// Copyright (c) 2007 Omer Rauchwerger (a.k.a rauchy) (omer@rauchy.net)
// All rights reserved.
//
// This file is part of Regionerate.
// 
// This program is free software; you can redistribute it and/or modify it 
// under the terms of the GNU General Public License as published by 
// the Free Software Foundation; either version 3 of the License, 
// or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

using System;
using System.Collections.Generic;
using System.Text;
using Rauchy.Regionerate.Shared.Components;

namespace Rauchy.Regionerate.ServiceLayer.Components.Tools
{
    /// <summary>
    /// TODO: comment
    /// </summary>
    public abstract class TypeCodeTextRemover
    {
        #region Methods (3)

        /// <summary>
        /// Removes text from the specified code.
        /// </summary>
        /// <param name="code">The code.</param>
        /// <returns>The same code blocks, without the unwanted text.</returns>
        /// <exception cref="ArgumentNullException">
        /// Thrown when <c>code</c> is <c>null</c>.
        /// </exception>
        /// <remarks>
        /// Handles type-level text only, does not remove method-level, property-level or region-level text.
        /// </remarks>
        public string Remove( string code )
        {
            if ( code == null )
            {
                throw new ArgumentNullException( "code" );
            }

            IList<string> lines = code.GetLines();

            StringBuilder filteredCode = new StringBuilder();
            int currentIndentationlevel = 0;
            bool insideRegion = false;
            foreach ( string line in lines )
            {
                if ( line.Trim().StartsWith( "#region" ) )
                {
                    insideRegion = true;
                }
                else if ( line.Trim().StartsWith( "#endregion" ) )
                {
                    insideRegion = false;
                }

                if ( insideRegion )
                {
                    // Keep lines inside existing regions.
                    filteredCode.Append( line );
                }
                else
                {
                    // Not inside region, check if inside method or inside property.

                    currentIndentationlevel += CountInstances( line, Language.BeginBlock.ToCharArray() );
                    currentIndentationlevel -= CountInstances( line, Language.EndBlock.ToCharArray() );

                    if ( currentIndentationlevel >= 2 )
                    {
                        // Indentation level is above the safe level (usually meaning we are
                        // dealing with a property or method), there is no need to remove regions here.
                        filteredCode.Append( line );
                    }
                    else
                    {
                        // Indentation level is below the safe level (usually meaning we are
                        // dealing with a class or struct), remove this line if it whitespace.
                        bool isRegionDeclaration = ShouldRemove( line );
                        if ( !isRegionDeclaration )
                        {
                            filteredCode.Append( line );
                        }
                    }
                }
            }

            return filteredCode.ToString();
        }

        /// <summary>
        /// Determines wether a line, when not placed in a method or property (or such), should be removed.
        /// </summary>
        /// <param name="line">The line.</param>
        protected abstract bool ShouldRemove( string line );

        /// <summary>
        /// Counts the instances of a specific characters in a string.
        /// </summary>
        /// <param name="line">The line.</param>
        /// <param name="characters">The characters.</param>
        /// <returns></returns>
        private static int CountInstances( string line, params char[] characters )
        {
            return line.Split( characters ).Length - 1;
        }

        #endregion
    }
}