import 'dart:math' as math;
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter/semantics.dart';
import '../../shared/theme/app_theme.dart';
import '../../shared/theme/theme_extensions.dart';

/// Enhanced accessibility service for WCAG 2.2 AA compliance
class EnhancedAccessibilityService {
  /// Announce text to screen readers
  static void announce(
    String message, {
    TextDirection textDirection = TextDirection.ltr,
  }) {
    SemanticsService.announce(message, textDirection);
  }

  /// Announce loading state
  static void announceLoading(String loadingMessage) {
    announce('Loading: $loadingMessage');
  }

  /// Announce error with helpful context
  static void announceError(String error, {String? suggestion}) {
    final message = suggestion != null
        ? 'Error: $error. $suggestion'
        : 'Error: $error';
    announce(message);
  }

  /// Announce success with context
  static void announceSuccess(String successMessage) {
    announce('Success: $successMessage');
  }

  /// Check if reduce motion is enabled
  static bool shouldReduceMotion(BuildContext context) {
    return MediaQuery.of(context).disableAnimations;
  }

  /// Get appropriate animation duration based on motion settings
  static Duration getAnimationDuration(
    BuildContext context,
    Duration defaultDuration,
  ) {
    return shouldReduceMotion(context) ? Duration.zero : defaultDuration;
  }

  /// Get text scale factor with bounds for accessibility
  static double getBoundedTextScaleFactor(BuildContext context) {
    final textScaler = MediaQuery.of(context).textScaler;
    final textScaleFactor = textScaler.scale(1.0);
    // Ensure text doesn't get too small or too large
    return textScaleFactor.clamp(0.8, 3.0);
  }

  /// Create accessible button with proper semantics
  static Widget createAccessibleButton({
    required Widget child,
    required VoidCallback? onPressed,
    required String semanticLabel,
    String? semanticHint,
    bool isDestructive = false,
  }) {
    return Builder(
      builder: (context) => Semantics(
        label: semanticLabel,
        hint: semanticHint,
        button: true,
        enabled: onPressed != null,
        child: ElevatedButton(
          onPressed: onPressed,
          style: ElevatedButton.styleFrom(
            minimumSize: const Size(44, 44), // WCAG minimum touch target
            backgroundColor: isDestructive ? context.conduitTheme.error : null,
          ),
          child: child,
        ),
      ),
    );
  }

  /// Create accessible icon button with proper semantics
  static Widget createAccessibleIconButton({
    required IconData icon,
    required VoidCallback? onPressed,
    required String semanticLabel,
    String? semanticHint,
    Color? iconColor,
    double iconSize = 24,
  }) {
    return Semantics(
      label: semanticLabel,
      hint: semanticHint,
      button: true,
      enabled: onPressed != null,
      child: SizedBox(
        width: 44, // Minimum touch target
        height: 44,
        child: IconButton(
          onPressed: onPressed,
          icon: Icon(icon, size: iconSize, color: iconColor),
          padding: EdgeInsets.zero,
        ),
      ),
    );
  }

  /// Create accessible text field with proper labels
  static Widget createAccessibleTextField({
    required String label,
    TextEditingController? controller,
    String? hintText,
    String? errorText,
    bool isRequired = false,
    TextInputType? keyboardType,
    bool obscureText = false,
    ValueChanged<String>? onChanged,
  }) {
    final effectiveLabel = isRequired ? '$label *' : label;

    return Semantics(
      label: effectiveLabel,
      hint: hintText,
      textField: true,
      child: TextFormField(
        controller: controller,
        keyboardType: keyboardType,
        obscureText: obscureText,
        onChanged: onChanged,
        decoration: InputDecoration(
          labelText: effectiveLabel,
          hintText: hintText,
          errorText: errorText,
          helperText: isRequired ? '* Required field' : null,
          prefixIcon: errorText != null
              ? Builder(
                  builder: (context) => Icon(
                    Icons.error_outline,
                    color: context.conduitTheme.error,
                  ),
                )
              : null,
        ),
      ),
    );
  }

  /// Create accessible card with proper semantics
  static Widget createAccessibleCard({
    required Widget child,
    VoidCallback? onTap,
    String? semanticLabel,
    String? semanticHint,
    bool isSelected = false,
  }) {
    return Semantics(
      label: semanticLabel,
      hint: semanticHint,
      button: onTap != null,
      selected: isSelected,
      child: Card(
        child: InkWell(
          onTap: onTap,
          child: Padding(
            padding: const EdgeInsets.all(Spacing.md),
            child: child,
          ),
        ),
      ),
    );
  }

  /// Create accessible loading indicator
  static Widget createAccessibleLoadingIndicator({
    String? loadingMessage,
    double size = 24,
  }) {
    return Semantics(
      label: loadingMessage ?? 'Loading',
      liveRegion: true,
      child: SizedBox(
        width: size,
        height: size,
        child: const CircularProgressIndicator(),
      ),
    );
  }

  /// Create accessible image with alt text
  static Widget createAccessibleImage({
    required ImageProvider image,
    required String altText,
    bool isDecorative = false,
    double? width,
    double? height,
    BoxFit fit = BoxFit.cover,
  }) {
    if (isDecorative) {
      return Semantics(
        excludeSemantics: true,
        child: Image(image: image, width: width, height: height, fit: fit),
      );
    }

    return Semantics(
      label: altText,
      image: true,
      child: Image(image: image, width: width, height: height, fit: fit),
    );
  }

