import "dart:math";

import "package:capstone_project/models/event_signal.dart";
import "package:capstone_project/utils/signal_buckets.dart";
import "package:fl_chart/fl_chart.dart";
import "package:google_fonts/google_fonts.dart";
import "package:shadcn_flutter/shadcn_flutter.dart";


const Color _growthColor = Color(0xFF16a34a);
const Color _declineColor = Color(0xFFdc2626);
const Color _neutralColor = Color(0xFF888888);

// one day in milliseconds — used to convert between DateTime and the chart's x axis
const double _msPerDay = 1000 * 60 * 60 * 24;


// Scatter of signals: X is the signal date, Y is the impact, color is direction,
// opacity scales with probability (low-credibility signals fade into the back).
// No line connecting them — signals are discrete events, not a time series.
class SignalProbabilityChart extends StatelessWidget {
  final List<EventSignal> signals;
  final double height;
  final bool compact;

  const SignalProbabilityChart({
    super.key,
    required this.signals,
    this.height = 200,
    this.compact = false,
  });

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    if (signals.isEmpty) {
      return Container(
        width: double.infinity,
        height: height,
        decoration: BoxDecoration(
          color: theme.colorScheme.secondary,
          borderRadius: BorderRadius.circular(4),
          border: Border.all(color: theme.colorScheme.border, width: 1),
        ),
        alignment: Alignment.center,
        child: Text("No signal history yet").muted.small,
      );
    }

    // sort so index ordering lines up with the spots list (used for tooltip lookup)
    final sorted = [...signals]..sort((a, b) => a.createdAt.compareTo(b.createdAt));

    final xs = sorted.map((s) => _toDays(s.createdAt)).toList();
    final rawMinX = xs.reduce(min);
    final rawMaxX = xs.reduce(max);

    // keep a minimum visual span so a single-date cluster doesn't collapse the axis
    final span = (rawMaxX - rawMinX) < 1.0 ? 1.0 : (rawMaxX - rawMinX);
    final xPad = span * 0.06;
    final minX = rawMinX - xPad;
    final maxX = rawMaxX + xPad;

    final spots = <ScatterSpot>[];
    for (final s in sorted) {
      final base = _directionColor(s.direction);
      // probability drives the alpha: 0.0 → 0.30, 1.0 → 0.95
      final alpha = 0.30 + (s.probability.clamp(0.0, 1.0) * 0.65);
      spots.add(
        ScatterSpot(
          _toDays(s.createdAt),
          s.impact,
          dotPainter: FlDotCirclePainter(
            radius: 5,
            color: base.withValues(alpha: alpha),
            strokeWidth: 1,
            strokeColor: theme.colorScheme.background,
          ),
        ),
      );
    }

    final labelStyle = GoogleFonts.ibmPlexMono(
      fontSize: 10,
      height: 1,
      fontWeight: FontWeight.w500,
      color: theme.colorScheme.mutedForeground,
    );

    return SizedBox(
      width: double.infinity,
      height: height,
      child: ScatterChart(
        ScatterChartData(
          minX: minX,
          maxX: maxX,
          minY: 0,
          maxY: 1,
          scatterSpots: spots,

          gridData: FlGridData(
            show: !compact,
            drawVerticalLine: false,
            horizontalInterval: 0.25,
            getDrawingHorizontalLine: (_) => FlLine(
              color: theme.colorScheme.border,
              strokeWidth: 1,
            ),
          ),

          borderData: FlBorderData(
            show: !compact,
            border: Border.all(color: theme.colorScheme.border, width: 1),
          ),

          titlesData: FlTitlesData(
            topTitles: const AxisTitles(sideTitles: SideTitles(showTitles: false)),
            rightTitles: const AxisTitles(sideTitles: SideTitles(showTitles: false)),

            bottomTitles: AxisTitles(
              sideTitles: SideTitles(
                showTitles: !compact,
                reservedSize: 22,
                interval: _xTickInterval(minX, maxX),
                getTitlesWidget: (value, meta) {
                  final d = DateTime.fromMillisecondsSinceEpoch(
                    (value * _msPerDay).round(),
                  );
                  return Padding(
                    padding: const EdgeInsets.only(top: 4),
                    child: RichText(text: TextSpan(text: _shortDate(d), style: labelStyle)),
                  );
                },
              ),
            ),

            leftTitles: AxisTitles(
              sideTitles: SideTitles(
                showTitles: !compact,
                reservedSize: 42,
                interval: 0.25,
                getTitlesWidget: (value, meta) => RichText(
                  text: TextSpan(
                    text: "${(value * 100).round()}%",
                    style: labelStyle,
                  ),
                ),
              ),
            ),
          ),

          scatterTouchData: compact
              ? ScatterTouchData(enabled: false)
              : ScatterTouchData(
                  enabled: true,
                  touchTooltipData: ScatterTouchTooltipData(
                    getTooltipColor: (_) => theme.colorScheme.background,
                    tooltipBorder: BorderSide(color: theme.colorScheme.border, width: 1),
                    tooltipPadding: const EdgeInsets.symmetric(horizontal: 10, vertical: 6),
                    maxContentWidth: 220,
                    getTooltipItems: (ScatterSpot touched) {
                      // match back to the source signal by x+y — ScatterSpot equality
                      // isn't guaranteed to line up with our original instances
                      final idx = sorted.indexWhere((s) =>
                        _toDays(s.createdAt) == touched.x && s.impact == touched.y);
                      if (idx < 0) return null;
                      final s = sorted[idx];

                      return ScatterTooltipItem(
                        "${_shortDate(s.createdAt)}\n"
                        "impact ${(s.impact * 100).toStringAsFixed(0)}%  ·  ${s.direction}\n"
                        "probability ${(s.probability * 100).toStringAsFixed(0)}%",
                        textStyle: GoogleFonts.ibmPlexMono(
                          fontSize: 11,
                          fontWeight: FontWeight.w600,
                          color: theme.colorScheme.foreground,
                        ),
                        textAlign: TextAlign.left,
                      );
                    },
                  ),
                ),
        ),
      ),
    );
  }
}


double _toDays(DateTime d) => d.millisecondsSinceEpoch / _msPerDay;


Color _directionColor(String direction) => switch (direction) {
  "positive" => _growthColor,
  "negative" => _declineColor,
  _ => _neutralColor,
};


// pick a sensible x-axis tick interval (in days) based on the visible range
double _xTickInterval(double minX, double maxX) {
  final days = (maxX - minX).abs();
  if (days <= 7) return 1;
  if (days <= 30) return 7;
  if (days <= 90) return 14;
  if (days <= 365) return 30;
  return (days / 6).ceilToDouble();
}


String _shortDate(DateTime d) {
  const months = ["Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"];
  return "${months[d.month - 1]} ${d.day}";
}