namespace FooEditEngine
{
    class TextRender
    {
        /// <summary>
        /// (X,Y)に文字列を描く
        /// </summary>
        /// <param name="str">文字列</param>
        /// <param name="x">Ｘ座標</param>
        /// <param name="y">Ｙ座標</param>
        public void DrawString(string str, int x, int y)
        {
            int letterwidth = this.Graphics.GetStringWidth(" ");
            int ClipWidthChars = ( 0 - x +  this.ClipRect.Width) / letterwidth + 50;
            
            int xpos = x;
            TextRunCollection runs = new TextRunCollection(str, this.SelectRange,this.Hilighter,ClipWidthChars);
            foreach (TextRun run in runs)
            {
                //this.Graphics.DrawStringは文字列を描くメソッド
                if (run.str == "\t")
                    this.Graphics.DrawString(this.GetExpandedTab(0),this.TabWidth - ((xpos - x) % this.TabWidth), TokenType.Control, run.hilight,ref xpos,ref y);
                else if (run.str == Document.InternalNewLine.ToString())
                    this.Graphics.DrawString(NewLineSymbol, TokenType.Control, run.hilight, ref xpos, ref y);
                else if (run.str == Document.EndOfFile.ToString())
                    this.Graphics.DrawString(EndOfFileSymbol, TokenType.Control, run.hilight, ref xpos, ref y);
                else
                    this.Graphics.DrawString(run.str, run.token, run.hilight, ref xpos, ref y);
                if (xpos > this.ClipRect.Right)
                    break;
            }
        }
    }

    internal struct TextRun
    {
        public string str;
        public int index;
        public HilightType hilight;
        public TokenType token;
        public TextRun(string str, HilightType hilight,int index)
        {
            this.str = str;
            this.hilight = hilight;
            this.index = index;
            this.token = TokenType.None;
        }
        public TextRun(string str, HilightType hilight,TokenType token, int index)
        {
            this.str = str;
            this.hilight = hilight;
            this.index = index;
            this.token = token;
        }
    }

    internal class TextRunCollection : IEnumerable<TextRun>
    {
        List<TextRun> runs = new List<TextRun>();
    
        public TextRunCollection(string str, Selection selection,IHilighter hilighter,int clipwidthchars)
        {
            StringBuilder margedstr = new StringBuilder();
            HilightType oldSelected = HilightType.None,isSelected = HilightType.None;
            int startRun = 0;
            for (int i = 0; i < str.Length && i < clipwidthchars; i++)
            {
                oldSelected = isSelected;
                isSelected = this.isSelected(i,selection) ? HilightType.Select : HilightType.None;
                if (str[i] != '\t' && str[i] != Document.InternalNewLine && str[i] != Document.EndOfFile && isSelected == oldSelected)
                {
                    margedstr.Append(str[i]);
                    continue;
                }
                if (margedstr.Length > 0)
                {
                    this.runs.Add(new TextRun(margedstr.ToString(), oldSelected,startRun));
                    margedstr.Clear();
                }
                startRun = i;
                if(str[i] == '\t' || str[i] == Document.InternalNewLine || str[i] == Document.EndOfFile)
                    this.runs.Add(new TextRun(str[i].ToString(), isSelected,i));
                else
                    margedstr.Append(str[i]);
            }
            if (margedstr.Length > 0)
                this.runs.Add(new TextRun(margedstr.ToString(), isSelected,startRun));
        }
    }
}