import 'package:flutter/material.dart';

import 'annotate_api.dart';

/// 标注器：逐张画框提交。交互：空白处拖拽画框、点框选中（高亮）、
/// 撤销/删除选中；每张提交进「待审核」，满 rewardPerImages 张自动到账时长。
class AnnotatorScreen extends StatefulWidget {
  final AnnotateApi api;
  final AnnotateTaskInfo task;
  final List<AnnotateClaimImage> images;

  const AnnotatorScreen({
    super.key,
    required this.api,
    required this.task,
    required this.images,
  });

  @override
  State<AnnotatorScreen> createState() => _AnnotatorScreenState();
}

/// 归一化框（cx,cy 中心 + w,h，0~1，同服务端 AdminLabelBox）
class _NormBox {
  double cx;
  double cy;
  double w;
  double h;
  _NormBox(this.cx, this.cy, this.w, this.h);

  bool hit(Offset p) =>
      p.dx >= cx - w / 2 && p.dx <= cx + w / 2 && p.dy >= cy - h / 2 && p.dy <= cy + h / 2;
}

class _AnnotatorScreenState extends State<AnnotatorScreen> {
  int _index = 0;
  final List<_NormBox> _boxes = [];
  int? _selected;
  Offset? _dragStart; // 拖拽画框进行中（归一化坐标）
  Offset? _dragCur;
  bool _submitting = false;
  bool _earnedThisBatch = false;

  AnnotateClaimImage get _current => widget.images[_index];

  void _clamp(_NormBox b) {
    // 边界钳制 + 防越界（归一化 0~1，同服务端校验）
    b.cx = b.cx.clamp(0.0, 1.0);
    b.cy = b.cy.clamp(0.0, 1.0);
    b.w = b.w.clamp(0.001, 1.0);
    b.h = b.h.clamp(0.001, 1.0);
  }

  void _onPanStart(DragStartDetails d) {
    _dragStart = d.localPosition;
    _dragCur = d.localPosition;
    setState(() {});
  }

  void _onPanUpdate(DragUpdateDetails d) {
    _dragCur = d.localPosition;
    setState(() {});
  }

  void _onPanEnd(DragEndDetails d) {
    final s = _dragStart;
    final e = _dragCur;
    _dragStart = null;
    _dragCur = null;
    if (s == null || e == null) {
      setState(() {});
      return;
    }
    final dx = (e.dx - s.dx).abs();
    final dy = (e.dy - s.dy).abs();
    if (dx < 8 || dy < 8) {
      setState(() {}); // 过小视为误触
      return;
    }
    final box = _NormBox(
      (s.dx + e.dx) / 2,
      (s.dy + e.dy) / 2,
      dx,
      dy,
    );
    final size = _canvasSize;
    if (size == null || size.width <= 0 || size.height <= 0) {
      setState(() {});
      return;
    }
    box.cx /= size.width;
    box.cy /= size.height;
    box.w /= size.width;
    box.h /= size.height;
    _clamp(box);
    setState(() {
      _boxes.add(box);
      _selected = _boxes.length - 1;
    });
  }

  Size? _canvasSize;

  void _onTapUp(TapUpDetails d) {
    final p = d.localPosition;
    final size = _canvasSize;
    if (size == null) return;
    final n = Offset(p.dx / size.width, p.dy / size.height);
    int? hit;
    for (var i = _boxes.length - 1; i >= 0; i--) {
      if (_boxes[i].hit(n)) {
        hit = i;
        break;
      }
    }
    setState(() => _selected = hit);
  }

  void _deleteSelected() {
    if (_selected == null) return;
    setState(() {
      _boxes.removeAt(_selected!);
      _selected = null;
    });
  }

  void _undo() {
    if (_boxes.isEmpty) return;
    setState(() {
      _boxes.removeLast();
      _selected = null;
    });
  }

  Future<void> _submit({required bool noTarget}) async {
    if (_submitting) return;
    if (!noTarget && _boxes.isEmpty) {
      ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('请先画框，或使用「画面无目标」提交')));
      return;
    }
    setState(() => _submitting = true);
    try {
      final payload = noTarget
          ? <Map<String, dynamic>>[]
          : _boxes
              .map((b) => <String, dynamic>{
                    'class': 0,
                    'cx': b.cx,
                    'cy': b.cy,
                    'w': b.w,
                    'h': b.h,
                    'confidence': 1,
                  })
              .toList();
      final res = await widget.api.submit(_current.imageId, payload);
      if (res.granted) _earnedThisBatch = true;
      if (!mounted) return;
      if (res.granted) {
        ScaffoldMessenger.of(context).showSnackBar(SnackBar(
          content: Text(
              '恭喜！累计提交满档，${res.minutes} 分钟时长已到账（今日已得 ${res.todayEarnedMinutes} 分钟）'),
          backgroundColor: Colors.green,
        ));
      }
      _next();
    } on SessionExpiredException {
      if (mounted) Navigator.of(context).pop(false);
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(SnackBar(
            content: Text('$e'.replaceFirst('Exception: ', ''))));
      }
    } finally {
      if (mounted) setState(() => _submitting = false);
    }
  }

  void _next() {
    if (_index + 1 >= widget.images.length) {
      // 本批完成：回任务列表刷新进度
      ScaffoldMessenger.of(context).showSnackBar(SnackBar(
          content: Text(_earnedThisBatch ? '本批完成，奖励已到账' : '本批完成，继续加油！')));
      Navigator.of(context).pop(true);
      return;
    }
    setState(() {
      _index++;
      _boxes.clear();
      _selected = null;
      _dragStart = null;
      _dragCur = null;
    });
  }

