/// Material 3 light and dark themes — charcoal surfaces, mint accent.
library;

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

/// Builds the [ThemeData] used by [MaterialApp] for light and dark mode.
abstract final class AppTheme {
  /// Mint / emerald accent from the product look.
  static const Color accent = Color(0xFF4FA894);

  /// Soft rose for expenses / money out.
  static const Color expense = Color(0xFFE07A7A);

  /// Near-black charcoal scaffold (dark).
  static const Color darkCanvas = Color(0xFF0B0D0C);

  static const Color darkSurface = Color(0xFF141716);

  static const Color darkContainer = Color(0xFF1E2321);

  static const Color darkContainerHigh = Color(0xFF2A302D);

  static ThemeData light() => _build(Brightness.light);

  static ThemeData dark() => _build(Brightness.dark);

  static ColorScheme _scheme(Brightness brightness) {
    if (brightness == Brightness.dark) {
      return const ColorScheme.dark(
        primary: accent,
        onPrimary: Color(0xFF06201A),
        primaryContainer: Color(0xFF1F4F44),
        onPrimaryContainer: Color(0xFFB8E6D8),
        secondary: Color(0xFF8FB5AB),
        onSecondary: Color(0xFF0B1F1A),
        secondaryContainer: Color(0xFF2A403A),
        onSecondaryContainer: Color(0xFFD0E8E0),
        tertiary: expense,
        onTertiary: Color(0xFF2A0F0F),
        tertiaryContainer: Color(0xFF5C2E2E),
        onTertiaryContainer: Color(0xFFFFDAD6),
        error: expense,
        onError: Color(0xFF2A0F0F),
        errorContainer: Color(0xFF5C2E2E),
        onErrorContainer: Color(0xFFFFDAD6),
        surface: darkSurface,
        onSurface: Color(0xFFE8EEEC),
        onSurfaceVariant: Color(0xFFA3AFA9),
        surfaceContainerLowest: darkCanvas,
        surfaceContainerLow: Color(0xFF171B19),
        surfaceContainer: darkContainer,
        surfaceContainerHigh: darkContainerHigh,
        surfaceContainerHighest: Color(0xFF343B38),
        outline: Color(0xFF6B7671),
        outlineVariant: Color(0xFF3A423E),
        shadow: Colors.black,
        scrim: Colors.black,
        inverseSurface: Color(0xFFE8EEEC),
        onInverseSurface: Color(0xFF1A1F1D),
        inversePrimary: Color(0xFF0F766E),
      );
    }

    return ColorScheme.fromSeed(
      seedColor: accent,
      brightness: Brightness.light,
      primary: const Color(0xFF1F6B5C),
      error: const Color(0xFFC45C5C),
    ).copyWith(
      surface: const Color(0xFFF4F7F5),
      surfaceContainerLowest: const Color(0xFFFFFFFF),
      surfaceContainerLow: const Color(0xFFEEF3F0),
      surfaceContainer: const Color(0xFFE6EDE9),
      surfaceContainerHigh: const Color(0xFFDCE6E1),
      surfaceContainerHighest: const Color(0xFFD0DCD6),
      onSurface: const Color(0xFF15201C),
      onSurfaceVariant: const Color(0xFF4A5A54),
      outline: const Color(0xFF7A8A83),
      outlineVariant: const Color(0xFFC5D0CB),
      tertiary: expense,
      error: expense,
    );
  }

  static ThemeData _build(Brightness brightness) {
    final colorScheme = _scheme(brightness);
    final isDark = brightness == Brightness.dark;
    final textTheme = _textTheme(colorScheme);
    const radius = 14.0;
    const radiusLg = 18.0;

