// <file>
//     <copyright see="prj:///doc/copyright.txt"/>
//     <license see="prj:///doc/license.txt"/>
//     <owner name="Mike Krüger" email="mike@icsharpcode.net"/>
//     <version>$Revision$</version>
// </file>

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

using ICSharpCode.TextEditor.Document;

namespace ICSharpCode.TextEditor
{
	/// <summary>
	/// This class handles all mouse stuff for a textArea.
	/// </summary>
	public class TextAreaMouseHandler
	{
		TextArea  textArea;
		bool      doubleclick = false;
		bool      clickedOnSelectedText = false;
		
		MouseButtons button;
		
		static readonly Point nilPoint = new Point(-1, -1);
		Point mousedownpos       = nilPoint;
		Point lastmousedownpos   = nilPoint;
		
		bool gotmousedown = false;
		bool dodragdrop = false;
		
		public TextAreaMouseHandler(TextArea ttextArea)
		{
			textArea = ttextArea;
		}
		
		public void Attach()
		{
			textArea.Click       += new EventHandler(TextAreaClick);
			textArea.MouseMove   += new MouseEventHandler(TextAreaMouseMove);
			
			textArea.MouseDown   += new MouseEventHandler(OnMouseDown);
			textArea.DoubleClick += new EventHandler(OnDoubleClick);
			textArea.MouseLeave  += new EventHandler(OnMouseLeave);
			textArea.MouseUp     += new MouseEventHandler(OnMouseUp);
			textArea.LostFocus   += new EventHandler(TextAreaLostFocus);
			textArea.ToolTipRequest += new ToolTipRequestEventHandler(OnToolTipRequest);
		}
		
		void OnToolTipRequest(object sender, ToolTipRequestEventArgs e)
		{
			if (e.ToolTipShown)
				return;
			Point mousepos = e.MousePosition;
			FoldMarker marker = textArea.TextView.GetFoldMarkerFromPosition(mousepos.X - textArea.TextView.DrawingPosition.X,
			                                                                mousepos.Y - textArea.TextView.DrawingPosition.Y);
			if (marker != null && marker.IsFolded) {
				StringBuilder sb = new StringBuilder(marker.InnerText);
				
				// max 10 lines
				int endLines = 0;
				for (int i = 0; i < sb.Length; ++i) {
					if (sb[i] == '\n') {
						++endLines;
						if (endLines >= 10) {
							sb.Remove(i + 1, sb.Length - i - 1);
							sb.Append(Environment.NewLine);
							sb.Append("...");
							break;
							
						}
					}
				}
				sb.Replace("\t", "    ");
				e.ShowToolTip(sb.ToString());
				return;
			}
			
			List<TextMarker> markers = textArea.Document.MarkerStrategy.GetMarkers(e.LogicalPosition);
			foreach (TextMarker tm in markers) {
				if (tm.ToolTip != null) {
					e.ShowToolTip(tm.ToolTip.Replace("\t", "    "));
					return;
				}
			}
		}
		
		void ShowHiddenCursorIfMovedOrLeft()
		{
			textArea.ShowHiddenCursor(!textArea.Focused ||
			                          !textArea.ClientRectangle.Contains(textArea.PointToClient(Cursor.Position)));
		}
		
		void TextAreaLostFocus(object sender, EventArgs e)
		{
			// The call to ShowHiddenCursorIfMovedOrLeft is delayed
			// until pending messages have been processed
			// so that it can properly detect whether the TextArea
			// has really lost focus.
			// For example, the CodeCompletionWindow gets focus when it is shown,
			// but immediately gives back focus to the TextArea.
			textArea.BeginInvoke(new MethodInvoker(ShowHiddenCursorIfMovedOrLeft));
		}
		
		void OnMouseLeave(object sender, EventArgs e)
		{
			ShowHiddenCursorIfMovedOrLeft();
			gotmousedown = false;
			mousedownpos = nilPoint;
		}
		
