tasq/lib/theme/app_surfaces.dart

import 'package:flutter/material.dart';

/// Cyber/IT surface tokens.
///
/// Cards use **tonal elevation** (color tints) plus a hairline outline instead
/// of drop-shadows. The shape language is tightened to a precise 12–16 dp
/// technical feel: standard cards 12 dp, compact items 10 dp, large containers
/// 16 dp, dialogs/sheets 20 dp, and chips/badges 8 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 – 12 dp (cyber/IT medium shape).
  final double cardRadius;

  /// Compact card radius for dense list tiles – 10 dp.
  final double compactCardRadius;

  /// Large container radius – 16 dp.
  final double containerRadius;

  /// Dialog / bottom-sheet radius – 20 dp.
  final double dialogRadius;

  /// Chip / badge radius – 8 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: 12,
          compactCardRadius: 10,
          containerRadius: 16,
          dialogRadius: 20,
          chipRadius: 8,
        );
  }

  @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;