import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';
import 'app_colors.dart';

/// ADHD-friendly Material 3 theme.
///
/// Design principles:
///  - Calming primary colors (teal / soft blue) — NO aggressive reds.
///  - High-contrast text for readability.
///  - Large touch targets (minimum 48 dp).
///  - Rounded corners everywhere (16 dp radius).
///  - Gentle animations, no jarring transitions.
///  - Nunito for headers (friendly, rounded), Inter for body.
///  - Subtle, soft card shadows.
class AppTheme {
  AppTheme._();

  static const double _borderRadius = 16.0;
  static final _roundedShape = RoundedRectangleBorder(
    borderRadius: BorderRadius.circular(_borderRadius),
  );

  // ── Typography ───────────────────────────────────────────────────
  static TextTheme _buildTextTheme(TextTheme base, Color primary, Color secondary) {
    final headlineFont = GoogleFonts.nunitoTextTheme(base);
    final bodyFont = GoogleFonts.interTextTheme(base);

    return bodyFont.copyWith(
      displayLarge: headlineFont.displayLarge?.copyWith(color: primary, fontWeight: FontWeight.w700),
      displayMedium: headlineFont.displayMedium?.copyWith(color: primary, fontWeight: FontWeight.w700),
      displaySmall: headlineFont.displaySmall?.copyWith(color: primary, fontWeight: FontWeight.w700),
      headlineLarge: headlineFont.headlineLarge?.copyWith(color: primary, fontWeight: FontWeight.w700),
      headlineMedium: headlineFont.headlineMedium?.copyWith(color: primary, fontWeight: FontWeight.w600),
      headlineSmall: headlineFont.headlineSmall?.copyWith(color: primary, fontWeight: FontWeight.w600),
      titleLarge: headlineFont.titleLarge?.copyWith(color: primary, fontWeight: FontWeight.w600),
      titleMedium: headlineFont.titleMedium?.copyWith(color: primary, fontWeight: FontWeight.w600),
      titleSmall: headlineFont.titleSmall?.copyWith(color: primary, fontWeight: FontWeight.w500),
      bodyLarge: bodyFont.bodyLarge?.copyWith(color: primary, fontSize: 16),
      bodyMedium: bodyFont.bodyMedium?.copyWith(color: secondary, fontSize: 14),
      bodySmall: bodyFont.bodySmall?.copyWith(color: secondary, fontSize: 12),
      labelLarge: bodyFont.labelLarge?.copyWith(color: primary, fontWeight: FontWeight.w600, fontSize: 16),
      labelMedium: bodyFont.labelMedium?.copyWith(color: secondary),
      labelSmall: bodyFont.labelSmall?.copyWith(color: secondary),
    );
  }

  // ── Light theme ──────────────────────────────────────────────────
  static ThemeData get light {
    final colorScheme = ColorScheme.light(
      primary: AppColors.primary,
      onPrimary: Colors.white,
      primaryContainer: AppColors.primaryLight,
      onPrimaryContainer: AppColors.primaryDark,
      secondary: AppColors.secondary,
      onSecondary: Colors.white,
      secondaryContainer: AppColors.secondaryLight,
      onSecondaryContainer: AppColors.secondaryDark,
      tertiary: AppColors.tertiary,
      onTertiary: Colors.white,
      tertiaryContainer: AppColors.tertiaryLight,
      onTertiaryContainer: AppColors.tertiaryDark,
      surface: AppColors.surfaceLight,
      onSurface: AppColors.textPrimaryLight,
      surfaceContainerHighest: AppColors.surfaceVariantLight,
      onSurfaceVariant: AppColors.textSecondaryLight,
      error: AppColors.error,
      onError: Colors.white,
    );

    final textTheme = _buildTextTheme(
      ThemeData.light().textTheme,
      AppColors.textPrimaryLight,
      AppColors.textSecondaryLight,
    );

    return ThemeData(
      useMaterial3: true,
      colorScheme: colorScheme,
      scaffoldBackgroundColor: AppColors.backgroundLight,
      textTheme: textTheme,

      // AppBar
      appBarTheme: AppBarTheme(
        elevation: 0,
        scrolledUnderElevation: 1,
        backgroundColor: AppColors.backgroundLight,
        foregroundColor: AppColors.textPrimaryLight,
        titleTextStyle: textTheme.titleLarge,
      ),

