// <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.Linq;
using System.Windows.Forms;
using ICSharpCode.TextEditor.Document;

namespace ICSharpCode.TextEditor
{
    /// <summary>
    ///     This class views the line numbers and folding markers.
    /// </summary>
    public class FoldMargin : AbstractMargin
    {
        private int selectedFoldLine = -1;

        public FoldMargin(TextArea textArea) : base(textArea)
        {
        }

        public override int Width => textArea.TextView.FontHeight;

        public override bool IsVisible => textArea.TextEditorProperties.EnableFolding;

        public override void Paint(Graphics g, Rectangle rect)
        {
            if (rect.Width <= 0 || rect.Height <= 0)
                return;
            var lineNumberPainterColor = textArea.Document.HighlightingStrategy.GetColorFor("LineNumbers");

            for (var y = 0; y < (DrawingPosition.Height + textArea.TextView.VisibleLineDrawingRemainder)/textArea.TextView.FontHeight + 1; ++y)
            {
                var markerRectangle = new Rectangle(
                    DrawingPosition.X,
                    DrawingPosition.Top + y*textArea.TextView.FontHeight - textArea.TextView.VisibleLineDrawingRemainder,
                    DrawingPosition.Width,
                    textArea.TextView.FontHeight);

                if (rect.IntersectsWith(markerRectangle))
                {
                    g.FillRectangle(BrushRegistry.GetBrush(textArea.Enabled
                            ? lineNumberPainterColor.BackgroundColor
                            : SystemColors.InactiveBorder),
                        markerRectangle);

                    if (textArea.Document.TextEditorProperties.EnableFolding)
                    {
                        // draw dotted separator line
                        g.DrawLine(
                            BrushRegistry.GetDotPen(lineNumberPainterColor.Color),
                            drawingPosition.X,
                            markerRectangle.Y,
                            drawingPosition.X,
                            markerRectangle.Bottom);

                        var currentLine = textArea.Document.GetFirstLogicalLine(textArea.TextView.FirstPhysicalLine + y);
                        if (currentLine < textArea.Document.TotalNumberOfLines)
                            PaintFoldMarker(g, currentLine, markerRectangle);
                    }
                }
            }
        }

        private void PaintFoldMarker(Graphics g, int lineNumber, Rectangle drawingRectangle)
        {
            var foldLineColor = textArea.Document.HighlightingStrategy.GetColorFor("FoldLine");
            var selectedLine = textArea.Document.HighlightingStrategy.GetColorFor("SelectedFoldLine");

            var foldingsWithStart = textArea.Document.FoldingManager.GetFoldingsWithStart(lineNumber);
            var foldingsBetween = textArea.Document.FoldingManager.GetFoldingsContainsLineNumber(lineNumber);
            var foldingsWithEnd = textArea.Document.FoldingManager.GetFoldingsWithEnd(lineNumber);

            var isFoldStart = foldingsWithStart.Count > 0;
            var isBetween = foldingsBetween.Count > 0;
            var isFoldEnd = foldingsWithEnd.Count > 0;

            var isStartSelected = SelectedFoldingFrom(foldingsWithStart);
            var isBetweenSelected = SelectedFoldingFrom(foldingsBetween);
            var isEndSelected = SelectedFoldingFrom(foldingsWithEnd);

            bool SelectedFoldingFrom(IEnumerable<FoldMarker> list)
                => list?.Any(t => selectedFoldLine == t.StartLine) == true;

            var foldMarkerSize = (int)Math.Round(textArea.TextView.FontHeight*0.57f);
            foldMarkerSize -= foldMarkerSize%2;
            var foldMarkerYPos = drawingRectangle.Y + (drawingRectangle.Height - foldMarkerSize)/2;
            var xPos = drawingRectangle.X + (drawingRectangle.Width - foldMarkerSize)/2 + foldMarkerSize/2;

            if (isFoldStart)
            {
                var isVisible = true;
                var moreLinedOpenFold = false;
                foreach (var foldMarker in foldingsWithStart)
                    if (foldMarker.IsFolded)
                        isVisible = false;
                    else
                        moreLinedOpenFold = foldMarker.EndLine > foldMarker.StartLine;

                var isFoldEndFromUpperFold = false;
                foreach (var foldMarker in foldingsWithEnd)
                    if (foldMarker.EndLine > foldMarker.StartLine && !foldMarker.IsFolded)
                        isFoldEndFromUpperFold = true;

                DrawFoldMarker(
                    g, new RectangleF(
                        drawingRectangle.X + (drawingRectangle.Width - foldMarkerSize)/2f,
                        foldMarkerYPos,
                        foldMarkerSize,
                        foldMarkerSize),
                    isVisible,
                    isStartSelected
                );

                // draw line above fold marker
                if (isBetween || isFoldEndFromUpperFold)
                    g.DrawLine(
                        BrushRegistry.GetPen(isBetweenSelected ? selectedLine.Color : foldLineColor.Color),
                        xPos,
                        drawingRectangle.Top,
                        xPos,
                        foldMarkerYPos - 1);

