import 'dart:math' as math;
import 'package:flutter/material.dart';
import '../../../theme/etm_tokens.dart';
import '../models/dashboard_models.dart';

class DayPlanPainter extends CustomPainter {
  final DayPlan plan;
  final Color surfaceColor;
  final Color lineColor;
  final Color inkColor;
  final Color mutedColor;
  final bool isDark;

  const DayPlanPainter({
    required this.plan,
    required this.surfaceColor,
    required this.lineColor,
    required this.inkColor,
    required this.mutedColor,
    required this.isDark,
  });

  static const double _weatherH = 44.0;
  static const double _xAxisH   = 22.0;
  static const double _leftPad  = 28.0;
  static const double _maxPosKwh = 4.0;
  static const double _maxNegKwh = 1.8;

  @override
  void paint(Canvas canvas, Size size) {
    final chartH = size.height - _weatherH - _xAxisH;
    final chartW = size.width - _leftPad;
    final zeroY  = _weatherH + chartH * (_maxPosKwh / (_maxPosKwh + _maxNegKwh));

    final posScale = chartH * (_maxPosKwh / (_maxPosKwh + _maxNegKwh)) / _maxPosKwh;
    final negScale = chartH * (_maxNegKwh / (_maxPosKwh + _maxNegKwh)) / _maxNegKwh;

    final nowX = _leftPad + plan.nowHour / 24 * chartW;

    // ── Future background
    if (nowX < size.width) {
      canvas.drawRect(
        Rect.fromLTRB(nowX, _weatherH, size.width, _weatherH + chartH),
        Paint()
          ..color = (isDark
                  ? const Color(0xFF06141D)
                  : const Color(0xFFEEF2F5))
              .withValues(alpha: 0.55),
      );
      _drawHatch(canvas, Rect.fromLTRB(nowX, _weatherH, size.width, _weatherH + chartH));
    }

    // ── Bars (24 hours)
    final barW = chartW / 24;
    for (final h in plan.hours) {
      final x = _leftPad + h.hour * barW;
      _drawStackedBars(canvas, x, barW, zeroY, posScale, negScale, h);
    }

    // ── Y axis labels
    _drawYLabels(canvas, zeroY, posScale, size);

    // ── Zero line
    canvas.drawLine(
      Offset(_leftPad, zeroY),
      Offset(size.width, zeroY),
      Paint()
        ..color = lineColor
        ..strokeWidth = 1.0,
    );

    // ── X axis labels (0h 6h 12h 18h 24h)
    for (final h in [0, 6, 12, 18, 24]) {
      final x = _leftPad + h / 24 * chartW;
      _paintText(
        canvas,
        h == 24 ? '24h' : '${h}h',
        Offset(x, _weatherH + chartH + 4),
        mutedColor,
        9,
        center: true,
      );
    }

    // ── "Now" line + label
    if (nowX > _leftPad && nowX < size.width) {
      canvas.drawLine(
        Offset(nowX, _weatherH),
        Offset(nowX, _weatherH + chartH),
        Paint()
          ..color = inkColor.withValues(alpha: 0.6)
          ..strokeWidth = 1.2
          ..style = PaintingStyle.stroke,
      );
      final now = DateTime.now();
      final label =
          '${now.hour.toString().padLeft(2, '0')}:${now.minute.toString().padLeft(2, '0')}';
      _drawNowBadge(canvas, nowX, _weatherH, label);
    }

    // ── Weather band
    _drawWeatherBand(canvas, chartW, plan.weather);
  }

  void _drawStackedBars(Canvas canvas, double x, double barW, double zeroY,
      double posScale, double negScale, HourlyFlow h) {
    const gap = 1.5;
    final bw  = barW - gap;

    // Positive stack (upward from zeroY)
    double topY = zeroY;
    void stackPos(double kWh, Color color) {
      if (kWh < 0.01) return;
      final h2 = kWh * posScale;
      canvas.drawRRect(
        RRect.fromRectAndRadius(
          Rect.fromLTWH(x + gap / 2, topY - h2, bw, h2),
          const Radius.circular(1.5),
        ),
        Paint()..color = color,
      );
      topY -= h2;
    }

    stackPos(h.solToHouse, EtmTokens.solToHouse);
    stackPos(h.solToEcs,   EtmTokens.solToEcs);
    stackPos(h.solToVe,    EtmTokens.solToVe);
    stackPos(h.solToBatt,  EtmTokens.solToBatt);
    stackPos(h.solToGrid,  EtmTokens.solToGrid);

