app/lib/theme.dart

import 'package:flutter/material.dart';

/// Muted clinical color palette.
class AppColors {
  static const primary = Color(0xFF4A90A4); // Muted teal
  static const primaryDark = Color(0xFF2D6073);
  static const primaryLight = Color(0xFF7BB8CC);

  static const surface = Color(0xFFF8FAFB);
  static const surfaceVariant = Color(0xFFEEF2F4);
  static const background = Color(0xFFFFFFFF);

  static const textPrimary = Color(0xFF1A2B33);
  static const textSecondary = Color(0xFF5A6B73);
  static const textTertiary = Color(0xFF8A9BA3);

  static const success = Color(0xFF4A9A7C);
  static const warning = Color(0xFFB8934A);
  static const error = Color(0xFFA45A5A);

  static const divider = Color(0xFFDDE4E8);
}

/// App-wide theme.
ThemeData buildAppTheme() {
  return ThemeData(
    useMaterial3: true,
    colorScheme: ColorScheme.light(
      primary: AppColors.primary,
      onPrimary: Colors.white,
      secondary: AppColors.primaryLight,
      surface: AppColors.surface,
      onSurface: AppColors.textPrimary,
    ),
    scaffoldBackgroundColor: AppColors.background,
    appBarTheme: const AppBarTheme(
      backgroundColor: AppColors.background,
      foregroundColor: AppColors.textPrimary,
      elevation: 0,
      centerTitle: true,
      titleTextStyle: TextStyle(
        fontFamily: 'SF Pro Display',
        fontSize: 17,
        fontWeight: FontWeight.w600,
        color: AppColors.textPrimary,
        letterSpacing: -0.3,
      ),
    ),
    textTheme: const TextTheme(
      headlineLarge: TextStyle(
        fontSize: 28,
        fontWeight: FontWeight.w600,
        color: AppColors.textPrimary,
        letterSpacing: -0.5,
        height: 1.2,
      ),
      headlineMedium: TextStyle(
        fontSize: 22,
        fontWeight: FontWeight.w600,
        color: AppColors.textPrimary,
        letterSpacing: -0.3,
        height: 1.3,
      ),
      headlineSmall: TextStyle(
        fontSize: 18,
        fontWeight: FontWeight.w600,
        color: AppColors.textPrimary,
        letterSpacing: -0.2,
      ),
      bodyLarge: TextStyle(
        fontSize: 16,
        fontWeight: FontWeight.w400,
        color: AppColors.textPrimary,
        height: 1.5,
      ),
      bodyMedium: TextStyle(
        fontSize: 14,
        fontWeight: FontWeight.w400,
        color: AppColors.textSecondary,
        height: 1.5,
      ),
      bodySmall: TextStyle(
        fontSize: 12,
        fontWeight: FontWeight.w400,
        color: AppColors.textTertiary,
        height: 1.4,
      ),
      labelLarge: TextStyle(
        fontSize: 16,
        fontWeight: FontWeight.w600,
        color: AppColors.textPrimary,
        letterSpacing: 0.1,
      ),
    ),
    elevatedButtonTheme: ElevatedButtonThemeData(
      style: ElevatedButton.styleFrom(
        backgroundColor: AppColors.primary,
        foregroundColor: Colors.white,
        elevation: 0,
        padding: const EdgeInsets.symmetric(horizontal: 32, vertical: 16),
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(12),
        ),
        textStyle: const TextStyle(
          fontSize: 16,
          fontWeight: FontWeight.w600,
          letterSpacing: 0.2,
        ),
      ),
    ),
    outlinedButtonTheme: OutlinedButtonThemeData(
      style: OutlinedButton.styleFrom(
        foregroundColor: AppColors.primary,
        side: const BorderSide(color: AppColors.primary, width: 1.5),
        padding: const EdgeInsets.symmetric(horizontal: 32, vertical: 16),
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(12),
        ),
        textStyle: const TextStyle(
          fontSize: 16,
          fontWeight: FontWeight.w600,
          letterSpacing: 0.2,
        ),
      ),
    ),
    inputDecorationTheme: InputDecorationTheme(
      filled: true,
      fillColor: AppColors.surfaceVariant,
      border: OutlineInputBorder(
        borderRadius: BorderRadius.circular(12),
        borderSide: BorderSide.none,
      ),
      focusedBorder: OutlineInputBorder(
        borderRadius: BorderRadius.circular(12),
        borderSide: const BorderSide(color: AppColors.primary, width: 2),
      ),
      contentPadding: const EdgeInsets.symmetric(horizontal: 16, vertical: 14),
      labelStyle: const TextStyle(color: AppColors.textSecondary),
    ),
    dividerTheme: const DividerThemeData(
      color: AppColors.divider,
      thickness: 1,
    ),
    cardTheme: CardThemeData(
      color: AppColors.surface,
      elevation: 0,
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(16),
        side: const BorderSide(color: AppColors.divider, width: 1),
      ),
    ),
  );
}