  /// Create accessible toggle switch
  static Widget createAccessibleSwitch({
    required bool value,
    required ValueChanged<bool>? onChanged,
    required String label,
    String? description,
  }) {
    return Builder(
      builder: (context) => Semantics(
        label: label,
        value: value ? 'On' : 'Off',
        hint: description,
        toggled: value,
        onTap: onChanged != null ? () => onChanged(!value) : null,
        child: SwitchListTile(
          title: Text(
            label,
            style: TextStyle(color: context.conduitTheme.textPrimary),
          ),
          subtitle: description != null
              ? Text(
                  description,
                  style: TextStyle(color: context.conduitTheme.textSecondary),
                )
              : null,
          value: value,
          onChanged: onChanged,
        ),
      ),
    );
  }

  /// Create accessible slider
  static Widget createAccessibleSlider({
    required double value,
    required ValueChanged<double>? onChanged,
    required String label,
    double min = 0.0,
    double max = 1.0,
    int? divisions,
    String Function(double)? valueFormatter,
  }) {
    final formattedValue =
        valueFormatter?.call(value) ?? value.toStringAsFixed(1);

    return Semantics(
      label: label,
      value: formattedValue,
      increasedValue:
          valueFormatter?.call((value + 0.1).clamp(min, max)) ??
          (value + 0.1).clamp(min, max).toStringAsFixed(1),
      decreasedValue:
          valueFormatter?.call((value - 0.1).clamp(min, max)) ??
          (value - 0.1).clamp(min, max).toStringAsFixed(1),
      onIncrease: onChanged != null
          ? () => onChanged((value + 0.1).clamp(min, max))
          : null,
      onDecrease: onChanged != null
          ? () => onChanged((value - 0.1).clamp(min, max))
          : null,
      child: Slider(
        value: value,
        min: min,
        max: max,
        divisions: divisions,
        onChanged: onChanged,
        label: formattedValue,
      ),
    );
  }

  /// Create accessible modal with focus management
  static Future<T?> showAccessibleModal<T>({
    required BuildContext context,
    required Widget child,
    required String title,
    bool barrierDismissible = true,
  }) {
    return showDialog<T>(
      context: context,
      barrierDismissible: barrierDismissible,
      builder: (context) => Semantics(
        scopesRoute: true,
        explicitChildNodes: true,
        label: 'Dialog: $title',
        child: AlertDialog(
          title: Semantics(header: true, child: Text(title)),
          content: child,
        ),
      ),
    );
  }

  /// Check color contrast ratio (simplified implementation)
  static bool hasGoodContrast(Color foreground, Color background) {
    // Simplified contrast calculation
    final fgLuminance = _getLuminance(foreground);
    final bgLuminance = _getLuminance(background);

    final lighter = fgLuminance > bgLuminance ? fgLuminance : bgLuminance;
    final darker = fgLuminance > bgLuminance ? bgLuminance : fgLuminance;

    final contrast = (lighter + 0.05) / (darker + 0.05);

    // WCAG AA requires 4.5:1 for normal text, 3:1 for large text
    return contrast >= 4.5;
  }

  /// Calculate relative luminance of a color
  static double _getLuminance(Color color) {
    final r = _gammaCorrect((color.r * 255.0).round() / 255.0);
    final g = _gammaCorrect((color.g * 255.0).round() / 255.0);
    final b = _gammaCorrect((color.b * 255.0).round() / 255.0);

    return 0.2126 * r + 0.7152 * g + 0.0722 * b;
  }

  /// Apply gamma correction
  static double _gammaCorrect(double value) {
    return value <= 0.03928
        ? value / 12.92
        : math.pow((value + 0.055) / 1.055, 2.4).toDouble();
  }

  /// Provide haptic feedback if available
  static void hapticFeedback() {
    HapticFeedback.lightImpact();
  }

  /// Create accessible focus border
  static BoxDecoration createFocusBorder({
    required bool hasFocus,
    Color? focusColor,
    double borderWidth = 2.0,
    BorderRadius? borderRadius,
  }) {
    return BoxDecoration(
      border: hasFocus
          ? Border.all(
              color:
                  focusColor ??
                  AppTheme.brandPrimary, // Brand primary as fallback
              width: borderWidth,
            )
          : null,
      borderRadius: borderRadius,
    );
  }

  /// Create accessible text with proper scaling
  static Widget createAccessibleText(
    String text, {
    TextStyle? style,
    TextAlign? textAlign,
    bool isHeader = false,
    int? maxLines,
  }) {
    return Builder(
      builder: (context) {
        final textScaleFactor = getBoundedTextScaleFactor(context);

        Widget textWidget = Text(
          text,
          style:
              style?.copyWith(
                fontSize: style.fontSize != null
                    ? style.fontSize! * textScaleFactor
                    : null,
              ) ??
              TextStyle(fontSize: AppTypography.bodyLarge * textScaleFactor),
          textAlign: textAlign,
          maxLines: maxLines,
          overflow: maxLines != null ? TextOverflow.ellipsis : null,
        );

        if (isHeader) {
          textWidget = Semantics(header: true, child: textWidget);
        }

        return textWidget;
      },
    );
  }
}