import 'package:flutter/material.dart';

import 'lawheatmap_tokens.dart';

/// ThemeData assembly for the F∆I Law-Heatmap client.
///
/// Dark mode is the default (consistent with fai_web's
/// `color-scheme: dark`). Light mode falls back to the paper
/// palette for printing/screenshot work.
class LawHeatmapTheme {
  LawHeatmapTheme._();

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

  static ThemeData _build(Brightness brightness) {
    final isDark = brightness == Brightness.dark;
    final canvas = isDark ? LawHeatmapColors.ink : LawHeatmapColors.paper;
    final surface =
        isDark ? LawHeatmapColors.inkRaised : LawHeatmapColors.paperRaised;
    final onSurface = isDark
        ? const Color(0xFFE9E7E2)
        : const Color(0xFF1A1B1E);

    final colorScheme = ColorScheme(
      brightness: brightness,
      primary: LawHeatmapColors.signal,
      onPrimary: LawHeatmapColors.ink,
      secondary: LawHeatmapColors.mute,
      onSecondary: onSurface,
      error: const Color(0xFFD8723A),
      onError: LawHeatmapColors.ink,
      surface: surface,
      onSurface: onSurface,
    );

    final textTheme = _textTheme(onSurface);

    return ThemeData(
      useMaterial3: true,
      brightness: brightness,
      colorScheme: colorScheme,
      scaffoldBackgroundColor: canvas,
      canvasColor: canvas,
      fontFamily: LawHeatmapTypography.body,
      textTheme: textTheme,
      cardTheme: CardThemeData(
        color: surface,
        elevation: 0,
        margin: EdgeInsets.zero,
        shape: const RoundedRectangleBorder(
          borderRadius: BorderRadius.all(LawHeatmapRadius.md),
          side: BorderSide(color: Color(0x24FFFFFF)),
        ),
      ),
      dividerTheme: DividerThemeData(
        color: onSurface.withValues(alpha: LawHeatmapColors.hairlineDarkOpacity),
        thickness: 1,
        space: 1,
      ),
      filledButtonTheme: FilledButtonThemeData(
        style: FilledButton.styleFrom(
          backgroundColor: LawHeatmapColors.signal,
          foregroundColor: LawHeatmapColors.ink,
          shape: const RoundedRectangleBorder(
            borderRadius: BorderRadius.all(LawHeatmapRadius.sm),
          ),
          textStyle: textTheme.labelLarge,
          padding: const EdgeInsets.symmetric(
            horizontal: LawHeatmapSpace.lg,
            vertical: LawHeatmapSpace.md,
          ),
        ),
      ),
    );
  }

  static TextTheme _textTheme(Color onSurface) {
    const display = LawHeatmapTypography.display;
    const body = LawHeatmapTypography.body;
    return TextTheme(
      displaySmall: TextStyle(
        fontFamily: display,
        fontSize: 28,
        fontWeight: FontWeight.w600,
        letterSpacing: -0.02 * 28,
        color: onSurface,
      ),
      headlineSmall: TextStyle(
        fontFamily: display,
        fontSize: 20,
        fontWeight: FontWeight.w600,
        letterSpacing: -0.02 * 20,
        color: onSurface,
      ),
      titleMedium: TextStyle(
        fontFamily: body,
        fontSize: 16,
        fontWeight: FontWeight.w500,
        color: onSurface,
      ),
      bodyLarge: TextStyle(
        fontFamily: body,
        fontSize: 14,
        height: 1.45,
        color: onSurface,
      ),
      labelLarge: TextStyle(
        fontFamily: body,
        fontSize: 13,
        fontWeight: FontWeight.w500,
        color: onSurface,
      ),
      labelSmall: TextStyle(
        fontFamily: body,
        fontSize: 11,
        fontWeight: FontWeight.w500,
        color: onSurface.withValues(alpha: 0.72),
      ),
    );
  }

  /// Convenience: JetBrains-Mono variant of an existing style for
  /// technical content (ELI/CELEX, SHA-256, audit-event IDs).
  static TextStyle mono(TextStyle base) =>
      base.copyWith(fontFamily: LawHeatmapTypography.mono);
}