                // draw line below fold marker
                if (isBetween || moreLinedOpenFold)
                    g.DrawLine(
                        BrushRegistry.GetPen(isEndSelected || isStartSelected && isVisible || isBetweenSelected ? selectedLine.Color : foldLineColor.Color),
                        xPos,
                        foldMarkerYPos + foldMarkerSize + 1,
                        xPos,
                        drawingRectangle.Bottom);
            }
            else
            {
                if (isFoldEnd)
                {
                    var midy = drawingRectangle.Top + drawingRectangle.Height/2;

                    // draw fold end marker
                    g.DrawLine(
                        BrushRegistry.GetPen(isEndSelected ? selectedLine.Color : foldLineColor.Color),
                        xPos,
                        midy,
                        xPos + foldMarkerSize/2,
                        midy);

                    // draw line above fold end marker
                    // must be drawn after fold marker because it might have a different color than the fold marker
                    g.DrawLine(
                        BrushRegistry.GetPen(isBetweenSelected || isEndSelected ? selectedLine.Color : foldLineColor.Color),
                        xPos,
                        drawingRectangle.Top,
                        xPos,
                        midy);

                    // draw line below fold end marker
                    if (isBetween)
                        g.DrawLine(
                            BrushRegistry.GetPen(isBetweenSelected ? selectedLine.Color : foldLineColor.Color),
                            xPos,
                            midy + 1,
                            xPos,
                            drawingRectangle.Bottom);
                }
                else if (isBetween)
                {
                    // just draw the line :)
                    g.DrawLine(
                        BrushRegistry.GetPen(isBetweenSelected ? selectedLine.Color : foldLineColor.Color),
                        xPos,
                        drawingRectangle.Top,
                        xPos,
                        drawingRectangle.Bottom);
                }
            }
        }

        public override void HandleMouseMove(Point mousepos, MouseButtons mouseButtons)
        {
            var showFolding = textArea.Document.TextEditorProperties.EnableFolding;
            var physicalLine = +((mousepos.Y + textArea.VirtualTop.Y)/textArea.TextView.FontHeight);
            var realline = textArea.Document.GetFirstLogicalLine(physicalLine);

            if (!showFolding || realline < 0 || realline + 1 >= textArea.Document.TotalNumberOfLines)
                return;

            var foldMarkers = textArea.Document.FoldingManager.GetFoldingsWithStart(realline);
            var oldSelection = selectedFoldLine;
            if (foldMarkers.Count > 0)
                selectedFoldLine = realline;
            else
                selectedFoldLine = -1;
            if (oldSelection != selectedFoldLine)
                textArea.Refresh(this);
        }

        public override void HandleMouseDown(Point mousepos, MouseButtons mouseButtons)
        {
            var showFolding = textArea.Document.TextEditorProperties.EnableFolding;
            var physicalLine = +((mousepos.Y + textArea.VirtualTop.Y)/textArea.TextView.FontHeight);
            var realline = textArea.Document.GetFirstLogicalLine(physicalLine);

            // focus the textarea if the user clicks on the line number view
            textArea.Focus();

            if (!showFolding || realline < 0 || realline + 1 >= textArea.Document.TotalNumberOfLines)
                return;

            var foldMarkers = textArea.Document.FoldingManager.GetFoldingsWithStart(realline);
            foreach (var fm in foldMarkers)
                fm.IsFolded = !fm.IsFolded;
            textArea.Document.FoldingManager.NotifyFoldingsChanged(EventArgs.Empty);
        }

        public override void HandleMouseLeave(EventArgs e)
        {
            if (selectedFoldLine != -1)
            {
                selectedFoldLine = -1;
                textArea.Refresh(this);
            }
        }

        #region Drawing functions

        private void DrawFoldMarker(Graphics g, RectangleF rectangle, bool isOpened, bool isSelected)
        {
            var foldMarkerColor = textArea.Document.HighlightingStrategy.GetColorFor("FoldMarker");
            var foldLineColor = textArea.Document.HighlightingStrategy.GetColorFor("FoldLine");
            var selectedLine = textArea.Document.HighlightingStrategy.GetColorFor("SelectedFoldLine");

            var intRect = new Rectangle((int)rectangle.X, (int)rectangle.Y, (int)rectangle.Width, (int)rectangle.Height);
            g.FillRectangle(BrushRegistry.GetBrush(foldMarkerColor.BackgroundColor), intRect);
            g.DrawRectangle(BrushRegistry.GetPen(isSelected ? selectedLine.Color : foldLineColor.Color), intRect);

            var space = (int)Math.Round(rectangle.Height/8d) + 1;
            var mid = intRect.Height/2 + intRect.Height%2;

            // draw minus
            g.DrawLine(
                BrushRegistry.GetPen(foldMarkerColor.Color),
                rectangle.X + space,
                rectangle.Y + mid,
                rectangle.X + rectangle.Width - space,
                rectangle.Y + mid);

            // draw plus
            if (!isOpened)
                g.DrawLine(
                    BrushRegistry.GetPen(foldMarkerColor.Color),
                    rectangle.X + mid,
                    rectangle.Y + space,
                    rectangle.X + mid,
                    rectangle.Y + rectangle.Height - space);
        }

        #endregion
    }
}