slogan/lib/shared/widgets/avatar_viewer.dart

import 'dart:async';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter_gl/flutter_gl.dart';
import 'package:three_dart/three_dart.dart' as three;
import 'package:three_dart_jsm/three_dart_jsm.dart' as three_jsm;

import '../../core/config/app_config.dart';

/// 是否启用 three_dart 3D 渲染。
/// MVP 阶段服务端尚无预烘焙 GLB 资产（/workspace/templates/*.glb 为构建产物），
/// 默认关闭展示信息占位；接入真实 GLB 资源后置为 true 即可启用。
const bool kEnable3D = false;

/// 3D 化身查看组件：three_dart 渲染 GLB，加载失败/未启用时展示信息占位
class AvatarViewer extends StatelessWidget {
  final String? glbUrl;
  final String title;
  final String subtitle;
  final double height;

  const AvatarViewer({
    super.key,
    required this.glbUrl,
    required this.title,
    required this.subtitle,
    this.height = 360,
  });

  @override
  Widget build(BuildContext context) {
    if (!kEnable3D || glbUrl == null || glbUrl!.isEmpty) {
      return _AvatarPlaceholder(
          title: title, subtitle: subtitle, height: height);
    }
    return _ThreeDAvatarViewer(
      url: AppConfig.resolveUrl(glbUrl!),
      title: title,
      subtitle: subtitle,
      height: height,
    );
  }
}

/// three_dart 实现：flutter_gl 初始化 + GLTFLoader 加载 + 自动旋转渲染
class _ThreeDAvatarViewer extends StatefulWidget {
  final String url;
  final String title;
  final String subtitle;
  final double height;

  const _ThreeDAvatarViewer({
    required this.url,
    required this.title,
    required this.subtitle,
    required this.height,
  });

  @override
  State<_ThreeDAvatarViewer> createState() => _ThreeDAvatarViewerState();
}

class _ThreeDAvatarViewerState extends State<_ThreeDAvatarViewer> {
  FlutterGlPlugin? _gl;
  three.WebGLRenderer? _renderer;
  three.Scene? _scene;
  three.Camera? _camera;
  three.Object3D? _model;
  dynamic _sourceTexture;
  double _width = 300;
  double _dpr = 1;
  bool _ready = false;
  bool _failed = false;
  bool _disposed = false;
  Timer? _timer;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) => _init());
  }

  @override
  void dispose() {
    _disposed = true;
    _timer?.cancel();
    super.dispose();
  }

  Future<void> _init() async {
    final mq = MediaQuery.of(context);
    _width = mq.size.width;
    _dpr = mq.devicePixelRatio;
    try {
      final gl = FlutterGlPlugin();
      await gl.initialize(options: {
        'antialias': true,
        'alpha': false,
        'width': _width.toInt(),
        'height': widget.height.toInt(),
        'dpr': _dpr,
      });
      await gl.prepareContext();

      final renderer = three.WebGLRenderer({
        'width': _width,
        'height': widget.height,
        'gl': gl.gl,
        'antialias': true,
        'canvas': gl.element,
      });
      renderer.setPixelRatio(_dpr);
      renderer.setSize(_width, widget.height, false);

      final target = three.WebGLMultisampleRenderTarget(
          (_width * _dpr).toInt(), (widget.height * _dpr).toInt(),
          three.WebGLRenderTargetOptions({'format': three.RGBAFormat}));
      target.samples = 4;
      renderer.setRenderTarget(target);
      final sourceTexture = renderer.getRenderTargetGLTexture(target);

      await _loadModel(gl, renderer);

      _gl = gl;
      _renderer = renderer;
      _sourceTexture = sourceTexture;
      if (mounted) setState(() => _ready = true);
      _timer = Timer.periodic(
          const Duration(milliseconds: 33), (_) => _render());
    } catch (e) {
      debugPrint('3D 渲染不可用，回退占位：$e');
      if (mounted) setState(() => _failed = true);
    }
  }

  Future<void> _loadModel(
      FlutterGlPlugin gl, three.WebGLRenderer renderer) async {
    final scene = three.Scene();
    final camera = three.PerspectiveCamera(45, _width / widget.height, 0.1, 100);
    camera.position.set(0, 1.4, 3.2);
    scene.add(three.AmbientLight(0xffffff, 0.9));
    final keyLight = three.DirectionalLight(0xffffff, 0.9);
    keyLight.position.set(2, 4, 3);
    scene.add(keyLight);
    scene.add(camera);
    camera.lookAt(three.Vector3(0, 1, 0));

    final loader = three_jsm.GLTFLoader(null);
    final result = await loader.loadAsync(widget.url);
    final model = result['scene'] as three.Object3D?;
    if (model != null) {
      model.rotation.y = 0.6;
      scene.add(model);
    }

    _scene = scene;
    _camera = camera;
    _model = model;
  }

  void _render() {
    if (_disposed || _renderer == null || _scene == null || _camera == null) {
      return;
    }
    final model = _model;
    if (model != null) {
      model.rotation.y += 0.01; // 自动旋转
    }
    _renderer!.render(_scene!, _camera!);
    _gl!.gl.flush();
    if (!kIsWeb) {
      _gl!.updateTexture(_sourceTexture);
    }
  }

  @override
  Widget build(BuildContext context) {
    if (_failed) {
      return _AvatarPlaceholder(
          title: widget.title, subtitle: widget.subtitle, height: widget.height);
    }
    return SizedBox(
      height: widget.height,
      width: double.infinity,
      child: _ready
          ? (kIsWeb
              ? HtmlElementView(viewType: _gl!.textureId!.toString())
              : Texture(textureId: _gl!.textureId!))
          : const Center(child: CircularProgressIndicator()),
    );
  }
}

/// 占位：GLB 资产未接入或加载失败时展示化身信息
class _AvatarPlaceholder extends StatelessWidget {
  final String title;
  final String subtitle;
  final double height;

  const _AvatarPlaceholder({
    required this.title,
    required this.subtitle,
    required this.height,
  });

  @override
  Widget build(BuildContext context) {
    final scheme = Theme.of(context).colorScheme;
    return Container(
      height: height,
      width: double.infinity,
      decoration: BoxDecoration(
        gradient: LinearGradient(
          begin: Alignment.topCenter,
          end: Alignment.bottomCenter,
          colors: [scheme.primaryContainer, scheme.primary.withValues(alpha: 0.3)],
        ),
        borderRadius: BorderRadius.circular(16),
      ),
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Icon(Icons.accessibility_new, size: 72, color: scheme.primary),
          const SizedBox(height: 12),
          Text(title,
              style:
                  const TextStyle(fontSize: 16, fontWeight: FontWeight.bold)),
          const SizedBox(height: 4),
          Padding(
            padding: const EdgeInsets.symmetric(horizontal: 24),
            child: Text(
              subtitle.isEmpty ? '3D 渲染接入中（v2）' : subtitle,
              textAlign: TextAlign.center,
              style: const TextStyle(color: Colors.grey, fontSize: 12),
            ),
          ),
        ],
      ),
    );
  }
}