// 笔画数据模型 — 手写不可变类（避免 build_runner 依赖）

import 'dart:collection';

/// 画笔类型
enum BrushType {
  pen('pen'),
  pencil('pencil'),
  marker('marker'),
  eraser('eraser');

  const BrushType(this.value);
  final String value;
}

/// 笔画点
class StrokePoint {
  const StrokePoint({
    required this.x,
    required this.y,
    this.pressure = 0.5,
    this.timestamp = 0,
  });

  final double x;
  final double y;
  final double pressure;
  final int timestamp;

  StrokePoint copyWith({
    double? x,
    double? y,
    double? pressure,
    int? timestamp,
  }) =>
      StrokePoint(
        x: x ?? this.x,
        y: y ?? this.y,
        pressure: pressure ?? this.pressure,
        timestamp: timestamp ?? this.timestamp,
      );

  Map<String, dynamic> toJson() => {
        'x': x,
        'y': y,
        'pressure': pressure,
        'timestamp': timestamp,
      };

  factory StrokePoint.fromJson(Map<String, dynamic> json) => StrokePoint(
        x: (json['x'] as num).toDouble(),
        y: (json['y'] as num).toDouble(),
        pressure: (json['pressure'] as num?)?.toDouble() ?? 0.5,
        timestamp: (json['timestamp'] as int?) ?? 0,
      );
}

/// 笔画
class Stroke {
  const Stroke({
    required this.id,
    required this.points,
    this.brushType = BrushType.pen,
    this.color = '#2D2420',
    this.width = 3.0,
  });

  final String id;
  final List<StrokePoint> points;
  final BrushType brushType;
  final String color;
  final double width;

  Stroke copyWith({
    String? id,
    List<StrokePoint>? points,
    BrushType? brushType,
    String? color,
    double? width,
  }) =>
      Stroke(
        id: id ?? this.id,
        points: points ?? this.points,
        brushType: brushType ?? this.brushType,
        color: color ?? this.color,
        width: width ?? this.width,
      );

  Map<String, dynamic> toJson() => {
        'id': id,
        'points': points.map((p) => p.toJson()).toList(),
        'brushType': brushType.value,
        'color': color,
        'width': width,
      };

  factory Stroke.fromJson(Map<String, dynamic> json) => Stroke(
        id: json['id'] as String,
        points: UnmodifiableListView(
          (json['points'] as List)
              .map((p) => StrokePoint.fromJson(p as Map<String, dynamic>))
              .toList(),
        ),
        brushType: BrushType.values.firstWhere(
          (b) => b.value == json['brushType'],
          orElse: () => BrushType.pen,
        ),
        color: (json['color'] as String?) ?? '#2D2420',
        width: (json['width'] as num?)?.toDouble() ?? 3.0,
      );
}