      // Cards — subtle, soft shadows
      cardTheme: CardThemeData(
        elevation: 2,
        shadowColor: Colors.black.withAlpha(25),
        shape: _roundedShape,
        margin: const EdgeInsets.symmetric(horizontal: 16, vertical: 6),
      ),

      // Elevated buttons — large touch targets
      elevatedButtonTheme: ElevatedButtonThemeData(
        style: ElevatedButton.styleFrom(
          minimumSize: const Size(double.infinity, 52),
          shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(_borderRadius)),
          textStyle: textTheme.labelLarge,
          elevation: 2,
          shadowColor: Colors.black.withAlpha(25),
        ),
      ),

      // Filled buttons
      filledButtonTheme: FilledButtonThemeData(
        style: FilledButton.styleFrom(
          minimumSize: const Size(double.infinity, 52),
          shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(_borderRadius)),
          textStyle: textTheme.labelLarge,
        ),
      ),

      // Outlined buttons
      outlinedButtonTheme: OutlinedButtonThemeData(
        style: OutlinedButton.styleFrom(
          minimumSize: const Size(double.infinity, 52),
          shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(_borderRadius)),
          textStyle: textTheme.labelLarge,
        ),
      ),

      // Text buttons
      textButtonTheme: TextButtonThemeData(
        style: TextButton.styleFrom(
          minimumSize: const Size(48, 48),
          textStyle: textTheme.labelLarge,
        ),
      ),

      // Input decoration
      inputDecorationTheme: InputDecorationTheme(
        filled: true,
        fillColor: AppColors.surfaceVariantLight,
        contentPadding: const EdgeInsets.symmetric(horizontal: 20, vertical: 18),
        border: OutlineInputBorder(
          borderRadius: BorderRadius.circular(_borderRadius),
          borderSide: BorderSide.none,
        ),
        enabledBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(_borderRadius),
          borderSide: BorderSide.none,
        ),
        focusedBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(_borderRadius),
          borderSide: const BorderSide(color: AppColors.primary, width: 2),
        ),
        errorBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(_borderRadius),
          borderSide: const BorderSide(color: AppColors.error, width: 1),
        ),
        labelStyle: textTheme.bodyMedium,
        hintStyle: textTheme.bodyMedium?.copyWith(color: AppColors.textSecondaryLight.withAlpha(150)),
      ),

      // FABs
      floatingActionButtonTheme: FloatingActionButtonThemeData(
        backgroundColor: AppColors.primary,
        foregroundColor: Colors.white,
        elevation: 4,
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(20)),
      ),

      // Chips
      chipTheme: ChipThemeData(
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
        padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 4),
      ),

      // Bottom nav
      bottomNavigationBarTheme: BottomNavigationBarThemeData(
        elevation: 8,
        selectedItemColor: AppColors.primary,
        unselectedItemColor: AppColors.textSecondaryLight,
        type: BottomNavigationBarType.fixed,
        backgroundColor: AppColors.surfaceLight,
      ),

      // Snackbar
      snackBarTheme: SnackBarThemeData(
        behavior: SnackBarBehavior.floating,
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
      ),

      // Divider
      dividerTheme: const DividerThemeData(
        color: AppColors.dividerLight,
        thickness: 1,
        space: 1,
      ),

      // Page transitions — gentle
      pageTransitionsTheme: const PageTransitionsTheme(
        builders: {
          TargetPlatform.android: FadeUpwardsPageTransitionsBuilder(),
          TargetPlatform.iOS: CupertinoPageTransitionsBuilder(),
        },
      ),
    );
  }

  // ── Dark theme — true dark with muted accents ────────────────────
  static ThemeData get dark {
    final colorScheme = ColorScheme.dark(
      primary: AppColors.primaryLight,
      onPrimary: AppColors.primaryDark,
      primaryContainer: AppColors.primaryDark,
      onPrimaryContainer: AppColors.primaryLight,
      secondary: AppColors.secondary,
      onSecondary: Colors.black,
      secondaryContainer: AppColors.secondaryDark,
      onSecondaryContainer: AppColors.secondaryLight,
      tertiary: AppColors.tertiaryLight,
      onTertiary: Colors.black,
      tertiaryContainer: AppColors.tertiaryDark,
      onTertiaryContainer: AppColors.tertiaryLight,
      surface: AppColors.surfaceDark,
      onSurface: AppColors.textPrimaryDark,
      surfaceContainerHighest: AppColors.surfaceVariantDark,
      onSurfaceVariant: AppColors.textSecondaryDark,
      error: AppColors.errorLight,
      onError: Colors.black,
    );

