import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../../../core/protocol/dtc_map.dart';
import '../../../core/providers/bt_provider.dart';
import '../../../core/providers/sensor_provider.dart';
import '../../../core/providers/settings_provider.dart';
import '../../../core/bluetooth/bt_poller.dart';
import 'widgets/dtc_row.dart';

class DtcScreen extends ConsumerStatefulWidget {
  const DtcScreen({super.key});

  @override
  ConsumerState<DtcScreen> createState() => _DtcScreenState();
}

class _DtcScreenState extends ConsumerState<DtcScreen> {
  bool _clearing = false;
  Uint8List? _lastRaw;

  String _hex(Uint8List bytes) {
    final parts = <String>[];
    for (var i = 0; i < bytes.length; i++) {
      if (i > 0 && i % 16 == 0) parts.add('\n');
      parts.add(bytes[i].toRadixString(16).padLeft(2, '0'));
    }
    return parts.join(' ');
  }

  void _showRawCapture() {
    final raw = _lastRaw;
    if (raw == null) return;
    final hex = _hex(raw);
    showDialog<void>(
      context: context,
      builder: (context) => AlertDialog(
        title: Text('Raw capture (${raw.length} bytes)'),
        content: SizedBox(
          width: double.maxFinite,
          child: SingleChildScrollView(
            child: SelectableText(
              hex,
              style: const TextStyle(fontFamily: 'monospace', fontSize: 11),
            ),
          ),
        ),
        actions: [
          TextButton(
            onPressed: () async {
              await Clipboard.setData(ClipboardData(text: hex));
              if (context.mounted) {
                ScaffoldMessenger.of(context).showSnackBar(
                  const SnackBar(content: Text('Copied')),
                );
              }
            },
            child: const Text('Copy'),
          ),
          TextButton(
            onPressed: () => Navigator.pop(context),
            child: const Text('Close'),
          ),
        ],
      ),
    );
  }

  Future<void> _confirmAndClear() async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('Clear Trouble Codes'),
        content: const Text(
          'This sends a reset command to the ECU and erases all stored '
          'fault codes. This cannot be undone.',
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context, false),
            child: const Text('Cancel'),
          ),
          TextButton(
            onPressed: () => Navigator.pop(context, true),
            child: const Text('Clear',
                style: TextStyle(color: Colors.red)),
          ),
        ],
      ),
    );
    if (confirmed != true) return;

    setState(() => _clearing = true);
    final result = await ref.read(btProvider.notifier).clearDtcs();
    if (!mounted) return;
    setState(() {
      _clearing = false;
      _lastRaw = result.raw;
    });

    // Success is judged from the live data: the adapter does not send the
    // ack. Codes for faults that are still present return right away.
    final String message;
    if (result.codesBefore == 0) {
      message = 'No stored trouble codes to clear';
    } else if (result.codesCleared > 0) {
      final cleared = result.codesCleared;
      final back = result.codesBefore - cleared;
      message = back == 0
          ? 'Trouble codes cleared'
          : '$cleared of ${result.codesBefore} codes cleared — $back came '
              'straight back (active fault, fix the cause first)';
    } else if (result.acknowledged) {
      message = 'ECU confirmed the reset, but every code came straight back '
          '(active faults)';
    } else if (result.raw.isEmpty) {
      // Can't tell apart from "every fault re-set before the next frame".
      message = 'No codes cleared — the ECU ignored the reset, or every '
          'fault is still active';
    } else {
      // "View" opens the raw reply hex to check by hand.
      message = 'Unexpected reply (${result.raw.length} bytes) — codes did '
          'not clear';
    }

    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(
        content: Text(message),
        action: (!result.acknowledged && result.raw.isNotEmpty)
            ? SnackBarAction(label: 'View', onPressed: _showRawCapture)
            : null,
        duration: const Duration(seconds: 6),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    final state = ref.watch(latestSensorProvider);
    final bt = ref.watch(btProvider);
    final ecuType = ref.watch(settingsProvider).ecuType;

    final dtcMap =
        ecuType == EcuType.s300 ? s300DtcMap : kproDtcMap;
    final active = decodeDtcs(state.errBytes, dtcMap);

    return Column(
      children: [
        // Header bar
        Container(
          color: const Color(0xFF1A1A1A),
          padding:
              const EdgeInsets.symmetric(horizontal: 16, vertical: 10),
          child: Row(
            children: [
              Icon(
                active.isEmpty
                    ? Icons.check_circle_outline
                    : Icons.warning_amber_rounded,
                color: active.isEmpty ? Colors.green : Colors.amber,
                size: 18,
              ),
              const SizedBox(width: 8),
              Text(
                active.isEmpty
                    ? 'No active fault codes'
                    : '${active.length} active DTC${active.length > 1 ? "s" : ""}',
                style: TextStyle(
                  color: active.isEmpty ? Colors.green : Colors.amber,
                  fontSize: 13,
                  fontWeight: FontWeight.w600,
                ),
              ),
              const Spacer(),
              Text(
                ecuType == EcuType.s300 ? 'S300' : 'KPro',
                style:
                    const TextStyle(color: Colors.grey, fontSize: 12),
              ),
            ],
          ),
        ),
        const Divider(height: 1, color: Colors.white10),

        // DTC list
        Expanded(
          child: active.isEmpty
              ? const Center(
                  child: Column(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      Icon(Icons.check_circle_outline,
                          size: 56, color: Colors.green),
                      SizedBox(height: 12),
                      Text('All clear — no fault codes',
                          style: TextStyle(
                              color: Colors.grey, fontSize: 15)),
                    ],
                  ),
                )
              : ListView.separated(
                  itemCount: active.length,
                  separatorBuilder: (_, __) =>
                      const Divider(height: 1, color: Colors.white10),
                  itemBuilder: (context, i) {
                    final full = active[i]; // "P0130 — O2 Sensor (front)"
                    final parts = full.split(' — ');
                    final code = parts.first.trim();
                    final desc =
                        parts.length > 1 ? parts.sublist(1).join(' — ') : '';
                    return DtcRow(code: code, description: desc);
                  },
                ),
        ),
        SafeArea(
          top: false,
          child: Padding(
            padding: const EdgeInsets.all(16),
            child: SizedBox(
              width: double.infinity,
              child: ElevatedButton(
                style: ElevatedButton.styleFrom(
                  backgroundColor: Colors.red,
                  foregroundColor: Colors.white,
                  padding: const EdgeInsets.symmetric(vertical: 14),
                ),
                onPressed: (bt.isConnected && !_clearing)
                    ? _confirmAndClear
                    : null,
                child: Text(
                  _clearing ? 'Clearing…' : 'CLEAR TROUBLE CODES',
                  style: const TextStyle(fontWeight: FontWeight.bold),
                ),
              ),
            ),
          ),
        ),
      ],
    );
  }
}