    return ThemeData(
      useMaterial3: true,
      brightness: brightness,
      colorScheme: colorScheme,
      textTheme: textTheme,
      scaffoldBackgroundColor:
          isDark ? darkCanvas : colorScheme.surfaceContainerLowest,
      canvasColor: isDark ? darkCanvas : colorScheme.surface,
      appBarTheme: AppBarTheme(
        centerTitle: false,
        elevation: 0,
        scrolledUnderElevation: 0,
        backgroundColor: isDark ? darkCanvas : colorScheme.surfaceContainerLowest,
        foregroundColor: colorScheme.onSurface,
        titleTextStyle: textTheme.titleLarge,
        systemOverlayStyle: isDark
            ? SystemUiOverlayStyle.light.copyWith(
                statusBarColor: Colors.transparent,
                systemNavigationBarColor: darkCanvas,
              )
            : SystemUiOverlayStyle.dark.copyWith(
                statusBarColor: Colors.transparent,
              ),
      ),
      cardTheme: CardThemeData(
        elevation: 0,
        color: colorScheme.surfaceContainer,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(radiusLg),
        ),
        clipBehavior: Clip.antiAlias,
        margin: EdgeInsets.zero,
      ),
      navigationBarTheme: NavigationBarThemeData(
        elevation: 0,
        height: 72,
        backgroundColor: isDark ? darkSurface : colorScheme.surfaceContainer,
        indicatorColor: colorScheme.primary.withValues(alpha: 0.22),
        labelTextStyle: WidgetStateProperty.resolveWith((states) {
          final selected = states.contains(WidgetState.selected);
          return textTheme.labelMedium?.copyWith(
            fontWeight: selected ? FontWeight.w600 : FontWeight.w500,
            color: selected ? colorScheme.primary : colorScheme.onSurfaceVariant,
          );
        }),
        iconTheme: WidgetStateProperty.resolveWith((states) {
          final selected = states.contains(WidgetState.selected);
          return IconThemeData(
            color: selected ? colorScheme.primary : colorScheme.onSurfaceVariant,
          );
        }),
      ),
      inputDecorationTheme: InputDecorationTheme(
        filled: true,
        fillColor: colorScheme.surfaceContainerHigh,
        border: OutlineInputBorder(
          borderRadius: BorderRadius.circular(radius),
          borderSide: BorderSide.none,
        ),
        enabledBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(radius),
          borderSide: BorderSide(
            color: colorScheme.outlineVariant.withValues(alpha: 0.6),
          ),
        ),
        focusedBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(radius),
          borderSide: BorderSide(color: colorScheme.primary, width: 1.5),
        ),
        contentPadding: const EdgeInsets.symmetric(
          horizontal: 16,
          vertical: 14,
        ),
        hintStyle: textTheme.bodyMedium?.copyWith(
          color: colorScheme.onSurfaceVariant.withValues(alpha: 0.75),
        ),
      ),
      filledButtonTheme: FilledButtonThemeData(
        style: FilledButton.styleFrom(
          minimumSize: const Size.fromHeight(48),
          backgroundColor: colorScheme.primary,
          foregroundColor: colorScheme.onPrimary,
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(radius),
          ),
          textStyle: textTheme.labelLarge?.copyWith(fontWeight: FontWeight.w700),
        ),
      ),
      textButtonTheme: TextButtonThemeData(
        style: TextButton.styleFrom(
          foregroundColor: colorScheme.primary,
          textStyle: textTheme.labelLarge,
        ),
      ),
      outlinedButtonTheme: OutlinedButtonThemeData(
        style: OutlinedButton.styleFrom(
          foregroundColor: colorScheme.onSurface,
          side: BorderSide(color: colorScheme.outlineVariant),
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(radius),
          ),
          minimumSize: const Size(48, 44),
        ),
      ),
      iconButtonTheme: IconButtonThemeData(
        style: IconButton.styleFrom(
          foregroundColor: colorScheme.onSurfaceVariant,
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(12),
          ),
        ),
      ),
      floatingActionButtonTheme: FloatingActionButtonThemeData(
        backgroundColor: colorScheme.primary,
        foregroundColor: colorScheme.onPrimary,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(radiusLg),
        ),
      ),
      dividerTheme: DividerThemeData(
        color: colorScheme.outlineVariant.withValues(alpha: 0.55),
        space: 1,
        thickness: 1,
      ),
      snackBarTheme: SnackBarThemeData(
        behavior: SnackBarBehavior.floating,
        backgroundColor: colorScheme.inverseSurface,
        contentTextStyle: textTheme.bodyMedium?.copyWith(
          color: colorScheme.onInverseSurface,
        ),
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(radius),
        ),
      ),
      listTileTheme: ListTileThemeData(
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(radius),
        ),
        iconColor: colorScheme.primary,
        textColor: colorScheme.onSurface,
      ),
      chipTheme: ChipThemeData(
        backgroundColor: colorScheme.surfaceContainerHigh,
        selectedColor: colorScheme.primary.withValues(alpha: 0.28),
        deleteIconColor: colorScheme.onSurfaceVariant,
        labelStyle: textTheme.labelLarge?.copyWith(fontWeight: FontWeight.w600),
        secondaryLabelStyle: textTheme.labelMedium,
        padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 0),
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(20),
          side: BorderSide(
            color: colorScheme.outlineVariant.withValues(alpha: 0.5),
          ),
        ),
        side: BorderSide(
          color: colorScheme.outlineVariant.withValues(alpha: 0.5),
        ),
      ),
      dialogTheme: DialogThemeData(
        backgroundColor: colorScheme.surfaceContainer,
        surfaceTintColor: Colors.transparent,
        elevation: 8,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(24),
        ),
        titleTextStyle: textTheme.titleLarge,
        contentTextStyle: textTheme.bodyMedium,
      ),
      bottomSheetTheme: BottomSheetThemeData(
        backgroundColor: colorScheme.surfaceContainer,
        surfaceTintColor: Colors.transparent,
        elevation: 8,
        shape: const RoundedRectangleBorder(
          borderRadius: BorderRadius.vertical(top: Radius.circular(24)),
        ),
        dragHandleColor: colorScheme.outlineVariant,
        showDragHandle: true,
      ),
      // Avoid textStyle here — SegmentedButton lerps selected/unselected styles
      // and crashes if inherit flags disagree.
      segmentedButtonTheme: SegmentedButtonThemeData(
        style: ButtonStyle(
          backgroundColor: WidgetStateProperty.resolveWith((states) {
            if (states.contains(WidgetState.selected)) {
              return colorScheme.primary;
            }
            return colorScheme.surfaceContainerHigh;
          }),
          foregroundColor: WidgetStateProperty.resolveWith((states) {
            if (states.contains(WidgetState.selected)) {
              return colorScheme.onPrimary;
            }
            return colorScheme.onSurfaceVariant;
          }),
          side: WidgetStatePropertyAll(
            BorderSide(color: colorScheme.outlineVariant.withValues(alpha: 0.7)),
          ),
          shape: WidgetStatePropertyAll(
            RoundedRectangleBorder(
              borderRadius: BorderRadius.circular(12),
            ),
          ),
          visualDensity: VisualDensity.compact,
        ),
      ),
      sliderTheme: SliderThemeData(
        activeTrackColor: colorScheme.primary,
        inactiveTrackColor: colorScheme.outlineVariant.withValues(alpha: 0.5),
        thumbColor: colorScheme.primary,
        overlayColor: colorScheme.primary.withValues(alpha: 0.16),
        rangeThumbShape: const RoundRangeSliderThumbShape(enabledThumbRadius: 8),
        trackHeight: 4,
      ),
      checkboxTheme: CheckboxThemeData(
        fillColor: WidgetStateProperty.resolveWith((states) {
          if (states.contains(WidgetState.selected)) {
            return colorScheme.primary;
          }
          return Colors.transparent;
        }),
        checkColor: WidgetStatePropertyAll(colorScheme.onPrimary),
        side: BorderSide(color: colorScheme.outline, width: 1.5),
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(4)),
      ),
      progressIndicatorTheme: ProgressIndicatorThemeData(
        color: colorScheme.primary,
        linearTrackColor: colorScheme.outlineVariant.withValues(alpha: 0.35),
      ),
      shadowColor: isDark ? Colors.black : const Color(0x1A0F172A),
    );
  }

