import 'package:flutter/material.dart';
import 'package:fl_chart/fl_chart.dart';
import 'package:flutter_markdown/flutter_markdown.dart';
import 'package:markdown/markdown.dart' as md;
import '../theme.dart';

class ChartSpec {
  final String type;
  final String? title;
  final List<String> labels;
  final List<double> data;

  const ChartSpec({
    required this.type,
    required this.labels,
    required this.data,
    this.title,
  });

  static ChartSpec? tryParse(String raw) {
    final lines = raw.split('\n').where((l) => l.trim().isNotEmpty);
    final map = <String, String>{};
    for (final line in lines) {
      final colon = line.indexOf(':');
      if (colon < 0) continue;
      map[line.substring(0, colon).trim().toLowerCase()] =
          line.substring(colon + 1).trim();
    }
    final type = (map['type'] ?? 'bar').toLowerCase();
    final labels = (map['labels'] ?? '')
        .split(',')
        .map((s) => s.trim())
        .where((s) => s.isNotEmpty)
        .toList();
    final data = (map['data'] ?? '')
        .split(',')
        .map((s) => double.tryParse(s.trim()))
        .whereType<double>()
        .toList();
    if (labels.isEmpty || data.isEmpty || labels.length != data.length) {
      return null;
    }
    return ChartSpec(type: type, title: map['title'], labels: labels, data: data);
  }
}

class ChartBlock extends StatelessWidget {
  final ChartSpec spec;
  const ChartBlock({super.key, required this.spec});

  static const _palette = <Color>[
    AppColors.primaryLight,
    AppColors.accent,
    AppColors.warning,
    AppColors.error,
    AppColors.success,
    AppColors.primaryDark,
    AppColors.accentLight,
  ];

  @override
  Widget build(BuildContext context) {
    return Container(
      margin: const EdgeInsets.symmetric(vertical: 8),
      padding: const EdgeInsets.fromLTRB(4, 8, 4, 4),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          if (spec.title != null && spec.title!.isNotEmpty) ...[
            Text(
              spec.title!,
              style: TextStyle(
                fontSize: 13,
                fontWeight: FontWeight.w600,
                color: AppColors.textPrimary,
              ),
            ),
            const SizedBox(height: 8),
          ],
          SizedBox(height: 180, child: _buildChart()),
          if (spec.type == 'pie') ...[
            const SizedBox(height: 8),
            _buildLegend(),
          ],
        ],
      ),
    );
  }

  Widget _buildChart() {
    switch (spec.type) {
      case 'line':
        return _scrollable(_buildLine());
      case 'pie':
        return _buildPie();
      case 'bar':
      default:
        return _scrollable(_buildBar());
    }
  }

  Widget _scrollable(Widget chart) {
    const perPoint = 56.0;
    final intrinsicWidth = spec.data.length * perPoint;
    return LayoutBuilder(
      builder: (context, constraints) {
        final width = intrinsicWidth > constraints.maxWidth
            ? intrinsicWidth
            : constraints.maxWidth;
        return SingleChildScrollView(
          scrollDirection: Axis.horizontal,
          physics: const BouncingScrollPhysics(),
          child: SizedBox(width: width, child: chart),
        );
      },
    );
  }

  Widget _buildBar() {
    final maxY = spec.data.reduce((a, b) => a > b ? a : b);
    return BarChart(
      BarChartData(
        alignment: BarChartAlignment.spaceAround,
        maxY: maxY * 1.2,
        barTouchData: BarTouchData(enabled: false),
        gridData: FlGridData(
          show: true,
          drawVerticalLine: false,
          getDrawingHorizontalLine: (_) =>
              FlLine(color: AppColors.divider, strokeWidth: 0.5),
        ),
        borderData: FlBorderData(show: false),
        titlesData: FlTitlesData(
          topTitles: const AxisTitles(sideTitles: SideTitles(showTitles: false)),
          rightTitles:
              const AxisTitles(sideTitles: SideTitles(showTitles: false)),
          leftTitles: AxisTitles(
            sideTitles: SideTitles(
              showTitles: true,
              reservedSize: 32,
              getTitlesWidget: (v, _) => Text(
                v.toInt().toString(),
                style: TextStyle(fontSize: 10, color: AppColors.textTertiary),
              ),
            ),
          ),
          bottomTitles: AxisTitles(
            sideTitles: SideTitles(
              showTitles: true,
              reservedSize: 22,
              getTitlesWidget: (v, _) {
                final idx = v.toInt();
                if (idx < 0 || idx >= spec.labels.length) {
                  return const SizedBox();
                }
                return Padding(
                  padding: const EdgeInsets.only(top: 4),
                  child: Text(
                    spec.labels[idx],
                    style:
                        TextStyle(fontSize: 10, color: AppColors.textSecondary),
                  ),
                );
              },
            ),
          ),
        ),
        barGroups: [
          for (var i = 0; i < spec.data.length; i++)
            BarChartGroupData(
              x: i,
              barRods: [
                BarChartRodData(
                  toY: spec.data[i],
                  color: _palette[i % _palette.length],
                  width: 18,
                  borderRadius: const BorderRadius.vertical(
                    top: Radius.circular(4),
                  ),
                ),
              ],
            ),
        ],
      ),
    );
  }

