// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System.IO;
using Microsoft.CodeAnalysis.Text;

namespace Microsoft.VisualStudio.Text
{
    public class StringTextImage : ITextImage
    {
        private readonly SourceText _sourceText;
        private readonly string _text;

        public StringTextImage(string text)
        {
            _text = text;
            _sourceText = SourceText.From(text);
        }

        public char this[int position] => _text[position];

        public ITextImageVersion Version => null;

        public int Length => _text.Length;

        public int LineCount => _sourceText.Lines.Count;

        public void CopyTo(int sourceIndex, char[] destination, int destinationIndex, int count)
        {
            _text.CopyTo(sourceIndex, destination, destinationIndex, count);
        }

        public TextImageLine GetLineFromLineNumber(int lineNumber)
        {
            var line = _sourceText.Lines[lineNumber];
            return new TextImageLine(this, lineNumber, new Span(line.Start, line.End - line.Start), line.EndIncludingLineBreak - line.End);
        }

        public TextImageLine GetLineFromPosition(int position)
        {
            var line = _sourceText.Lines.GetLineFromPosition(position);
            return new TextImageLine(this, line.LineNumber, new Span(line.Start, line.End - line.Start), line.EndIncludingLineBreak - line.End);
        }

        public int GetLineNumberFromPosition(int position)
        {
            return _sourceText.Lines.GetLineFromPosition(position).LineNumber;
        }

        public ITextImage GetSubText(Span span)
        {
            return new StringTextImage(_text.Substring(span.Start, span.Length));
        }

        public string GetText(Span span)
        {
            return _text.Substring(span.Start, span.Length);
        }

        public char[] ToCharArray(int startIndex, int length)
        {
            return _text.ToCharArray(startIndex, length);
        }

        public void Write(TextWriter writer, Span span)
        {
            writer.Write(_text.Substring(span.Start, span.Length));
        }
    }
}