//-----------------------------------------------------------------------

// <copyright file="CollationKeyFilter.cs" company="Hibernating Rhinos LTD">

//     Copyright (c) Hibernating Rhinos LTD. All rights reserved.

// </copyright>

//-----------------------------------------------------------------------



using System;

using System.ComponentModel;

using System.Globalization;

using System.Linq.Expressions;

using System.Runtime.InteropServices;

using System.Security;

using Lucene.Net.Analysis;

using Lucene.Net.Analysis.Tokenattributes;

using Sparrow.Platform;



namespace Raven.Server.Documents.Indexes.Persistence.Lucene.Analyzers.Collation

{

    public class CollationKeyFilter : TokenFilter

    {

        private readonly TermAttribute _termAtt;

        private readonly CultureInfo _cultureInfo;



        public CollationKeyFilter(TokenStream input, CultureInfo cultureInfo) : base(input)

        {

            _cultureInfo = cultureInfo;

            _termAtt = (TermAttribute)AddAttribute<ITermAttribute>();

        }



        public override bool IncrementToken()

        {

            if (input.IncrementToken() == false)

                return false;



            var termBuffer = _termAtt.TermBuffer();

            var termText = new string(termBuffer, 0, _termAtt.TermLength());

            var collationKey = GetCollationKey(termText);

            var encodedLength = IndexableBinaryStringTools_UsingArrays.GetEncodedLength(collationKey);

            if (sizeof(int) > termBuffer.Length)

                termBuffer = _termAtt.ResizeTermBuffer(encodedLength);



            _termAtt.SetTermLength(encodedLength);

            IndexableBinaryStringTools_UsingArrays.Encode(collationKey, termBuffer);



            return true;

        }



        private byte[] GetCollationKey(string text)

        {

            if (PlatformDetails.RunningOnPosix)

                return GetCollationKeyPosix(text);



            return GetCollationKeyWin32(text);

        }



        private unsafe byte[] GetCollationKeyPosix(string text)

        {

            var sortHandle = PosixHelper.Instance.GetSortHandle(_cultureInfo.CompareInfo);



            var length = PosixNativeMethods.GetSortKey(sortHandle, text, text.Length, null, 0, CompareOptions.None);

            if (length == 0)

                throw new Win32Exception(Marshal.GetLastWin32Error(), "Failed to GetSortKey for text=" + text);



            var sortKey = new byte[length];



            fixed (byte* pSortKey = sortKey)

            {

                length = PosixNativeMethods.GetSortKey(sortHandle, text, text.Length, pSortKey, sortKey.Length, CompareOptions.None);

                if (length == 0)

                    throw new Win32Exception(Marshal.GetLastWin32Error(), "Failed to GetSortKey for text=" + text);

                return sortKey;

            }

        }



        private unsafe byte[] GetCollationKeyWin32(string text)

        {

            var length = Win32NativeMethods.LCMapStringEx(_cultureInfo.CompareInfo.Name, Win32NativeMethods.LCMAP_SORTKEY, text, text.Length, IntPtr.Zero, 0, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero);

            if (length == 0)

                throw new Win32Exception(Marshal.GetLastWin32Error(), "Failed to GetSortKey for text=" + text);



            var sortKey = new byte[length];



            fixed (byte* pSortKey = sortKey)

            {

                length = Win32NativeMethods.LCMapStringEx(_cultureInfo.CompareInfo.Name, Win32NativeMethods.LCMAP_SORTKEY, text, text.Length, (IntPtr)pSortKey, sortKey.Length, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero);

                if (length == 0)

                    throw new Win32Exception(Marshal.GetLastWin32Error(), "Failed to GetSortKey for text=" + text);



                return sortKey;

            }

        }



        private static class Win32NativeMethods

        {

            public const uint LCMAP_SORTKEY = 0x00000400;



            [DllImport("kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)]

            public static extern int LCMapStringEx(

                string lpLocaleName,

                uint dwMapFlags,

                string lpSrcStr,

                int cchSrc,

                [Out] IntPtr lpDestStr,

                int cchDest,

                IntPtr lpVersionInformation,

                IntPtr lpReserved,

                IntPtr sortHandle);

        }



        private static class PosixNativeMethods

        {

            [SecurityCritical]

            [DllImport("System.Globalization.Native", CharSet = CharSet.Unicode, EntryPoint = "GlobalizationNative_GetSortKey")]

            public static extern unsafe int GetSortKey(SafeHandle sortHandle, string str, int strLength, byte* sortKey, int sortKeyLength, CompareOptions options);

        }



        private sealed class PosixHelper

        {

            public delegate SafeHandle GetSortHandleDelegate(CompareInfo value);



            public static readonly PosixHelper Instance = new PosixHelper();



            public readonly GetSortHandleDelegate GetSortHandle;



            private PosixHelper()

            {

                GetSortHandle = CreateGetSortHandleMethod().Compile();

            }



            private static Expression<GetSortHandleDelegate> CreateGetSortHandleMethod()

            {

                var parameter = Expression.Parameter(typeof(CompareInfo), "value");

                var member = Expression.Field(parameter, "_sortHandle");



                return Expression.Lambda<GetSortHandleDelegate>(member, parameter);

            }

        }

    }

}