import 'dart:io';
import 'dart:math' as math;
import 'package:flutter/material.dart';
import 'package:flutter/gestures.dart';
import 'package:flutter/services.dart';

class ImageCanvas extends StatefulWidget {
  final String filePath;
  const ImageCanvas({super.key, required this.filePath});
  @override
  State<ImageCanvas> createState() => _ImageCanvasState();
}

class _ImageCanvasState extends State<ImageCanvas> {
  bool _isFilled = true;
  final GlobalKey _imageKey = GlobalKey();
  double _tx = 0, _ty = 0, _sc = 1.0;
  Size _vpSize = Size.zero;

  // ── Görüntü ayarları ──
  double _angle = 0;
  double _contrast = 1.0;
  double _saturation = 1.0;

  // ── Gesture tracking ──
  String _interactionMode = 'none'; // 'contrast' | 'rotate' | 'saturation'
  Offset _pointerDownPos = Offset.zero;
  double _startAngle = 0;
  double _startContrast = 1.0;
  double _startSaturation = 1.0;
  DateTime? _lastRightTapTime;
  Offset _lastRightTapPos = Offset.zero;

  // ── Klavye modifier tracking ──
  bool _ctrlPressed = false;
  bool _shiftPressed = false;

  void _clamp() {
    if (_vpSize.width <= 0 || _vpSize.height <= 0) return;
    if (_angle != 0) return; // rotate varsa serbest pan
    if (_isFilled) {
      final double w = _vpSize.width * _sc;
      final double h = _vpSize.height * _sc;
      if (w >= _vpSize.width) {
        if (_tx > 0) _tx = 0;
        else if (_tx + w < _vpSize.width) _tx = _vpSize.width - w;
      } else { if (_tx != 0) _tx = 0; }
      if (h >= _vpSize.height) {
        if (_ty > 0) _ty = 0;
        else if (_ty + h < _vpSize.height) _ty = _vpSize.height - h;
      } else { if (_ty != 0) _ty = 0; }
      return;
    }
    double m = 0, n = 0;
    double w = _vpSize.width * _sc;
    double h = _vpSize.height * _sc;
    final box = _imageKey.currentContext?.findRenderObject() as RenderBox?;
    if (box != null && box.hasSize && box.size.width > 0) {
      final Size img = box.size;
      m = (_vpSize.width - img.width) / 2;
      n = (_vpSize.height - img.height) / 2;
      w = img.width * _sc;
      h = img.height * _sc;
    }
    if (w >= _vpSize.width) {
      final double lo = -m * _sc;
      final double hi = _vpSize.width - m * _sc - w;
      if (lo <= hi) {
        if (_tx < lo) _tx = lo;
        if (_tx > hi) _tx = hi;
      } else {
        if (_tx < hi) _tx = hi;
        if (_tx > lo) _tx = lo;
      }
    } else {
      final double lo = -m * _sc;
      final double hi = _vpSize.width - m * _sc - w;
      if (_tx < lo) _tx = lo;
      if (_tx > hi) _tx = hi;
    }
    if (h >= _vpSize.height) {
      final double lo = -n * _sc;
      final double hi = _vpSize.height - n * _sc - h;
      if (lo <= hi) {
        if (_ty < lo) _ty = lo;
        if (_ty > hi) _ty = hi;
      } else {
        if (_ty < hi) _ty = hi;
        if (_ty > lo) _ty = lo;
      }
    } else {
      final double lo = -n * _sc;
      final double hi = _vpSize.height - n * _sc - h;
      if (_ty < lo) _ty = lo;
      if (_ty > hi) _ty = hi;
    }
  }

  @override
  void initState() {
    super.initState();
    HardwareKeyboard.instance.addHandler(_onHardwareKey);
  }

