/*
* Greenshot - a free and open source screenshot tool
* Copyright (C) 2007-2021 Thomas Braun, Jens Klingen, Robin Krom
*
* For more information see: http://getgreenshot.org/
* The Greenshot project is hosted on GitHub https://github.com/greenshot/greenshot
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 1 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Security.Permissions;
using System.Windows.Forms;
using Greenshot.Configuration;
using Greenshot.Helpers;
using GreenshotPlugin.Core;
using GreenshotPlugin.IniFile;
using log4net;

namespace Greenshot.Forms {
	/// <summary>
	/// The about form
	/// </summary>
	public sealed partial class AboutForm : AnimatingBaseForm {
		private static readonly ILog Log = LogManager.GetLogger(typeof(AboutForm));
		private Bitmap _bitmap;
		private readonly ColorAnimator _backgroundAnimation;
		private readonly List<RectangleAnimator> _pixels = new List<RectangleAnimator>();
		private readonly List<Color> _colorFlow = new List<Color>();
		private readonly List<Color> _pixelColors = new List<Color>();
		private readonly Random _rand = new Random();
		private readonly Color _backColor = Color.FromArgb(61, 61, 61);
		private readonly Color _pixelColor = Color.FromArgb(138, 255, 0);

		// Variables used for the color-cycle
		private int _waitFrames;
		private int _colorIndex;
		private int _scrollCount;
		private bool _hasAnimationsLeft;

		// Variables are used to define the location of the dots
		private const int W = 13;
		private const int P1 = 7;
		private const int P2 = P1 + W;
		private const int P3 = P2 + W;
		private const int P4 = P3 + W;
		private const int P5 = P4 + W;
		private const int P6 = P5 + W;
		private const int P7 = P6 + W;

		/// <summary>
		/// The location of every dot in the "G"
		/// </summary>
		private readonly List<Point> _gSpots = new List<Point>
        {
             	// Top row
             	new Point(P2, P1),	// 0
             	new Point(P3, P1),  // 1
             	new Point(P4, P1),  // 2
             	new Point(P5, P1),	// 3
             	new Point(P6, P1),	// 4

             	// Second row
             	new Point(P1, P2),	// 5
             	new Point(P2, P2),	// 6

             	// Third row
             	new Point(P1, P3),	// 7
             	new Point(P2, P3),	// 8

             	// Fourth row
             	new Point(P1, P4),	// 9
             	new Point(P2, P4),	// 10
             	new Point(P5, P4),	// 11
             	new Point(P6, P4),	// 12
             	new Point(P7, P4),	// 13

             	// Fifth row
             	new Point(P1, P5),	// 14
             	new Point(P2, P5),	// 15
             	new Point(P6, P5),	// 16
             	new Point(P7, P5),	// 17

             	// Sixth row
             	new Point(P1, P6),	// 18
             	new Point(P2, P6),	// 19
             	new Point(P3, P6),	// 20
             	new Point(P4, P6),	// 21
             	new Point(P5, P6),	// 22
             	new Point(P6, P6)	// 23
             };

		//     0  1  2  3  4
		//  5  6
		//  7  8
		//  9 10       11 12 13
		// 14 15          16 17
		// 18 19 20 21 22 23

		// The order in which we draw the dots & flow the colors.
		private readonly List<int> _flowOrder = new List<int>{ 4, 3, 2, 1, 0, 5, 6, 7, 8, 9, 10, 14, 15, 18, 19, 20, 21, 22, 23, 16, 17, 13, 12, 11 };

		/// <summary>
		/// Cleanup all the allocated resources
		/// </summary>
		private void Cleanup(object sender, EventArgs e) {
            if (_bitmap == null) return;
            _bitmap.Dispose();
            _bitmap = null;
        }

		/// <summary>
		/// Constructor
		/// </summary>
		public AboutForm() {
			// Make sure our resources are removed again.
			Disposed += Cleanup;
			FormClosing += Cleanup;

			// Enable animation for this form, when we don't set this the timer doesn't start as soon as the form is loaded.
			EnableAnimation = true;
			//
			// The InitializeComponent() call is required for Windows Forms designer support.
			//
			InitializeComponent();

