import 'package:flutter/material.dart';

import '../input/pen_config.dart';
import '../input/pressure_curve.dart';

String _shapeNameForGamma(double gamma) {
  if ((gamma - 0.6).abs() < 0.05) return 'soft';
  if ((gamma - 1.0).abs() < 0.05) return 'linear';
  if ((gamma - 2.0).abs() < 0.05) return 'quadratic';
  if ((gamma - 3.0).abs() < 0.05) return 'cubic';
  if ((gamma - 0.5).abs() < 0.05) return 'sqrt';
  return 'soft';
}

PressureCurve _curveForName(String name) => switch (name) {
      'linear' => PressureCurve.shaped(PressureCurveShape.linear),
      'quadratic' => PressureCurve.shaped(PressureCurveShape.quadratic),
      'cubic' => PressureCurve.shaped(PressureCurveShape.cubic),
      'sqrt' => PressureCurve.shaped(PressureCurveShape.sqrt),
      'logarithmic' => PressureCurve.shaped(PressureCurveShape.soft), // gamma proxy
      _ => PressureCurve.shaped(PressureCurveShape.soft),
    };

/// Shows a Material You modal bottom sheet for configuring pen input.
///
/// Changes are applied and persisted immediately via [controller] setters,
/// so the sheet reflects the live configuration at all times.
Future<void> showPenSettingsSheet(
  BuildContext context,
  PenConfigController controller,
) {
  return showModalBottomSheet<void>(
    context: context,
    isScrollControlled: true,
    backgroundColor: Theme.of(context).colorScheme.surfaceContainerHigh,
    shape: const RoundedRectangleBorder(
      borderRadius: BorderRadius.vertical(top: Radius.circular(28)),
    ),
    builder: (context) => _PenSettingsSheet(controller: controller),
  );
}

class _PenSettingsSheet extends StatelessWidget {
  const _PenSettingsSheet({required this.controller});

  final PenConfigController controller;

  @override
  Widget build(BuildContext context) {
    return ListenableBuilder(
      listenable: controller,
      builder: (context, _) {
        final config = controller.value;
        final colorScheme = Theme.of(context).colorScheme;

        return DraggableScrollableSheet(
          expand: false,
          initialChildSize: 0.7,
          minChildSize: 0.4,
          maxChildSize: 0.95,
          builder: (context, scrollController) {
            return ListView(
              controller: scrollController,
              padding: const EdgeInsets.fromLTRB(16, 8, 16, 32),
              children: [
                // Drag handle
                Center(
                  child: Container(
                    width: 32,
                    height: 4,
                    margin: const EdgeInsets.symmetric(vertical: 12),
                    decoration: BoxDecoration(
                      color: colorScheme.onSurfaceVariant.withAlpha(80),
                      borderRadius: BorderRadius.circular(2),
                    ),
                  ),
                ),
                Text(
                  'Pen Settings',
                  style: Theme.of(context).textTheme.titleLarge,
                  textAlign: TextAlign.center,
                ),
                const SizedBox(height: 16),

                // ── Button Actions ────────────────────────────────────────
                _SectionHeader(
                  title: 'Button Actions',
                  icon: Icons.touch_app,
                  colorScheme: colorScheme,
                ),
                const SizedBox(height: 8),
                _LabeledRow(
                  label: 'Side Button',
                  child: _ActionDropdown(
                    value: config.sideButton,
                    onChanged: controller.setSideButton,
                  ),
                ),
                const SizedBox(height: 8),
                _LabeledRow(
                  label: 'Eraser End',
                  child: _ActionDropdown(
                    value: config.eraserEnd,
                    onChanged: controller.setEraserEnd,
                  ),
                ),
                const SizedBox(height: 16),

                // ── Pressure ──────────────────────────────────────────────
                _SectionHeader(
                  title: 'Pressure',
                  icon: Icons.compress,
                  colorScheme: colorScheme,
                ),
                _SliderTile(
                  label: 'Pressure Sensitivity',
                  value: config.pressureSensitivity,
                  min: 0.0,
                  max: 1.0,
                  divisions: 20,
                  formatValue: (v) => v.toStringAsFixed(2),
                  onChanged: controller.setPressureSensitivity,
                ),
                _SliderTile(
                  label: 'Pressure Gamma',
                  value: config.pressureGamma,
                  min: 0.3,
                  max: 3.0,
                  divisions: 27,
                  formatValue: (v) => v.toStringAsFixed(2),
                  onChanged: controller.setPressureGamma,
                ),
                _LabeledRow(
                  label: 'Curve Preset (rnote)',
                  child: DropdownMenu<String>(
                    initialSelection: _shapeNameForGamma(config.pressureGamma),
                    onSelected: (name) {
                      if (name == null) return;
                      final shaped = _curveForName(name);
                      controller.setPressureGamma(shaped.gamma);
                    },
                    dropdownMenuEntries: const [
                      DropdownMenuEntry(value: 'soft', label: 'Soft (γ≈0.6)'),
                      DropdownMenuEntry(value: 'linear', label: 'Linear'),
                      DropdownMenuEntry(
                          value: 'quadratic', label: 'Quadratic / Pow2'),
                      DropdownMenuEntry(value: 'cubic', label: 'Cubic'),
                      DropdownMenuEntry(value: 'sqrt', label: 'Sqrt (pencil)'),
                    ],
                  ),
                ),
                const Padding(
                  padding: EdgeInsets.only(left: 8, bottom: 8),
                  child: Text(
                    '笔刷自带曲线优先（钢笔=二次/Pow2，铅笔=平方根）。全局 gamma 作后备。',
                    style: TextStyle(fontSize: 12),
                  ),
                ),