    final textTheme = _buildTextTheme(
      ThemeData.dark().textTheme,
      AppColors.textPrimaryDark,
      AppColors.textSecondaryDark,
    );

    return ThemeData(
      useMaterial3: true,
      colorScheme: colorScheme,
      scaffoldBackgroundColor: AppColors.backgroundDark,
      textTheme: textTheme,

      appBarTheme: AppBarTheme(
        elevation: 0,
        scrolledUnderElevation: 1,
        backgroundColor: AppColors.backgroundDark,
        foregroundColor: AppColors.textPrimaryDark,
        titleTextStyle: textTheme.titleLarge,
      ),

      cardTheme: CardThemeData(
        elevation: 2,
        shadowColor: Colors.black.withAlpha(60),
        shape: _roundedShape,
        color: AppColors.surfaceDark,
        margin: const EdgeInsets.symmetric(horizontal: 16, vertical: 6),
      ),

      elevatedButtonTheme: ElevatedButtonThemeData(
        style: ElevatedButton.styleFrom(
          minimumSize: const Size(double.infinity, 52),
          shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(_borderRadius)),
          textStyle: textTheme.labelLarge,
          elevation: 2,
          shadowColor: Colors.black.withAlpha(60),
        ),
      ),

      filledButtonTheme: FilledButtonThemeData(
        style: FilledButton.styleFrom(
          minimumSize: const Size(double.infinity, 52),
          shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(_borderRadius)),
          textStyle: textTheme.labelLarge,
        ),
      ),

      outlinedButtonTheme: OutlinedButtonThemeData(
        style: OutlinedButton.styleFrom(
          minimumSize: const Size(double.infinity, 52),
          shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(_borderRadius)),
          textStyle: textTheme.labelLarge,
        ),
      ),

      textButtonTheme: TextButtonThemeData(
        style: TextButton.styleFrom(
          minimumSize: const Size(48, 48),
          textStyle: textTheme.labelLarge,
        ),
      ),

      inputDecorationTheme: InputDecorationTheme(
        filled: true,
        fillColor: AppColors.surfaceVariantDark,
        contentPadding: const EdgeInsets.symmetric(horizontal: 20, vertical: 18),
        border: OutlineInputBorder(
          borderRadius: BorderRadius.circular(_borderRadius),
          borderSide: BorderSide.none,
        ),
        enabledBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(_borderRadius),
          borderSide: BorderSide.none,
        ),
        focusedBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(_borderRadius),
          borderSide: const BorderSide(color: AppColors.primaryLight, width: 2),
        ),
        errorBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(_borderRadius),
          borderSide: const BorderSide(color: AppColors.errorLight, width: 1),
        ),
        labelStyle: textTheme.bodyMedium,
        hintStyle: textTheme.bodyMedium?.copyWith(color: AppColors.textSecondaryDark.withAlpha(150)),
      ),

      floatingActionButtonTheme: FloatingActionButtonThemeData(
        backgroundColor: AppColors.primaryLight,
        foregroundColor: AppColors.primaryDark,
        elevation: 4,
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(20)),
      ),

      chipTheme: ChipThemeData(
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
        padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 4),
      ),

      bottomNavigationBarTheme: BottomNavigationBarThemeData(
        elevation: 8,
        selectedItemColor: AppColors.primaryLight,
        unselectedItemColor: AppColors.textSecondaryDark,
        type: BottomNavigationBarType.fixed,
        backgroundColor: AppColors.surfaceDark,
      ),

      snackBarTheme: SnackBarThemeData(
        behavior: SnackBarBehavior.floating,
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
      ),

      dividerTheme: const DividerThemeData(
        color: AppColors.dividerDark,
        thickness: 1,
        space: 1,
      ),

      pageTransitionsTheme: const PageTransitionsTheme(
        builders: {
          TargetPlatform.android: FadeUpwardsPageTransitionsBuilder(),
          TargetPlatform.iOS: CupertinoPageTransitionsBuilder(),
        },
      ),
    );
  }
}