// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)

using System;
using Tango.Scripting.Editors.Document;

namespace Tango.Scripting.Editors.Indentation.CSharp
{
    /// <summary>
    /// Smart indentation for C#.
    /// </summary>
    public class CSharpIndentationStrategy : DefaultIndentationStrategy
    {
        /// <summary>
        /// Creates a new CSharpIndentationStrategy.
        /// </summary>
        public CSharpIndentationStrategy()
        {
        }

        /// <summary>
        /// Creates a new CSharpIndentationStrategy and initializes the settings using the text editor options.
        /// </summary>
        public CSharpIndentationStrategy(TextEditorOptions options)
        {
            this.IndentationString = options.IndentationString;
        }

        string indentationString = "\t";

        /// <summary>
        /// Gets/Sets the indentation string.
        /// </summary>
        public string IndentationString
        {
            get { return indentationString; }
            set
            {
                if (string.IsNullOrEmpty(value))
                    throw new ArgumentException("Indentation string must not be null or empty");
                indentationString = value;
            }
        }

        /// <summary>
        /// Performs indentation using the specified document accessor.
        /// </summary>
        /// <param name="document">Object used for accessing the document line-by-line</param>
        /// <param name="keepEmptyLines">Specifies whether empty lines should be kept</param>
        public void Indent(IDocumentAccessor document, bool keepEmptyLines)
        {
            if (document == null)
                throw new ArgumentNullException("document");
            IndentationSettings settings = new IndentationSettings();
            settings.IndentString = this.IndentationString;
            settings.LeaveEmptyLines = keepEmptyLines;

            IndentationReformatter r = new IndentationReformatter();
            r.Reformat(document, settings);
        }

        /// <inheritdoc cref="IIndentationStrategy.IndentLine"/>
        public override void IndentLine(TextDocument document, DocumentLine line)
        {
            bool keepEmptyLines = true;

            if (line.PreviousLine != null && line.NextLine != null)
            {
                string previous_text = document.GetText(line.PreviousLine.Offset, line.PreviousLine.Length);
                string next_text = document.GetText(line.NextLine.Offset, line.NextLine.Length);

                if (previous_text.Contains("{") && next_text.Contains("}") && previous_text.Length == next_text.Length)
                {
                    keepEmptyLines = false;
                }
            }

            int lineNr = line.LineNumber;
            TextDocumentAccessor acc = new TextDocumentAccessor(document, lineNr, lineNr);
            Indent(acc, keepEmptyLines);

            string t = acc.Text;
            if (t.Length == 0)
            {
                // use AutoIndentation for new lines in comments / verbatim strings.
                base.IndentLine(document, line);
            }
        }

        /// <inheritdoc cref="IIndentationStrategy.IndentLines"/>
        public override void IndentLines(TextDocument document, int beginLine, int endLine)
        {
            Indent(new TextDocumentAccessor(document, beginLine, endLine), true);
        }
    }
}