onLog() {
    if (!mounted) return;
    setState(() {});
    if (_follow) {
      WidgetsBinding.instance.addPostFrameCallback((_) => _jumpToBottom());
    }
  }

  void _jumpToBottom() {
    if (!_controller.hasClients) return;
    _controller.jumpTo(_controller.position.maxScrollExtent);
  }

  Future<void> _copyAll() async {
    await Clipboard.setData(ClipboardData(text: LogStore.instance.asText()));
    if (!mounted) return;
    ScaffoldMessenger.of(context).showSnackBar(
      const SnackBar(content: Text('Log copied to clipboard')),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      color: TimbreColors.background,
      child: Column(
        children: [
          _header(),
          Expanded(
            child: ListenableBuilder(
              listenable: LogStore.instance,
              builder: (context, _) {
                final entries = LogStore.instance.entries;
                if (entries.isEmpty) {
                  return Center(
                    child: Text(
                      'No output captured yet.',
                      style: TextStyle(color: TimbreColors.dimmed),
                    ),
                  );
                }
                return Scrollbar(
                  controller: _controller,
                  child: ListView.builder(
                    controller: _controller,
                    padding: const EdgeInsets.symmetric(
                      horizontal: TimbreSpacing.lg,
                      vertical: TimbreSpacing.sm,
                    ),
                    itemCount: entries.length,
                    itemBuilder: (context, i) => _line(entries[i]),
                  ),
                );
              },
            ),
          ),
        ],
      ),
    );
  }

  Widget _header() {
    return Container(
      decoration: BoxDecoration(
        color: TimbreColors.surface,
        border: Border(bottom: BorderSide(color: TimbreColors.border)),
      ),
      padding: const EdgeInsets.symmetric(
        horizontal: TimbreSpacing.lg,
        vertical: TimbreSpacing.sm,
      ),
      child: Row(
        children: [
          Expanded(
            child: ListenableBuilder(
              listenable: LogStore.instance,
              builder: (context, _) => Text(
                'console · ${LogStore.instance.length} lines',
                style: TextStyle(color: TimbreColors.dimmed, fontSize: 12),
              ),
            ),
          ),
          _action(
            _follow ? Icons.vertical_align_bottom : Icons.pause,
            _follow ? 'follow' : 'paused',
            () {
              setState(() => _follow = !_follow);
              if (_follow) _jumpToBottom();
            },
            active: _follow,
          ),
          _action(Icons.copy, 'copy', _copyAll),
          _action(Icons.delete_outline, 'clear', LogStore.instance.clear),
        ],
      ),
    );
  }

  Widget _action(IconData icon, String label, VoidCallback onTap,
      {bool active = false}) {
    final accent = Theme.of(context).colorScheme.primary;
    final color = active ? accent : TimbreColors.dimmed;
    return InkWell(
      onTap: onTap,
      child: Padding(
        padding: const EdgeInsets.symmetric(horizontal: TimbreSpacing.md),
        child: Row(
          mainAxisSize: MainAxisSize.min,
          children: [
            Icon(icon, size: 14, color: color),
            const SizedBox(width: TimbreSpacing.xs),
            Text(label, style: TextStyle(color: color, fontSize: 12)),
          ],
        ),
      ),
    );
  }

  Widget _line(LogEntry e) {
    final isError = e.level == LogLevel.error;
    return Padding(
      padding: const EdgeInsets.only(bottom: 2),
      child: Text.rich(
        TextSpan(
          children: [
            TextSpan(
              text: '${e.timeLabel}  ',
              style: TextStyle(color: TimbreColors.dimmed, fontSize: 11),
            ),
            TextSpan(
              text: e.text,
              style: TextStyle(
                color: isError ? _errorColor : TimbreColors.foreground,
                fontSize: 12,
                height: 1.35,
              ),
            ),
          ],
        ),
      ),
    );
  }
}