		void OnMouseUp(object sender, MouseEventArgs e)
		{
			textArea.SelectionManager.selectFrom.where = WhereFrom.None;
			gotmousedown = false;
			mousedownpos = nilPoint;
		}
		
		void TextAreaClick(object sender, EventArgs e)
		{
			Point mousepos;
			mousepos = textArea.mousepos;
			
			if (dodragdrop)
			{
				return;
			}

			if (clickedOnSelectedText && textArea.TextView.DrawingPosition.Contains(mousepos.X, mousepos.Y))
			{
				textArea.SelectionManager.ClearSelection();

				TextLocation clickPosition = textArea.TextView.GetLogicalPosition(
					mousepos.X - textArea.TextView.DrawingPosition.X,
					mousepos.Y - textArea.TextView.DrawingPosition.Y);
				textArea.Caret.Position = clickPosition;
				textArea.SetDesiredColumn();
			}
		}
		
		
		void TextAreaMouseMove(object sender, MouseEventArgs e)
		{
			textArea.mousepos = e.Location;

			// honour the starting selection strategy
			switch (textArea.SelectionManager.selectFrom.where)
			{
				case WhereFrom.Gutter:
					ExtendSelectionToMouse();
					return;

				case WhereFrom.TArea:
					break;

			}
			textArea.ShowHiddenCursor(false);
			if (dodragdrop) {
				dodragdrop = false;
				return;
			}
			
			doubleclick = false;
			textArea.mousepos = new Point(e.X, e.Y);
			
			if (clickedOnSelectedText) {
				if (Math.Abs(mousedownpos.X - e.X) >= SystemInformation.DragSize.Width / 2 ||
				    Math.Abs(mousedownpos.Y - e.Y) >= SystemInformation.DragSize.Height / 2)
				{
					clickedOnSelectedText = false;
					ISelection selection = textArea.SelectionManager.GetSelectionAt(textArea.Caret.Offset);
					if (selection != null) {
						string text = selection.SelectedText;
						bool isReadOnly = SelectionManager.SelectionIsReadOnly(textArea.Document, selection);
						if (text != null && text.Length > 0) {
							DataObject dataObject = new DataObject ();
							dataObject.SetData(DataFormats.UnicodeText, true, text);
							dataObject.SetData(selection);
							dodragdrop = true;
							textArea.DoDragDrop(dataObject, isReadOnly ? DragDropEffects.All & ~DragDropEffects.Move : DragDropEffects.All);
						}
					}
				}
				
				return;
			}
			
			if (e.Button == MouseButtons.Left) {
				if (gotmousedown && textArea.SelectionManager.selectFrom.where == WhereFrom.TArea)
				{
					ExtendSelectionToMouse();
				}
			}
		}
		
		void ExtendSelectionToMouse()
		{
			Point mousepos;
			mousepos = textArea.mousepos;
			TextLocation realmousepos = textArea.TextView.GetLogicalPosition(
				Math.Max(0, mousepos.X - textArea.TextView.DrawingPosition.X),
				mousepos.Y - textArea.TextView.DrawingPosition.Y);
			int y = realmousepos.Y;
			realmousepos = textArea.Caret.ValidatePosition(realmousepos);
			TextLocation oldPos = textArea.Caret.Position;
			if (oldPos == realmousepos && textArea.SelectionManager.selectFrom.where != WhereFrom.Gutter)
			{
				return;
			}

			// the selection is from the gutter
			if (textArea.SelectionManager.selectFrom.where == WhereFrom.Gutter) {
				if(realmousepos.Y < textArea.SelectionManager.SelectionStart.Y) {
					// the selection has moved above the startpoint
					textArea.Caret.Position = new TextLocation(0, realmousepos.Y);
				} else {
					// the selection has moved below the startpoint
					textArea.Caret.Position = textArea.SelectionManager.NextValidPosition(realmousepos.Y);
				}
			} else {
				textArea.Caret.Position = realmousepos;
			}

