using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;

namespace DHSoftware.Views
{
    public partial class ImageViewerControl : UserControl
    {
        #region 内部控件
        private PictureBox pictureBox;
        private Label statusLabel;
        #endregion

        #region 核心字段
        private Bitmap _currentImage;
        private float _scale = 1.0f;
        private PointF _offset = PointF.Empty;
        private RectangleF _roiRect;
        private PointF _roiStart;
        private bool _isDrawing;
        private Point _dragStart;
        private bool _isDragging;
        private Pen _roiPen = new Pen(Color.Red, 2);
        #endregion

        #region 公开属性
        #region 公开属性
        public Bitmap Image
        {
            get => _currentImage;
            set
            {
                // 记录旧状态
                var oldSize = _currentImage?.Size ?? Size.Empty;
                var oldScale = _scale;
                var oldOffset = _offset;

                _currentImage?.Dispose();
                _currentImage = value;

                if (_currentImage != null)
                {
                    if (_currentImage.Size != oldSize)
                    {
                        // 尺寸不同时：重置ROI、自动适配
                        _roiRect = RectangleF.Empty;
                        AutoFit();
                    }
                    else
                    {
                        // 尺寸相同时：保留缩放和偏移
                        _scale = oldScale;
                        _offset = oldOffset;
                        ClampOffset();
                    }
                }

                pictureBox.Invalidate();
            }
        }
        #endregion

        public RectangleF CurrentROI => _roiRect;
        #endregion

        public ImageViewerControl()
        {
            InitializeComponents();
            SetupDoubleBuffering();
        }

        #region 初始化
        private void InitializeComponents()
        {
            // 主显示区域
            pictureBox = new PictureBox
            {
                Dock = DockStyle.Fill,
                BackColor = Color.DarkGray,
                Cursor = Cursors.Cross
            };

            // 状态栏
            statusLabel = new Label
            {
                Dock = DockStyle.Bottom,
                Height = 20,
                Text = "就绪",
                BorderStyle = BorderStyle.FixedSingle,
                Font = new Font("Consolas", 10)
            };

            // 事件绑定
            pictureBox.MouseDown += PictureBox_MouseDown;
            pictureBox.MouseMove += PictureBox_MouseMove;
            pictureBox.MouseUp += PictureBox_MouseUp;
            pictureBox.MouseWheel += PictureBox_MouseWheel;
            pictureBox.Paint += PictureBox_Paint;

            Controls.Add(pictureBox);
            Controls.Add(statusLabel);
        }

        private void SetupDoubleBuffering()
        {
            typeof(PictureBox).GetMethod("SetStyle",
                System.Reflection.BindingFlags.NonPublic |
                System.Reflection.BindingFlags.Instance)
                ?.Invoke(pictureBox, new object[] {
                    ControlStyles.OptimizedDoubleBuffer |
                    ControlStyles.AllPaintingInWmPaint,
                    true
                });
        }
        #endregion

        #region 核心功能
        private void AutoFit()
        {
            if (_currentImage == null) return;

            const float marginRatio = 0.1f;
            float marginWidth = Width * marginRatio;
            float marginHeight = Height * marginRatio;

            _scale = Math.Min(
                (Width - marginWidth * 2) / _currentImage.Width,
                (Height - marginHeight * 2) / _currentImage.Height
            );

            _offset.X = marginWidth + (Width - marginWidth * 2 - _currentImage.Width * _scale) / 2;
            _offset.Y = marginHeight + (Height - marginHeight * 2 - _currentImage.Height * _scale) / 2;
        }

        private void PictureBox_Paint(object sender, PaintEventArgs e)
        {
            if (_currentImage == null) return;

            // 绘制图像
            var destRect = new RectangleF(
                _offset.X,
                _offset.Y,
                _currentImage.Width * _scale,
                _currentImage.Height * _scale);

            e.Graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
            e.Graphics.DrawImage(_currentImage, destRect);

            // 绘制ROI
            if (!_roiRect.IsEmpty)
            {
                var displayRect = new RectangleF(
                    _roiRect.X * _scale + _offset.X,
                    _roiRect.Y * _scale + _offset.Y,
                    _roiRect.Width * _scale,
                    _roiRect.Height * _scale);

                using (var pen = new Pen(_roiPen.Color, _roiPen.Width / _scale))
                {
                    e.Graphics.DrawRectangle(pen,
                        displayRect.X,
                        displayRect.Y,
                        displayRect.Width,
                        displayRect.Height);
                }
            }
        }
        #endregion

