import 'package:flutter/material.dart';

/// M3 Expressive surface tokens.
///
/// Cards now use **tonal elevation** (color tints) instead of drop-shadows.
/// Large containers adopt the M3 standard 28 dp corner radius; compact items
/// use 16 dp; small chips/badges use 12 dp.
@immutable
class AppSurfaces extends ThemeExtension<AppSurfaces> {
  const AppSurfaces({
    required this.cardRadius,
    required this.compactCardRadius,
    required this.containerRadius,
    required this.dialogRadius,
    required this.chipRadius,
  });

  /// Standard card radius – 16 dp (M3 medium shape).
  final double cardRadius;

  /// Compact card radius for dense list tiles – 12 dp.
  final double compactCardRadius;

  /// Large container radius – 28 dp (M3 Expressive).
  final double containerRadius;

  /// Dialog / bottom-sheet radius – 28 dp.
  final double dialogRadius;

  /// Chip / badge radius – 12 dp.
  final double chipRadius;

  // convenience shapes
  RoundedRectangleBorder get standardShape =>
      RoundedRectangleBorder(borderRadius: BorderRadius.circular(cardRadius));
  RoundedRectangleBorder get compactShape => RoundedRectangleBorder(
    borderRadius: BorderRadius.circular(compactCardRadius),
  );
  RoundedRectangleBorder get containerShape => RoundedRectangleBorder(
    borderRadius: BorderRadius.circular(containerRadius),
  );
  RoundedRectangleBorder get dialogShape =>
      RoundedRectangleBorder(borderRadius: BorderRadius.circular(dialogRadius));

  static AppSurfaces of(BuildContext context) {
    final ext = Theme.of(context).extension<AppSurfaces>();
    return ext ??
        const AppSurfaces(
          cardRadius: 16,
          compactCardRadius: 12,
          containerRadius: 28,
          dialogRadius: 28,
          chipRadius: 12,
        );
  }

  @override
  AppSurfaces copyWith({
    double? cardRadius,
    double? compactCardRadius,
    double? containerRadius,
    double? dialogRadius,
    double? chipRadius,
  }) {
    return AppSurfaces(
      cardRadius: cardRadius ?? this.cardRadius,
      compactCardRadius: compactCardRadius ?? this.compactCardRadius,
      containerRadius: containerRadius ?? this.containerRadius,
      dialogRadius: dialogRadius ?? this.dialogRadius,
      chipRadius: chipRadius ?? this.chipRadius,
    );
  }

  @override
  AppSurfaces lerp(ThemeExtension<AppSurfaces>? other, double t) {
    if (other is! AppSurfaces) return this;
    return AppSurfaces(
      cardRadius: _lerpDouble(cardRadius, other.cardRadius, t),
      compactCardRadius: _lerpDouble(
        compactCardRadius,
        other.compactCardRadius,
        t,
      ),
      containerRadius: _lerpDouble(containerRadius, other.containerRadius, t),
      dialogRadius: _lerpDouble(dialogRadius, other.dialogRadius, t),
      chipRadius: _lerpDouble(chipRadius, other.chipRadius, t),
    );
  }
}

double _lerpDouble(double a, double b, double t) => a + (b - a) * t;