			// moves selection across whole words for double-click initiated selection
			if (!minSelection.IsEmpty && textArea.SelectionManager.SelectionCollection.Count > 0 && textArea.SelectionManager.selectFrom.where == WhereFrom.TArea) {
				// Extend selection when selection was started with double-click
				ISelection selection = textArea.SelectionManager.SelectionCollection[0];
				TextLocation min = textArea.SelectionManager.GreaterEqPos(minSelection, maxSelection) ? maxSelection : minSelection;
				TextLocation max = textArea.SelectionManager.GreaterEqPos(minSelection, maxSelection) ? minSelection : maxSelection;
				if (textArea.SelectionManager.GreaterEqPos(max, realmousepos) && textArea.SelectionManager.GreaterEqPos(realmousepos, min)) {
					textArea.SelectionManager.SetSelection(min, max);
				} else if (textArea.SelectionManager.GreaterEqPos(max, realmousepos)) {
					int moff = textArea.Document.PositionToOffset(realmousepos);
					min = textArea.Document.OffsetToPosition(FindWordStart(textArea.Document, moff));
					textArea.SelectionManager.SetSelection(min, max);
				} else {
					int moff = textArea.Document.PositionToOffset(realmousepos);
					max = textArea.Document.OffsetToPosition(FindWordEnd(textArea.Document, moff));
					textArea.SelectionManager.SetSelection(min, max);
				}
			} else {
				textArea.SelectionManager.ExtendSelection(oldPos, textArea.Caret.Position);
			}
			textArea.SetDesiredColumn();
		}
		
		void DoubleClickSelectionExtend()
		{
			Point mousepos;
			mousepos = textArea.mousepos;
			
			textArea.SelectionManager.ClearSelection();
			if (textArea.TextView.DrawingPosition.Contains(mousepos.X, mousepos.Y))
			{
				FoldMarker marker = textArea.TextView.GetFoldMarkerFromPosition(mousepos.X - textArea.TextView.DrawingPosition.X,
				                                                                mousepos.Y - textArea.TextView.DrawingPosition.Y);
				if (marker != null && marker.IsFolded) {
					marker.IsFolded = false;
					textArea.MotherTextAreaControl.AdjustScrollBars();
				}
				if (textArea.Caret.Offset < textArea.Document.TextLength) {
					switch (textArea.Document.GetCharAt(textArea.Caret.Offset)) {
						case '"':
							if (textArea.Caret.Offset < textArea.Document.TextLength) {
								int next = FindNext(textArea.Document, textArea.Caret.Offset + 1, '"');
								minSelection = textArea.Caret.Position;
								if (next > textArea.Caret.Offset && next < textArea.Document.TextLength)
									next += 1;
								maxSelection = textArea.Document.OffsetToPosition(next);
							}
							break;
						default:
							minSelection = textArea.Document.OffsetToPosition(FindWordStart(textArea.Document, textArea.Caret.Offset));
							maxSelection = textArea.Document.OffsetToPosition(FindWordEnd(textArea.Document, textArea.Caret.Offset));
							break;
							
					}
					textArea.Caret.Position = maxSelection;
					textArea.SelectionManager.ExtendSelection(minSelection, maxSelection);
				}

				if (textArea.SelectionManager.selectionCollection.Count > 0) {
					ISelection selection = textArea.SelectionManager.selectionCollection[0];
					
					selection.StartPosition = minSelection;
					selection.EndPosition = maxSelection;
					textArea.SelectionManager.SelectionStart = minSelection;
				}

				// after a double-click selection, the caret is placed correctly,
				// but it is not positioned internally.  The effect is when the cursor
				// is moved up or down a line, the caret will take on the column first
				// clicked on for the double-click
				textArea.SetDesiredColumn();

