// tools/statistical_charts.dart
//
// 统计图表：条形图 / 折线图 / 饼图 / 雷达图。
//
// 这一页没有数学计算，只是把用户输入变成坐标，所以**不接 Symja**；
// 数值用 double.tryParse 解析。包进 [ToolScaffold] 后，绘制由「计算」按钮触发，
// 重置按钮也和其它工具一致。图表类型、曲线类型、增删数据行这些操作会换 key
// 让外壳重建并重新计算，这样"点一下切换类型"仍然立刻重画。
import 'package:flutter/material.dart';
import 'package:fl_chart/fl_chart.dart';

import 'tool_kit.dart';

class StatisticalChartsPage extends StatefulWidget {
  const StatisticalChartsPage({super.key});

  @override
  State<StatisticalChartsPage> createState() => _StatisticalChartsPageState();
}

class _StatisticalChartsPageState extends State<StatisticalChartsPage> {
  static const List<String> _chartTypes = <String>['条形图', '折线图', '饼图', '雷达图'];

  int _type = 0;

  /// 折线图是否用光滑曲线（false = 直线）。
  bool _curved = true;

  /// 输入行：每两格是一行（标签、数值）。整条列表**就地增删**，
  /// 对象始终是同一个 —— 外壳靠 `identical(fields)` 判断要不要清空结果。
  final List<ToolField> _fields = [];

  /// 图表类型 / 曲线类型 / 增删数据行后换 key，让外壳重建并 autoRun 立即重画。
  int _runToken = 0;

  @override
  void initState() {
    super.initState();
    for (var i = 0; i < 5; i++) {
      _addRow(initialLabel: '数据${i + 1}', initialValue: '${(i + 1) * 10}');
    }
  }

  int get _rowCount => _fields.length ~/ 2;

  ToolField _labelAt(int i) => _fields[2 * i];

  ToolField _valueAt(int i) => _fields[2 * i + 1];

  void _addRow({String initialLabel = '新数据', String initialValue = '0'}) {
    final n = _rowCount + 1;
    final label = ToolField('第 $n 项标签', hint: '数据名');
    final value = ToolField('第 $n 项数值', hint: '例如 10');
    label.controller.text = initialLabel;
    value.controller.text = initialValue;
    _fields.addAll([label, value]);
  }

  void _onAddRow() => setState(() {
    _addRow();
    _runToken++;
  });

  void _onRemoveRow() {
    if (_rowCount <= 1) return;
    setState(() {
      _fields.removeRange(_fields.length - 2, _fields.length);
      _runToken++;
    });
  }

  void _selectType(int i) {
    if (_type == i) return;
    setState(() {
      _type = i;
      _runToken++;
    });
  }

  void _setCurved(bool value) {
    if (_curved == value) return;
    setState(() {
      _curved = value;
      _runToken++;
    });
  }

  Widget _intro() => Column(
    crossAxisAlignment: CrossAxisAlignment.start,
    children: [
      const SizedBox(height: 8),
      Wrap(
        spacing: 8,
        runSpacing: 8,
        children: [
          for (var i = 0; i < _chartTypes.length; i++)
            ChoiceChip(
              label: Text(_chartTypes[i]),
              selected: _type == i,
              onSelected: (_) => _selectType(i),
            ),
        ],
      ),
      if (_type == 1) ...[
        const SizedBox(height: 12),
        Row(
          children: [
            const Text('曲线类型：'),
            const SizedBox(width: 8),
            ChoiceChip(
              label: const Text('直线'),
              selected: !_curved,
              onSelected: (_) => _setCurved(false),
            ),
            const SizedBox(width: 8),
            ChoiceChip(
              label: const Text('光滑曲线'),
              selected: _curved,
              onSelected: (_) => _setCurved(true),
            ),
          ],
        ),
      ],
      const SizedBox(height: 12),
      Row(
        children: [
          OutlinedButton.icon(
            onPressed: _onAddRow,
            icon: const Icon(Icons.add),
            label: const Text('添加数据'),
          ),
          const SizedBox(width: 12),
          OutlinedButton.icon(
            onPressed: _rowCount > 1 ? _onRemoveRow : null,
            icon: const Icon(Icons.remove),
            label: const Text('删除数据'),
          ),
        ],
      ),
    ],
  );

  @override
  Widget build(BuildContext context) => ToolScaffold(
    key: ValueKey<int>(_runToken),
    title: '统计图表绘制',
    autoRun: true,
    fields: _fields,
    intro: _intro(),
    compute: (session) async {
      // 把输入行读成 (标签, 数值)。这里没有数学计算，只是把输入变成坐标，
      // 所以解析留在 Dart 侧；非数字就抛中文异常。
      final labels = <String>[];
      final values = <double>[];
      for (var i = 0; i < _rowCount; i++) {
        final label = _labelAt(i).text;
        final raw = _valueAt(i).text;
        if (label.isEmpty && raw.isEmpty) continue;
        if (raw.isEmpty) throw Exception('第 ${i + 1} 行的数值不能为空');
        final v = double.tryParse(raw);
        if (v == null || !v.isFinite) {
          throw Exception('第 ${i + 1} 行的「$raw」不是有效数字');
        }
        values.add(v);
        labels.add(label.isEmpty ? '第${i + 1}项' : label);
      }
      if (values.isEmpty) {
        throw Exception('请至少填写一行有效数据');
      }

      final chart = switch (_type) {
        1 => _lineChart(values, labels),
        2 => _pieChart(values),
        3 => _radarChart(values, labels),
        _ => _barChart(values, labels),
      };

      return <ToolOutput>[
        ToolChart(
          _chartTypes[_type],
          // fl_chart 需要一个确定高度，否则在无界的高度里会报错。
          SizedBox(height: 320, child: chart),
        ),
      ];
    },
  );