  @override
  void dispose() {
    HardwareKeyboard.instance.removeHandler(_onHardwareKey);
    super.dispose();
  }

  bool _onHardwareKey(KeyEvent event) {
    final key = event.logicalKey;
    if (event is KeyDownEvent) {
      if (key == LogicalKeyboardKey.controlLeft ||
          key == LogicalKeyboardKey.controlRight) {
        _ctrlPressed = true;
      } else if (key == LogicalKeyboardKey.shiftLeft ||
                 key == LogicalKeyboardKey.shiftRight) {
        _shiftPressed = true;
      }
    } else if (event is KeyUpEvent) {
      if (key == LogicalKeyboardKey.controlLeft ||
          key == LogicalKeyboardKey.controlRight) {
        _ctrlPressed = false;
      } else if (key == LogicalKeyboardKey.shiftLeft ||
                 key == LogicalKeyboardKey.shiftRight) {
        _shiftPressed = false;
      }
    }
    return false;
  }

  @override
  void didUpdateWidget(ImageCanvas old) {
    super.didUpdateWidget(old);
    if (old.filePath != widget.filePath) _resetView();
  }

  void _resetView() {
    setState(() {
      _tx = 0; _ty = 0; _sc = 1.0; _isFilled = true; _vpSize = Size.zero;
      _angle = 0; _contrast = 1.0; _saturation = 1.0;
    });
  }

  void _toggleFillFit() {
    setState(() {
      _isFilled = !_isFilled; _tx = 0; _ty = 0; _sc = 1.0; _vpSize = Size.zero;
      _angle = 0; _contrast = 1.0; _saturation = 1.0;
    });
  }

  void _handleDoubleTap() => _toggleFillFit();

  void _handleScroll(PointerScrollEvent e) {
    if (_vpSize.width <= 0 || _vpSize.height <= 0) return;
    final double vx = _angle == 0 ? e.localPosition.dx : _vpSize.width / 2;
    final double vy = _angle == 0 ? e.localPosition.dy : _vpSize.height / 2;
    final double cx = (vx - _tx) / _sc;
    final double cy = (vy - _ty) / _sc;
    const double factor = 1.1;
    final double rawSc = _sc * (e.scrollDelta.dy < 0 ? factor : 1.0 / factor);
    final double newSc = rawSc.clamp(1.0, 10.0);
    if (_angle == 0) {
      _tx = _tx + cx * _sc - cx * newSc;
      _ty = _ty + cy * _sc - cy * newSc;
    } else {
      // Rotate'li zoom: viewport merkezini koru
      final double dw = _vpSize.width * (newSc - _sc);
      final double dh = _vpSize.height * (newSc - _sc);
      _tx -= dw / 2;
      _ty -= dh / 2;
    }
    _sc = newSc;
    _clamp();
    setState(() {});
  }

  void _onPanUpdate(DragUpdateDetails d) {
    _tx += d.delta.dx;
    _ty += d.delta.dy;
    _clamp();
    setState(() {});
  }

  void _onPointerDown(PointerDownEvent e) {
    if (e.buttons != kSecondaryMouseButton) return;

    _pointerDownPos = e.localPosition;

    final now = DateTime.now();
    if (_lastRightTapTime != null &&
        now.difference(_lastRightTapTime!) < const Duration(milliseconds: 400) &&
        (e.localPosition - _lastRightTapPos).distance < 20) {
      setState(() {
        _angle = 0;
        _contrast = 1.0;
        _saturation = 1.0;
        _interactionMode = 'none';
      });
      _lastRightTapTime = null;
      return;
    }
    _lastRightTapTime = now;
    _lastRightTapPos = e.localPosition;

    if (_ctrlPressed) {
      _interactionMode = 'saturation';
      _startSaturation = _saturation;
    } else if (_shiftPressed) {
      _interactionMode = 'rotate';
      _startAngle = _angle;
    } else {
      _interactionMode = 'contrast';
      _startContrast = _contrast;
    }
  }

  void _onPointerMove(PointerMoveEvent e) {
    if (e.buttons != kSecondaryMouseButton) return;

    final dy = e.localPosition.dy - _pointerDownPos.dy;

    switch (_interactionMode) {
      case 'contrast':
        setState(() {
          _contrast = (_startContrast + dy * 0.005).clamp(0.0, 2.0);
        });
        break;
      case 'rotate':
        setState(() {
          _angle = _startAngle + dy * 0.9;
        });
        break;
      case 'saturation':
        setState(() {
          _saturation = (_startSaturation + dy * 0.005).clamp(0.0, 2.0);
        });
        break;
    }
  }

  void _onPointerUp(PointerUpEvent e) {
    _interactionMode = 'none';
  }

  // ── Combined color filter (saturation × contrast) ──

  static const double _rLum = 0.2126;
  static const double _gLum = 0.7152;
  static const double _bLum = 0.0722;