				// HACK WARNING !!!
				// must refresh here, because when a error tooltip is showed and the underlined
				// code is double clicked the textArea don't update corrctly, updateline doesn't
				// work ... but the refresh does.
				// Mike
				textArea.Refresh();
			}
		}

		void OnMouseDown(object sender, MouseEventArgs e)
		{
			Point mousepos;
			textArea.mousepos = e.Location;
			mousepos = e.Location;

			if (dodragdrop)
			{
				return;
			}
			
			if (doubleclick) {
				doubleclick = false;
				return;
			}
			
			if (textArea.TextView.DrawingPosition.Contains(mousepos.X, mousepos.Y)) {
				gotmousedown = true;
				textArea.SelectionManager.selectFrom.where = WhereFrom.TArea;
				button = e.Button;
				
				// double-click
				if (button == MouseButtons.Left && e.Clicks == 2) {
					int deltaX   = Math.Abs(lastmousedownpos.X - e.X);
					int deltaY   = Math.Abs(lastmousedownpos.Y - e.Y);
					if (deltaX <= SystemInformation.DoubleClickSize.Width &&
					    deltaY <= SystemInformation.DoubleClickSize.Height) {
						DoubleClickSelectionExtend();
						lastmousedownpos = new Point(e.X, e.Y);

						if (textArea.SelectionManager.selectFrom.where == WhereFrom.Gutter) {
							if (!minSelection.IsEmpty && !maxSelection.IsEmpty && textArea.SelectionManager.SelectionCollection.Count > 0) {
								textArea.SelectionManager.SelectionCollection[0].StartPosition = minSelection;
								textArea.SelectionManager.SelectionCollection[0].EndPosition = maxSelection;
								textArea.SelectionManager.SelectionStart = minSelection;

								minSelection = TextLocation.Empty;
								maxSelection = TextLocation.Empty;
							}
						}
						return;
					}
				}
				minSelection = TextLocation.Empty;
				maxSelection = TextLocation.Empty;
				
				lastmousedownpos = mousedownpos = new Point(e.X, e.Y);
				
				if (button == MouseButtons.Left) {
					FoldMarker marker = textArea.TextView.GetFoldMarkerFromPosition(mousepos.X - textArea.TextView.DrawingPosition.X,
					                                                                mousepos.Y - textArea.TextView.DrawingPosition.Y);
					if (marker != null && marker.IsFolded) {
						if (textArea.SelectionManager.HasSomethingSelected) {
							clickedOnSelectedText = true;
						}
						
						TextLocation startLocation = new TextLocation(marker.StartColumn, marker.StartLine);
						TextLocation endLocation = new TextLocation(marker.EndColumn, marker.EndLine);
						textArea.SelectionManager.SetSelection(new DefaultSelection(textArea.TextView.Document, startLocation, endLocation));
						textArea.Caret.Position = startLocation;
						textArea.SetDesiredColumn();
						textArea.Focus();
						return;
					}

					if ((Control.ModifierKeys & Keys.Shift) == Keys.Shift) {
						ExtendSelectionToMouse();
					} else {
						TextLocation realmousepos = textArea.TextView.GetLogicalPosition(mousepos.X - textArea.TextView.DrawingPosition.X, mousepos.Y - textArea.TextView.DrawingPosition.Y);
						clickedOnSelectedText = false;
						
						int offset = textArea.Document.PositionToOffset(realmousepos);
						
