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

/// Custom authentication button with loading states and variants
class AuthButton extends StatefulWidget {
  final String text;
  final VoidCallback? onPressed;
  final bool isLoading;
  final bool isSuccess;
  final String? loadingText;
  final String? successText;
  final AuthButtonVariant variant;
  final bool fullWidth;
  final Widget? icon;
  final Duration successDuration;

  const AuthButton({
    super.key,
    required this.text,
    this.onPressed,
    this.isLoading = false,
    this.isSuccess = false,
    this.loadingText,
    this.successText,
    this.variant = AuthButtonVariant.primary,
    this.fullWidth = true,
    this.icon,
    this.successDuration = const Duration(seconds: 2),
  });

  @override
  State<AuthButton> createState() => _AuthButtonState();
}

class _AuthButtonState extends State<AuthButton> 
    with SingleTickerProviderStateMixin {
  late AnimationController _animationController;
  late Animation<double> _scaleAnimation;
  late Animation<double> _opacityAnimation;
  bool _isPressed = false;
  DateTime? _lastPressedTime;

  @override
  void initState() {
    super.initState();
    _animationController = AnimationController(
      duration: const Duration(milliseconds: 200),
      vsync: this,
    );
    _scaleAnimation = Tween<double>(
      begin: 1.0,
      end: 0.95,
    ).animate(CurvedAnimation(
      parent: _animationController,
      curve: Curves.easeInOut,
    ));
    _opacityAnimation = Tween<double>(
      begin: 1.0,
      end: 0.7,
    ).animate(CurvedAnimation(
      parent: _animationController,
      curve: Curves.easeInOut,
    ));
  }

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

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colors = _getColors(theme);
    final isDisabled = widget.isLoading || widget.onPressed == null;
    final displayText = _getDisplayText();
    final displayIcon = _getDisplayIcon();

    return AnimatedBuilder(
      animation: _animationController,
      builder: (context, child) {
        return Transform.scale(
          scale: _scaleAnimation.value,
          child: Opacity(
            opacity: _opacityAnimation.value,
            child: Semantics(
              button: true,
              label: _getAccessibilityLabel(),
              hint: _getAccessibilityHint(),
              child: SizedBox(
                width: widget.fullWidth ? double.infinity : null,
                height: 48,
                child: ElevatedButton(
                  onPressed: isDisabled ? null : _handlePressed,
                  style: ElevatedButton.styleFrom(
                    backgroundColor: _getBackgroundColor(colors),
                    foregroundColor: _getForegroundColor(colors),
                    disabledBackgroundColor: colors.disabledBackground,
                    disabledForegroundColor: colors.disabledForeground,
                    elevation: widget.variant == AuthButtonVariant.primary ? 2 : 0,
                    shape: RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(8),
                      side: widget.variant == AuthButtonVariant.outline
                          ? BorderSide(color: colors.background)
                          : BorderSide.none,
                    ),
                  ),
                  child: _buildButtonContent(displayText, displayIcon, colors.foreground, theme),
                ),
              ),
            ),
          ),
        );
      },
    );
  }

  Widget _buildButtonContent(String text, Widget? icon, Color foregroundColor, ThemeData theme) {
    if (widget.isLoading) {
      return Row(
        mainAxisSize: MainAxisSize.min,
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          SizedBox(
            height: 20,
            width: 20,
            child: CircularProgressIndicator(
              strokeWidth: 2,
              valueColor: AlwaysStoppedAnimation<Color>(foregroundColor),
            ),
          ),
          const SizedBox(width: 12),
          Text(
            widget.loadingText ?? 'Loading...',
            style: theme.textTheme.labelLarge?.copyWith(
              fontWeight: FontWeight.w600,
              color: foregroundColor,
            ),
          ),
        ],
      );
    }

    if (widget.isSuccess) {
      return Row(
        mainAxisSize: MainAxisSize.min,
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Icon(
            Icons.check_circle,
            color: foregroundColor,
            size: 20,
          ),
          const SizedBox(width: 8),
          Text(
            widget.successText ?? 'Success!',
            style: theme.textTheme.labelLarge?.copyWith(
              fontWeight: FontWeight.w600,
              color: foregroundColor,
            ),
          ),
        ],
      );
    }

    return Row(
      mainAxisSize: MainAxisSize.min,
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        if (icon != null) ...[
          icon!,
          const SizedBox(width: 8),
        ],
        Text(
          text,
          style: theme.textTheme.labelLarge?.copyWith(
            fontWeight: FontWeight.w600,
            color: foregroundColor,
          ),
        ),
      ],
    );
  }