    // Negative stack (downward from zeroY)
    double botY = zeroY;
    void stackNeg(double kWh, Color color) {
      if (kWh < 0.01) return;
      final h2 = kWh * negScale;
      canvas.drawRRect(
        RRect.fromRectAndRadius(
          Rect.fromLTWH(x + gap / 2, botY, bw, h2),
          const Radius.circular(1.5),
        ),
        Paint()..color = color.withValues(alpha: 0.7),
      );
      botY += h2;
    }

    stackNeg(h.battToHouse, EtmTokens.battToHouse);
    stackNeg(h.gridToHouse, EtmTokens.gridToHouse);
  }

  void _drawHatch(Canvas canvas, Rect rect) {
    canvas.save();
    canvas.clipRect(rect);
    final hatchPaint = Paint()
      ..color = surfaceColor.withValues(alpha: 0.5)
      ..strokeWidth = 1.0
      ..style = PaintingStyle.stroke;
    const step = 8.0;
    for (double d = -rect.height; d < rect.width + rect.height; d += step) {
      canvas.drawLine(
        Offset(rect.left + d, rect.top),
        Offset(rect.left + d + rect.height, rect.bottom),
        hatchPaint,
      );
    }
    canvas.restore();
  }

  void _drawYLabels(Canvas canvas, double zeroY, double posScale, Size size) {
    for (final kWh in [2.0, 4.0]) {
      final y = zeroY - kWh * posScale;
      _paintText(canvas, '${kWh.toInt()}', Offset(0, y - 5), mutedColor, 8);
      canvas.drawLine(
        Offset(_leftPad, y),
        Offset(size.width, y),
        Paint()
          ..color = lineColor.withValues(alpha: 0.6)
          ..strokeWidth = 0.5,
      );
    }
  }

  void _drawNowBadge(Canvas canvas, double x, double top, String label) {
    final tp = TextPainter(
      text: TextSpan(
        text: label,
        style: TextStyle(
          fontFamily: 'IBMPlexMono',
          fontSize: 9,
          fontWeight: FontWeight.w600,
          color: surfaceColor,
        ),
      ),
      textDirection: TextDirection.ltr,
    )..layout();
    const pad = 4.0;
    final rect = Rect.fromCenter(
      center: Offset(x, top - tp.height / 2 - pad - 2),
      width: tp.width + pad * 2,
      height: tp.height + pad,
    );
    canvas.drawRRect(
      RRect.fromRectAndRadius(rect, const Radius.circular(4)),
      Paint()..color = inkColor.withValues(alpha: 0.75),
    );
    tp.paint(canvas, Offset(rect.left + pad, rect.top + pad / 2));
  }

  void _drawWeatherBand(
      Canvas canvas, double chartW, List<WeatherPoint> points) {
    for (final p in points) {
      final x = _leftPad + p.hour / 24 * chartW;
      final iconColor = p.kind == WeatherKind.sun || p.kind == WeatherKind.partlyCloudy
          ? EtmTokens.solar
          : mutedColor;
      _drawWeatherIcon(canvas, Offset(x, 12), p.kind, iconColor);
      _paintText(
        canvas,
        '${p.tempC}°',
        Offset(x, 26),
        mutedColor,
        9,
        center: true,
      );
    }
  }

  void _drawWeatherIcon(
      Canvas canvas, Offset center, WeatherKind kind, Color color) {
    final paint = Paint()..color = color..style = PaintingStyle.fill;
    switch (kind) {
      case WeatherKind.sun:
        _drawSun(canvas, center, color);
      case WeatherKind.partlyCloudy:
        _drawSun(canvas, center + const Offset(-3, -3), color, r: 5);
        _drawCloud(canvas, center + const Offset(2, 2), color.withValues(alpha: 0.9));
      case WeatherKind.cloudy:
        _drawCloud(canvas, center, mutedColor);
      case WeatherKind.moon:
        _drawMoon(canvas, center, color, paint);
    }
  }

  void _drawSun(Canvas canvas, Offset c, Color color, {double r = 6}) {
    final p = Paint()..color = color..style = PaintingStyle.fill;
    canvas.drawCircle(c, r, p);
    final rp = Paint()
      ..color = color
      ..strokeWidth = 1.2
      ..style = PaintingStyle.stroke;
    for (int i = 0; i < 8; i++) {
      final a = i * math.pi / 4;
      canvas.drawLine(
        c + Offset(math.cos(a), math.sin(a)) * (r + 2),
        c + Offset(math.cos(a), math.sin(a)) * (r + 5),
        rp,
      );
    }
  }

  void _drawCloud(Canvas canvas, Offset c, Color color) {
    final p = Paint()..color = color..style = PaintingStyle.fill;
    canvas.drawCircle(c + const Offset(-4, 1), 4, p);
    canvas.drawCircle(c + const Offset(1, -1), 5.5, p);
    canvas.drawCircle(c + const Offset(6, 2), 3.5, p);
    canvas.drawRect(
      Rect.fromLTWH(c.dx - 7, c.dy + 1, 16, 4),
      p,
    );
  }

  void _drawMoon(Canvas canvas, Offset c, Color color, Paint paint) {
    final path = Path()..addOval(Rect.fromCircle(center: c, radius: 7));
    final cut  = Path()..addOval(Rect.fromCircle(center: c + const Offset(4, -3), radius: 6));
    final crescent = Path.combine(PathOperation.difference, path, cut);
    canvas.drawPath(crescent, paint);
  }

  void _paintText(Canvas canvas, String text, Offset pos, Color color,
      double size, {bool center = false}) {
    final tp = TextPainter(
      text: TextSpan(
        text: text,
        style: TextStyle(fontSize: size, color: color, fontWeight: FontWeight.w500),
      ),
      textDirection: TextDirection.ltr,
    )..layout();
    tp.paint(
      canvas,
      center ? Offset(pos.dx - tp.width / 2, pos.dy) : pos,
    );
  }

  @override
  bool shouldRepaint(DayPlanPainter old) =>
      old.plan != plan || old.isDark != isDark;
}