						if (textArea.SelectionManager.HasSomethingSelected &&
						    textArea.SelectionManager.IsSelected(offset)) {
							clickedOnSelectedText = true;
						} else {
							textArea.SelectionManager.ClearSelection();
							if (mousepos.Y > 0 && mousepos.Y < textArea.TextView.DrawingPosition.Height) {
								TextLocation pos = new TextLocation();
								pos.Y = Math.Min(textArea.Document.TotalNumberOfLines - 1,  realmousepos.Y);
								pos.X = realmousepos.X;
								textArea.Caret.Position = pos;
								textArea.SetDesiredColumn();
							}
						}
					}
				} else if (button == MouseButtons.Right) {
					// Rightclick sets the cursor to the click position unless
					// the previous selection was clicked
					TextLocation realmousepos = textArea.TextView.GetLogicalPosition(mousepos.X - textArea.TextView.DrawingPosition.X, mousepos.Y - textArea.TextView.DrawingPosition.Y);
					int offset = textArea.Document.PositionToOffset(realmousepos);
					if (!textArea.SelectionManager.HasSomethingSelected ||
					    !textArea.SelectionManager.IsSelected(offset))
					{
						textArea.SelectionManager.ClearSelection();
						if (mousepos.Y > 0 && mousepos.Y < textArea.TextView.DrawingPosition.Height) {
							TextLocation pos = new TextLocation();
							pos.Y = Math.Min(textArea.Document.TotalNumberOfLines - 1,  realmousepos.Y);
							pos.X = realmousepos.X;
							textArea.Caret.Position = pos;
							textArea.SetDesiredColumn();
						}
					}
				}
			}
			textArea.Focus();
		}
		
		int FindNext(IDocument document, int offset, char ch)
		{
			LineSegment line = document.GetLineSegmentForOffset(offset);
			int         endPos = line.Offset + line.Length;
			
			while (offset < endPos && document.GetCharAt(offset) != ch) {
				++offset;
			}
			return offset;
		}
		
		bool IsSelectableChar(char ch)
		{
			return Char.IsLetterOrDigit(ch) || ch=='_';
		}
		
		int FindWordStart(IDocument document, int offset)
		{
			LineSegment line = document.GetLineSegmentForOffset(offset);
			
			if (offset > 0 && Char.IsWhiteSpace(document.GetCharAt(offset - 1)) && Char.IsWhiteSpace(document.GetCharAt(offset))) {
				while (offset > line.Offset && Char.IsWhiteSpace(document.GetCharAt(offset - 1))) {
					--offset;
				}
			} else  if (IsSelectableChar(document.GetCharAt(offset)) || (offset > 0 && Char.IsWhiteSpace(document.GetCharAt(offset)) && IsSelectableChar(document.GetCharAt(offset - 1))))  {
				while (offset > line.Offset && IsSelectableChar(document.GetCharAt(offset - 1))) {
					--offset;
				}
			} else {
				if (offset > 0 && !Char.IsWhiteSpace(document.GetCharAt(offset - 1)) && !IsSelectableChar(document.GetCharAt(offset - 1)) ) {
					return Math.Max(0, offset - 1);
				}
			}
			return offset;
		}
		
		int FindWordEnd(IDocument document, int offset)
		{
			LineSegment line   = document.GetLineSegmentForOffset(offset);
			if (line.Length == 0)
				return offset;
			int         endPos = line.Offset + line.Length;
			offset = Math.Min(offset, endPos - 1);
			
			if (IsSelectableChar(document.GetCharAt(offset)))  {
				while (offset < endPos && IsSelectableChar(document.GetCharAt(offset))) {
					++offset;
				}
			} else if (Char.IsWhiteSpace(document.GetCharAt(offset))) {
				if (offset > 0 && Char.IsWhiteSpace(document.GetCharAt(offset - 1))) {
					while (offset < endPos && Char.IsWhiteSpace(document.GetCharAt(offset))) {
						++offset;
					}
				}
			} else {
				return Math.Max(0, offset + 1);
			}
			
			return offset;
		}
		TextLocation minSelection = TextLocation.Empty;
		TextLocation maxSelection = TextLocation.Empty;
		
		void OnDoubleClick(object sender, System.EventArgs e)
		{
			if (dodragdrop) {
				return;
			}
			
			textArea.SelectionManager.selectFrom.where = WhereFrom.TArea;
			doubleclick = true;
			
		}
	}
}