			// Only use double-buffering when we are NOT in a Terminal Server session
			DoubleBuffered = !IsTerminalServerSession;

			// Use the self drawn image, first we create the background to be the back-color (as we animate from this)

			_bitmap = ImageHelper.CreateEmpty(90, 90, PixelFormat.Format24bppRgb, BackColor, 96, 96);
			pictureBox1.Image = _bitmap;

            lblTitle.Text = $@"Greenshot {EnvironmentInfo.GetGreenshotVersion()} {(IniConfig.IsPortable ? " Portable" : "")} ({OsInfo.Bits}) bit)";

			// Number of frames the pixel animation takes
			int frames = FramesForMillis(2000);
			// The number of frames the color-cycle waits before it starts
			_waitFrames = FramesForMillis(6000);

			// Every pixel is created after pixelWaitFrames frames, which is increased in the loop.
			int pixelWaitFrames = FramesForMillis(2000);
			// Create pixels
			for (int index = 0; index < _gSpots.Count; index++) {
				// Read the pixels in the order of the flow
				Point gSpot = _gSpots[_flowOrder[index]];
				// Create the animation, first we do nothing (on the final destination)
				RectangleAnimator pixelAnimation;

				// Make the pixel grow from the middle, if this offset isn't used it looks like it's shifted
				int offset = (W - 2) / 2;

				// If the optimize for Terminal Server is set we make the animation without much ado
				if (IsTerminalServerSession) {
					// No animation
					pixelAnimation = new RectangleAnimator(new Rectangle(gSpot.X, gSpot.Y, W - 2, W - 2), new Rectangle(gSpot.X, gSpot.Y, W - 2, W - 2), 1, EasingType.Cubic, EasingMode.EaseIn);
				} else {
					// Create the animation, first we do nothing (on the final destination)
					Rectangle standingStill = new Rectangle(gSpot.X + offset, gSpot.Y + offset, 0, 0);
					pixelAnimation = new RectangleAnimator(standingStill, standingStill, pixelWaitFrames, EasingType.Quintic, EasingMode.EaseIn);
					// And than we size to the wanted size.
					pixelAnimation.QueueDestinationLeg(new Rectangle(gSpot.X, gSpot.Y, W - 2, W - 2), frames);
				}
				// Increase the wait frames
				pixelWaitFrames += FramesForMillis(100);
				// Add to the list of to be animated pixels
				_pixels.Add(pixelAnimation);
				// Add a color to the list for this pixel.
				_pixelColors.Add(_pixelColor);
			}
			// Make sure the frame "loop" knows we have to animate
			_hasAnimationsLeft = true;

			// Pixel Color cycle colors, here we use a pre-animated loop which stores the values.
			ColorAnimator pixelColorAnimator = new ColorAnimator(_pixelColor, Color.FromArgb(255, 255, 255), 6, EasingType.Quadratic, EasingMode.EaseIn);
			pixelColorAnimator.QueueDestinationLeg(_pixelColor, 6, EasingType.Quadratic, EasingMode.EaseOut);
			do {
				_colorFlow.Add(pixelColorAnimator.Current);
				pixelColorAnimator.Next();
			} while (pixelColorAnimator.HasNext);

			// color animation for the background
			_backgroundAnimation = new ColorAnimator(BackColor, _backColor, FramesForMillis(5000), EasingType.Linear, EasingMode.EaseIn);
		}

		/// <summary>
		/// This is called when a link is clicked
		/// </summary>
		/// <param name="sender"></param>
		/// <param name="e"></param>
		private void LinkLabelClicked(object sender, LinkLabelLinkClickedEventArgs e)
        {
            if (!(sender is LinkLabel linkLabel)) return;
            try {
                linkLabel.LinkVisited = true;
                Process.Start(linkLabel.Text);
            } catch (Exception) {
                MessageBox.Show(Language.GetFormattedString(LangKey.error_openlink, linkLabel.Text), Language.GetString(LangKey.error));
            }
        }