  /// 坐标轴的"好看"上限：最大值再留 20% 余量；全零或全负时给个 1，免得轴退化。
  static double _niceMax(List<double> values) {
    var maxV = values.first;
    for (final v in values) {
      if (v > maxV) maxV = v;
    }
    return maxV <= 0 ? 1 : maxV * 1.2;
  }

  static SideTitles _bottomTitles(List<String> labels) => SideTitles(
    showTitles: true,
    getTitlesWidget: (value, meta) {
      final index = value.toInt();
      if (index < 0 || index >= labels.length) {
        return const SizedBox.shrink();
      }
      return Padding(
        padding: const EdgeInsets.only(top: 8),
        child: Text(
          labels[index],
          style: const TextStyle(fontSize: 10),
          maxLines: 2,
          overflow: TextOverflow.ellipsis,
        ),
      );
    },
  );

  Widget _barChart(List<double> values, List<String> labels) => BarChart(
    BarChartData(
      alignment: BarChartAlignment.spaceAround,
      maxY: _niceMax(values),
      barTouchData: BarTouchData(
        enabled: true,
        touchTooltipData: const BarTouchTooltipData(),
      ),
      titlesData: FlTitlesData(
        show: true,
        bottomTitles: AxisTitles(sideTitles: _bottomTitles(labels)),
        leftTitles: const AxisTitles(
          sideTitles: SideTitles(showTitles: true, reservedSize: 40),
        ),
      ),
      gridData: const FlGridData(show: true),
      borderData: FlBorderData(show: true),
      barGroups: <BarChartGroupData>[
        for (var i = 0; i < values.length; i++)
          BarChartGroupData(
            x: i,
            barRods: [
              BarChartRodData(
                toY: values[i],
                color: Colors.primaries[i % Colors.primaries.length],
                width: 16,
              ),
            ],
          ),
      ],
    ),
  );

  Widget _lineChart(List<double> values, List<String> labels) => LineChart(
    LineChartData(
      lineTouchData: const LineTouchData(enabled: true),
      gridData: const FlGridData(show: true),
      titlesData: FlTitlesData(
        show: true,
        bottomTitles: AxisTitles(sideTitles: _bottomTitles(labels)),
        leftTitles: const AxisTitles(
          sideTitles: SideTitles(showTitles: true, reservedSize: 40),
        ),
      ),
      borderData: FlBorderData(show: true),
      minX: 0,
      maxX: values.length > 1 ? (values.length - 1).toDouble() : 1,
      minY: 0,
      maxY: _niceMax(values),
      lineBarsData: <LineChartBarData>[
        LineChartBarData(
          spots: <FlSpot>[
            for (var i = 0; i < values.length; i++)
              FlSpot(i.toDouble(), values[i]),
          ],
          isCurved: _curved,
          color: Colors.blue,
          barWidth: 4,
          belowBarData: BarAreaData(show: false),
          dotData: FlDotData(
            show: true,
            getDotPainter: (spot, percent, barData, index) =>
                FlDotCirclePainter(
                  radius: 4,
                  color: Colors.blue,
                  strokeWidth: 2,
                  strokeColor: Colors.white,
                ),
          ),
        ),
      ],
    ),
  );

  Widget _pieChart(List<double> values) {
    var total = 0.0;
    for (final v in values) {
      total += v;
    }
    return PieChart(
      PieChartData(
        sectionsSpace: 4,
        centerSpaceRadius: 40,
        sections: <PieChartSectionData>[
          for (var i = 0; i < values.length; i++)
            PieChartSectionData(
              color: Colors.primaries[i % Colors.primaries.length],
              value: values[i],
              // 百分比：数据本身没问题时才算，全零就留空。
              title: total == 0
                  ? ''
                  : '${(values[i] / total * 100).toStringAsFixed(1)}%',
              radius: 50,
              titleStyle: const TextStyle(
                fontSize: 12,
                fontWeight: FontWeight.bold,
                color: Colors.white,
              ),
            ),
        ],
      ),
    );
  }

  Widget _radarChart(List<double> values, List<String> labels) {
    if (values.length < 3) {
      return const Center(
        child: Text(
          '雷达图需要至少 3 个数据点\n请添加更多数据',
          textAlign: TextAlign.center,
          style: TextStyle(fontSize: 16, color: Colors.grey),
        ),
      );
    }
    return RadarChart(
      RadarChartData(
        dataSets: <RadarDataSet>[
          RadarDataSet(
            dataEntries: <RadarEntry>[
              for (final v in values) RadarEntry(value: v),
            ],
            fillColor: Colors.blue.withValues(alpha: 0.3),
            borderColor: Colors.blue,
            borderWidth: 2,
          ),
        ],
        radarBackgroundColor: Colors.transparent,
        radarBorderData: const BorderSide(color: Colors.grey, width: 1),
        tickBorderData: const BorderSide(color: Colors.grey, width: 1),
        gridBorderData: const BorderSide(color: Colors.grey, width: 1),
        ticksTextStyle: const TextStyle(color: Colors.black, fontSize: 10),
        tickCount: 5,
        getTitle: (index, angle) {
          if (index >= 0 && index < labels.length) {
            return RadarChartTitle(text: labels[index], angle: angle);
          }
          return const RadarChartTitle(text: '');
        },
        titleTextStyle: const TextStyle(
          color: Colors.black,
          fontSize: 12,
          fontWeight: FontWeight.bold,
        ),
        titlePositionPercentageOffset: 0.15,
      ),
      swapAnimationDuration: const Duration(milliseconds: 500),
      swapAnimationCurve: Curves.easeInOut,
    );
  }
}