import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import '../theme.dart';

// Duolingo-style pressable button.
// Stack of two containers: dark "shadow" bottom + colored top that translates down on press.
class SButton extends StatefulWidget {
  final String label;
  final VoidCallback? onTap;
  final bool enabled;
  final Color? color;
  final Color? shadowColor;
  final Color? textColor;

  const SButton({
    super.key,
    required this.label,
    required this.onTap,
    this.enabled = true,
    this.color,
    this.shadowColor,
    this.textColor,
  });

  @override
  State<SButton> createState() => _SButtonState();
}

class _SButtonState extends State<SButton> {
  bool _pressed = false;

  bool get _active => widget.enabled && widget.onTap != null;

  static const _shadowH = 4.0;
  static const _btnH = 52.0;
  static const _radius = 16.0;

  @override
  Widget build(BuildContext context) {
    final bg = _active ? (widget.color ?? SColors.primary) : const Color(0xFFE5E5E5);
    final shadow = _active ? (widget.shadowColor ?? SColors.primaryDark) : const Color(0xFFB8B8B8);
    final textCol = _active ? (widget.textColor ?? Colors.white) : SColors.textDisabled;
    final offset = (_pressed && _active) ? _shadowH : 0.0;

    return GestureDetector(
      onTapDown: (_) { if (_active) setState(() => _pressed = true); },
      onTapUp: (_) {
        if (!_active) return;
        setState(() => _pressed = false);
        HapticFeedback.mediumImpact();
        widget.onTap!();
      },
      onTapCancel: () { if (_active) setState(() => _pressed = false); },
      child: SizedBox(
        height: _btnH + _shadowH,
        child: Stack(
          children: [
            // Shadow layer (always at bottom)
            Positioned.fill(
              child: Container(
                decoration: BoxDecoration(
                  color: shadow,
                  borderRadius: BorderRadius.circular(_radius),
                ),
              ),
            ),
            // Button layer (translates down on press, "sinking" into shadow)
            AnimatedPositioned(
              duration: const Duration(milliseconds: 80),
              top: offset,
              left: 0,
              right: 0,
              height: _btnH,
              child: Container(
                decoration: BoxDecoration(
                  color: bg,
                  borderRadius: BorderRadius.circular(_radius),
                ),
                alignment: Alignment.center,
                child: Text(widget.label, style: SText.button(textCol)),
              ),
            ),
          ],
        ),
      ),
    );
  }
}