  Widget _buildLine() {
    final maxY = spec.data.reduce((a, b) => a > b ? a : b);
    final minY = spec.data.reduce((a, b) => a < b ? a : b);
    final pad = (maxY - minY).abs() * 0.2 + 1;
    return LineChart(
      LineChartData(
        minY: minY - pad,
        maxY: maxY + pad,
        gridData: FlGridData(
          show: true,
          drawVerticalLine: false,
          getDrawingHorizontalLine: (_) =>
              FlLine(color: AppColors.divider, strokeWidth: 0.5),
        ),
        borderData: FlBorderData(show: false),
        titlesData: FlTitlesData(
          topTitles: const AxisTitles(sideTitles: SideTitles(showTitles: false)),
          rightTitles:
              const AxisTitles(sideTitles: SideTitles(showTitles: false)),
          leftTitles: AxisTitles(
            sideTitles: SideTitles(
              showTitles: true,
              reservedSize: 32,
              getTitlesWidget: (v, _) => Text(
                v.toInt().toString(),
                style: TextStyle(fontSize: 10, color: AppColors.textTertiary),
              ),
            ),
          ),
          bottomTitles: AxisTitles(
            sideTitles: SideTitles(
              showTitles: true,
              reservedSize: 22,
              getTitlesWidget: (v, _) {
                final idx = v.toInt();
                if (idx < 0 || idx >= spec.labels.length) {
                  return const SizedBox();
                }
                return Padding(
                  padding: const EdgeInsets.only(top: 4),
                  child: Text(
                    spec.labels[idx],
                    style:
                        TextStyle(fontSize: 10, color: AppColors.textSecondary),
                  ),
                );
              },
            ),
          ),
        ),
        lineBarsData: [
          LineChartBarData(
            spots: [
              for (var i = 0; i < spec.data.length; i++)
                FlSpot(i.toDouble(), spec.data[i]),
            ],
            isCurved: true,
            color: AppColors.primaryLight,
            barWidth: 2.5,
            dotData: FlDotData(
              show: true,
              getDotPainter: (spot, _, __, ___) => FlDotCirclePainter(
                radius: 3,
                color: AppColors.primaryLight,
                strokeWidth: 1.5,
                strokeColor: AppColors.surface,
              ),
            ),
            belowBarData: BarAreaData(
              show: true,
              color: AppColors.primaryLight.withOpacity(0.15),
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildPie() {
    final total = spec.data.fold<double>(0, (a, b) => a + b);
    return PieChart(
      PieChartData(
        sectionsSpace: 2,
        centerSpaceRadius: 28,
        sections: [
          for (var i = 0; i < spec.data.length; i++)
            PieChartSectionData(
              value: spec.data[i],
              color: _palette[i % _palette.length],
              radius: 50,
              title: total == 0
                  ? ''
                  : '${(spec.data[i] / total * 100).toStringAsFixed(0)}%',
              titleStyle: const TextStyle(
                color: Colors.white,
                fontSize: 10,
                fontWeight: FontWeight.w600,
              ),
            ),
        ],
      ),
    );
  }

  Widget _buildLegend() {
    return Wrap(
      spacing: 12,
      runSpacing: 4,
      children: [
        for (var i = 0; i < spec.labels.length; i++)
          Row(
            mainAxisSize: MainAxisSize.min,
            children: [
              Container(
                width: 10,
                height: 10,
                decoration: BoxDecoration(
                  color: _palette[i % _palette.length],
                  borderRadius: BorderRadius.circular(2),
                ),
              ),
              const SizedBox(width: 4),
              Text(
                '${spec.labels[i]} ${spec.data[i].toInt()}',
                style: TextStyle(fontSize: 11, color: AppColors.textSecondary),
              ),
            ],
          ),
      ],
    );
  }
}

class ChartCodeBuilder extends MarkdownElementBuilder {
  @override
  Widget? visitElementAfter(md.Element element, TextStyle? preferredStyle) {
    final lang = element.attributes['class'] ?? '';
    if (!lang.contains('language-chart')) return null;
    final raw = element.textContent;
    final spec = ChartSpec.tryParse(raw);
    if (spec == null) return null;
    return ChartBlock(spec: spec);
  }
}