import 'package:flutter/material.dart';

import '../theme/app_theme.dart';

/// Animated 3-dot typing indicator styled as an assistant bubble.
class TypingIndicator extends StatefulWidget {
  const TypingIndicator({super.key});

  @override
  State<TypingIndicator> createState() => _TypingIndicatorState();
}

class _TypingIndicatorState extends State<TypingIndicator>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      vsync: this,
      duration: const Duration(milliseconds: 1200),
    )..repeat();
  }

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

  @override
  Widget build(BuildContext context) {
    final isDark = Theme.of(context).brightness == Brightness.dark;

    return Align(
      alignment: Alignment.centerLeft,
      child: Container(
        margin: const EdgeInsets.only(left: 16, bottom: 8, right: 80),
        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
        decoration: BoxDecoration(
          color: isDark ? AppColors.assistantBubble : AppColors.lightAssistantBubble,
          borderRadius: const BorderRadius.only(
            topLeft: Radius.circular(16),
            topRight: Radius.circular(16),
            bottomRight: Radius.circular(16),
            bottomLeft: Radius.circular(4),
          ),
        ),
        child: AnimatedBuilder(
          animation: _controller,
          builder: (context, _) {
            return Row(
              mainAxisSize: MainAxisSize.min,
              children: List.generate(3, (i) {
                final delay = i * 0.2;
                final t = (_controller.value - delay).clamp(0.0, 1.0);
                // Bounce: sin wave for smooth up/down
                final offset = -4.0 * _bounce(t);
                return Transform.translate(
                  offset: Offset(0, offset),
                  child: Container(
                    width: 8,
                    height: 8,
                    margin: EdgeInsets.only(right: i < 2 ? 4 : 0),
                    decoration: BoxDecoration(
                      color: isDark
                          ? AppColors.darkTextSecondary
                          : AppColors.lightTextSecondary,
                      shape: BoxShape.circle,
                    ),
                  ),
                );
              }),
            );
          },
        ),
      ),
    );
  }

  double _bounce(double t) {
    // Simple sine bounce
    if (t <= 0 || t >= 1) return 0;
    return (t < 0.5)
        ? (t * 2) * (t * 2) // ease in
        : 1 - ((t - 0.5) * 2) * ((t - 0.5) * 2); // ease out
  }
}