  ColorFilter? _cachedFilter;
  double _cachedSat = -1;
  double _cachedCon = -1;

  ColorFilter _buildCombinedFilter() {
    if (_cachedFilter != null && _cachedSat == _saturation && _cachedCon == _contrast) {
      return _cachedFilter!;
    }
    _cachedSat = _saturation;
    _cachedCon = _contrast;

    final s = _saturation;
    final c = _contrast;
    final t = (1.0 - c) / 2.0;
    final invS = 1.0 - s;

    final sR_R = invS * _rLum + s, sR_G = invS * _gLum,     sR_B = invS * _bLum;
    final sG_R = invS * _rLum,     sG_G = invS * _gLum + s, sG_B = invS * _bLum;
    final sB_R = invS * _rLum,     sB_G = invS * _gLum,     sB_B = invS * _bLum + s;

    _cachedFilter = ColorFilter.matrix(<double>[
      c * sR_R, c * sR_G, c * sR_B, 0, t,
      c * sG_R, c * sG_G, c * sG_B, 0, t,
      c * sB_R, c * sB_G, c * sB_B, 0, t,
      0,        0,        0,        1, 0,
    ]);
    return _cachedFilter!;
  }

  Widget _buildImage() {
    return Image.file(
      key: _imageKey,
      File(widget.filePath),
      fit: _isFilled ? BoxFit.cover : BoxFit.contain,
      filterQuality: FilterQuality.high,
      errorBuilder: (_, _, _) => _errorWidget(),
    );
  }

  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(
      builder: (context, constraints) {
        _vpSize = constraints.biggest;
        _clamp();

        final vpCenterX = _vpSize.width / 2;
        final vpCenterY = _vpSize.height / 2;
        final angleRad = _angle * math.pi / 180;

        Widget imageContent = Builder(
          builder: (context) {
            final hasFilter = _saturation != 1.0 || _contrast != 1.0;
            final image = _isFilled
                ? SizedBox.expand(child: _buildImage())
                : Center(child: _buildImage());
            return hasFilter
                ? ColorFiltered(colorFilter: _buildCombinedFilter(), child: image)
                : image;
          },
        );

        if (_angle != 0) {
          imageContent = Transform(
            alignment: Alignment.topLeft,
            transform: Matrix4.identity()
              ..translate(vpCenterX, vpCenterY)
              ..rotateZ(angleRad)
              ..translate(-vpCenterX, -vpCenterY),
            child: imageContent,
          );
        }

        return SizedBox.expand(
          child: Stack(
            children: [
              ClipRect(
                child: Listener(
                  onPointerDown: _onPointerDown,
                  onPointerMove: _onPointerMove,
                  onPointerUp: _onPointerUp,
                  onPointerSignal: (event) {
                    if (event is PointerScrollEvent) _handleScroll(event);
                  },
                  child: GestureDetector(
                    onDoubleTap: _handleDoubleTap,
                    onPanUpdate: _onPanUpdate,
                    child: Transform(
                      alignment: Alignment.topLeft,
                      transform: Matrix4.identity()
                        ..translate(_tx, _ty)
                        ..scale(_sc),
                      child: imageContent,
                    ),
                  ),
                ),
              ),
            ],
          ),
        );
      },
    );
  }

  Widget _errorWidget() {
    return const Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          Icon(Icons.broken_image, size: 48, color: Colors.white38),
          SizedBox(height: 8),
          Text('Resim yüklenemedi', style: TextStyle(color: Colors.white38)),
        ],
      ),
    );
  }
}