  @override
  Widget build(BuildContext context) {
    final img = _current;
    final aspect =
        img.width > 0 && img.height > 0 ? img.width / img.height : 4 / 3;
    return Scaffold(
      appBar: AppBar(
        title: Text('${widget.task.name}（${_index + 1}/${widget.images.length}）'),
      ),
      body: SafeArea(
        child: Column(
          children: [
            Padding(
              padding: const EdgeInsets.all(12),
              child: FutureBuilder<Map<String, String>>(
                future: widget.api.imageHeaders(),
                builder: (context, snap) {
                  final headers = snap.data ?? const <String, String>{};
                  return LayoutBuilder(builder: (context, constraints) {
                    final maxW = constraints.maxWidth;
                    final maxH = constraints.maxHeight.isInfinite
                        ? MediaQuery.of(context).size.height * 0.55
                        : constraints.maxHeight;
                    var w = maxW;
                    var h = w / aspect;
                    if (h > maxH) {
                      h = maxH;
                      w = h * aspect;
                    }
                    _canvasSize = Size(w, h);
                    return Center(
                      child: GestureDetector(
                        onPanStart: _onPanStart,
                        onPanUpdate: _onPanUpdate,
                        onPanEnd: _onPanEnd,
                        onTapUp: _onTapUp,
                        child: Stack(
                          children: [
                            SizedBox(
                              width: w,
                              height: h,
                              child: Image.network(
                                widget.api.imageUrl(img.url).toString(),
                                headers: headers,
                                fit: BoxFit.fill,
                                loadingBuilder: (c, child, progress) =>
                                    progress == null
                                        ? child
                                        : const Center(
                                            child: CircularProgressIndicator()),
                                errorBuilder: (c, e, st) => const Center(
                                    child: Text('图片加载失败',
                                        style: TextStyle(color: Colors.red))),
                              ),
                            ),
                            Positioned.fill(
                              child: CustomPaint(
                                painter: _BoxesPainter(
                                  boxes: _boxes,
                                  selected: _selected,
                                  dragStart: _dragStart == null
                                      ? null
                                      : Offset(_dragStart!.dx / w,
                                          _dragStart!.dy / h),
                                  dragCur: _dragCur == null
                                      ? null
                                      : Offset(
                                          _dragCur!.dx / w, _dragCur!.dy / h),
                                ),
                              ),
                            ),
                          ],
                        ),
                      ),
                    );
                  });
                },
              ),
            ),
            Padding(
              padding: const EdgeInsets.symmetric(horizontal: 12),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: [
                  TextButton.icon(
                    onPressed: _boxes.isEmpty ? null : _undo,
                    icon: const Icon(Icons.undo),
                    label: const Text('撤销'),
                  ),
                  TextButton.icon(
                    onPressed: _selected == null ? null : _deleteSelected,
                    icon: const Icon(Icons.delete_outline),
                    label: const Text('删除选中'),
                  ),
                  Text(
                    '${_boxes.length} 框',
                    style: Theme.of(context).textTheme.bodyMedium,
                  ),
                ],
              ),
            ),
            const Spacer(),
            Padding(
              padding: const EdgeInsets.all(16),
              child: Row(
                children: [
                  Expanded(
                    child: OutlinedButton(
                      onPressed: _submitting ? null : () => _submit(noTarget: true),
                      child: const Text('画面无目标'),
                    ),
                  ),
                  const SizedBox(width: 12),
                  Expanded(
                    flex: 2,
                    child: FilledButton.icon(
                      onPressed: _submitting ? null : () => _submit(noTarget: false),
                      icon: _submitting
                          ? const SizedBox(
                              width: 18,
                              height: 18,
                              child: CircularProgressIndicator(strokeWidth: 2))
                          : const Icon(Icons.check),
                      label: Text(_submitting
                          ? '提交中…'
                          : '提交${_boxes.isEmpty ? '' : '（${_boxes.length} 框）'}'),
                    ),
                  ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class _BoxesPainter extends CustomPainter {
  final List<_NormBox> boxes;
  final int? selected;
  final Offset? dragStart; // 归一化
  final Offset? dragCur;

  _BoxesPainter({
    required this.boxes,
    required this.selected,
    required this.dragStart,
    required this.dragCur,
  });

  @override
  void paint(Canvas canvas, Size size) {
    final border = Paint()
      ..style = PaintingStyle.stroke
      ..strokeWidth = 2;
    for (var i = 0; i < boxes.length; i++) {
      final b = boxes[i];
      border.color = i == selected ? Colors.orange : Colors.green;
      canvas.drawRect(
        Rect.fromLTWH((b.cx - b.w / 2) * size.width, (b.cy - b.h / 2) * size.height,
            b.w * size.width, b.h * size.height),
        border,
      );
    }
    final s = dragStart;
    final e = dragCur;
    if (s != null && e != null) {
      border.color = Colors.blue;
      canvas.drawRect(
        Rect.fromPoints(Offset(s.dx * size.width, s.dy * size.height),
            Offset(e.dx * size.width, e.dy * size.height)),
        border,
      );
    }
  }

  @override
  bool shouldRepaint(covariant _BoxesPainter old) =>
      old.boxes != boxes || old.selected != selected || old.dragCur != dragCur;
}