		/// <summary>
		/// Called from the AnimatingForm, for every frame
		/// </summary>
		protected override void Animate() {
			if (_bitmap == null) {
				return;
			}
			if (!IsTerminalServerSession) {
				// Color cycle
				if (_waitFrames != 0) {
					_waitFrames--;
					// Check if there is something else to do, if not we return so we don't occupy the CPU
					if (!_hasAnimationsLeft) {
						return;
					}
				} else if (_scrollCount < _pixelColors.Count + _colorFlow.Count) {
					// Scroll colors, the scrollCount is the amount of pixels + the amount of colors to cycle.
					for (int index = _pixelColors.Count - 1; index > 0; index--) {
						_pixelColors[index] = _pixelColors[index - 1];
					}
					// Keep adding from  the colors to cycle until there is nothing left
					if (_colorIndex < _colorFlow.Count) {
						_pixelColors[0] = _colorFlow[_colorIndex++];
					}
					_scrollCount++;
				} else {
					// Reset values, wait X time for the next one
					_waitFrames = FramesForMillis(3000 + _rand.Next(35000));
					_colorIndex = 0;
					_scrollCount = 0;
					// Check if there is something else to do, if not we return so we don't occupy the CPU
					if (!_hasAnimationsLeft) {
						return;
					}
				}
			} else if (!_hasAnimationsLeft) {
				return;
			}

			// Draw the "G"
			using (Graphics graphics = Graphics.FromImage(_bitmap)) {
				graphics.SmoothingMode = SmoothingMode.HighQuality;
				graphics.InterpolationMode = InterpolationMode.HighQualityBilinear;
				graphics.CompositingQuality = CompositingQuality.HighQuality;
				graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;

				graphics.Clear(_backgroundAnimation.Next());

				graphics.TranslateTransform(2, -2);
				graphics.RotateTransform(20);

                using SolidBrush brush = new SolidBrush(_pixelColor);
                int index = 0;
                // We assume there is nothing to animate in the next Animate loop
                _hasAnimationsLeft = false;
                // Pixels of the G
                foreach (RectangleAnimator pixel in _pixels) {
                    brush.Color = _pixelColors[index++];
                    graphics.FillEllipse(brush, pixel.Current);
                    // If a pixel still has frames left, the hasAnimationsLeft will be true
                    _hasAnimationsLeft |= pixel.HasNext;
                    pixel.Next();
                }
            }
			pictureBox1.Invalidate();
		}

		/// <summary>
		/// CmdKey handler
		/// </summary>
		/// <param name="msg"></param>
		/// <param name="keyData"></param>
		/// <returns></returns>
		[SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
		protected override bool ProcessCmdKey(ref Message msg, Keys keyData) {
			try {
				switch (keyData) {
					case Keys.Escape:
						DialogResult = DialogResult.Cancel;
						break;
					case Keys.E:
						MessageBox.Show(EnvironmentInfo.EnvironmentToString(true));
						break;
					case Keys.L:
						try {
							if (File.Exists(MainForm.LogFileLocation)) {
								using (Process.Start("\"" + MainForm.LogFileLocation + "\"")) {
									// nothing to do, just using dispose to cleanup
								}
							} else {
								MessageBox.Show(@"Greenshot can't find the logfile, it should have been here: " + MainForm.LogFileLocation);
							}
						} catch (Exception) {
							MessageBox.Show(@"Couldn't open the greenshot.log, it's located here: " + MainForm.LogFileLocation, @"Error opening greenshot.log", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
						}
						break;
					case Keys.I:
						try {
							using (Process.Start("\"" + IniConfig.ConfigLocation + "\"")) {
							}
						} catch (Exception) {
							MessageBox.Show(@"Couldn't open the greenshot.ini, it's located here: " + IniConfig.ConfigLocation, @"Error opening greenshot.ini", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
						}
						break;
					default:
						return base.ProcessCmdKey(ref msg, keyData);
				}
			} catch (Exception ex) {
				Log.Error($"Error handling key '{keyData}'", ex);
			}
			return true;
		}
	}
}