        #region 鼠标事件
        private void PictureBox_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left && _currentImage != null)
            {
                _roiStart = ClampCoordinates(ConvertToImageCoords(e.Location));
                _isDrawing = true;
            }
            else if (e.Button == MouseButtons.Right)
            {
                _dragStart = e.Location;
                _isDragging = true;
            }
        }

        private void PictureBox_MouseMove(object sender, MouseEventArgs e)
        {
            if (_isDragging)
            {
                _offset.X += e.X - _dragStart.X;
                _offset.Y += e.Y - _dragStart.Y;
                _dragStart = e.Location;
                ClampOffset();
                pictureBox.Invalidate();
            }
            else if (_isDrawing && _currentImage != null)
            {
                PointF current = ClampCoordinates(ConvertToImageCoords(e.Location));
                _roiRect = new RectangleF(
                    Math.Min(_roiStart.X, current.X),
                    Math.Min(_roiStart.Y, current.Y),
                    Math.Abs(_roiStart.X - current.X),
                    Math.Abs(_roiStart.Y - current.Y)
                );
                pictureBox.Invalidate();
            }

            UpdateStatus(e.Location);
        }

        private void PictureBox_MouseUp(object sender, MouseEventArgs e)
        {
            _isDragging = false;
            _isDrawing = false;
        }

        private void PictureBox_MouseWheel(object sender, MouseEventArgs e)
        {
            if (_currentImage == null) return;

            PointF mousePos = e.Location;
            PointF imgPosBefore = ConvertToImageCoords(mousePos);

            if (imgPosBefore.X < 0 || imgPosBefore.X > _currentImage.Width ||
                imgPosBefore.Y < 0 || imgPosBefore.Y > _currentImage.Height) return;

            float zoom = e.Delta > 0 ? 1.1f : 0.9f;
            float newScale = Math.Clamp(_scale * zoom, 0.1f, 10f);

            _offset.X = mousePos.X - imgPosBefore.X * newScale;
            _offset.Y = mousePos.Y - imgPosBefore.Y * newScale;

            _scale = newScale;
            ClampOffset();
            pictureBox.Invalidate();
        }
        #endregion

        #region 辅助方法
        private PointF ConvertToImageCoords(PointF mousePos)
        {
            return new PointF(
                (mousePos.X - _offset.X) / _scale,
                (mousePos.Y - _offset.Y) / _scale);
        }

        private PointF ClampCoordinates(PointF point)
        {
            return new PointF(
                Math.Max(0, Math.Min(_currentImage.Width, point.X)),
                Math.Max(0, Math.Min(_currentImage.Height, point.Y)));
        }

        private void ClampOffset()
        {
            if (_currentImage == null) return;

            float imgWidth = _currentImage.Width * _scale;
            float imgHeight = _currentImage.Height * _scale;

            if (imgWidth <= Width)
            {
                _offset.X = Math.Clamp(_offset.X, 0, Width - imgWidth);
            }
            else
            {
                _offset.X = Math.Clamp(_offset.X, Width - imgWidth, 0);
            }

            if (imgHeight <= Height)
            {
                _offset.Y = Math.Clamp(_offset.Y, 0, Height - imgHeight);
            }
            else
            {
                _offset.Y = Math.Clamp(_offset.Y, Height - imgHeight, 0);
            }
        }

        private void UpdateStatus(Point mousePos)
        {
            if (_currentImage == null) return;

            PointF imgPos = ConvertToImageCoords(mousePos);
            bool inImage = imgPos.X >= 0 && imgPos.X <= _currentImage.Width &&
                          imgPos.Y >= 0 && imgPos.Y <= _currentImage.Height;

            string roiInfo = _roiRect.IsEmpty ?
                "未选择区域" :
                $"选区: X={_roiRect.X:0} Y={_roiRect.Y:0} {_roiRect.Width:0}x{_roiRect.Height:0}";

            statusLabel.Text = inImage ?
                $"坐标: ({imgPos.X:0}, {imgPos.Y:0}) | 缩放: {_scale * 100:0}% | {roiInfo}" :
                $"图像尺寸: {_currentImage.Width}x{_currentImage.Height} | 缩放: {_scale * 100:0}% | {roiInfo}";
        }

        public void ClearROI()
        {
            _roiRect = RectangleF.Empty;
            pictureBox.Invalidate(); // 触发重绘
            UpdateStatus(Point.Empty); // 更新状态栏
        }

        #endregion
    }
}