                // ── Input ─────────────────────────────────────────────────
                _SectionHeader(
                  title: 'Input',
                  icon: Icons.pan_tool_alt,
                  colorScheme: colorScheme,
                ),
                _SliderTile(
                  label: 'Palm Rejection',
                  value: config.palmRejectionMs,
                  min: 0,
                  max: 500,
                  divisions: 50,
                  formatValue: (v) => '${v.round()} ms',
                  onChanged: controller.setPalmRejectionMs,
                ),
                SwitchListTile(
                  title: const Text('Finger Drawing'),
                  subtitle: const Text(
                    'Allow touch strokes when no pen is detected',
                  ),
                  value: config.fingerDrawing,
                  onChanged: controller.setFingerDrawing,
                  contentPadding: EdgeInsets.zero,
                ),

                // ── Stroke Widths ─────────────────────────────────────────
                _SectionHeader(
                  title: 'Stroke Widths',
                  icon: Icons.line_weight,
                  colorScheme: colorScheme,
                ),
                _SliderTile(
                  label: 'Pen Width',
                  value: config.penWidth,
                  min: 0.001,
                  max: 0.02,
                  divisions: 19,
                  formatValue: (v) => v.toStringAsFixed(4),
                  onChanged: controller.setPenWidth,
                ),
                _SliderTile(
                  label: 'Highlighter Width',
                  value: config.highlighterWidth,
                  min: 0.005,
                  max: 0.06,
                  divisions: 22,
                  formatValue: (v) => v.toStringAsFixed(4),
                  onChanged: controller.setHighlighterWidth,
                ),

                // ── Eraser ────────────────────────────────────────────────
                _SectionHeader(
                  title: 'Eraser',
                  icon: Icons.cleaning_services_outlined,
                  colorScheme: colorScheme,
                ),
                _SliderTile(
                  label: 'Eraser Size',
                  value: config.eraserRadius,
                  min: 0.005,
                  max: 0.1,
                  divisions: 19,
                  formatValue: (v) => v.toStringAsFixed(3),
                  onChanged: controller.setEraserRadius,
                ),
                SwitchListTile(
                  title: const Text('Stroke Eraser'),
                  subtitle: const Text(
                    'Erase a whole stroke on contact (off: erase by segment)',
                  ),
                  value: config.eraserWholeStroke,
                  onChanged: controller.setEraserWholeStroke,
                  contentPadding: EdgeInsets.zero,
                ),
              ],
            );
          },
        );
      },
    );
  }
}

// ── Shared section header ────────────────────────────────────────────────────

class _SectionHeader extends StatelessWidget {
  const _SectionHeader({
    required this.title,
    required this.icon,
    required this.colorScheme,
  });

  final String title;
  final IconData icon;
  final ColorScheme colorScheme;

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.only(top: 8, bottom: 4),
      child: Row(
        children: [
          Icon(icon, size: 18, color: colorScheme.primary),
          const SizedBox(width: 8),
          Text(
            title,
            style: Theme.of(context).textTheme.titleSmall?.copyWith(
                  color: colorScheme.primary,
                  fontWeight: FontWeight.bold,
                ),
          ),
          const SizedBox(width: 8),
          Expanded(child: Divider(color: colorScheme.outlineVariant)),
        ],
      ),
    );
  }
}

// ── Label + widget row ───────────────────────────────────────────────────────

class _LabeledRow extends StatelessWidget {
  const _LabeledRow({required this.label, required this.child});

  final String label;
  final Widget child;

  @override
  Widget build(BuildContext context) {
    return Row(
      children: [
        SizedBox(
          width: 120,
          child: Text(
            label,
            style: const TextStyle(fontWeight: FontWeight.w500),
          ),
        ),
        Expanded(child: child),
      ],
    );
  }
}

// ── Action dropdown ──────────────────────────────────────────────────────────

class _ActionDropdown extends StatelessWidget {
  const _ActionDropdown({required this.value, required this.onChanged});

  final PenButtonAction value;
  final ValueChanged<PenButtonAction> onChanged;

  static String _label(PenButtonAction action) => switch (action) {
        PenButtonAction.none => '无',
        PenButtonAction.eraser => '橡皮',
        PenButtonAction.undo => '撤销',
        PenButtonAction.toggleTool => '切换工具',
        PenButtonAction.pan => '平移',
        PenButtonAction.select => '选择（笔迹）',
        PenButtonAction.selectText => '选择文本',
      };

  @override
  Widget build(BuildContext context) {
    return DropdownMenu<PenButtonAction>(
      initialSelection: value,
      expandedInsets: EdgeInsets.zero,
      onSelected: (action) {
        if (action != null) onChanged(action);
      },
      dropdownMenuEntries: PenButtonAction.values
          .map(
            (a) => DropdownMenuEntry(value: a, label: _label(a)),
          )
          .toList(),
    );
  }
}

// ── Slider with live value label ─────────────────────────────────────────────

class _SliderTile extends StatelessWidget {
  const _SliderTile({
    required this.label,
    required this.value,
    required this.min,
    required this.max,
    required this.divisions,
    required this.formatValue,
    required this.onChanged,
  });

  final String label;
  final double value;
  final double min;
  final double max;
  final int divisions;
  final String Function(double) formatValue;
  final ValueChanged<double> onChanged;

  @override
  Widget build(BuildContext context) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Row(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: [
            Text(label, style: const TextStyle(fontWeight: FontWeight.w500)),
            Text(
              formatValue(value),
              style: TextStyle(
                fontFamily: 'monospace',
                color: Theme.of(context).colorScheme.onSurfaceVariant,
                fontSize: 13,
              ),
            ),
          ],
        ),
        Slider(
          value: value.clamp(min, max),
          min: min,
          max: max,
          divisions: divisions,
          label: formatValue(value),
          onChanged: onChanged,
        ),
      ],
    );
  }
}