  String _getDisplayText() {
    if (widget.isLoading) {
      return widget.loadingText ?? 'Loading...';
    }
    if (widget.isSuccess) {
      return widget.successText ?? 'Success!';
    }
    return widget.text;
  }

  Widget? _getDisplayIcon() {
    if (widget.isLoading || widget.isSuccess) {
      return null; // Loading spinner or checkmark will be shown
    }
    return widget.icon;
  }

  Color _getBackgroundColor(_ButtonColors colors) {
    if (widget.isSuccess) {
      return Theme.of(context).colorScheme.primary;
    }
    return colors.background;
  }

  Color _getForegroundColor(_ButtonColors colors) {
    if (widget.isSuccess) {
      return Theme.of(context).colorScheme.onPrimary;
    }
    return colors.foreground;
  }

  String _getAccessibilityLabel() {
    if (widget.isLoading) {
      return '${widget.loadingText ?? "Loading"} button';
    }
    if (widget.isSuccess) {
      return '${widget.successText ?? "Success"} completed';
    }
    return widget.text;
  }

  String _getAccessibilityHint() {
    if (widget.isLoading) {
      return 'Please wait while operation completes';
    }
    if (widget.isSuccess) {
      return 'Operation completed successfully';
    }
    return 'Double tap to ${widget.text.toLowerCase()}';
  }

  void _handlePressed() async {
    // Prevent double-tap within 500ms
    final now = DateTime.now();
    if (_lastPressedTime != null && 
        now.difference(_lastPressedTime!).inMilliseconds < 500) {
      return;
    }
    _lastPressedTime = now;

    // Provide haptic feedback if available
    try {
      HapticFeedback.lightImpact();
    } catch (e) {
      // Haptic feedback not available on all platforms
    }

    // Animate press
    _animationController.forward().then((_) {
      _animationController.reverse();
    });

    // Announce for accessibility
    _announceForAccessibility('${widget.text} activated');

    // Execute callback
    await widget.onPressed?.call();

    // Auto-reset success state after duration
    if (widget.isSuccess) {
      Future.delayed(widget.successDuration, () {
        if (mounted) {
          // Success state reset should be handled by parent
          _announceForAccessibility('Success state completed');
        }
      });
    }
  }

  void _announceForAccessibility(String message) {
    SemanticsService.announce(message, TextDirection.ltr);
  }

  _ButtonColors _getColors(ThemeData theme) {
    switch (variant) {
      case AuthButtonVariant.primary:
        return _ButtonColors(
          background: theme.colorScheme.primary,
          foreground: theme.colorScheme.onPrimary,
          disabledBackground: theme.colorScheme.primary.withOpacity(0.12),
          disabledForeground: theme.colorScheme.onPrimary.withOpacity(0.38),
        );
      case AuthButtonVariant.secondary:
        return _ButtonColors(
          background: theme.colorScheme.secondary,
          foreground: theme.colorScheme.onSecondary,
          disabledBackground: theme.colorScheme.secondary.withOpacity(0.12),
          disabledForeground: theme.colorScheme.onSecondary.withOpacity(0.38),
        );
      case AuthButtonVariant.outline:
        return _ButtonColors(
          background: Colors.transparent,
          foreground: theme.colorScheme.primary,
          disabledBackground: Colors.transparent,
          disabledForeground: theme.colorScheme.primary.withOpacity(0.38),
        );
    }
  }
}

enum AuthButtonVariant {
  primary,
  secondary,
  outline,
}

  _ButtonColors _getColors(ThemeData theme) {
    switch (widget.variant) {
      case AuthButtonVariant.primary:
        return _ButtonColors(
          background: theme.colorScheme.primary,
          foreground: theme.colorScheme.onPrimary,
          disabledBackground: theme.colorScheme.primary.withOpacity(0.12),
          disabledForeground: theme.colorScheme.onPrimary.withOpacity(0.38),
        );
      case AuthButtonVariant.secondary:
        return _ButtonColors(
          background: theme.colorScheme.secondary,
          foreground: theme.colorScheme.onSecondary,
          disabledBackground: theme.colorScheme.secondary.withOpacity(0.12),
          disabledForeground: theme.colorScheme.onSecondary.withOpacity(0.38),
        );
      case AuthButtonVariant.outline:
        return _ButtonColors(
          background: Colors.transparent,
          foreground: theme.colorScheme.primary,
          disabledBackground: Colors.transparent,
          disabledForeground: theme.colorScheme.primary.withOpacity(0.38),
        );
    }
  }
}

class _ButtonColors {
  final Color background;
  final Color foreground;
  final Color disabledBackground;
  final Color disabledForeground;

  const _ButtonColors({
    required this.background,
    required this.foreground,
    required this.disabledBackground,
    required this.disabledForeground,
  });
}