  /// Built from Material 2021 typography so every style shares `inherit: false`
  /// and theme animations / SegmentedButton can lerp safely.
  static TextTheme _textTheme(ColorScheme colors) {
    final base = Typography.material2021().englishLike.apply(
      bodyColor: colors.onSurface,
      displayColor: colors.onSurface,
    );

    return base.copyWith(
      displaySmall: base.displaySmall?.copyWith(
        fontSize: 36,
        fontWeight: FontWeight.w700,
        letterSpacing: -0.6,
      ),
      headlineMedium: base.headlineMedium?.copyWith(
        fontSize: 28,
        fontWeight: FontWeight.w600,
        letterSpacing: -0.4,
      ),
      titleLarge: base.titleLarge?.copyWith(
        fontSize: 22,
        fontWeight: FontWeight.w600,
        letterSpacing: -0.2,
      ),
      titleMedium: base.titleMedium?.copyWith(
        fontSize: 16,
        fontWeight: FontWeight.w600,
      ),
      titleSmall: base.titleSmall?.copyWith(
        fontSize: 14,
        fontWeight: FontWeight.w600,
      ),
      bodyLarge: base.bodyLarge?.copyWith(
        fontSize: 16,
        height: 1.4,
        fontWeight: FontWeight.w500,
      ),
      bodyMedium: base.bodyMedium?.copyWith(
        fontSize: 14,
        height: 1.4,
        color: colors.onSurfaceVariant,
      ),
      bodySmall: base.bodySmall?.copyWith(
        fontSize: 12,
        height: 1.35,
        color: colors.onSurfaceVariant,
      ),
      labelLarge: base.labelLarge?.copyWith(
        fontSize: 14,
        fontWeight: FontWeight.w600,
        letterSpacing: 0.1,
      ),
      labelMedium: base.labelMedium?.copyWith(
        fontSize: 12,
        fontWeight: FontWeight.w500,
        letterSpacing: 0.2,
        color: colors.onSurfaceVariant,
      ),
      labelSmall: base.labelSmall?.copyWith(
        fontSize: 11,
        fontWeight: FontWeight.w500,
        letterSpacing: 0.3,
        color: colors.onSurfaceVariant,
      ),
    );
  }
}