/// Renders the Top Bar widget for the FocusFlow Flutter UI.
library;

import 'package:flutter/material.dart';

import '../theme/focus_flow_tokens.dart';

/// Header bar for the compact Today view.
class TopBar extends StatelessWidget {
  /// Creates a top bar with a display-ready [dateLabel].
  const TopBar({required this.dateLabel, super.key});

  /// Date label shown beside the date navigation controls.
  final String dateLabel;

  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(
      builder: (context, constraints) {
        final metrics = _TopBarMetrics.fromWidth(constraints.maxWidth);
        return SizedBox(
          height: _TopBarMetrics.referenceHeight,
          child: Row(
            children: [
              SizedBox(
                width: metrics.titleWidth,
                height: _TopBarMetrics.referenceHeight,
                child: FittedBox(
                  alignment: Alignment.centerLeft,
                  fit: BoxFit.scaleDown,
                  child: Text(
                    'Today',
                    style: Theme.of(context).textTheme.headlineLarge?.copyWith(
                      fontSize: metrics.titleSize,
                    ),
                  ),
                ),
              ),
              SizedBox(width: metrics.titleGap),
              _IconButton(
                icon: Icons.calendar_today,
                metrics: metrics,
                onPressed: () {},
              ),
              _IconButton(
                icon: Icons.chevron_left,
                metrics: metrics,
                onPressed: () {},
              ),
              SizedBox(
                width: metrics.dateWidth,
                height: metrics.controlHeight,
                child: Center(
                  child: FittedBox(
                    fit: BoxFit.scaleDown,
                    child: Text(
                      dateLabel,
                      style: TextStyle(
                        color: FocusFlowTokens.textPrimary,
                        fontSize: metrics.dateSize,
                      ),
                    ),
                  ),
                ),
              ),
              _IconButton(
                icon: Icons.chevron_right,
                metrics: metrics,
                onPressed: () {},
              ),
              const Spacer(),
              _ModeToggle(metrics: metrics),
              SizedBox(width: metrics.settingsGap),
              _SettingsButton(metrics: metrics),
            ],
          ),
        );
      },
    );
  }
}

class _TopBarMetrics {
  const _TopBarMetrics(this.scale);

  static const referenceHeight = 48.0;
  static const _referenceWidth = 900.0;
  static const _minimumScale = 0.44;

  factory _TopBarMetrics.fromWidth(double width) {
    final safeWidth = width.isFinite ? width : _referenceWidth;
    final scale = (safeWidth / _referenceWidth).clamp(_minimumScale, 1.0);
    return _TopBarMetrics(scale.toDouble());
  }

  final double scale;

  double get titleWidth => 112 * scale;
  double get titleSize => FocusFlowTokens.pageTitleSize * scale;
  double get titleGap => 30 * scale;
  double get controlHeight => referenceHeight * scale;
  double get iconButtonSize => referenceHeight * scale;
  double get iconSize => 24 * scale;
  double get dateWidth => 144 * scale;
  double get dateSize => 17 * scale;
  double get modeWidth => 220 * scale;
  double get modeHeight => referenceHeight * scale;
  double get modeLabelSize => 17 * scale;
  double get settingsGap => 28 * scale;
  double get settingsWidth => 136 * scale;
  double get settingsHeight => referenceHeight * scale;
  double get settingsIconSize => 20 * scale;
  double get settingsTextSize => 15 * scale;
  double get settingsTextGap => 8 * scale;
  double get borderRadius => FocusFlowTokens.smallButtonRadius * scale;
  double get borderWidth => scale < 0.7 ? 0.8 : 1;
  EdgeInsets get buttonPadding => EdgeInsets.symmetric(horizontal: 12 * scale);
}

class _SettingsButton extends StatelessWidget {
  const _SettingsButton({required this.metrics});

  final _TopBarMetrics metrics;

  @override
  Widget build(BuildContext context) {
    return OutlinedButton(
      onPressed: () {},
      style: OutlinedButton.styleFrom(
        foregroundColor: FocusFlowTokens.textPrimary,
        side: BorderSide(
          color: FocusFlowTokens.subtleBorder,
          width: metrics.borderWidth,
        ),
        fixedSize: Size(metrics.settingsWidth, metrics.settingsHeight),
        minimumSize: Size.zero,
        padding: metrics.buttonPadding,
        tapTargetSize: MaterialTapTargetSize.shrinkWrap,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(metrics.borderRadius),
        ),
      ),
      child: FittedBox(
        fit: BoxFit.scaleDown,
        child: Row(
          mainAxisSize: MainAxisSize.min,
          children: [
            Icon(Icons.wb_sunny_outlined, size: metrics.settingsIconSize),
            SizedBox(width: metrics.settingsTextGap),
            Text(
              'Settings',
              style: TextStyle(
                fontSize: metrics.settingsTextSize,
                fontWeight: FontWeight.w600,
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class _IconButton extends StatelessWidget {
  const _IconButton({
    required this.icon,
    required this.metrics,
    required this.onPressed,
  });

  final IconData icon;
  final _TopBarMetrics metrics;
  final VoidCallback onPressed;

  @override
  Widget build(BuildContext context) {
    return IconButton(
      onPressed: onPressed,
      constraints: BoxConstraints.tightFor(
        width: metrics.iconButtonSize,
        height: metrics.iconButtonSize,
      ),
      color: FocusFlowTokens.textPrimary,
      iconSize: metrics.iconSize,
      padding: EdgeInsets.zero,
      icon: Icon(icon),
      visualDensity: VisualDensity.compact,
    );
  }
}

class _ModeToggle extends StatelessWidget {
  const _ModeToggle({required this.metrics});

  final _TopBarMetrics metrics;

  @override
  Widget build(BuildContext context) {
    return Container(
      height: metrics.modeHeight,
      width: metrics.modeWidth,
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(metrics.borderRadius),
        border: Border.all(
          color: FocusFlowTokens.subtleBorder,
          width: metrics.borderWidth,
        ),
      ),
      child: Row(
        children: [
          Expanded(
            child: Container(
              alignment: Alignment.center,
              decoration: BoxDecoration(
                color: FocusFlowTokens.glassPanelStrong,
                borderRadius: BorderRadius.circular(metrics.borderRadius),
                border: Border.all(
                  color: FocusFlowTokens.navBorder,
                  width: metrics.borderWidth,
                ),
              ),
              child: FittedBox(
                fit: BoxFit.scaleDown,
                child: Text(
                  'Compact',
                  style: TextStyle(fontSize: metrics.modeLabelSize),
                ),
              ),
            ),
          ),
          Expanded(
            child: TextButton(
              onPressed: () {},
              style: TextButton.styleFrom(
                minimumSize: Size.zero,
                padding: EdgeInsets.zero,
                tapTargetSize: MaterialTapTargetSize.shrinkWrap,
              ),
              child: FittedBox(
                fit: BoxFit.scaleDown,
                child: Text(
                  'Normal',
                  style: TextStyle(
                    color: FocusFlowTokens.textPrimary,
                    fontSize: metrics.modeLabelSize,
                  ),
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}