import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';

import '../providers/pass_slip_provider.dart';

/// A persistent banner that shows a countdown to the pass slip 1-hour expiry.
///
/// Watches [activePassSlipProvider] for the current user's active pass slip.
/// When active, calculates remaining time until `slipStart + 1 hour`.
/// Auto-dismisses when the pass slip is completed.
/// Shows "EXCEEDED" when time has passed the 1-hour mark.
class PassSlipCountdownBanner extends ConsumerStatefulWidget {
  const PassSlipCountdownBanner({required this.child, super.key});

  final Widget child;

  @override
  ConsumerState<PassSlipCountdownBanner> createState() =>
      _PassSlipCountdownBannerState();
}

class _PassSlipCountdownBannerState
    extends ConsumerState<PassSlipCountdownBanner> {
  Timer? _timer;
  Duration _remaining = Duration.zero;
  bool _exceeded = false;

  @override
  void dispose() {
    _timer?.cancel();
    super.dispose();
  }

  void _startTimer(DateTime expiresAt) {
    _timer?.cancel();
    _updateRemaining(expiresAt);
    _timer = Timer.periodic(const Duration(seconds: 1), (_) {
      _updateRemaining(expiresAt);
    });
  }

  void _stopTimer() {
    _timer?.cancel();
    _timer = null;
    if (mounted) {
      setState(() {
        _remaining = Duration.zero;
        _exceeded = false;
      });
    }
  }

  void _updateRemaining(DateTime expiresAt) {
    final now = DateTime.now();
    final diff = expiresAt.difference(now);
    if (mounted) {
      setState(() {
        if (diff.isNegative || diff == Duration.zero) {
          _remaining = Duration.zero;
          _exceeded = true;
        } else {
          _remaining = diff;
          _exceeded = false;
        }
      });
    }
  }

  String _formatDuration(Duration d) {
    final minutes = d.inMinutes.remainder(60).toString().padLeft(2, '0');
    final seconds = d.inSeconds.remainder(60).toString().padLeft(2, '0');
    if (d.inHours > 0) {
      return '${d.inHours}:$minutes:$seconds';
    }
    return '$minutes:$seconds';
  }

  @override
  Widget build(BuildContext context) {
    final activeSlip = ref.watch(activePassSlipProvider);

    // Start/stop timer based on active pass slip state
    if (activeSlip != null && activeSlip.slipStart != null) {
      final expiresAt =
          activeSlip.slipStart!.add(const Duration(hours: 1));
      if (_timer == null) {
        WidgetsBinding.instance.addPostFrameCallback((_) {
          _startTimer(expiresAt);
        });
      }
    } else if (_timer != null) {
      WidgetsBinding.instance.addPostFrameCallback((_) {
        _stopTimer();
      });
    }

    final showBanner =
        activeSlip != null && activeSlip.slipStart != null;

    if (!showBanner) {
      return widget.child;
    }

    final isUrgent = !_exceeded && _remaining.inMinutes < 5;
    final bgColor = _exceeded || isUrgent
        ? Theme.of(context).colorScheme.errorContainer
        : Theme.of(context).colorScheme.tertiaryContainer;
    final fgColor = _exceeded || isUrgent
        ? Theme.of(context).colorScheme.onErrorContainer
        : Theme.of(context).colorScheme.onTertiaryContainer;

    final String message;
    final IconData icon;
    if (_exceeded) {
      message = 'Pass slip time EXCEEDED — Please return and complete it';
      icon = Icons.warning_amber_rounded;
    } else {
      message = 'Pass slip expires in ${_formatDuration(_remaining)}';
      icon = Icons.directions_walk_rounded;
    }

    return Column(
      children: [
        Material(
          child: InkWell(
            onTap: () => context.go('/attendance'),
            child: Container(
              width: double.infinity,
              padding:
                  const EdgeInsets.symmetric(horizontal: 16, vertical: 10),
              decoration: BoxDecoration(color: bgColor),
              child: Row(
                children: [
                  Icon(icon, size: 20, color: fgColor),
                  const SizedBox(width: 8),
                  Expanded(
                    child: Text(
                      message,
                      style:
                          Theme.of(context).textTheme.bodyMedium?.copyWith(
                                color: fgColor,
                                fontWeight: FontWeight.w600,
                              ),
                    ),
                  ),
                  Text(
                    'Tap to complete',
                    style: Theme.of(context).textTheme.bodySmall?.copyWith(
                          color: fgColor.withValues(alpha: 0.7),
                        ),
                  ),
                  const SizedBox(width: 4),
                  Icon(
                    Icons.chevron_right,
                    size: 18,
                    color: fgColor.withValues(alpha: 0.7),
                  ),
                ],
              ),
            ),
          ),
        ),
        Expanded(child: widget.child),
      ],
    );
  }
}