import 'package:flutter/material.dart';
import 'package:latlong2/latlong.dart' hide Path;

import '../../domain/waypoint/flat_waypoint_list.dart';

/// Kompaktes, nicht interaktives Hoehenprofil in der Fusszeile
/// (HTML-Demonstrator: #altProfile/buildProfileSvg()). Fuer die grosse,
/// per Drag editierbare Ansicht siehe die Altitude-Tab im
/// WaypointListPanel.
class MiniAltitudeProfile extends StatelessWidget {
  const MiniAltitudeProfile({
    super.key,
    required this.waypoints,
    required this.legClimbBad,
    required this.vertexBad,
    required this.activeIndex,
  });

  final List<Waypoint> waypoints;
  final List<bool> legClimbBad;
  final List<bool> vertexBad;
  final int activeIndex;

  static const _distance = Distance(roundResult: false);

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      height: 56,
      width: double.infinity,
      child: waypoints.length < 2
          ? const Center(
              child: Text(
                'Altitude profile',
                style: TextStyle(color: Colors.white38, fontSize: 11),
              ),
            )
          : CustomPaint(
              size: Size.infinite,
              painter: _MiniProfilePainter(
                waypoints: waypoints,
                legClimbBad: legClimbBad,
                vertexBad: vertexBad,
                activeIndex: activeIndex,
              ),
            ),
    );
  }
}

class _MiniProfilePainter extends CustomPainter {
  const _MiniProfilePainter({
    required this.waypoints,
    required this.legClimbBad,
    required this.vertexBad,
    required this.activeIndex,
  });

  final List<Waypoint> waypoints;
  final List<bool> legClimbBad;
  final List<bool> vertexBad;
  final int activeIndex;

  static const _pad = 4.0;

  @override
  void paint(Canvas canvas, Size size) {
    final n = waypoints.length;
    final boxW = size.width - 16;
    final boxH = size.height - 4;

    final cum = <double>[0];
    for (var i = 1; i < n; i++) {
      final a = LatLng(waypoints[i - 1].lat, waypoints[i - 1].lon);
      final b = LatLng(waypoints[i].lat, waypoints[i].lon);
      cum.add(cum[i - 1] + MiniAltitudeProfile._distance(a, b));
    }
    final totalD = cum.last == 0 ? 1.0 : cum.last;

    final alts = [for (final w in waypoints) w.altitudeM];
    var altMin = alts.reduce((a, b) => a < b ? a : b);
    var altMax = alts.reduce((a, b) => a > b ? a : b);
    if (altMax - altMin < 10) {
      altMax += 5;
      altMin -= 5;
    }

    double xAt(int idx) => _pad + (cum[idx] / totalD) * (boxW - 2 * _pad);
    double yAt(double alt) =>
        boxH - _pad - ((alt - altMin) / (altMax - altMin)) * (boxH - 2 * _pad);

    final areaPath = Path()..moveTo(xAt(0), boxH - _pad);
    for (var i = 0; i < n; i++) {
      areaPath.lineTo(xAt(i), yAt(alts[i]));
    }
    areaPath.lineTo(xAt(n - 1), boxH - _pad);
    areaPath.close();
    canvas.drawPath(
      areaPath,
      Paint()..color = const Color(0xFF4D9DFF).withValues(alpha: 0.18),
    );

    for (var i = 0; i < n - 1; i++) {
      final bad = i < legClimbBad.length && legClimbBad[i];
      canvas.drawLine(
        Offset(xAt(i), yAt(alts[i])),
        Offset(xAt(i + 1), yAt(alts[i + 1])),
        Paint()
          ..color = bad ? const Color(0xFFE2574A) : Colors.white
          ..strokeWidth = 2,
      );
    }

    for (var i = 0; i < n; i++) {
      final active = i == activeIndex;
      final bad = i < vertexBad.length && vertexBad[i];
      final color = active
          ? const Color(0xFF4D9DFF)
          : (bad ? const Color(0xFFE2574A) : Colors.white);
      canvas.drawCircle(
        Offset(xAt(i), yAt(alts[i])),
        active ? 4.5 : 2.4,
        Paint()..color = color,
      );
      if (active) {
        canvas.drawCircle(
          Offset(xAt(i), yAt(alts[i])),
          4.5,
          Paint()
            ..color = Colors.white
            ..style = PaintingStyle.stroke
            ..strokeWidth = 1.5,
        );
      }
    }
  }

  @override
  bool shouldRepaint(covariant _MiniProfilePainter oldDelegate) =>
      oldDelegate.waypoints != waypoints ||
      oldDelegate.legClimbBad != legClimbBad ||
      oldDelegate.vertexBad != vertexBad ||
      oldDelegate.activeIndex != activeIndex;
}