using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Windows.Forms;

namespace TBF.UI.Calendar
{
    internal partial class ScrollPanelCtrl : UserControl
    {
        private int _scrollOffset;
        private bool _mouseDown;
        private Point _oldMouseCoords;
        private int _bmpSize;

        [DllImport("user32.dll")]
        static extern short GetKeyState(int nVirtKey);

        public event MouseEventHandler RightButtonClicked;

        public ScrollPanelCtrl()
        {
            InitializeComponent();
            _scrollOffset = 0;
            _mouseDown = false;
            _oldMouseCoords = new Point(0, 0);
        }

        public int ScrollOffset
        {
            get { return _scrollOffset; }
        }

        private void ScrollPanel_Load(object sender, EventArgs e)
        {
            //BackColor = Color.Blue;
        }

        private void ScrollPanel_Paint(object sender, PaintEventArgs e)
        {
            var c = (CalendarCtrl)Parent;

            Bitmap bmp = c.RequestImage();
            if (bmp == null)
                return;

            e.Graphics.DrawImage(bmp, new Rectangle(0, 0, ClientSize.Width, ClientSize.Height),
                                 new Rectangle(0, _scrollOffset, ClientSize.Width, ClientSize.Height),
                                 GraphicsUnit.Pixel);
            _bmpSize = bmp.Height;
            //e.Graphics.Dispose();
            bmp.Dispose();
        }

        private void ScrollPanel_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                _mouseDown = true;
                _oldMouseCoords = e.Location;
            }
        }

        private void ScrollPanel_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
                _mouseDown = false;
        }

        private void ScrollPanel_MouseMove(object sender, MouseEventArgs e)
        {
            if (_mouseDown && e.Location.Y < _oldMouseCoords.Y && _scrollOffset < _bmpSize - _scrollOffset - ClientSize.Height)
            {
                int offset = _oldMouseCoords.Y - e.Location.Y;
                _scrollOffset += offset;
                Refresh();
            }
            if (_mouseDown && e.Location.Y > _oldMouseCoords.Y && _scrollOffset > 0)
            {
                int offset = e.Location.Y - _oldMouseCoords.Y;
                _scrollOffset -= offset;
                Refresh();
            }
            _oldMouseCoords = e.Location;
        }

        private void ScrollPanel_MouseClick(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Right)
            {
                if (RightButtonClicked != null)
                    RightButtonClicked(sender, e);
            }
        }
    }
}