import 'dart:math' as math;

import 'package:flutter/material.dart';

import '../theme/lawheatmap_tokens.dart';

/// The F∆I / Ch∆In brand mark: an upward triangle (the `∆`) with
/// a petrol "eye" at the centre. Geometry mirrors fai_web's
/// Logo.astro — the triangle IS the "A"; the eye-dot IS the dot
/// of the "i".
///
/// Subtle 9s breathing pulse on the eye (matches fai_web's
/// `.eye-pulse`). Set [animated] to false for static contexts
/// (icons, screenshots).
class DeltaMark extends StatefulWidget {
  const DeltaMark({super.key, this.size = 64, this.animated = true});

  final double size;
  final bool animated;

  @override
  State<DeltaMark> createState() => _DeltaMarkState();
}

class _DeltaMarkState extends State<DeltaMark>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      vsync: this,
      duration: const Duration(seconds: 9),
    );
    if (widget.animated) {
      _controller.repeat();
    }
  }

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

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _controller,
      builder: (context, _) {
        final t = _controller.value;
        // Breathe: scale 1 → 1.28 → 1 over the cycle.
        final pulse = 1.0 + 0.28 * (1 - (math.cos(t * 2 * math.pi).abs()));
        return CustomPaint(
          size: Size.square(widget.size),
          painter: _DeltaPainter(pulse: widget.animated ? pulse : 1.0),
        );
      },
    );
  }
}

class _DeltaPainter extends CustomPainter {
  _DeltaPainter({required this.pulse});

  final double pulse;

  @override
  void paint(Canvas canvas, Size size) {
    final w = size.width;
    final h = size.height;

    // Upward triangle, geometric centre.
    final stroke = Paint()
      ..color = const Color(0xFFE9E7E2)
      ..style = PaintingStyle.stroke
      ..strokeWidth = w * 0.04
      ..strokeJoin = StrokeJoin.miter;

    final inset = w * 0.08;
    final tri = Path()
      ..moveTo(w / 2, inset)
      ..lineTo(w - inset, h - inset)
      ..lineTo(inset, h - inset)
      ..close();
    canvas.drawPath(tri, stroke);

    // Eye — petrol fill, centred on the triangle's centroid.
    final eyeCentre = Offset(w / 2, inset + (h - 2 * inset) * 2 / 3);
    final eyeR = w * 0.06 * pulse;
    final eye = Paint()..color = LawHeatmapColors.signal;
    canvas.drawCircle(eyeCentre, eyeR, eye);
  }

  @override
  bool shouldRepaint(covariant _DeltaPainter old) => old.pulse != pulse;
}