import 'dart:math' as math;
import 'package:flutter/material.dart';

import '../../../../core/theme/app_colors.dart';

/// Non-anxiety-inducing timer widget.
///
/// Design rules:
///  - Circular progress (NOT countdown — progress forward).
///  - Soft pulsing animation.
///  - Color stays calm (teal/blue).
///  - No alarming sounds or red colors.
///  - Shows "X min so far" not "X min remaining."
class GentleTimer extends StatefulWidget {
  /// Total elapsed seconds.
  final int elapsedSeconds;

  /// Optional estimated total in seconds (used only for the progress ring).
  final int? estimatedTotalSeconds;

  /// Widget size (width & height).
  final double size;

  const GentleTimer({
    super.key,
    required this.elapsedSeconds,
    this.estimatedTotalSeconds,
    this.size = 180,
  });

  @override
  State<GentleTimer> createState() => _GentleTimerState();
}

class _GentleTimerState extends State<GentleTimer>
    with SingleTickerProviderStateMixin {
  late final AnimationController _pulseController;
  late final Animation<double> _pulse;

  @override
  void initState() {
    super.initState();
    _pulseController = AnimationController(
      vsync: this,
      duration: const Duration(seconds: 2),
    )..repeat(reverse: true);
    _pulse = Tween<double>(begin: 0.96, end: 1.0).animate(
      CurvedAnimation(parent: _pulseController, curve: Curves.easeInOut),
    );
  }

  @override
  void dispose() {
    _pulseController.dispose();
    super.dispose();
  }

  String _formatElapsed() {
    final m = widget.elapsedSeconds ~/ 60;
    final s = widget.elapsedSeconds % 60;
    if (m == 0) return '${s}s so far';
    return '${m}m ${s.toString().padLeft(2, '0')}s so far';
  }

  double get _progress {
    final total = widget.estimatedTotalSeconds;
    if (total == null || total == 0) {
      // No estimate — use a slow modular fill so the ring still moves.
      return (widget.elapsedSeconds % 300) / 300;
    }
    return (widget.elapsedSeconds / total).clamp(0.0, 1.0);
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    return AnimatedBuilder(
      animation: _pulse,
      builder: (context, child) {
        return Transform.scale(
          scale: _pulse.value,
          child: child,
        );
      },
      child: SizedBox(
        width: widget.size,
        height: widget.size,
        child: CustomPaint(
          painter: _GentleTimerPainter(
            progress: _progress,
            color: AppColors.primary,
            backgroundColor: AppColors.primary.withAlpha(25),
          ),
          child: Center(
            child: Text(
              _formatElapsed(),
              style: theme.textTheme.titleMedium?.copyWith(
                fontWeight: FontWeight.w600,
                color: AppColors.primary,
              ),
              textAlign: TextAlign.center,
            ),
          ),
        ),
      ),
    );
  }
}

class _GentleTimerPainter extends CustomPainter {
  final double progress;
  final Color color;
  final Color backgroundColor;

  _GentleTimerPainter({
    required this.progress,
    required this.color,
    required this.backgroundColor,
  });

  @override
  void paint(Canvas canvas, Size size) {
    final center = Offset(size.width / 2, size.height / 2);
    final radius = (size.shortestSide / 2) - 10;
    const strokeWidth = 10.0;
    const startAngle = -math.pi / 2;

    // Background circle
    canvas.drawCircle(
      center,
      radius,
      Paint()
        ..color = backgroundColor
        ..style = PaintingStyle.stroke
        ..strokeWidth = strokeWidth
        ..strokeCap = StrokeCap.round,
    );

    // Progress arc
    if (progress > 0) {
      canvas.drawArc(
        Rect.fromCircle(center: center, radius: radius),
        startAngle,
        2 * math.pi * progress,
        false,
        Paint()
          ..color = color
          ..style = PaintingStyle.stroke
          ..strokeWidth = strokeWidth
          ..strokeCap = StrokeCap.round,
      );
    }
  }

  @override
  bool shouldRepaint(covariant _GentleTimerPainter oldDelegate) =>
      progress != oldDelegate.progress;
}